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Brusevold IJ, Bie TMG, Baumgartner CS, Das R, Espelid I. Molar incisor malformation in six cases: description and diagnostic protocol. Oral Surg Oral Med Oral Pathol Oral Radiol 2017; 124:52-61. [DOI: 10.1016/j.oooo.2017.03.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 03/20/2017] [Accepted: 03/26/2017] [Indexed: 10/19/2022]
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52
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Liu Y, Du H, Wang Y, Liu M, Deng S, Fan L, Zhang L, Sun Y, Zhang Q. Osteoprotegerin-Knockout Mice Developed Early Onset Root Resorption. J Endod 2017; 42:1516-22. [PMID: 27663616 DOI: 10.1016/j.joen.2016.07.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/06/2016] [Accepted: 07/08/2016] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Recent studies indicate that the osteoprotegerin (OPG)/RANKL/RANK pathway takes part in root resorption. However, the relationship between OPG and root resorption is vague. The purpose of our study was to investigate the role of OPG in root resorption. METHODS The first molars of the mandibles of osteoprotegerin-knockout (Opg-KO) mice and wild-type (WT) mice were evaluated by micro-computed tomography, histology, and immunohistochemistry at 4, 6, 26, and 52 weeks. To detect the activity of the osteoclasts, we induced bone marrow macrophages into osteoclast-like cells from Opg-KO mice and wild-type mice in vitro and then compared their osteoclast activities. To evaluate the cementum quality, an osteoclast-cementum co-culture model was established in vitro. RESULTS In Opg-KO mice, root resorption began at the age of 4 weeks. At 6 weeks the cementum damage extended to the coronal and apical regions, and at 52 weeks the damage reached the predentin. At all observed stages, more tartrate-resistant acid phosphatase (TRAP)-positive cells were found on the surface of cementum in Opg-KO mice. In vitro, the mRNA levels of cathepsin K, TRAP, matrix metalloproteinase-9, and matrix metalloproteinase-1, as well as the protein expression of nuclear factor of activated T cell 1 and TRAP, increased significantly in osteoclast-like cells from Opg-KO mice. In addition, the cementum resorption pits of Opg-KO mice were larger when co-cultured with osteoclast-like cells. CONCLUSIONS Our study demonstrated that loss of OPG led to root resorption via increasing activation of osteoclasts and reducing mineralization of cementum.
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Affiliation(s)
- Yi Liu
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Haiming Du
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Yunfei Wang
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Mengmeng Liu
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Shijian Deng
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Linlin Fan
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Lili Zhang
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Yao Sun
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Qi Zhang
- Department of Endodontics, School and Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China.
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Star H, Chandrasekaran D, Miletich I, Tucker AS. Impact of hypofunctional occlusion on upper and lower molars after cessation of root development in adult mice. Eur J Orthod 2017; 39:243-250. [PMID: 27567636 DOI: 10.1093/ejo/cjw051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Background Hypofunctional occlusion is known to lead to changes in the length of roots over time. The mechanisms that drive such changes, however, are poorly understood, with most studies concentrating on juvenile rats prior to the arrest of root development. In this article, we investigated the response of the upper and lower first molar roots to lack of occlusion concentrating on time-points after the development of the roots has ceased using the mouse as a model. Mouse molar roots finish development at weaning, much earlier than rat molars, and display a similar pattern of roots in the lower and upper jaw to humans. Methods Hypofunctional occlusion was achieved in adult mice at 5 and 9 weeks of age by flattening the cusps of the upper first molar. Mice were then sacrificed after 6 and 2 weeks, respectively, along with control littermates. microCT was used to measure root length, alveolar bone height, and the amount of tooth eruption, followed by sectioning to understand the mechanisms behind the changes at the histological level. Results In the lower first molar, the response to hypofunctional occlusion was characterized by elongation of both the mesial root and its surrounding alveolar bone, while the distal root was unaffected. In contrast, the response of the upper first molar was characterized by over-eruption of the mesial side of the tooth without any significant change in the alveolar bone or root length. From histologic sections, it was clear that increased deposition of cellular cementum played an important role in the changes that occurred in the lower mesial root. Conclusions In a mouse model, upper and lower molars responded differently to hypofunctional occlusion, with adult mice showing a different response to that previously reported for juvenile rats, highlighting the importance of considering age and tooth position in cases of hypofunction.
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Affiliation(s)
- Haza Star
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London, UK
| | - Dhivya Chandrasekaran
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London, UK
| | - Isabelle Miletich
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London, UK
| | - Abigail S Tucker
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London, UK
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Zeng L, Zhao N, Han D, Liu H, Liu Y, Wang Y, Feng H. DLX3 mutation negatively regulates odontogenic differentiation of human dental pulp cells. Arch Oral Biol 2017; 77:12-17. [DOI: 10.1016/j.archoralbio.2017.01.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 01/05/2017] [Accepted: 01/16/2017] [Indexed: 12/25/2022]
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Dai J, Si J, Ouyang N, Zhang J, Wu D, Wang X, Shen G. Dental and periodontal phenotypes of Dlx2 overexpression in mice. Mol Med Rep 2017; 15:2443-2450. [PMID: 28447749 PMCID: PMC5428916 DOI: 10.3892/mmr.2017.6315] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 12/12/2016] [Indexed: 11/29/2022] Open
Abstract
Distal-less homeobox 2 (Dlx2) is a member of the homeodomain family of transcription factors and is important for the development of cranial neural crest cells (CNCCs)-derived craniofacial tissues. Previous studies revealed that Dlx2 was expressed in the cementum and a targeted null mutation disrupted tooth development in mice. However, whether Dlx2 overexpression may impair in vivo tooth morphogenesis remains to be elucidated. The present study used a transgenic mouse model to specifically overexpress Dlx2 in neural crest cells in order to identify the dental phenotypes in mice by observation, micro-computed tomography and histological examination. The Dlx2-overexpressed mice exhibited tooth abnormalities including incisor cross-bite, shortened tooth roots, increased cementum deposition, periodontal ligament disorganization and osteoporotic alveolar bone. Therefore, Dlx2 overexpression may alter the alveolar bone, cementum and periodontal ligament (PDL) phenotypes in mice.
