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Emken S, Witzel C, Kierdorf U, Frölich K, Kierdorf H. A labeling study of dentin formation rates during crown and root growth of porcine mandibular first molars. Anat Rec (Hoboken) 2024; 307:2103-2120. [PMID: 38051150 DOI: 10.1002/ar.25358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 12/07/2023]
Abstract
We used fluorochrome labeling to study spatiotemporal variation of dentin apposition (DAR) and extension (DER) rates during crown and root formation of mandibular first molars from wild boar and domestic pigs. DAR was reconstructed along the course of dentinal tubules in four zones of the crown and in the upper root area. In all five zones, mean DAR increased during the first 30% to 40% of apposition, reaching highest values (22-23 μm/day) in the upper-lateral crown zone. Lowest values were recorded near the dentin-pulp interface (DPI). Typically, DARs in contemporaneously formed dentin areas were higher in more cuspally compared to more cervically/apically located zones. DER was high (>200 μm/day) in early postnatal crown dentin and then decreased markedly in cervical direction, with lowest values in the cervical crown zone. After this nadir, DER sharply increased in the upper 30% to 40% of the root extension, reaching values equaling (wild boar) or even surpassing (domestic pigs) those recorded in the upper lateral crown. After this peak, DER again decreased. While DAR did not differ markedly between wild boar and domestic pigs, the DER showed marked differences, both regarding maximum values (208.1 μm/day in wild boar, 272.2 μm/day in domestic pigs) and the timing of the root growth spurt, which occurred earlier in the domestic pigs. We consider the more rapid recruitment of secretory odontoblasts in domestic pigs (reflected by higher DER) a side effect of selection for rapid body growth during pig domestication.
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Affiliation(s)
- Simon Emken
- Department of Biology, University of Hildesheim, Hildesheim, Germany
| | - Carsten Witzel
- Department of Biology, University of Hildesheim, Hildesheim, Germany
| | - Uwe Kierdorf
- Department of Biology, University of Hildesheim, Hildesheim, Germany
| | - Kai Frölich
- Department of Biology, University of Hildesheim, Hildesheim, Germany
- Tierpark Arche Warder e.V., Warder, Germany
| | - Horst Kierdorf
- Department of Biology, University of Hildesheim, Hildesheim, Germany
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2
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Gan XY, Li QW, Yuan Q. [Research progress in methylation modification in tooth root development]. Zhonghua Kou Qiang Yi Xue Za Zhi 2024; 59:502-506. [PMID: 38637005 DOI: 10.3760/cma.j.cn112144-20240115-00023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
Methylation modification is one of the most common epigenetic modification regulation in eukaryotes, including histone methylation, DNA methylation, RNA methylation, etc., which plays an important regulatory role in physiological processes and pathologic occurrence and development. Tooth root development is carried out by both epithelial and mesenchymal cells and involves a variety of cell-molecular interactions. In recent years, a large number of studies have found that methylation plays a key role in the regulation of tooth root development and expands the mechanism network of tooth root development. In this paper, we review the role and mechanism of methylation modification during root development.
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Affiliation(s)
- X Y Gan
- Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University & State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, Chengdu 610041, China
| | - Q W Li
- Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University & State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, Chengdu 610041, China
| | - Q Yuan
- Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University & State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, Chengdu 610041, China
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Du J, Jing J, Yuan Y, Feng J, Han X, Chen S, Li X, Peng W, Xu J, Ho TV, Jiang X, Chai Y. Arid1a-Plagl1-Hh signaling is indispensable for differentiation-associated cell cycle arrest of tooth root progenitors. Cell Rep 2021; 35:108964. [PMID: 33826897 PMCID: PMC8132592 DOI: 10.1016/j.celrep.2021.108964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 02/10/2021] [Accepted: 03/17/2021] [Indexed: 12/04/2022] Open
Abstract
Chromatin remodelers often show broad expression patterns in multiple cell types yet can elicit cell-specific effects in development and diseases. Arid1a binds DNA and regulates gene expression during tissue development and homeostasis. However, it is unclear how Arid1a achieves its functional specificity in regulating progenitor cells. Using the tooth root as a model, we show that loss of Arid1a impairs the differentiation-associated cell cycle arrest of tooth root progenitors through Hedgehog (Hh) signaling regulation, leading to shortened roots. Our data suggest that Plagl1, as a co-factor, endows Arid1a with its cell-type/spatial functional specificity. Furthermore, we show that loss of Arid1a leads to increased expression of Arid1b, which is also indispensable for odontoblast differentiation but is not involved in regulation of Hh signaling. This study expands our knowledge of the intricate interactions among chromatin remodelers, transcription factors, and signaling molecules during progenitor cell fate determination and lineage commitment.
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Affiliation(s)
- Jiahui Du
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA; Department of Prosthodontics, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Junjun Jing
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Yuan Yuan
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Jifan Feng
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Xia Han
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Shuo Chen
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Xiang Li
- Department of Physics, George Washington University, Washington, DC 20052, USA
| | - Weiqun Peng
- Department of Physics, George Washington University, Washington, DC 20052, USA
| | - Jian Xu
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Thach-Vu Ho
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Xinquan Jiang
- Department of Prosthodontics, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Yang Chai
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA.
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He J, Jing J, Feng J, Han X, Yuan Y, Guo T, Pei F, Ma Y, Cho C, Ho TV, Chai Y. Lhx6 regulates canonical Wnt signaling to control the fate of mesenchymal progenitor cells during mouse molar root patterning. PLoS Genet 2021; 17:e1009320. [PMID: 33596195 PMCID: PMC7920342 DOI: 10.1371/journal.pgen.1009320] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 03/01/2021] [Accepted: 12/21/2020] [Indexed: 02/05/2023] Open
Abstract
Mammalian tooth crown formation has long served as a model for investigating how patterning and morphogenesis are orchestrated during development. However, the mechanism underlying root patterning and morphogenesis remains poorly understood. In this study, we find that Lhx6 labels a subpopulation of root progenitor cells in the apical dental mesenchyme, which is closely associated with furcation development. Loss of Lhx6 leads to furcation and root number defects, indicating that Lhx6 is a key root patterning regulator. Among the multiple cellular events regulated by Lhx6 is the odontoblast fate commitment of progenitor cells, which it controls in a cell-autonomous manner. Specifically, Lhx6 loss leads to elevated expression of the Wnt antagonist Sfrp2 and down-regulation of Wnt signaling in the furcation region, while overactivation of Wnt signaling in Lhx6+ progenitor cells partially restore the furcation defects in Lhx6-/- mice. Collectively, our findings have important implications for understanding organ morphogenesis and future strategies for tooth root regeneration.
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Affiliation(s)
- Jinzhi He
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Chengdu, Sichuan province, China
| | - Junjun Jing
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Jifan Feng
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Xia Han
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Yuan Yuan
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Tingwei Guo
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Fei Pei
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Yuanyuan Ma
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Courtney Cho
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Thach-Vu Ho
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Yang Chai
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
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Ravi V, Sp AS, Balla SB, Kanaparthi A, Ch G, N LP. Evaluation of secondary dentin deposition in lower first molars to indicate a legal age threshold of 14 years using receiver operating characteristic curves. Med Sci Law 2020; 60:249-256. [PMID: 32627673 DOI: 10.1177/0025802420936507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The age threshold of 14 years has become vital in proving legal violations involving children, particularly in cases of suspected child labour, child pornography and the minimum age of criminal responsibility. In recent years, there has been great interest in the evaluation of age in children and sub-adults using analysis of regressive changes in teeth, with a particular focus on age thresholds that are of medico-legal importance. This research aimed to compare the sensitivity and specificity of stages of root pulp visibility by Olze et al. in a sample of South Indian children aged between 12 and 16 years, with an age threshold of 14 years, using receiver operating characteristic curves and the area under the curve (AUC). Among the four stages of root pulp visibility, stage 2 showed the highest AUC in both female and male cohorts. For stage 2, lower sensitivity and higher specificity values were recorded, indicating the possibility of type II errors (i.e. false negatives). In both sexes, stage 2 had a higher AUC (i.e. 0.696 in females and 0.706 in males, respectively). Based on our findings, it can be concluded that this staging method in lower first molars is of limited value in indicating the legal age threshold of 14 years. Future research should validate the proposed approach in a larger sample and consider how to improve predictions in this area.
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Affiliation(s)
- Vishali Ravi
- Department of Periodontics, Panineeya Institute of Dental Sciences and Research Centre, India
| | | | - Sudheer B Balla
- Department of Forensic Odontology, Panineeya Institute of Dental Sciences and Research Centre, India
| | - Alekhya Kanaparthi
- Department of Oral Medicine and Radiology, 78273MNR Dental College and Hospital, India
| | - Gayathri Ch
- Department of Oral Pathology, Panineeya Institute of Dental Sciences and Research Centre, India
| | - Laxmi Prasanna N
- Department of Oral Pathology, 233614Drs Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, India
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Duan Y, Li X, Zhang S, Wang S, Wang T, Chen H, Yang Y, Jia S, Chen G, Tian W. Therapeutic potential of HERS spheroids in tooth regeneration. Theranostics 2020; 10:7409-7421. [PMID: 32642002 PMCID: PMC7330840 DOI: 10.7150/thno.44782] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 05/25/2020] [Indexed: 02/05/2023] Open
Abstract
Hertwig's epithelial root sheath (HERS) plays indispensable roles in tooth root development, including controlling the shape and number of roots, dentin formation, and helping generate the cementum. Based on these characteristics, HERS cell is a potential seed cell type for tooth-related tissue regeneration. However, the application is severely limited by a lack of appropriate culture methods and small cell numbers. Methods: Here, we constructed a 3D culture method to expand functional HERS cells into spheroids, and investigated characteristics and application of dental tissue regeneration of these spheroids. HERS spheroids and HERS cells (2D monolayer culture) were compared in terms of biological characteristics (such as proliferation, self-renewal capacity, and stemness) in vitro and functions (including differentiation potential and inductive ability of dentin formation) both in vitro and in vivo. Further, transcriptome analysis was utilized to reveal the molecular mechanisms of their obvious differences. Results: HERS spheroids showed obvious superiority in biological characteristics and functions compared to 2D monolayers of HERS cells in vitro. In vivo, HERS spheroids generated more mineralized tissue; when combined with dental papilla cells (DPCs), HERS spheroids contributed to dentin-like tissue formation. Moreover, the generation and expansion of HERS spheroids rely to some degree on the HIF-1 pathway. Conclusion: HERS spheroid generation is beneficial for functional HERS cell expansion and can provide a useful cell source for further tooth regeneration and mechanistic research. Notably, HIF-1 pathway plays a critical role in HERS spheroid formation and function.
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Affiliation(s)
- Yufeng Duan
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuebing Li
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Sicheng Zhang
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Shikai Wang
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Tao Wang
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hong Chen
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yan Yang
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Sixun Jia
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Guoqing Chen
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Weidong Tian
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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Gama A, Vargas-Franco JW, Sánchez Mesa DC, Restrepo Bedoya E, Amiaud J, Babajko S, Berdal A, Acevedo AC, Heymann D, Lézot F, Castaneda B. Origins of Alterations to Rankl Null Mutant Mouse Dental Root Development. Int J Mol Sci 2020; 21:ijms21062201. [PMID: 32209985 PMCID: PMC7139335 DOI: 10.3390/ijms21062201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 02/07/2023] Open
Abstract
The purpose of the present study was to assess the early stages of development of mouse first molar roots in the osteopetrotic context of RANKL invalidation in order to demonstrate that the radicular phenotype observed resulted not only from defective osteoclasts, but also from loss of cell-to-cell communication among dental, periodontium and alveolar bone cells involving RANKL signaling. Two experimental models were used in this study: Rankl mutants with permanent RANKL invalidation, and C57BL/6J mice injected during the first postnatal week with a RANKL neutralizing antibody corresponding to a transient RANKL invalidation. The dento-alveolar complex was systematically analyzed using micro-CT, and histological and immunohistochemical approaches. These experiments showed that the root elongation alterations observed in the Rankl-/- mice were associated with reduced proliferation of the RANK-expressing HERS cells with a significant decrease in proliferating cell nuclear antigen (PCNA) expression and a significant increase in P21 expression. The phenotypic comparison of the adult first molar root at 35 days between permanent and transitory invalidations of RANKL made it possible to demonstrate that alterations in dental root development have at least two origins, one intrinsic and linked to proliferation/differentiation perturbations in dental-root-forming cells, the other extrinsic and corresponding to disturbances of bone cell differentiation/function.
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Affiliation(s)
- Andrea Gama
- Centre de Recherche des Cordeliers, INSERM UMR-1138, Sorbonne Université, Université de Paris, Laboratoire de Physiopathologie Orale Moléculaire, F-75006 Paris, France; (A.G.); (D.C.S.M.); (E.R.B.); (S.B.); (A.B.)
- Odontologic Center of District Federal Military Police, Brasília 70297-400, Brazil
- Laboratory of Oral Histopathology, Health Sciences Faculty, University of Brasília, Brasília 70910-900, Brazil;
| | - Jorge William Vargas-Franco
- INSERM, UMR-1238, Equipe 1, Faculté de Médecine, Université de Nantes, F-44035 Nantes, France; (J.W.V.-F.); (J.A.); (F.L.)
- Department of Basic Studies, Faculty of Odontology, University of Antioquia, Medellin A.A1226, Colombia
| | - Diana Carolina Sánchez Mesa
- Centre de Recherche des Cordeliers, INSERM UMR-1138, Sorbonne Université, Université de Paris, Laboratoire de Physiopathologie Orale Moléculaire, F-75006 Paris, France; (A.G.); (D.C.S.M.); (E.R.B.); (S.B.); (A.B.)
- Department of Orthodontics, Faculty of Odontology, University of Antioquia, Medellin A.A1226, Colombia
| | - Elizabeth Restrepo Bedoya
- Centre de Recherche des Cordeliers, INSERM UMR-1138, Sorbonne Université, Université de Paris, Laboratoire de Physiopathologie Orale Moléculaire, F-75006 Paris, France; (A.G.); (D.C.S.M.); (E.R.B.); (S.B.); (A.B.)
- Department of Orthodontics, Faculty of Odontology, University of Antioquia, Medellin A.A1226, Colombia
| | - Jérome Amiaud
- INSERM, UMR-1238, Equipe 1, Faculté de Médecine, Université de Nantes, F-44035 Nantes, France; (J.W.V.-F.); (J.A.); (F.L.)
| | - Sylvie Babajko
- Centre de Recherche des Cordeliers, INSERM UMR-1138, Sorbonne Université, Université de Paris, Laboratoire de Physiopathologie Orale Moléculaire, F-75006 Paris, France; (A.G.); (D.C.S.M.); (E.R.B.); (S.B.); (A.B.)
| | - Ariane Berdal
- Centre de Recherche des Cordeliers, INSERM UMR-1138, Sorbonne Université, Université de Paris, Laboratoire de Physiopathologie Orale Moléculaire, F-75006 Paris, France; (A.G.); (D.C.S.M.); (E.R.B.); (S.B.); (A.B.)
| | - Ana Carolina Acevedo
- Laboratory of Oral Histopathology, Health Sciences Faculty, University of Brasília, Brasília 70910-900, Brazil;
- Oral Center for Inherited Diseases, Hospital of University of Brasilia, University of Brasília, Brasília 70910-900, Brazil
| | - Dominique Heymann
- INSERM, LEA Sarcoma Research Unit, University of Sheffield, Department of Oncology and Human Metabolism, Medical School, Sheffield S10 2RX, UK;
- INSERM, UMR-1232, LabCT, CRCNA, Université de Nantes, Université d’Angers, Institut de Cancérologie de l’Ouest, site René Gauducheau, F-44805 Saint-Herblain, France
| | - Frédéric Lézot
- INSERM, UMR-1238, Equipe 1, Faculté de Médecine, Université de Nantes, F-44035 Nantes, France; (J.W.V.-F.); (J.A.); (F.L.)
| | - Beatriz Castaneda
- Service d’Odontologie-Stomatologie, Hôpital Pitié-Salpêtrière, AP-HP, F-75013 Paris, France
- Correspondence: ; Tel.: +33-142-178-416
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Hosoya A, Shalehin N, Takebe H, Shimo T, Irie K. Sonic Hedgehog Signaling and Tooth Development. Int J Mol Sci 2020; 21:ijms21051587. [PMID: 32111038 PMCID: PMC7084732 DOI: 10.3390/ijms21051587] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/11/2022] Open
Abstract
Sonic hedgehog (Shh) is a secreted protein with important roles in mammalian embryogenesis. During tooth development, Shh is primarily expressed in the dental epithelium, from initiation to the root formation stages. A number of studies have analyzed the function of Shh signaling at different stages of tooth development and have revealed that Shh signaling regulates the formation of various tooth components, including enamel, dentin, cementum, and other soft tissues. In addition, dental mesenchymal cells positive for Gli1, a downstream transcription factor of Shh signaling, have been found to have stem cell properties, including multipotency and the ability to self-renew. Indeed, Gli1-positive cells in mature teeth appear to contribute to the regeneration of dental pulp and periodontal tissues. In this review, we provide an overview of recent advances related to the role of Shh signaling in tooth development, as well as the contribution of this pathway to tooth homeostasis and regeneration.
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Affiliation(s)
- Akihiro Hosoya
- Division of Histology, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan; (N.S.); (H.T.); (K.I.)
- Correspondence: ; Tel.: +81-133-23-1938; Fax: +81-133-23-1236
| | - Nazmus Shalehin
- Division of Histology, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan; (N.S.); (H.T.); (K.I.)
| | - Hiroaki Takebe
- Division of Histology, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan; (N.S.); (H.T.); (K.I.)
| | - Tsuyoshi Shimo
- Division of Reconstructive Surgery for Oral and Maxillofacial Region, Department of Human Biology and Pathophysiology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan;
| | - Kazuharu Irie
- Division of Histology, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan; (N.S.); (H.T.); (K.I.)
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Xing S, Tafforeau P, O’Hara M, Modesto-Mata M, Martín-Francés L, Martinón-Torres M, Zhang L, Schepartz LA, de Castro JMB, Guatelli-Steinberg D. First systematic assessment of dental growth and development in an archaic hominin (genus, Homo) from East Asia. Sci Adv 2019; 5:eaau0930. [PMID: 30746445 PMCID: PMC6357757 DOI: 10.1126/sciadv.aau0930] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 12/06/2018] [Indexed: 05/28/2023]
Abstract
Several human dental traits typical of modern humans appear to be associated with the prolonged period of development that is a key human attribute. Understanding when, and in which early hominins, these dental traits first appeared is thus of strong interest. Using x-ray multiresolution synchrotron phase-contrast microtomography, we quantify dental growth and development in an archaic Homo juvenile from the Xujiayao site in northern China dating to 161,000-224,000 years or 104,000-125,000 years before present. Despite the archaic morphology of Xujiayao hominins, most aspects of dental development of this juvenile fall within modern human ranges (e.g., prolonged crown formation time and delayed first molar eruption). For its estimated age-at-death (6.5 years), its state of dental development is comparable to that of equivalently aged modern children. These findings suggest that several facets of modern human dental growth and development evolved in East Asia before the appearance of fully modern human morphology.