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Affiliation(s)
- Jiewen Dai
- Department of Oral and Cranio‑maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, P.R. China
| | - Jiawen Si
- Department of Oral and Cranio‑maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, P.R. China
| | - Ningjuan Ouyang
- Department of Oral and Cranio‑maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, P.R. China
| | - Jianfei Zhang
- Department of Oral and Cranio‑maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, P.R. China
| | - Dandan Wu
- Department of Oral and Cranio‑maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, P.R. China
| | - Xudong Wang
- Department of Oral and Cranio‑maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, P.R. China
| | - Guofang Shen
- Department of Oral and Cranio‑maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, P.R. China
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Spatial signalling mediated by the transforming growth factor-β signalling pathway during tooth formation. Int J Oral Sci 2016; 8:199-204. [PMID: 27982023 PMCID: PMC5168420 DOI: 10.1038/ijos.2016.45] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2016] [Indexed: 02/05/2023] Open
Abstract
Tooth development relies on sequential and reciprocal interactions between the epithelial and mesenchymal tissues, and it is continuously regulated by a variety of conserved and specific temporal-spatial signalling pathways. It is well known that suspensions of tooth germ cells can form tooth-like structures after losing the positional information provided by the epithelial and mesenchymal tissues. However, the particular stage in which the tooth germ cells start to form tooth-like structures after losing their positional information remains unclear. In this study, we investigated the reassociation of tooth germ cells suspension from different morphological stages during tooth development and the phosphorylation of Smad2/3 in this process. Four tooth morphological stages were designed in this study. The results showed that tooth germ cells formed odontogenic tissue at embryonic day (E) 14.5, which is referred to as the cap stage, and they formed tooth-like structures at E16.5, which is referred to as the early bell stage, and E18.5, which is referred to as the late bell stage. Moreover, the transforming growth factor-β signalling pathway might play a role in this process.
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Qari H, Kessler H, Narayana N, Premaraj S. Symmetric multiquadrant isolated dentin dysplasia (SMIDD), a unique presentation mimicking dentin dysplasia type 1b. Oral Surg Oral Med Oral Pathol Oral Radiol 2016; 123:e164-e169. [PMID: 28215628 DOI: 10.1016/j.oooo.2016.11.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 11/18/2016] [Accepted: 11/29/2016] [Indexed: 10/20/2022]
Abstract
Dentin dysplasia (DD) is a rare developmental dentin disorder that causes root malformation. It is divided into radicular DD type 1 (DD-1) and coronal DD type 2 (DD-2). Recently, a new entity causing localized root malformation of permanent first molars that resembles DD-1b has been described as molar-incisor malformation (MIM). We report and compare 4 new cases that exhibit similar clinical, histologic, and radiographic features to the new entity, MIM. We believe MIM and our 4 cases to be the same entity, which is nonhereditary and, because of the isolated but bilaterally symmetric pattern of involvement, may be caused by a short-duration environmental insult that disrupts normal development/function of Hertwig's epithelial root sheath. We propose the name symmetrical multiquadrant isolated dentin dysplasia as the most appropriate descriptive designation for this unusual but highly distinctive anomaly.
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Affiliation(s)
- Hiba Qari
- Texas A&M University College of Dentistry, Dallas, TX, USA.
| | - Harvey Kessler
- Texas A&M University College of Dentistry, Dallas, TX, USA
| | - Nagamani Narayana
- University of Nebraska Medical Center College of Dentistry, Lincoln, NE, USA
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Nascimento MAB, Nonaka CFW, Barboza CAG, Freitas RDA, Pereira Pinto L, Souza LBD. Immunoexpression of BMP-2 and BMP-4 and their receptors, BMPR-IA and BMPR-II, in ameloblastomas and adenomatoid odontogenic tumors. Arch Oral Biol 2016; 73:223-229. [PMID: 27780042 DOI: 10.1016/j.archoralbio.2016.10.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 09/23/2016] [Accepted: 10/17/2016] [Indexed: 12/12/2022]
Abstract
OBJECTIVES The present study evaluated the immunohistochemical expression of BMP-2 and BMP-4 and of their receptors (BMPR-IA and BMPR-II) in solid ameloblastoma (SA), unicystic ameloblastoma (UA) and adenomatoid odontogenic tumor (AOT) in order to obtain a better understanding of their role in the development and biological behavior of these tumors. DESIGN This study analyzed these proteins in 30 cases of SA, 10 cases of UA, and 30 cases of AOT. Immunoexpression was evaluated in the parenchyma and stroma by attributing the following scores: 0, no stained cells; 1, ≤10%; 2, >10% and ≤25%; 3, >25% and ≤50%; 4, >50% and ≤75%.; 5, >75% stained cells. RESULTS In SAs, positive correlations were observed between the stromal and parenchymal expression of BMP-2 (p<0.001) and between the stromal expression of BMP-2 and BMP-4 (p=0.020), as well as between the stromal expression of BMPR-II and BMP-4 (p=0.001) and the stromal and parenchymal expression of BMPR-II (p<0.001). In UAs, correlations were detected between the stromal and parenchymal expression of BMP-4 (p=0.035) and between the stromal expression of BMP-4 and BMPR-IA (p=0.022). In AOTs, analysis of immunoexpression in the parenchyma revealed positive correlations between all proteins. CONCLUSION BMPs and their receptors play an important role in the differentiation and development of ameloblastomas and AOTs, but may not explain the different biological behaviors of these lesions. The positive correlation observed in AOTs might be related to the formation of mineralized material in this tumor.