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Affiliation(s)
- Song Xing
- Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
| | - Paul Tafforeau
- European Synchrotron Radiation Facility, CS-40220, 38043 Grenoble Cedex 09, France
| | - Mackie O’Hara
- Department of Anthropology, The Ohio State University, Columbus, OH 43210, USA
| | - Mario Modesto-Mata
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca 3, 09002 Burgos, Spain
- Equipo Primeros Pobladores de Extremadura, Casa de la Cultura Rodríguez Moñino, Av. Cervantes s/n, 10003 Cáceres, Spain
- Anthropology Department, University College London, 14 Taviton Street, London WC1H 0BW, UK
| | - Laura Martín-Francés
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca 3, 09002 Burgos, Spain
- UMR 5189 PACEA Université de Bordeaux, CNRS MCC, Bordeaux, France
| | - María Martinón-Torres
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca 3, 09002 Burgos, Spain
- Anthropology Department, University College London, 14 Taviton Street, London WC1H 0BW, UK
| | - Limin Zhang
- Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
| | - Lynne A. Schepartz
- HVIRU, School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - José María Bermúdez de Castro
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca 3, 09002 Burgos, Spain
- Anthropology Department, University College London, 14 Taviton Street, London WC1H 0BW, UK
| | - Debbie Guatelli-Steinberg
- Department of Anthropology, The Ohio State University, Columbus, OH 43210, USA
- Department of Anthropology/Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA
- School of Anthropology and Conservation, University of Kent, Canterbury, Kent CT2 7NR, UK
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Abstract
RATIONALE Oculofaciocardiodental syndrome (OFCD) patients who show radiculomegaly are very rare. We treated a new OFCD patient orthodontically, and performed longitudinal observation for 30 years. New findings, termed calcified-dental-papillae (CDPs) beneath open-apices (OAs) of developing radiculomegalies, pulp-stone-like-calcifications (PSLCs) and the process of radiculomegaly development were observed. A novel mutation of BCL-6 interacting corepressor (BCOR) was identified. Cone-beam-computed-tomography (CBCT) images of the radiculomegalies clarified their morphology. PATIENT CONCERNS A female patient and her parents were referred to orthodontic clinic for alignment of the teeth. DIAGNOSIS A CDP that harbored bulbous-round-calcified-tissue in the dental papilla beneath the OA of a developing radiculomegaly was found radiographically. PSLCs were observed in the dental pulp. Genetic analysis revealed a novel mutation c.265G>A on Exon 4 and diagnosed as OFCD. CBCT images confirmed round-calcified-tissue and PSLC and that the length of an affected canine was 38.0 mm and calculated as +14.8SD. These novel findings were not observed in lateral incisors and molars. INTERVENTIONS Observation was performed for 29 years and 3 months including orthodontic treatment for 2 years and 9 months. OUTCOME Longitudinal follow-up for 26 years and 7 months after the treatment revealed that the development of radiculomegaly every few months or years, CDPs beneath OAs and PSLCs were observed. CDPs, PSLCs, and OAs were associated with radiculomegaly. The patient and the affected teeth including aligned teeth showed no particular change after the completion of the radiculomegaly. CBCT images showed bulbous-calcified-tissue and PSLCs in the mature dental pulp associated with radiculomegaly. LESSONS The radiographical findings of CDP, OA and PSLC help early diagnose of OFCD and have importance for initiating orthodontic treatment until radiculomegaly completion.
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Affiliation(s)
- Joji Kato
- Chairman, Kato Orthodontic Office, Ibaraki
| | | | - Fumikazu Kushima
- Chairman Emeritus, Kushima Orthodontic Clinic, Abeno, Osaka, Japan
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11
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Chen H, Guo S, Xia Y, Yuan L, Lu M, Zhou M, Fang M, Meng L, Xiao Z, Ma J. The role of Rho-GEF Trio in regulating tooth root development through the p38 MAPK pathway. Exp Cell Res 2018; 372:158-167. [PMID: 30268758 DOI: 10.1016/j.yexcr.2018.09.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 08/28/2018] [Accepted: 09/26/2018] [Indexed: 12/13/2022]
Abstract
Trio, the Rho guanine nucleotide exchange factor (Rho-GEF), plays diverse roles in cell migration, cell axon guidance and cytoskeleton reorganization. Conserved during evolution, Trio encodes two guanine nucleotide exchange factor domains (GEFs) and activates small GTPases. The Rho-family small GTPases RhoA and Rac1, which are target molecules of Trio, have been described to engage in craniofacial development and tooth formation. However, the exact role of Trio in tooth development remains elusive. In this study, we generated Wnt1-cre;Triofl/fl mice to address the potential function of Trio in tooth development. Wnt1-cre;Triofl/fl mice showed short root deformity as well as decreased expression of odontogenic makers such as RUNX2, OSX, OCN, and OPN. In vitro, Trio was silenced in human stem cells of dental papilla (SCAPs). Compared with the control group, the proliferation and migration ability in the experimental group was disrupted. After knocking down Trio in SCAPs, the cells showed phenotypes of poor odontogenic differentiation and weak mineralized nodules. To study the underlying mechanism, we investigated the p38 MAPK pathway and found that loss of Trio blocked the cascade transduction of p38 MAPK signaling. In conclusion, we identified Trio as a novel coordinator in regulating root development and clarified its relevant molecular events.
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Affiliation(s)
- Huimin Chen
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China
| | - Shuyu Guo
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China
| | - Yang Xia
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China
| | - Lichan Yuan
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China
| | - Mengting Lu
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China
| | - Meng Zhou
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China
| | - Mengru Fang
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China
| | - Li Meng
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China
| | - Zhongdang Xiao
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu 210096, China
| | - Junqing Ma
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, Jiangsu, China.
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Huang H, Wang J, Zhang Y, Zhu G, Li YP, Ping J, Chen W. Bone resorption deficiency affects tooth root development in RANKL mutant mice due to attenuated IGF-1 signaling in radicular odontoblasts. Bone 2018; 114:161-171. [PMID: 29292230 DOI: 10.1016/j.bone.2017.12.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/27/2017] [Accepted: 12/28/2017] [Indexed: 01/05/2023]
Abstract
The tooth root is essential for normal tooth physiological function. Studies on mice with mutations or targeted gene deletions revealed that osteoclasts (OCs) play an important role in tooth root development. However, knowledge on the cellular and molecular mechanism underlying how OCs mediate root formation is limited. During bone formation, growth factors (e.g. Insulin-like growth factor-1, IGF-1) liberated from bone matrix by osteoclastic bone resorption stimulate osteoblast differentiation. Thus, we hypothesize that OC-osteoblast coupling may also apply to OC-odontoblast coupling; therefore OCs may have a direct impact on odontoblast differentiation through the release of growth factor(s) from bone matrix, and consequently regulate tooth root formation. To test this hypothesis, we used a receptor activator of NF-κB ligand (RANKL) knockout mouse model in which OC differentiation and function was entirely blocked. We found that molar root formation and tooth eruption were defective in RANKL-/- mice. Disrupted elongation and disorganization of Hertwig's epithelial root sheath (HERS) was observed in RANKL-/- mice. Reduced expression of nuclear factor I C (NFIC), osterix, and dentin sialoprotein, markers essential for radicular (root) odontogenic cell differentiation indicated that odontoblast differentiation was disrupted in RANKL deficient mice likely contributing to the defect in root formation. Moreover, down-regulation of IGF/AKT/mTOR activity in odontoblast indicated that IGF signaling transduction in odontoblasts of the mutant mice was impaired. Treating odontoblast cells in vitro with conditioned medium from RANKL-/- OCs cultured on bone slices resulted in inhibition of odontoblast differentiation. Moreover, depletion of IGF-1 in bone resorption-conditioned medium (BRCM) from wild-type (WT) OC significantly compromised the ability of WT osteoclastic BRCM to induce odontoblast differentiation while addition of IGF-1 into RANKL-/- osteoclastic BRCM rescued impaired odontoblast differentiation, confirming that root and eruption defect in RANKL deficiency mice may result from failure of releasing of IGF-1 from bone matrix through OC bone resorption. These results suggest that OCs are important for odontoblast differentiation and tooth root formation, possibly through IGF/AKT/mTOR signaling mediated by cell-bone matrix interaction. These findings provide significant insights into regulatory mechanism of tooth root development, and also lay the foundation for root regeneration studies.
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Affiliation(s)
- Hong Huang
- The Affiliated Hospital of Stomatology, Chongqing Medical University, 5 Shangqingsi Rd, Yuzhong Qu, Chongqing Shi 400065, China; Department of Pathology, School of Medicine, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Jue Wang
- Department of Pathology, School of Medicine, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Yan Zhang
- The Affiliated Hospital of Stomatology, Chongqing Medical University, 5 Shangqingsi Rd, Yuzhong Qu, Chongqing Shi 400065, China; Department of Pathology, School of Medicine, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Guochun Zhu
- Department of Pathology, School of Medicine, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Yi-Ping Li
- Department of Pathology, School of Medicine, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Ji Ping
- The Affiliated Hospital of Stomatology, Chongqing Medical University, 5 Shangqingsi Rd, Yuzhong Qu, Chongqing Shi 400065, China.
| | - Wei Chen
- Department of Pathology, School of Medicine, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA.