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Affiliation(s)
| | | | | | | | - Leão Pereira Pinto
- Postgraduate Program in Oral Pathology, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - Lélia Batista de Souza
- Postgraduate Program in Oral Pathology, Federal University of Rio Grande do Norte, Natal, RN, Brazil.
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Puthiyaveetil JSV, Kota K, Chakkarayan R, Chakkarayan J, Thodiyil AKP. Epithelial - Mesenchymal Interactions in Tooth Development and the Significant Role of Growth Factors and Genes with Emphasis on Mesenchyme - A Review. J Clin Diagn Res 2016; 10:ZE05-ZE09. [PMID: 27790596 DOI: 10.7860/jcdr/2016/21719.8502] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 07/26/2016] [Indexed: 11/24/2022]
Abstract
The recent advancements in medical research field mainly highlights the genetic and molecular aspects of various disease processes and related treatment options, in a specialized "custom-made" approach. The medical and dental field has made tremendous progress in providing even with the smallest insight into pathological entities, thus, making patient management more fruitful. But, short comings have occurred in dental treatments involving odontogenic lesions mainly due to poor understanding of the developmental cycle involved during early stages of developmental process. Multiple numbers of interactions take place during embryo formation and further proliferation of tissue. One such important step is the interaction between epithelium and mesenchyme which tantamount to functional requirements of an individual tooth. The role of extra cellular molecules and genes has to be studied in depth to assess the impact and significance attached to it as the synergistic function of various elements underlines the complex process of development.
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Affiliation(s)
| | - Kasim Kota
- Professor and Head, Department of Oral Pathology and Microbiology, Kannur Dental College , Kannur, Kerala, India
| | - Roopesh Chakkarayan
- Senior Lecturer, Department of Conservative Dentistry and Endodontics, Kannur Dental College , Kannur, Kerala, India
| | - Jithesh Chakkarayan
- Reader, Department of Orthodontics and Dentofacial Orthopaedics, Kannur Dental College , Kannur, Kerala, India
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60
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Kim SH, Kim S, Shin Y, Lee HS, Jeon M, Kim SO, Cho SW, Ruparel NB, Song JS. Comparative Gene Expression Analysis of the Coronal Pulp and Apical Pulp Complex in Human Immature Teeth. J Endod 2016; 42:752-9. [DOI: 10.1016/j.joen.2016.01.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 01/24/2016] [Accepted: 01/30/2016] [Indexed: 12/20/2022]
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61
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He YD, Sui BD, Li M, Huang J, Chen S, Wu LA. Site-specific function and regulation of Osterix in tooth root formation. Int Endod J 2016; 49:1124-1131. [PMID: 26599722 DOI: 10.1111/iej.12585] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 11/16/2015] [Indexed: 02/06/2023]
Abstract
Congenital diseases of tooth roots, in terms of developmental abnormalities of short and thin root phenotypes, can lead to loss of teeth. A more complete understanding of the genetic molecular pathways and biological processes controlling tooth root formation is required. Recent studies have revealed that Osterix (Osx), a key mesenchymal transcriptional factor participating in both the processes of osteogenesis and odontogenesis, plays a vital role underlying the mechanisms of developmental differences between root and crown. During tooth development, Osx expression has been identified from late embryonic to postnatal stages when the tooth root develops, particularly in odontoblasts and cementoblasts to promote their differentiation and mineralization. Furthermore, the site-specific function of Osx in tooth root formation has been confirmed, because odontoblastic Osx-conditional knockout mice demonstrate primarily short and thin root phenotypes with no apparent abnormalities in the crown (Journal of Bone and Mineral Research 30, 2014 and 742, Journal of Dental Research 94, 2015 and 430). These findings suggest that Osx functions to promote odontoblast and cementoblast differentiation and root elongation only in root, but not in crown formation. Mechanistic research shows regulatory networks of Osx expression, which can be controlled through manipulating the epithelial BMP signalling, mesenchymal Runx2 expression and cellular phosphorylation levels, indicating feasible routes of promoting Osx expression postnatally (Journal of Cellular Biochemistry 114, 2013 and 975). In this regard, a promising approach might be available to regenerate the congenitally diseased root and that regenerative therapy would be the best choice for patients with developmental tooth diseases.