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Tarpomanov Y, Rimalovska S, Belcheva A, Yordanova M, Yordanova S, Kukleva M. Root Development of Permanent Incisors and Mandibular Molars in Correlation with Treatment Plan. Folia Med (Plovdiv) 2018; 60:283-290. [PMID: 30355817 DOI: 10.1515/folmed-2017-0093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Accepted: 09/11/2017] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The incisors and molars play a major role in the formation and function of permanent dentition. Much research has been devoted to investigating the eruption of teeth and their root development. AIM To study the root development of permanent incisors and mandibular molars in correlation with treatment plan and proper treatment protocols. MATERIALS AND METHODS The Demirjian's method was used to assess the root development of incisors and mandibular molars in children between 7 and 12 years old. RESULTS In 7-year-old children most of the lower first mandibular molars (76%) had complete root length, but open apices. Eighty-two percent of the roots of the first mandibular molars of the 8-year-old children and 54% of these molars of the 9-year-old children were with open apices. The first mandibular molars had incomplete roots in the 10-year-olds (6%) and even in the 11-year-old children (4%). We detected Stage E in 32% of the 10-year-olds and in 24% of the 11-year-old children. Even in 12-year-old children we found Stage E in 4% of them from their panoramic X-rays. We detected complete root development in all of the children at the age of 12. CONCLUSIONS Dental practitioners have to wait until the age of 10, 11 and even 12 to extract the first molars, when the furcation is formed. Proper clinical examination and diagnostic radiographs should be done before the beginning of the treatment of molars and incisors at the age between 7 and 12.
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Affiliation(s)
- Yordan Tarpomanov
- Department of Pediatric Dentistry, Faculty of Dental Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Sevda Rimalovska
- Department of Pediatric Dentistry, Faculty of Dental Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Ani Belcheva
- Department of Pediatric Dentistry, Faculty of Dental Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Miroslava Yordanova
- Department of Orthodontics, Faculty of Dental Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Svetla Yordanova
- Department of Orthodontics, Faculty of Dental Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Maria Kukleva
- Department of Pediatric Dentistry, Faculty of Dental Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
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14
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Hikita Y, Yamaguchi T, Tomita D, Adel M, Nakawaki T, Katayama K, Maki K, Kimura R. Growth hormone receptor gene is related to root length and tooth length in human teeth. Angle Orthod 2018; 88:575-581. [PMID: 29667468 DOI: 10.2319/092917-659.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES To examine the relationship between tooth length and growth hormone receptor (GHR) gene variants in a healthy Japanese population. MATERIALS AND METHODS The subjects consisted of 193 Japanese adults (69 men, 124 women), aged 13 to 56 years. Genomic DNA was extracted from saliva and genotyped GHR rs6184 and rs6180 variants using the Taqman genotyping. Computed tomography (CT) images were acquired using a dental cone-beam CT scanner and reconstructed using open-source OsiriX medical image processing software. The maxillary (upper; U) and mandibular (lower, L) central incisors (1), lateral incisors (2), canines (3), first premolars (4), second premolars (5), first molars (6), and second premolars (7) were evaluated. Teeth were assessed for crown height (CH), root length (RL), overall tooth length (C+R), and crown to root ratio (C/R). The relationships between GHR variants and CH, RL, C+R, and C/R were statistically examined. RESULTS The GHR variant rs6184 was associated with the root lengths and tooth length for the upper and lower lateral incisors and upper canines (U2 RL; U3 RL, C+R; L2 RL [ P < .05]). CONCLUSIONS The results indicate that the GHR rs6184 variant is associated with tooth length and ratio dimensions in a Japanese cohort. Further studies utilizing a larger sample size are needed to confirm this finding.
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15
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Abstract
Dental Mesenchymal Cells (DMCs) are known to play a role in tooth development as well as in the repair and regeneration of dental tissue. A large number of signaling molecules regulate the proliferation and differentiation of DMC, though the underlying mechanisms are still not fully understood. Sirtuin-6 (SIRT6), a key regulator of aging, can exert an impact on embryonic stem cell (ESC) differentiation. The experimental deletion of Sirt6 in mouse bone marrow cells has been found to have an inhibiting impact on the bone mineral density and the osteogenic differentiation of these cells. The possible role of Sirt6 in tooth development, however, has at present remained largely unexplored. In the present study, we found that SIRT6 had no effect on tooth development before birth. However, Sirt6 gene deletion in knockout mice did have two post-natal impacts: a delay in tooth eruption and sluggishness in the development of dental roots. We propose an explanation of the possible molecular basis of the changes observed in Sirt6-/- mice. SIRT6 is expressed in mouse odontoblasts. Sirt6 deletion enhanced the proliferation of DMCs, as well as their capacity for adipogenic differentiation. On the other hand, it inhibited their capacity for in vitro osteogenic/chondrogenic differentiation. Further studies suggested that other factors may mediate the role of Sirt6 in odontogenesis. These include the nuclear factor kappa B (NF-κB), p38 mitogen-activated protein kinase (p38-MAPK), extracellular regulated MAP kinase (ERK) pathways and the mitochondrial energy. We demonstrated that Sirt6 plays a role in tooth root formation and confirmed that SIRT6 is necessary for DMC differentiation as well as for the development of the tooth root and for eventual tooth eruption. These results establish a new link between SIRT6 and tooth development.
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Affiliation(s)
- Xueyang Liao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Bo Feng
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Demao Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Peng Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ruimin Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Endodontics, Stomatology Hospital, General Hospital of NingXia Medical University, Yinchuan, China
- * E-mail: (LY); (RML)
| | - Ling Ye
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- * E-mail: (LY); (RML)
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16
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Abstract
Studies on individuals with sex chromosome anomalies have demonstrated the promoting effect of the Y chromosome on tooth crown enamel and dentin growth. The present research investigated permanent tooth root lengths in 47,XYY males. The measurements were made from panoramic radiographs. The results indicate longer tooth roots in 47,XYY males compared with those in control males and females. The promoting effect of the Y chromosome on dental growth thus continues in the form of root dentin after the completion of crown growth. The results, together with those on tooth crown sizes in 47,XYY males, suggest that growth excesses are evident and final, beginning a few months after birth and continuing up to the age of 14 years, at least. The excess root dentin growth in 47,XYY males, as well as sexual dimorphism in the growth of crown and root dentin, might be caused by the same factor on the Y chromosome.
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Abstract
Hertwig’s epithelial root sheath (HERS) plays an important role in tooth root formation. In this study, we examined root formation of the first molar in mice, focusing on cell proliferation, cell death, cell migration, and the expression patterns of the signaling molecules, including glycoproteins and proteoglycans between PN8 and PN26. The number of HERS cells decreased during root formation, although HERS retained total length until PN15. The migration of HERS cells did not occur during root formation. Moreover, the immunopositive reaction of laminin beta-3 and syndecan-1 in HERS indicates that both cell adhesion and cell proliferation are essential for HERS development. Bmp-2, Bmp-4, and Msx-2 were expressed in HERS cells during root formation. We also developed an in vitro culture system for investigating the periodontium and suggest that this system provides an excellent vehicle for full exploration, and hence improved understanding, of the development and regeneration of the periodontium. Together, our results provide a comprehensive model describing the morphogenesis of early root development in vertebrates.
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Affiliation(s)
- H Yamamoto
- Department of Oral Biology, Research Center for Orofacial Hard Tissue Regeneration, Oral Science Research Center, College of Dentistry, Brain Korea 21 project for Medical Science, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752, Korea
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18
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Abstract
The structure of peripheral cementum of mandibular and maxillary check teeth was studied In gross observation, light microscopy, and scanning and transmission election microscopy Teeth from four horses aged 4, 8, 17, and 30-years-old were examined. The cementum of the occlusal surface was thicker on the buccal aspect when compared with the lingual aspect of mandibular teeth. The cementum of the occlusal surface was thicker on tin-palatal aspect when compared with the buccal aspect of maxillary teeth. There was no peripheral cementum mi the interdental aspects of either mandibular or maxillary check teeth. In the adult tooth, cementum covered the crown and root surfaces. The peripheral com mum of the gingival region showed a dramatic increase in thickness compared with cementum covering the alveolar portion of the embedded tooth. At a microscopic level, three layers (primary, secondary, and tertiary) were identified within cementum. The increase in cementum in the gingival region was of tertiary cementum. All three layers contained vital cementocytes. There was a well-developed vascular system within the cementum. Nerve bundles were also present. Three cementoblast profiles were identified at the junction of the cementum with the periodontal ligament. The results reported in this paper show that cementum is a dynamic vital tissue. These findings should contribute in ii greater understanding of the etiology and pathogenesis of cemental caries and periodontal disease in the horse.
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Affiliation(s)
- S R Mitchell
- Division of Preclinical Veterinary Sciences, University of Edinburgh, Summerhall, Edinburgh, EH1 1QH.
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19
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Shi X, Xie X, Quan J, Wang X, Sun X, Zhang C, Zheng S. Evaluation of root and alveolar bone development of unilateral osseous impacted immature maxillary central incisors after the closed-eruption technique. Am J Orthod Dentofacial Orthop 2015; 148:587-98. [PMID: 26432314 DOI: 10.1016/j.ajodo.2015.04.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 04/01/2015] [Accepted: 04/01/2015] [Indexed: 11/19/2022]
Affiliation(s)
- Xiangru Shi
- Postgraduate student, Department of Preventive Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Xiaoyan Xie
- Resident, Department of Oral and Maxillofacial Radiology, Peking University School and Hospital of Stomatology, Beijing, China
| | - Junkang Quan
- Resident, Department of Preventive Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Xiaozhe Wang
- Resident, Department of Preventive Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Xiangyu Sun
- Resident, Department of Preventive Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Chenying Zhang
- Resident, Department of Preventive Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Shuguo Zheng
- Professor, Department of Preventive Dentistry, Peking University School and Hospital of Stomatology, Beijing, China.