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Affiliation(s)
- Y D He
- Department of Pediatric Dentistry, School of Stomatology, The Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Military Stomatology, School of Stomatology, The Fourth Military Medical University, Xi'an, China
| | - B D Sui
- State Key Laboratory of Military Stomatology, School of Stomatology, The Fourth Military Medical University, Xi'an, China.,Research and Development Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi'an, China
| | - M Li
- State Key Laboratory of Military Stomatology, School of Stomatology, The Fourth Military Medical University, Xi'an, China
| | - J Huang
- Department of Pediatric Dentistry, School of Stomatology, The Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Military Stomatology, School of Stomatology, The Fourth Military Medical University, Xi'an, China.,Department of Anatomy, Histology & Embryology, Basic Medical College, The Fourth Military Medical University, Xi'an, China
| | - S Chen
- Department of Pediatric Dentistry, School of Stomatology, The Fourth Military Medical University, Xi'an, China.,Department of Developmental Dentistry, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - L A Wu
- Department of Pediatric Dentistry, School of Stomatology, The Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Military Stomatology, School of Stomatology, The Fourth Military Medical University, Xi'an, China
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Abstract
The most common root malformations in humans arise from either developmental disorders of the root alone or disorders of radicular development as part of a general tooth dysplasia. The aim of this review is to relate the characteristics of these root malformations to potentially disrupted processes involved in radicular morphogenesis. Radicular morphogenesis proceeds under the control of Hertwig's epithelial root sheath (HERS) which determines the number, length, and shape of the root, induces the formation of radicular dentin, and participates in the development of root cementum. Formation of HERS at the transition from crown to root development appears to be very insensitive to adverse effects, with the result that rootless teeth are extremely rare. In contrast, shortened roots as a consequence of impaired or prematurely halted apical growth of HERS constitute the most prevalent radicular dysplasia which occurs due to trauma and unknown reasons as well as in association with dentin disorders. While odontoblast differentiation inevitably stops when growth of HERS is arrested, it seems to be unaffected even in cases of severe dentin dysplasias such as regional odontodysplasia and dentin dysplasia type I. As a result radicular dentin formation is at least initiated and progresses for a limited time. The only condition affecting cementogenesis is hypophosphatasia which disrupts the formation of acellular cementum through an inhibition of mineralization. A process particularly susceptible to adverse effects appears to be the formation of the furcation in multirooted teeth. Impairment or disruption of this process entails taurodontism, single-rooted posterior teeth, and misshapen furcations. Thus, even though many characteristics of human root malformations can be related to disorders of specific processes involved in radicular morphogenesis, precise inferences as to the pathogenesis of these dysplasias are hampered by the still limited knowledge on root formation.
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Affiliation(s)
- Hans U Luder
- Center of Dental Medicine, Institute of Oral Biology, University of Zurich Zurich, Switzerland
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63
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Wright JT, Curran A, Kim KJ, Yang YM, Nam SH, Shin TJ, Hyun HK, Kim YJ, Lee SH, Kim JW. Molar root-incisor malformation: considerations of diverse developmental and etiologic factors. Oral Surg Oral Med Oral Pathol Oral Radiol 2015; 121:164-72. [PMID: 26682518 DOI: 10.1016/j.oooo.2015.08.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 08/04/2015] [Accepted: 08/07/2015] [Indexed: 02/04/2023]
Abstract
OBJECTIVE The objective of this study was to evaluate the variation in the condition referred to as molar root-incisor malformation (MRIM) and elucidate the distribution of affected teeth. This study further aimed to identify associated environmental stressors. STUDY DESIGN Individuals were identified through retrospective review of dental radiographs and through referral to the investigators. Histologic evaluation included examination of mineralized and decalcified sections of affected first permanent molar teeth. RESULTS Thirty cases of MRIM were identified, with all having affected first permanent molars with dysplastic root formation. The primary second molars were affected in 57% of the cases, with permanent anterior teeth being involved in 40% of the cases. A variety of medical conditions were associated with MRIM, the most common being neurologic. Several affected individuals reported no significant past medical history or environmental stressors. CONCLUSIONS The etiology of MRIM remains unclear, and this unique developmental defect of the first permanent molar roots appears to occur in populations throughout the world. Clinicians identifying the MRIM phenotype should carefully evaluate the permanent incisors for associated developmental defects that could result in pulpal necrosis.
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Affiliation(s)
- John Timothy Wright
- Department of Pediatric Dentistry School of Dentistry, University of North Carolina, NC, USA
| | - Alice Curran
- Department of Diagnostic Sciences, School of Dentistry, University of North Carolina, NC, USA
| | - Kyoung-Jin Kim
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Yeon-Mi Yang
- Department of Pediatric Dentistry, School of Dentistry, Chonbuk National University, Jeonju-si, Jeollabuk-do, Korea
| | - Soon-Hyeun Nam
- Department of Pediatric Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Teo Jeon Shin
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Hong-Keun Hyun
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Young-Jae Kim
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Sang-Hoon Lee
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jung-Wook Kim
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea; Department of Molecular Genetics & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea.
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64
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MicroRNA 665 Regulates Dentinogenesis through MicroRNA-Mediated Silencing and Epigenetic Mechanisms. Mol Cell Biol 2015; 35:3116-30. [PMID: 26124283 DOI: 10.1128/mcb.00093-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/18/2015] [Indexed: 12/26/2022] Open
Abstract
Studies of proteins involved in microRNA (miRNA) processing, maturation, and silencing have indicated the importance of miRNAs in skeletogenesis, but the specific miRNAs involved in this process are incompletely defined. Here, we identified miRNA 665 (miR-665) as a potential repressor of odontoblast maturation. Studies with cultured cell lines and primary embryonic cells showed that miR-665 represses the expression of early and late odontoblast marker genes and stage-specific proteases involved in dentin maturation. Notably, miR-665 directly targeted Dlx3 mRNA and decreased Dlx3 expression. Furthermore, RNA-induced silencing complex (RISC) immunoprecipitation and biotin-labeled miR-665 pulldown studies identified Kat6a as another potential target of miR-665. KAT6A interacted physically and functionally with RUNX2, activating tissue-specific promoter activity and prompting odontoblast differentiation. Overexpression of miR-665 reduced the recruitment of KAT6A to Dspp and Dmp1 promoters and prevented KAT6A-induced chromatin remodeling, repressing gene transcription. Taken together, our results provide novel molecular evidence that miR-665 functions in an miRNA-epigenetic regulatory network to control dentinogenesis.