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20
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Lei L, Yan F, Li H, Li H. Treatment of Dilacerated Incisors in Early and Late Stages of Root Development. J Clin Orthod 2015; 49:497-507. [PMID: 26332262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Lang Lei
- Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210008, China
| | - Fuhua Yan
- Department of Periodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210008, China
| | - Houxuan Li
- Department of Periodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210008, China.
| | - Huang Li
- Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210008, China
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21
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Underwood CJ, Johanson Z, Welten M, Metscher B, Rasch LJ, Fraser GJ, Smith MM. Development and evolution of dentition pattern and tooth order in the skates and rays (batoidea; chondrichthyes). PLoS One 2015; 10:e0122553. [PMID: 25874547 PMCID: PMC4398376 DOI: 10.1371/journal.pone.0122553] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 02/23/2015] [Indexed: 11/20/2022] Open
Abstract
Shark and ray (elasmobranch) dentitions are well known for their multiple generations of teeth, with isolated teeth being common in the fossil record. However, how the diverse dentitions characteristic of elasmobranchs form is still poorly understood. Data on the development and maintenance of the dental patterning in this major vertebrate group will allow comparisons to other morphologically diverse taxa, including the bony fishes, in order to identify shared pattern characters for the vertebrate dentition as a whole. Data is especially lacking from the Batoidea (skates and rays), hence our objective is to compile data on embryonic and adult batoid tooth development contributing to ordering of the dentition, from cleared and stained specimens and micro-CT scans, with 3D rendered models. We selected species (adult and embryonic) spanning phylogenetically significant batoid clades, such that our observations may raise questions about relationships within the batoids, particularly with respect to current molecular-based analyses. We include developmental data from embryos of recent model organisms Leucoraja erinacea and Raja clavata to evaluate the earliest establishment of the dentition. Characters of the batoid dentition investigated include alternate addition of teeth as offset successional tooth rows (versus single separate files), presence of a symphyseal initiator region (symphyseal tooth present, or absent, but with two parasymphyseal teeth) and a restriction to tooth addition along each jaw reducing the number of tooth families, relative to addition of successor teeth within each family. Our ultimate aim is to understand the shared characters of the batoids, and whether or not these dental characters are shared more broadly within elasmobranchs, by comparing these to dentitions in shark outgroups. These developmental morphological analyses will provide a solid basis to better understand dental evolution in these important vertebrate groups as well as the general plesiomorphic vertebrate dental condition.
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Affiliation(s)
- Charlie J. Underwood
- Department of Earth and Planetary Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, United Kingdom
- * E-mail:
| | - Zerina Johanson
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom
| | - Monique Welten
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom
| | - Brian Metscher
- Department of Theoretical Biology, University of Vienna, Althanstrasse 14, 1090 Wien, Austria
| | - Liam J. Rasch
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Gareth J. Fraser
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Moya Meredith Smith
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom
- King's College London, Dental Institute, Craniofacial Development, London SE1 9RT, United Kingdom
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Komarnitki I, Tomczyk J, Ciszek B, Zalewska M. Proposed classification of auriculotemporal nerve, based on the root system. PLoS One 2015; 10:e0123120. [PMID: 25856464 PMCID: PMC4391942 DOI: 10.1371/journal.pone.0123120] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 02/21/2015] [Indexed: 01/14/2023] Open
Abstract
The topography of the auriculotemporal nerve (ATN) root system is the main criterion of this nerve classification. Previous publications indicate that ATN may have between one and five roots. Most common is a one- or two-root variant of the nerve structure. The problem of many publications is the inconsistency of nomenclature which concerns the terms “roots”, “connecting branches”, or “branches” that are used to identify the same structures. This study was performed on 80 specimens (40 adults and 40 fetuses) to propose a classification based on: (i) the number of roots, (ii) way of root division, and (iii) configuration of interradicular fibers that form the ATN trunk. This new classification is a remedy for inconsistency of nomenclature of ATN in the infratemporal fossa. This classification system has proven beneficial when organizing all ATN variants described in previous studies and could become a helpful tool for surgeons and dentists. Examination of ATN from the infratemporal fossa of fetuses (the youngest was at 18 weeks gestational age) showed that, at that stage, the nerve is fully developed.
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Affiliation(s)
- Iulian Komarnitki
- Department of Descriptive and Clinical Anatomy, Medical University of Warsaw, Warsaw, Poland
- * E-mail:
| | - Jacek Tomczyk
- Department of Biological Anthropology, Cardinal Stefan Wyszynski University, Warsaw, Poland
| | - Bogdan Ciszek
- Department of Descriptive and Clinical Anatomy, Medical University of Warsaw, Warsaw, Poland
| | - Marta Zalewska
- Department of Environmental Hazard Prevention and Allergology, Medical University of Warsaw, Warsaw, Poland
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Shi XR, Hu Z, Wang XZ, Sun XY, Zhang CY, Si Y, Zheng SG. Evaluation of the Effect of the Closed-eruption Technique on Impacted Immature Maxillary Incisors. Chin J Dent Res 2015; 18:111-115. [PMID: 26167549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
OBJECTIVE To investigate the effects of the closed-eruption technique on impacted immature maxillary incisors. METHODS The contour and position of the gingival margin, root development, and pulp status were evaluated in 50 impacted immature maxillary incisors immediately after treatment and 2 years later. RESULTS Chronic periapical periodontitis and trauma of the primary teeth were the main causes of impacted immature maxillary incisors. The average treatment time was 11 months. After treatment, the contour of the impacted incisor gingival margin, which had already erupted, conformed with the contralateral incisors; the gingival margin positions of 34 (68%) impacted incisors were the same as those of the contralateral incisors but the other 16 (32%) were more apical. All roots developed normally; pulp vitality was normal and conformed with the contralateral incisor change into a period. Three (6%) impacted incisors were slightly labially inclined because the dilacerated part of their roots was too long. CONCLUSION The closed-eruption technique is an effective method of treating impacted immature maxillary incisors.
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Abstract
OBJECTIVE The purpose of this study was to evaluate the developmental stage of teeth adjacent to the agenesis site in comparison to their antimeres. MATERIALS AND METHODS Panoramic views of 39 patients with unilateral dental agenesis and 42 normal controls were evaluated. The dental developmental stage (normal or delayed) of the teeth adjacent to the agenesis site was determined for each patient using the Haavikko's method, while the overall dental age was determined by Becker's method. RESULTS No statistically significant difference was found in the developmental stage of teeth adjacent to the agenesis, compared to their antimere and to the same teeth in the normal control group. However, the prevalence of cases with no difference in development was almost double for the tooth distal to the agenesis site compared to the tooth mesial to the agenesis site in the hypodontia group (84.6% distal and 43.6% mesial; p < 0.001) and in the control group (83.3% distal and 52.4% mesial; p < 0.002). In most of the cases the tooth distal to the agenesis site was the 1st permanent molar. CONCLUSIONS (1) No difference was found between the developmental stage of teeth adjacent to the agenesis site and their antimeres. (2) Teeth mesial to the agenesis site showed some delay in development compared to teeth distal to the agenesis site, in this study. (3) The 1st molars, which were in most of the cases the distal adjacent tooth to the site of agenesis, showed developmental stability. (4) Additional longitudinal studies are needed to examine the dental developmental pattern in patients with agenesis.
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Affiliation(s)
- Yocheved Ben-Bassat
- Department of Orthodontics, Hebrew University-Hadassah School of Dental Medicine , Jerusalem , Israel
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25
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Zhao X. Re: Effects of long-term occlusal hypofunction and its recovery on the morphogenesis of molar roots and the periodontium in rats. The Angle Orthodontist 2013(4) 597-604. Angle Orthod 2014; 84:575. [PMID: 24749709 DOI: 10.2319/0003-3219-84.3.575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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26
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Maltha JC. [Mechanisms of tooth eruption]. Ned Tijdschr Tandheelkd 2014; 121:209-214. [PMID: 24881262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Tooth eruption is of the utmost importance for the normal development of the dentition and the face. Since the 1980s, it has been known that the tooth germ itself is not essential for facilitating the processes that make tooth eruption possible. For that reason, recent research on the regulatory mechanisms of tooth eruption has focused mainly on the enamel organ and the dental follicle. Different regulatory mechanisms act on the occlusal and the apical sides of an erupting tooth. On the occlusal side osteoclast differentiation is stimulated. This leads to the development of an eruption canal, a process in which macrophages and matrix metalloproteases also play an important role. On the apical side the most important factors are the transcription factor RUNX2 and the bone morphogenic protein 2. They are responsible for the deposition of trabecular bone in that area. Many regulatory mechanisms which are involved in tooth eruption are also active in other developmental processes. This explains that certain syndromes can also have an effect on the tooth eruption process.