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65
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Abstract
Alveolar bone remodeling is a continuous process that takes place during development and in response to various physiological and pathological stimuli. However, detailed knowledge regarding the underlying mechanisms involved in alveolar bone development is still lacking. This study aims at improving our understanding of alveolar bone formation and the role of bone morphogenetic proteins (Bmps) in this process. Mice at embryonic (E) day 13.5 to postnatal (PN) day 15.5 were selected to observe the process of alveolar bone development. Alveolar bone development was found to be morphologically observable at E14.5. Molar teeth isolated from mice at PN7.5 were pretreated with Bmp2, Bmp4, Noggin, or BSA, and grafted subcutaneously into mice. The subcutaneously implanted tooth germs formed alveolar bone indicating the role of the dental follicle in alveolar bone development. Alveolar bone formation was increased after pretreatment with Bmp2 and Bmp4, but not with Noggin. Gene expression levels in dental follicle cells from murine molars were also determined by real-time RT-PCR. The expression levels of Runx2, Bsp, and Ocn were significantly higher in dental follicle cells cultured with Bmp2 or Bmp4, and significantly lower in those cultured with Noggin when compared with that of the BSA controls. Our results suggest that the dental follicle participates in alveolar bone formation and Bmp2/4 appears to accelerate alveolar bone development.
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Affiliation(s)
- Mingming Ou
- Department of Stomatology, Beijing Friendship Hospital, Capital Medical University , Beijing , China
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Kim TH, Bae CH, Lee JC, Kim JE, Yang X, de Crombrugghe B, Cho ES. Osterix regulates tooth root formation in a site-specific manner. J Dent Res 2015; 94:430-8. [PMID: 25568170 DOI: 10.1177/0022034514565647] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Bone and dentin share similar biochemical compositions and physiological properties. Dentin, a major tooth component, is formed by odontoblasts; in contrast, bone is produced by osteoblasts. Osterix (Osx), a zinc finger-containing transcription factor, has been identified as an essential regulator of osteoblast differentiation and bone formation. However, it has been difficult to establish whether Osx functions in odontoblast differentiation and dentin formation. To understand the role of Osx in dentin formation, we analyzed mice in which Osx was subjected to tissue-specific ablation under the control of either the Col1a1 or the OC promoter. Two independent Osx conditional knockout mice exhibited similar molar abnormalities. Although no phenotype was found in the crowns of these teeth, both mutant lines exhibited short molar roots due to impaired root elongation. Furthermore, the interradicular dentin in these mice showed severe hypoplastic features, which were likely caused by disruptions in odontoblast differentiation and dentin formation. These phenotypes were closely related to the temporospatial expression pattern of Osx during tooth development. These findings indicate that Osx is required for root formation by regulating odontoblast differentiation, maturation, and root elongation. Cumulatively, our data strongly indicate that Osx is a site-specific regulator in tooth root formation.
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Affiliation(s)
- T H Kim
- Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, South Korea
| | - C H Bae
- Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, South Korea
| | - J C Lee
- Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, South Korea
| | - J E Kim
- Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - X Yang
- Genetic Laboratory of Development and Disease, Institute of Biotechnology, Beijing, China
| | - B de Crombrugghe
- Department of Molecular Genetics, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
| | - E S Cho
- Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, South Korea
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Bosshardt DD, Stadlinger B, Terheyden H. Cell-to-cell communication--periodontal regeneration. Clin Oral Implants Res 2015; 26:229-39. [PMID: 25639287 DOI: 10.1111/clr.12543] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2014] [Indexed: 01/11/2023]
Abstract
BACKGROUND Although regenerative treatment options are available, periodontal regeneration is still regarded as insufficient and unpredictable. AIM This review article provides scientific background information on the animated 3D film Cell-to-Cell Communication - Periodontal Regeneration. RESULTS Periodontal regeneration is understood as a recapitulation of embryonic mechanisms. Therefore, a thorough understanding of cellular and molecular mechanisms regulating normal tooth root development is imperative to improve existing and develop new periodontal regenerative therapies. However, compared to tooth crown and earlier stages of tooth development, much less is known about the development of the tooth root. The formation of root cementum is considered the critical element in periodontal regeneration. Therefore, much research in recent years has focused on the origin and differentiation of cementoblasts. Evidence is accumulating that the Hertwig's epithelial root sheath (HERS) has a pivotal role in root formation and cementogenesis. Traditionally, ectomesenchymal cells in the dental follicle were thought to differentiate into cementoblasts. According to an alternative theory, however, cementoblasts originate from the HERS. What happens when the periodontal attachment system is traumatically compromised? Minor mechanical insults to the periodontium may spontaneously heal, and the tissues can structurally and functionally be restored. But what happens to the periodontium in case of periodontitis, an infectious disease, after periodontal treatment? A non-regenerative treatment of periodontitis normally results in periodontal repair (i.e., the formation of a long junctional epithelium) rather than regeneration. Thus, a regenerative treatment is indicated to restore the original architecture and function of the periodontium. Guided tissue regeneration or enamel matrix proteins are such regenerative therapies, but further improvement is required. As remnants of HERS persist as epithelial cell rests of Malassez in the periodontal ligament, these epithelial cells are regarded as a stem cell niche that can give rise to new cementoblasts. Enamel matrix proteins and members of the transforming growth factor beta (TGF-ß) superfamily have been implicated in cementoblast differentiation. CONCLUSION A better knowledge of cell-to-cell communication leading to cementoblast differentiation may be used to develop improved regenerative therapies to reconstitute periodontal tissues that were lost due to periodontitis.
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Affiliation(s)
- Dieter D Bosshardt
- Robert K. Schenk Laboratory of Oral Histology, University of Bern, Bern, Switzerland; Department of Periodontology, University of Bern, Bern, Switzerland; Department of Oral Surgery and Stomatology, University of Bern, Bern, Switzerland
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Microscopic analysis of molar--incisor malformation. Oral Surg Oral Med Oral Pathol Oral Radiol 2014; 119:544-52. [PMID: 25544405 DOI: 10.1016/j.oooo.2014.10.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 10/10/2014] [Accepted: 10/19/2014] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Molar-incisor malformation (MIM) is a newly discovered type of dental anomaly that involves a characteristic root malformation of the permanent first molars. The aim of this study was to reveal the microstructure of MIM teeth in order to determine their origin. STUDY DESIGN Four MIM teeth were extracted from a 9-year-old girl due to severe mobility. The detailed microstructure of the teeth was determined by examinations with micro-computed tomography (micro-CT), hematoxylin and eosin (H&E) staining, immunohistochemical staining, and scanning electron microscopy to reveal the detailed microstructure. RESULTS Micro-CT and H&E staining revealed the pulpal floor comprising three layers: upper, middle, and lower. Amorphous hard tissues and hyperactive cells were observed in the middle layer of the pulpal floor, and the cells stained positively for dentin sialoprotein and osteocalcin, but not for collagen XII. CONCLUSION The results of the present study imply that MIM-affected molars probably result from inappropriate differentiation of the apical pulp and dental follicle.
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Chen J, Chen G, Yan Z, Guo Y, Yu M, Feng L, Jiang Z, Guo W, Tian W. TGF-β1 and FGF2 stimulate the epithelial-mesenchymal transition of HERS cells through a MEK-dependent mechanism. J Cell Physiol 2014; 229:1647-59. [PMID: 24610459 DOI: 10.1002/jcp.24610] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 03/05/2014] [Indexed: 02/06/2023]
Abstract
Hertwig's epithelial root sheath (HERS) cells participate in cementum formation through epithelial-mesenchymal transition (EMT). Previous studies have shown that transforming growth factor beta 1 (TGF-β1) and fibroblast growth factor 2 (FGF2) are involved in inducing EMT. However, their involvement in HERS cell transition remains elusive. In this study, we confirmed that HERS cells underwent EMT during the formation of acellular cementum. We found that both TGF-β1 and FGF2 stimulated the EMT of HERS cells. The TGF-β1 regulated the differentiation of HERS cells into periodontal ligament fibroblast-like cells, and FGF2 directed the differentiation of HERS cells into cementoblast-like cells. Treatment with TGF-β1 or FGF2 inhibitor could effectively suppress HERS cells differential transition. Combined stimulation with both TGF-β1 and FGF-2 did not synergistically accelerate the EMT of HERS. Moreover, TGF-β1/FGF2-mediated EMT of HERS cells was reversed by the MEK1/2 inhibitor U0126. These results suggest that TGF-β1 and FGF2 induce the EMT of HERS through a MAPK/ERK-dependent signaling pathway. They also exert their different tendency of cellular differentiation during tooth root formation. This study further expands our knowledge of tooth root morphogenesis and provides more evidence for the use of alternative cell sources in clinical treatment of periodontal diseases.
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Affiliation(s)
- Jie Chen
- National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, P.R. China; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, P.R. China; Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, P.R. China
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Bleicher F. Odontoblast physiology. Exp Cell Res 2014; 325:65-71. [DOI: 10.1016/j.yexcr.2013.12.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/03/2013] [Accepted: 12/08/2013] [Indexed: 11/25/2022]
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Lee HS, Kim SH, Kim SO, Lee JH, Choi HJ, Jung HS, Song JS. A new type of dental anomaly: molar-incisor malformation (MIM). Oral Surg Oral Med Oral Pathol Oral Radiol 2014; 118:101-109.e3. [DOI: 10.1016/j.oooo.2014.03.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 03/07/2014] [Accepted: 03/12/2014] [Indexed: 10/25/2022]
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Strontium promotes cementoblasts differentiation through inhibiting sclerostin expression in vitro. BIOMED RESEARCH INTERNATIONAL 2014; 2014:487535. [PMID: 25003114 PMCID: PMC4070504 DOI: 10.1155/2014/487535] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 03/13/2014] [Accepted: 04/12/2014] [Indexed: 11/18/2022]
Abstract
Cementogenesis, performed by cementoblasts, is important for the repair of root resorption caused by orthodontic treatment. Based on recent studies, strontium has been applied for osteoporosis treatment due to its positive effect on osteoblasts. Although promising, the effect of strontium on cementoblasts is still unclear. So the aim of this research was to clarify and investigate the effect of strontium on cementogenesis via employing cementoblasts as model. A series of experiments including MTT, alkaline phosphatase activity, gene analysis, alizarin red staining, and western blot were carried out to evaluate the proliferation and differentiation of cementoblasts. In addition, expression of sclerostin was checked to analyze the possible mechanism. Our results show that strontium inhibits the proliferation of cementoblasts with a dose dependent manner; however, it can promote the differentiation of cementoblasts via downregulating sclerostin expression. Taking together, strontium may facilitate cementogenesis and benefit the treatment of root resorption at a low dose.