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Kumakami-Sakano M, Otsu K, Fujiwara N, Harada H. Regulatory mechanisms of Hertwig׳s epithelial root sheath formation and anomaly correlated with root length. Exp Cell Res 2014; 325:78-82. [PMID: 24560742 DOI: 10.1016/j.yexcr.2014.02.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 02/07/2014] [Indexed: 11/18/2022]
Abstract
Teeth are composed of two domains, the enamel-covered crown and cementum-covered root. The mechanism for determining the transition from crown to root is important for understanding root anomaly diseases. Hertwig׳s epithelial root sheath (HERS) is derived from the dental epithelium and is known to drive the growth of root dentin and periodontal tissue. Some clinical cases of hypoplastic tooth root are caused by the cessation of HERS development. Understanding the mechanisms of HERS development will contribute to the study of the disease and dental regenerative medicine. However, the developmental biology of tooth root formation has not been fully studied, particularly regarding HERS formation. Here, we describe the mechanisms of HERS formation on the basis of analysis of cell dynamics using imaging and summarize how the growth factor and its receptor regulate cell behavior of the dental epithelium.
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Affiliation(s)
- Mika Kumakami-Sakano
- Division of Developmental Biology and Regenerative Medicine, Department of Anatomy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba, Iwate 028-3694, Japan
| | - Keishi Otsu
- Division of Developmental Biology and Regenerative Medicine, Department of Anatomy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba, Iwate 028-3694, Japan
| | - Naoki Fujiwara
- Division of Developmental Biology and Regenerative Medicine, Department of Anatomy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba, Iwate 028-3694, Japan
| | - Hidemitsu Harada
- Division of Developmental Biology and Regenerative Medicine, Department of Anatomy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba, Iwate 028-3694, Japan.
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Abstract
The aim of present study was to determine the chronology of third molar root mineralization and to establish south Indian reference data. Therefore, a cross-sectional study was undertaken by evaluating 192 intraoral periapical radiographs in order to assess the root mineralization status of the mandibular third molar of south Indian individuals (101 males and 91 females) between the age of 13 and 25. The evaluation was carried out using the seven-stage developmental scheme of Kullman et al. (1992). The range, mean age, standard deviation, Student t test and percentile distributions are presented for each stage of mineralization. Statistically significant differences between males and females were not found. All individuals from this study with mature third molar roots were at least 18 years of age. For medicolegal purposes, the likelihood of whether a south Indian individual is older than 18 years or not was determined.
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Affiliation(s)
- Venkatesh Maled
- Department of Forensic Medicine, SDM College of Medical Sciences & Hospital, Dharwad, Karnataka, India
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29
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Wang Y, Cox MK, Coricor G, MacDougall M, Serra R. Inactivation of Tgfbr2 in Osterix-Cre expressing dental mesenchyme disrupts molar root formation. Dev Biol 2013; 382:27-37. [PMID: 23933490 DOI: 10.1016/j.ydbio.2013.08.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 08/01/2013] [Indexed: 11/19/2022]
Abstract
It has been difficult to examine the role of TGF-ß in post-natal tooth development due to perinatal lethality in many of the signaling deficient mouse models. To address the role of Tgfbr2 in postnatal tooth development, we generated a mouse in which Tgfbr2 was deleted in odontoblast- and bone-producing mesenchyme. Osx-Cre;Tgfbr2(fl/fl) mice were generated (Tgfbr2(cko)) and post-natal tooth development was compared in Tgfbr2(cko) and control littermates. X-ray and μCT analysis showed that in Tgfbr2(cko) mice radicular dentin matrix density was reduced in the molars. Molar shape was abnormal and molar eruption was delayed in the mutant mice. Most significantly, defects in root formation, including failure of the root to elongate, were observed by postnatal day 10. Immunostaining for Keratin-14 (K14) was used to delineate Hertwig's epithelial root sheath (HERS). The results showed a delay in elongation and disorganization of the HERS in Tgfbr2(cko) mice. In addition, the HERS was maintained and the break up into epithelial rests was attenuated suggesting that Tgfbr2 acts on dental mesenchyme to indirectly regulate the formation and maintenance of the HERS. Altered odontoblast organization and reduced Dspp expression indicated that odontoblast differentiation was disrupted in the mutant mice likely contributing to the defect in root formation. Nevertheless, expression of Nfic, a key mesenchymal regulator of root development, was similar in Tgfbr2(cko) mice and controls. The number of osteoclasts in the bone surrounding the tooth was reduced and osteoblast differentiation was disrupted likely contributing to both root and eruption defects. We conclude that Tgfbr2 in dental mesenchyme and bone is required for tooth development particularly root formation.
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Affiliation(s)
- Ying Wang
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Megan K Cox
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - George Coricor
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Mary MacDougall
- Institute of Oral Health Research, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Rosa Serra
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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30
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Slutzky-Goldberg I, Heling I. [Revascularization? Only as the last resort!]. Refuat Hapeh Vehashinayim (1993) 2013; 30:30-62. [PMID: 24303740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Revascularization has been suggested for treatment of necrotic immature permanent teeth. The desirable outcome of the treatment is continuous growth of the root, maturation of the dentin walls underneath the cervical seal and apical closure. Despite of increasing numbers of case reports, a uniform treatment protocol has not been set. This procedure has many shortcomings of which tooth discoloration is the most prevalent and easy to observe. The severe discoloration is attributed to the use of Mincocycline in the antibiotic dressing, or to the use of MTA for the seal. The maturation of the root is not predictable and does not always occur. The outcome should be evaluated radiographically and clinically. Sensibility testing may not be possible due to the large MTA plug in the root canal. It is recommended only when alternative procedures such as apexificaiton, pulpotomy or pulp capping are impossible. The patient and his parents should be aware of the potential discoloration and must be committed to routine follow ups. Currently, this procedure should be limited to incisor or premolar teeth in which the crown is longer than the root, or the canal's width is larger than that of the dentinal wall.
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Affiliation(s)
- I Slutzky-Goldberg
- Dept. of Endodontics, Faculty of Dental Medicine of the Hebrew University, Hadassah
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31
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Hargreaves KM, Diogenes A, Teixeira FB. Treatment options: biological basis of regenerative endodontic procedures. Pediatr Dent 2013; 35:129-140. [PMID: 23635981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Dental trauma occurs frequently in children and often can lead to pulpal necrosis. The occurrence of pulpal necrosis in the permanent but immature tooth represents a challenging clinical situation because the thin and often short roots increase the risk of subsequent fracture. Current approaches for treating the traumatized immature tooth with pulpal necrosis do not reliably achieve the desired clinical outcomes, consisting of healing of apical periodontitis, promotion of continued root development, and restoration of the functional competence of pulpal tissue. An optimal approach for treating the immature permanent tooth with a necrotic pulp would be to regenerate functional pulpal tissue. This review summarizes the current literature supporting a biological rationale for considering regenerative endodontic treatment procedures in treating the immature permanent tooth with pulp necrosis.
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Affiliation(s)
- Kenneth M Hargreaves
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
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32
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Seghi RR, Nasrin S, Draney J, Katsube N. Root fortification. Pediatr Dent 2013; 35:153-159. [PMID: 23635983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
An incompletely formed tooth is left with thin dentin walls and experiences a higher incidence of cervical root fracture that reduces the long-term overall prognosis of the tooth. Faced with these situations, clinicians have attempted to use various restorative methods to reinforce the remaining root. Various techniques have been reported, and the scientific evidence for each has been reviewed. The biomechanical considerations of reinforcing a weakened root are also reviewed, and the most current information about failure analysis, fracture characteristics of natural dentin, and in vitro test configurations used have been considered. In light of these additional considerations, some recommendations for future understanding of this complex problem have been proposed.
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Affiliation(s)
- Robert R Seghi
- College of Dentistry, The Ohio State University, Columbus, Ohio, USA.
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33
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Shabahang S. Treatment options: apexogenesis and apexification. Pediatr Dent 2013; 35:125-128. [PMID: 23635980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This article will describe requirements for case selection and review the procedures for apexogenesis and apexification in immature permanent teeth. Nonclinical and clinical data will be presented to support the recommendations, and outcomes will be presented from clinical studies. The dental pulp is an ectomesenchymally derived connective tissue with certain unique properties such as being encased in hard tissues, which limits its collateral circulation. The pulp provides a matrix for binding of its cells and provides support allowing communication between the cells. In addition to immune cells, the dental pulp contains odontoblasts, which are specialized cells capable of producing dentin. In the absence of a vital pulp, dentin deposition is arrested. When an immature tooth is affected by caries or trauma, the pulp requires proper management according to the degree of inflammation and its vitality. Maintenance of pulp vitality will allow continued root development along the entire root length. If the pulp is irreversibly inflamed or necrotic, root-end closure procedures are required when the apex has not fully formed.
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Hargreaves KM, Diogenes A, Teixeira FB. Treatment options: biological basis of regenerative endodontic procedures. J Endod 2013; 39:S30-43. [PMID: 23439043 PMCID: PMC3589799 DOI: 10.1016/j.joen.2012.11.025] [Citation(s) in RCA: 199] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 11/12/2012] [Accepted: 11/12/2012] [Indexed: 12/14/2022]
Abstract
Dental trauma occurs frequently in children and often can lead to pulpal necrosis. The occurrence of pulpal necrosis in the permanent but immature tooth represents a challenging clinical situation because the thin and often short roots increase the risk of subsequent fracture. Current approaches for treating the traumatized immature tooth with pulpal necrosis do not reliably achieve the desired clinical outcomes, consisting of healing of apical periodontitis, promotion of continued root development, and restoration of the functional competence of pulpal tissue. An optimal approach for treating the immature permanent tooth with a necrotic pulp would be to regenerate functional pulpal tissue. This review summarizes the current literature supporting a biological rationale for considering regenerative endodontic treatment procedures in treating the immature permanent tooth with pulp necrosis.
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Affiliation(s)
- Kenneth M Hargreaves
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA.