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Yang Y, Ge Y, Chen G, Yan Z, Yu M, Feng L, Jiang Z, Guo W, Tian W. Hertwig's epithelial root sheath cells regulate osteogenic differentiation of dental follicle cells through the Wnt pathway. Bone 2014; 63:158-65. [PMID: 24657304 DOI: 10.1016/j.bone.2014.03.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 03/09/2014] [Accepted: 03/12/2014] [Indexed: 02/05/2023]
Abstract
The development of periodontal ligament-cementum complex (PLCC) originates from the interaction between epithelial cells of Hertwig's epithelial root sheath (HERS) and mesenchymal cells of the dental follicle. While previous studies have suggested that the Wnt pathway is involved in osteogenic differentiation of dental follicle cells (DFCs) during tooth root development, its involvement in the interaction between DFCs and HERS cells (HERSCs) in tooth root mineralization remains unclear. Here, we investigated the hypothesis that HERSCs control osteogenic differentiation of DFCs via the Wnt pathway. We found that during co-culture with HERSCs, DFCs exhibited a greater tendency to form mineralized nodules. Moreover, under these conditions, DFCs expressed high levels of cementoblast/osteoblast differentiation-related markers, such as bone sialoprotein (BSP) and osteocalcin (OCN), the periodontal ligament phenotype-related gene type I collagen (COL1), and β-catenin (CTNNB1), a core player in the canonical Wnt pathway. In contrast, expression in DFCs of alkaline phosphatase (ALP) was greatly decreased in the presence of HERSCs. Expression of CTNNB1 in DFCs was stimulated by Wnt3a, a representative canonical member of the Wnt family of ligands, but suppressed by Dickkopf1 (DKK1), a Wnt/CTNNB1 signaling inhibitor. Furthermore, in the presence of treated dentin matrix (TDM), differentiation of DFCs was enhanced by Wnt3a when they were in direct contact with HERSCs, but was curtailed by DKK1. Taken together, these results indicate that during tooth root formation, HERSCs induce osteogenic differentiation of DFCs in a process involving the Wnt pathway and the dentin matrix. Our study not only contributes to our understanding of tooth root development and diseases of tooth root mineralization, but also proffers a novel potential strategy for controlling mineralization during tooth root regeneration.
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Affiliation(s)
- Yaling Yang
- State Key Laboratory of Oral Diseases, 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; Department of Oral and Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China
| | - Yaneng Ge
- State Key Laboratory of Oral Diseases, 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; Department of Oral and Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China
| | - Guoqing Chen
- State Key Laboratory of Oral Diseases, 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; Department of Oral and Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China
| | - Zhiling Yan
- State Key Laboratory of Oral Diseases, 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; Department of Oral and Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China
| | - Mei Yu
- State Key Laboratory of Oral Diseases, 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; Department of Oral and Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China
| | - Lian Feng
- State Key Laboratory of Oral Diseases, 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; Department of Oral and Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China
| | - Zongting Jiang
- State Key Laboratory of Oral Diseases, 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; Department of Oral and Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China
| | - Weihua Guo
- State Key Laboratory of Oral Diseases, 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; Department of Pedodontics, West China School of Stomatology, Sichuan University, No. 14, 3rd Sec., Ren Min Nan Road, Chengdu, 610041 Sichuan Province, China.
| | - Weidong Tian
- State Key Laboratory of Oral Diseases, 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; Department of Oral and Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China.
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Surapornsawasd T, Ogawa T, Tsuji M, Moriyama K. Oculofaciocardiodental syndrome: novel BCOR mutations and expression in dental cells. J Hum Genet 2014; 59:314-20. [DOI: 10.1038/jhg.2014.24] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 02/20/2014] [Accepted: 02/28/2014] [Indexed: 11/10/2022]
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Li R, Wang C, Tong J, Su Y, Lin Y, Zhou X, Ye L. WNT6 promotes the migration and differentiation of human dental pulp cells partly through c-Jun N-terminal kinase signaling pathway. J Endod 2014; 40:943-8. [PMID: 24935540 DOI: 10.1016/j.joen.2013.12.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 12/03/2013] [Accepted: 12/17/2013] [Indexed: 01/09/2023]
Abstract
INTRODUCTION During the dental pulp repair process, human dental pulp cells (HDPCs) migrate to injury sites where they may differentiate into odontoblastlike cells. WNT6 plays a role in dental development and can activate a noncanonical pathway including the c-Jun N-terminal kinase (JNK) pathway. The mechanism of WNT6 in dental pulp repair is still unknown. The purpose of this study was to explore the potential role of the WNT6/JNK signaling pathway in the promotion of cell migration and the differentiation of HDPCs. METHODS The third passage of HDPCs were cultured in vitro and treated with WNT6 conditioned medium with or without the pretreatment of JNK inhibitor SP600125. The activation of JNK was detected by Western blot, the expression of c-Jun was quantified by reverse-transcription polymerase chain reaction, the migration of HDPCs was determined by wound healing and transwell migration assays, and the differentiation of HDPCs was investigated using alkaline phosphatase staining and alizarin red staining. The expression of odontogenesis-related genes such as Runt-related transcription factor 2, dentin sialophosphoprotein, and dentin matrix protein 1 was quantified. RESULTS WNT6 activates the JNK pathway in HDPCs and enhances cell migration, mineralization nodule formation, and alkaline phosphatase activation. WNT6 also increases the expression of Runt-related transcription factor 2, dentin sialophosphoprotein, and dentin matrix protein messenger RNA in HDPCs. Blockage of the JNK pathway in HDPCs decreases but does not completely abolish the cell migration and differentiation capacity induced by WNT6. CONCLUSIONS WNT6 activates the JNK signaling pathway in HDPCs, leading to migration and differentiation.
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Affiliation(s)
- Ruimin Li
- State Key Laboratory of Oral Diseases West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Chenglin Wang
- State Key Laboratory of Oral Diseases West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Juan Tong
- State Key Laboratory of Oral Diseases West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Yingying Su
- State Key Laboratory of Oral Diseases West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Yunfeng Lin
- State Key Laboratory of Oral Diseases West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Ling Ye
- State Key Laboratory of Oral Diseases West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China.
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Emonet EG, Andossa L, Taïsso Mackaye H, Brunet M. Subocclusal dental morphology of sahelanthropus tchadensis and the evolution of teeth in hominins. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 153:116-23. [DOI: 10.1002/ajpa.22400] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 09/30/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Edouard-Georges Emonet
- Collège de France, Chaire de Paléontologie Humaine; 3, rue d'Ulm 75005 Paris France
- Institut international de Paléoprimatologie, Paléontologie Humaine: Evolution et Paléoenvironnements; UMR-CNRS 6046, faculté des Sciences, Université de Poitiers; 40 avenue du recteur Pineau 86022 Poitiers France
| | - Likius Andossa
- Département de Paléontologie; Université de N'Djamena; BP 1117 N'Djamena Tchad
| | | | - Michel Brunet
- Collège de France, Chaire de Paléontologie Humaine; 3, rue d'Ulm 75005 Paris France
- Institut international de Paléoprimatologie, Paléontologie Humaine: Evolution et Paléoenvironnements; UMR-CNRS 6046, faculté des Sciences, Université de Poitiers; 40 avenue du recteur Pineau 86022 Poitiers France
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Becerra P, Ricucci D, Loghin S, Gibbs JL, Lin LM. Histologic study of a human immature permanent premolar with chronic apical abscess after revascularization/revitalization. J Endod 2013; 40:133-9. [PMID: 24332005 DOI: 10.1016/j.joen.2013.07.017] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 07/17/2013] [Accepted: 07/23/2013] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Histologic studies of teeth from animal models of revascularization/revitalization are available; however, specimens from human studies are lacking. The nature of tissues formed in the canal of human revascularized/revitalized teeth was not well established. METHODS An immature mandibular premolar with infected necrotic pulp and a chronic apical abscess was treated with revascularization/revitalization procedures. At both the 18-month and 2-year follow-up visits, radiographic examination showed complete resolution of the periapical lesion, narrowing of the root apex without root lengthening, and minimal thickening of the canal walls. The revascularized/revitalized tooth was removed because of orthodontic treatment and processed for histologic examination. RESULTS The large canal space of revascularized/revitalized tooth was not empty and filled with fibrous connective tissue. The apical closure was caused by cementum deposition without dentin. Some cementum-like tissue was formed on the canal dentin walls. Inflammatory cells were observed in the coronal and middle third of revascularized/revitalized tissue. CONCLUSIONS In the present case, the tissue formed in the canal of a human revascularized/revitalized tooth was soft connective tissue similar to that in the periodontal ligament and cementum-like or bone-like hard tissue, which is comparable with the histology observed in the canals of teeth from animal models of revascularization/revitalization.
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Affiliation(s)
- Patricia Becerra
- Department of Endodontics, Faculty of Dentistry, University Santo Tomás in Bogotá, Bogotá, Colombia
| | | | | | - Jennifer L Gibbs
- Department of Endodontics, New York University, New York, New York
| | - Louis M Lin
- Department of Endodontics, New York University, New York, New York
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Bone morphogenetic protein-2 gene controls tooth root development in coordination with formation of the periodontium. Int J Oral Sci 2013; 5:75-84. [PMID: 23807640 PMCID: PMC3707077 DOI: 10.1038/ijos.2013.41] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/17/2013] [Indexed: 01/02/2023] Open
Abstract
Formation of the periodontium begins following onset of tooth-root formation in a coordinated manner after birth. Dental follicle progenitor cells are thought to form the cementum, alveolar bone and Sharpey's fibers of the periodontal ligament (PDL). However, little is known about the regulatory morphogens that control differentiation and function of these progenitor cells, as well as the progenitor cells involved in crown and root formation. We investigated the role of bone morphogenetic protein-2 (Bmp2) in these processes by the conditional removal of the Bmp2 gene using the Sp7-Cre-EGFP mouse model. Sp7-Cre-EGFP first becomes active at E18 in the first molar, with robust Cre activity at postnatal day 0 (P0), followed by Cre activity in the second molar, which occurs after P0. There is robust Cre activity in the periodontium and third molars by 2 weeks of age. When the Bmp2 gene is removed from Sp7(+) (Osterix(+)) cells, major defects are noted in root, cellular cementum and periodontium formation. First, there are major cell autonomous defects in root-odontoblast terminal differentiation. Second, there are major alterations in formation of the PDLs and cellular cementum, correlated with decreased nuclear factor IC (Nfic), periostin and α-SMA(+) cells. Third, there is a failure to produce vascular endothelial growth factor A (VEGF-A) in the periodontium and the pulp leading to decreased formation of the microvascular and associated candidate stem cells in the Bmp2-cKO(Sp7-Cre-EGFP). Fourth, ameloblast function and enamel formation are indirectly altered in the Bmp2-cKO(Sp7-Cre-EGFP). These data demonstrate that the Bmp2 gene has complex roles in postnatal tooth development and periodontium formation.
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