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35
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Hirose N, Shimazu A, Watanabe M, Tanimoto K, Koyota S, Sugiyama T, Uchida T, Tanne K. Ameloblastin in Hertwig's epithelial root sheath regulates tooth root formation and development. PLoS One 2013; 8:e54449. [PMID: 23372724 PMCID: PMC3553119 DOI: 10.1371/journal.pone.0054449] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 12/11/2012] [Indexed: 11/18/2022] Open
Abstract
Tooth root formation begins after the completion of crown morphogenesis. At the end edge of the tooth crown, inner and outer enamel epithelia form Hertwig’s epithelial root sheath (HERS). HERS extends along with dental follicular tissue for root formation. Ameloblastin (AMBN) is an enamel matrix protein secreted by ameloblasts and HERS derived cells. A number of enamel proteins are eliminated in root formation, except for AMBN. AMBN may be related to tooth root formation; however, its role in this process remains unclear. In this study, we found AMBN in the basal portion of HERS of lower first molar in mice, but not at the tip. We designed and synthesized small interfering RNA (siRNA) targeting AMBN based on the mouse sequence. When AMBN siRNA was injected into a prospective mandibular first molar of postnatal day 10 mice, the root became shorter 10 days later. Furthermore, HERS in these mice revealed a multilayered appearance and 5-bromo-2′-deoxyuridine (BrdU) positive cells increased in the outer layers. In vitro experiments, when cells were compared with and without transiently expressing AMBN mRNA, expression of growth suppressor genes such as p21Cip1 and p27Kip1 was enhanced without AMBN and BrdU incorporation increased. Thus, AMBN may regulate differentiation state of HERS derived cells. Moreover, our results suggest that the expression of AMBN in HERS functions as a trigger for normal root formation.
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Affiliation(s)
- Naoto Hirose
- Department of Orthodontics, Applied Life Sciences, Hiroshima University Institute of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, Japan.
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36
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Dean MC, Cole TJ. Human life history evolution explains dissociation between the timing of tooth eruption and peak rates of root growth. PLoS One 2013; 8:e54534. [PMID: 23342167 PMCID: PMC3544739 DOI: 10.1371/journal.pone.0054534] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 12/12/2012] [Indexed: 12/20/2022] Open
Abstract
We explored the relationship between growth in tooth root length and the modern human extended period of childhood. Tooth roots provide support to counter chewing forces and so it is advantageous to grow roots quickly to allow teeth to erupt into function as early as possible. Growth in tooth root length occurs with a characteristic spurt or peak in rate sometime between tooth crown completion and root apex closure. Here we show that in Pan troglodytes the peak in root growth rate coincides with the period of time teeth are erupting into function. However, the timing of peak root velocity in modern humans occurs earlier than expected and coincides better with estimates for tooth eruption times in Homo erectus. With more time to grow longer roots prior to eruption and smaller teeth that now require less support at the time they come into function, the root growth spurt no longer confers any advantage in modern humans. We suggest that a prolonged life history schedule eventually neutralised this adaptation some time after the appearance of Homo erectus. The root spurt persists in modern humans as an intrinsic marker event that shows selection operated, not primarily on tooth tissue growth, but on the process of tooth eruption. This demonstrates the overarching influence of life history evolution on several aspects of dental development. These new insights into tooth root growth now provide an additional line of enquiry that may contribute to future studies of more recent life history and dietary adaptations within the genus Homo.
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Affiliation(s)
- M Christopher Dean
- Cell and Developmental Biology, University College London, Gower Street, London, United Kingdom.
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37
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McTigue DJ, Subramanian K, Kumar A. Case series: management of immature permanent teeth with pulpal necrosis: a case series. Pediatr Dent 2013; 35:55-60. [PMID: 23635900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The management of immature permanent teeth with necrotic pulps has changed in recent years from apexification techniques to regenerative endodontic procedures, which enable apexogenesis with physiologic maturation of the roots. This regenerative technique lies squarely in the endodontist's scope of practice, but children presenting with necrotic immature incisors may pose behavior management problems that endodontists are untrained and unwilling to handle. Treatment of these immature permanent teeth provides an excellent opportunity for collaboration and shared patient management between pediatric dentists and endodontists that can yield optimal clinical outcomes. The purpose of this paper was to report a series of 32 regenerative endodontic cases in 28 children treated at the Nationwide Children's Hospital, Columbus, Ohio. The report describes procedural and patient management issues and the need for a collaborative relationship between pediatric dentists and endodontists in tackling these challenging cases.
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Affiliation(s)
- Dennis J McTigue
- Division of Pediatric Dentistry and Community Oral Health, College of Dentistry, The Ohio State University, Columbus, Ohio, USA.
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38
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Cabrales Salgado R, Carvajal Cabrales K, Pupo Marrugo S, Hernández González DF, Gracia Bárcenas JL. [In vitro evaluation of fracture resistance of teeth with incomplete root development and intracanal reinforcement with different materials]. Invest Clin 2012; 53:262-272. [PMID: 23248970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The aim of this study was to evaluate the fracture resistance of teeth with incomplete root development and intracanal reinforcement with adhesives materials. 50 human central and lateral incisors were instrumented and prepared to simulate an immature tooth and filled apically with MTA. The samples were divided into four experimental groups and one control group. Group 1: resin composite Filtek P90; Group 2: glass Ionomer Vitremer; Group 3: resin composite Filtek Z350 XT; Group 4: glass Ionomer Ketac N 100; Group 5: negative control (instrumented but not reinforced). After, the fracture test was performed using a fracture universal testing machine (Instron). The maximum values of resistance before catastrophic fracture were collected and analyzed by Anova (p = 0.05). The results show a significant difference between the groups compared (p = 0.02). A significant difference was found between group 1 (847.73 N) and group 5 (474.77 N) (p = 0.02) applying the Bonferroni test. Despite the limitations of the study, the conclusion is that micro-hybrid composite resins are ideal materials to strengthen teeth with incomplete root development endodontically treated.
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Cuccia AM, Pisano T. An unusual presence of primary retention of permanent teeth in subject with hyperthyroidism. Minerva Stomatol 2011; 60:573-578. [PMID: 22210461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
To date neither the eruption mechanism nor the factors controlling eruption have been completely understood. Primary retention of permanent teeth is an isolated condition associated with a localized failure of eruption with no other identifiable local or systemic involvement. Multiple primary retention may be related to lack of eruptive force, rotation of tooth buds, syndromes and metabolic disorders. This article reports an unusual case of primary retention of permanent teeth inclusion in a 21-year-old woman with hyperthyroidism, diagnosed at 14 years of age.
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Affiliation(s)
- A M Cuccia
- "G. Messina" Department of Dental Sciences, University of Palermo, Italy.
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Hung Y, Huang X, Chai Y. Molecular regulatory mechanism of root development. J Calif Dent Assoc 2011; 39:321-324. [PMID: 21721476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
TGF-beta signaling is known to function during tooth formation. The authors' study investigated the role of TGF-beta signaling during tooth root development and determined how the common mediator for TGF-beta signaling, Smad4, affected root formation in mice. Smod4 was specifically inactivated in all epidermal-derived tissues by using a two-component genetic system. The authors' findings show that when Smad4 expression is eliminated in the dental epithelium, there is lack of root formation and severe crown defects.
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Affiliation(s)
- Yee Hung
- Herman Ostrow School of Dentistry, University of Southern California, USA.
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Korneli N, Hempel U, Koch R, Hannig C, Klimm W. P42-influence of TGF-ß1 and culturing medium on ALP expression in human pulp fibroblasts with different root development. Bull Group Int Rech Sci Stomatol Odontol 2011; 49:108. [PMID: 22750374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 04/11/2011] [Indexed: 06/01/2023]
Affiliation(s)
- N Korneli
- TU Dresden, Clinic of Conservative Dentistry, Fetscherstrasse 74, 01307 Dresden, Germany.
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Deshpande A, Deshpande N. Flexible wire composite splinting for root fracture of immature permanent incisors: a case report. Pediatr Dent 2011; 33:63-66. [PMID: 21406150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Root fracture injuries affect up to 7% of permanent teeth, and injury in teeth with immature root formation is even rarer. The purpose of this paper was to report the case of a 7-year-old girl who experienced pain in her permanent maxillary central incisors following a fall from a bicycle. A radiographic examination revealed immature maxillary central incisors with mid-root oblique and horizontal root fractures. Splinting was performed, and the child was observed under a regular follow-up regime. After 18 months, clinical examination showed normal tooth color and position, with a positive response to the pulp test. This case report also aims to provide an insight into the splinting duration and various splinting techniques and how this can affect the prognosis.
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Affiliation(s)
- Anshula Deshpande
- Department of Pediatric and Preventive Dentistry and Department of Periodontics, Faculty of Dentistry, DMIMS University, Wardha, India.
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Vardimon AD, Shoshani K, Shpack N, Reimann S, Bourauel C, Brosh T. Incremental growth of the maxillary tuberosity from 6 to 20 years-A cross-sectional study. Arch Oral Biol 2010; 55:655-62. [PMID: 20598669 DOI: 10.1016/j.archoralbio.2010.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 03/19/2010] [Accepted: 05/22/2010] [Indexed: 12/21/2022]
Abstract
OBJECTIVES Although the maxillary tuberosity (MT) is a major growth site of the maxilla, its time-related growth was not fully investigated. The objectives of the study were to evaluate the MT growth from 6 to 20 years of age defining the peak growth age and to assess time-related indicators. DESIGN Panoramic radiographs from 189 patients were divided in a cross-sectional study into six age groups. A special panoramic analysis was developed including 18 parameters and 3 time-related indicators, i.e., chronological age, crown/root development stages of the maxillary second (M(2)) and third (M(3)) molars and eruption stages. RESULTS From 6 to 20 years, the MT vertical growth was 5.17-fold greater than the horizontal. The horizontal growth covered 36% of the maxillary growth but was inadequate to secure space for third molar eruption despite a 51% increase in MT area. MT peak growth was between 8 and 9 years and 10-11 year. During these 14 years, the maxillary length increased by pneumatisation of the maxillary sinus (86%), growth of the MT (36%) and decrease of the anterior maxillary region (-22%). Of the 18 examined parameters, 83% showed dependency to the combination chronological age with M(2), M(3) crown/root development stage and 72% to the combination chronological age with M(2), M(3) eruption stage. CONCLUSION MT growth peak occurs with initiation of root development of M(2) and shortly before M(2) eruption (8-9 years to 10-11 years). Dental time-related indicators adjunct with the chronological age provide an effectual system to define MT growth potential.
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Affiliation(s)
- Alexander Dan Vardimon
- Department of Orthodontics, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel.
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Zhang H, Tompkins K, Garrigues J, Snead ML, Gibson CW, Somerman MJ. Full length amelogenin binds to cell surface LAMP-1 on tooth root/periodontium associated cells. Arch Oral Biol 2010; 55:417-25. [PMID: 20382373 PMCID: PMC2886511 DOI: 10.1016/j.archoralbio.2010.03.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 12/30/2009] [Accepted: 03/12/2010] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Lysosome-associated membrane protein-1 (LAMP-1) has been suggested to be a cell surface receptor for a specific amelogenin isoform, leucine-rich amelogenin peptide or LRAP. However, it is unclear if LAMP-1 is an amelogenin receptor for dental mesenchymal cells. The goal of this study was to determine if LAMP-1 serves as a cell surface binding site for full length amelogenin on tooth root/periodontium associated mesenchymal cells. DESIGN Murine dental follicle cells and cementoblasts (OCCM-30) were cultured for 2 days followed by addition of full length recombinant mouse amelogenin, rp(H)M180. Dose-response (0-100 microg/ml) and time course (0-120 min) assays were performed to determine the optimal conditions for live cell surface binding using immunofluorescent microscopy. A competitive binding assay was performed to determine binding specificity by adding Emdogain (1 mg/ml) to the media. An antibody against LAMP-1 was used to detect the location of LAMP-1 on the cell surface and the pattern was compared to cell surface bound amelogenin. Both amelogenin and cell surface LAMP-1 were immuno-co-localized to compare the amount and distribution pattern. RESULTS Maximum surface binding was achieved with 50 microg/ml of rp(H)M180 for 120 min. This binding was specific as demonstrated by competitive inhibition (79% lower) with the addition of Emdogain. The binding pattern for rp(H)M180 was similar to the distribution of surface LAMP-1 on dental follicle cells and cementoblasts. The high co-localization coefficient (0.92) for rp(H)M180 and LAMP-1 supports rp(H)M180 binding to cell surface LAMP-1. CONCLUSIONS The data from this study suggest that LAMP-1 can serve as a cell surface binding site for amelogenin on dental follicle cells and cementoblasts.
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Affiliation(s)
- Hai Zhang
- Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA 98195, USA.
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Abstract
Traditional methods of treatment of immature root with necrotic pulp and apical periodontitis pose multiple challenges. These challenges include disinfection of the root canal with standard protocols that aggressively use endodontic files, filling the root canal with an open apex that provides no barrier for stopping the root filling material before impinging on the periodontal tissues, and the susceptibility of the teeth to fracture because of their thin roots. Disinfection using sodium hypochlorite, apical barrier formation using calcium hydroxide as well as mineral trioxide aggregate, and pulp revascularization of fractured tooth with the help of blood clot and collagen-enhanced matrix has been discussed in detail in this article.
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Affiliation(s)
- Martin Trope
- University of Pennsylvania, Philadelphia, PA 19104, USA.
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Omer RSM, Anthonappa RP, King NM. Determination of the optimum time for surgical removal of unerupted anterior supernumerary teeth. Pediatr Dent 2010; 32:14-20. [PMID: 20298648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
PURPOSE The purpose of this study was to determine the optimum time for surgical removal of unerupted maxillary anterior supernumerary teeth. METHODS The study population consisted of 126 children. Stages C to H of the Demirjian classification were used to classify the dental development of the adjacent incisors. Associations were sought between the complications and the developmental stage of the adjacent maxillary incisors at the time of surgical removal. Tests of association were carried out using Fisher's exact test with a probability level of P=.05 for statistical significance. RESULTS Significant differences were evident: for mature maxillary central incisors (N=170); between all the proportions for root resorption, with the greatest difference being between stages E and H (P<.001); for arrested root development between stages D and E (P=.013), and D and H (P=.02); and for persistent malocclusion between stages E and G (P=.004), E and H (P=.02), F and G (P=.005), and F and H (P=.01). CONCLUSION Early removal of unerupted maxillary supernumerary teeth seems to be advantageous with a cutoff point of approximately 6 to 7 years old, after which more complications are expected.
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Affiliation(s)
- Rashied S M Omer
- Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
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Phillips VM, van Wyk Kotze TJ. Dental age related tables for children of various ethnic groups in South Africa. J Forensic Odontostomatol 2009; 27:29-44. [PMID: 22785094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The standard age estimation methods of Moorrees, Fanning & Hunt (1963) and that of Demirjian, Goldstein & Tanner (1973) have been shown by several authors to be inaccurate when applied to their juvenile population. This was similarly found to be true in South African children. Pantomographic radiographs of samples of South African children of White, Coloured, Indian and Black origin were used to develop dental age related tables for these ethnic groups. These dental age estimation tables were tested and are presented.
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Affiliation(s)
- V M Phillips
- Department of Oral and Maxillo-facial Pathology, University of the Western Cape, Tygerberg 7505, South Africa.
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Abstract
While there is gradually accumulating knowledge about molar crown formation and the timing of molar eruption in extant great apes, very little is known about root formation during the eruption process. We measured mandibular first and second molar root lengths in extant great ape osteological specimens that died while either the first or second molars were in the process of erupting. For most specimens, teeth were removed so that root lengths could be measured directly. When this was not possible, roots were measured radiographically. We were particularly interested in the variation in the lengths of first molar roots near the point of gingival emergence, so specimens were divided into early, middle and late phases of eruption based on the number of cusps that showed protein staining, with one or two cusps stained equated with immediate post-gingival emergence. For first molars at this stage, Gorilla has the longest roots, followed by Pongo and Pan. Variation in first molar mesial root lengths at this stage in Gorilla and Pan, which comprise the largest samples, is relatively low and represents no more than a few months of growth in both taxa. Knowledge of root length at first molar emergence permits an assessment of the contribution of root growth toward differences between great apes and humans in the age at first molar emergence. Root growth makes up a greater percentage of the time between birth and first molar emergence in humans than it does in any of the great apes.
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García MF, Moreno H, Rigalli A, Puche RC. Growth-associated changes in the periodontal bone and molar teeth of male rats. J Am Assoc Lab Anim Sci 2009; 48:475-481. [PMID: 19807966 PMCID: PMC2755015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 03/02/2009] [Accepted: 04/27/2009] [Indexed: 05/28/2023]
Abstract
Here we report quantitative data associating periodontal bone variables of young conventional rats with the growth process. The hemimandibles of male rats (IIM/Fm stock, 2 to 15 wk of age.) were excised and submitted to conventional morphologic, radiologic, and histologic evaluation. The length, area, or X-ray absorbance of various regions or structures was measured on digital images of radiographs by using an image-analysis program. The sum of periodontal bone areas undergoing resorption (interproximal + intraradicular) increased until 9 or 10 wk of age and decreased thereafter. Mineral accretion rates and mineral density asymptotes were not significantly different among molars. The mineral density of resorption areas in alveolar bone fitted sinusoidal kinetics, indicative of the 'instability' of the tissue due to its high metabolic activity. Mineral accretion rates and mineral density asymptotes were not significantly different among molars. The proportion of root length within alveolar bone exhibited a biphasic curve (minimum at 5 wk of age), due to differences in the growth rates of variables involved in its calculation (distance between the cementoenamel junction to the apex and height of the resorption areas). The distance between the cementoenamel junction and alveolar bone crest over time fitted a sigmoidal function with a point of inflection that did not differ significantly from that of body or mandible dry weight. In summary, the growth process appears to affect periodontal bone support and the distance between the cementoenamel junction and alveolar bone crest in male rats.
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Abstract
The implantation of cultured dental cell-cell re-associations allows for the reproduction of fully formed teeth, crown morphogenesis, epithelial histogenesis, mineralized dentin and enamel deposition, and root-periodontium development. Since vascularization is critical for organogenesis and tissue engineering, this work aimed to study: (a) blood vessel formation during tooth development, (b) the fate of blood vessels in cultured teeth and re-associations, and (c) vascularization after in vivo implantation. Ex vivo, blood vessels developed in the dental mesenchyme from the cap to bell stages and in the enamel organ, shortly before ameloblast differentiation. In cultured teeth and re-associations, blood-vessel-like structures remained in the peridental mesenchyme, but never developed into dental tissues. After implantation, both teeth and re-associations became revascularized, although later in the case of the re-associations. In implanted re-associations, newly formed blood vessels originated from the host, allowing for their survival, and affording conditions organ growth, mineralization, and enamel secretion.
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Affiliation(s)
- A Nait Lechguer
- INSERM UMR 595, Faculté de Médecine, 11, rue Humann, 67085 Strasbourg cedex, France
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