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Kenessey DE, Stojanowski CM, Paul KS. Evaluating predictions of the patterning cascade model of crown morphogenesis in the human lower mixed and permanent dentition. PLoS One 2024; 19:e0304455. [PMID: 38935640 PMCID: PMC11210800 DOI: 10.1371/journal.pone.0304455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 05/13/2024] [Indexed: 06/29/2024] Open
Abstract
OBJECTIVE The patterning cascade model of crown morphogenesis has been studied extensively in a variety of organisms to elucidate the evolutionary history surrounding postcanine tooth form. The current research is the first to use a large modern human sample to examine whether the crown configuration of lower deciduous and permanent molars aligns with expectations derived from the model. This study has two main goals: 1) to determine if metameric and antimeric pairs significantly differ in size, accessory trait expression, and relative intercusp spacing, and 2) assess whether the relative distance among early-forming cusps accounts for observed variation in accessory cusp expression. METHODS Tooth size, intercusp distance, and morphological trait expression data were collected from 3D scans of mandibular dental casts representing participants of the Harvard Solomon Islands Project. Paired tests were utilized to compare tooth size, accessory trait expression, and relative intercusp distance between diphyodont metameres and permanent antimeres. Proportional odds logistic regression was implemented to investigate how the odds of greater accessory cusp expression vary as a function of the distance between early-developing cusps. RESULTS/SIGNIFICANCE Comparing paired molars, significant differences were identified for tooth size and cusp 5 expression. Several relative intercusp distances emerged as important predictors of cusp 6 expression, however, results for cusp 5 and cusp 7 did not match expected patterns. These findings support previous quantitative genetic results and suggest the development of neighboring crown structures represents a zero-sum partitioning of cellular territory and resources. As such, this study contributes to a better understanding of the foundations of deciduous and permanent molar crown variation in humans.
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Affiliation(s)
- Dori E. Kenessey
- Department of Anthropology, U niversity of Nevada, Reno, Nevada, United States of America
| | - Christopher M. Stojanowski
- Center for Bioarchaeological Research, School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona, United States of America
| | - Kathleen S. Paul
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, United States of America
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Blankenship-Sefczek EC, Goodman AH, Hubbe M, Hunter JP, Guatelli-Steinberg D. Nutritional supplementation, tooth crown size, and trait expression in individuals from Tezonteopan, Mexico. PLoS One 2024; 19:e0305123. [PMID: 38843220 PMCID: PMC11156277 DOI: 10.1371/journal.pone.0305123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 05/23/2024] [Indexed: 06/09/2024] Open
Abstract
Understanding how epigenetic factors impact dental phenotypes can help refine the use of teeth for elucidating biological relationships among human populations. We explored relationships among crown size, principal cusp spacing, and accessory cusp expression in maxillary dental casts of nutritionally supplemented (n = 34) and non-supplemented (n = 39) individuals from Tezonteopan, Mexico. We hypothesized that the non-supplemented group would exhibit smaller molar crowns and reduced intercusp spacing. Since intercusp spacing is thought to be more sensitive to epigenetic influences than crown size, we predicted that the supplemented and non-supplemented groups would differ more in the former than the latter. Previous work suggests that molar accessory cusp expression may be elevated under conditions of stress. We therefore expected evidence of greater Carabelli and Cusp 5 trait expression in the non-supplemented group. We further hypothesized that anterior teeth would be affected by nutritional stress during development, with the non-supplemented group having smaller anterior tooth crowns and therefore limited space to form the tuberculum dentale. Finally, we tested whether the presence of molar accessory traits followed predictions of the Patterning Cascade Model of tooth morphogenesis in the entire sample. Our results supported the expectation that cusp spacing would differ more than molar crown size between the two groups. Carabelli trait showed little evidence of frequency differences between groups, but some evidence of greater trait scores in the non-supplemented group. The non-supplemented group also showed evidence of greater Cusp 5 frequency and expression. In the central incisors and canines, there was strong evidence for smaller crown sizes and reduced tuberculum dentale frequency in the non-supplemented group. With both groups pooled together, there was strong evidence of closer mesiodistal distances among principal cusps in molars with accessory cusps, a finding that is consistent with the PCM. Overall, our findings suggest that nutritional stress may affect accessory cusp expression.
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Affiliation(s)
- Erin C. Blankenship-Sefczek
- Department of Oral Biology, School of Dentistry, Creighton University, Omaha, Nebraska, United States of America
- Department of Anthropology, The Ohio State University, Columbus, Ohio, United States of America
| | - Alan H. Goodman
- School of Natural Sciences, Hampshire College, Amherst, Massachusetts, United States of America
| | - Mark Hubbe
- Department of Anthropology, The Ohio State University, Columbus, Ohio, United States of America
| | - John P. Hunter
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Newark, Ohio, United States of America
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3
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Shinde S, Elangovan R, Maganti DC, Milanes Zambrano D, Agholor CN, Das A. Protostylid: Contributing and Aggravating Factor for Periodontitis. Cureus 2024; 16:e58347. [PMID: 38756302 PMCID: PMC11096637 DOI: 10.7759/cureus.58347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 04/14/2024] [Indexed: 05/18/2024] Open
Abstract
Clinicians should be well-versed in the anatomy, variations, and teeth anomalies. Developmental disturbances of the teeth can lead to alterations in size, shape, number, structure, and eruption of the teeth. Developmental disturbances can lead to germination, fusion, concrescence, dilaceration, talons, cusps, dens in dente, etc. Protostylid, an additional cusp on the buccal aspect of the maxillary molar, which is a rare clinical finding, can lead to plaque accumulation, making oral hygiene maintenance difficult. This leads to clinical attachment loss and bone loss. This condition may often go undiagnosed. It should be diagnosed to prevent further complications. This case has been reported to make clinicians aware of the importance of diagnosing the case at the earliest possible time so that complications can be prevented and management is easier. From the perspective of forensic dentistry, this morphological feature, though uncommon, may be useful for the classification and identification of victims in mass causalities and bite marks on bodies or inanimate objects. This is one of the rarest cases of protostylids reported to date. This may not only pose a significant problem in endodontic therapy due to morphological alterations in root canals and periodontal therapy due to grove formation leading to an inability to maintain a plaque-free area (bone loss) but also be of very significant interest from the perspective of forensic dentistry.
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Affiliation(s)
- Sanket Shinde
- Periodontology, Ram Krishna Dharmarth Foundation University, Bhopal, IND
| | - Ramnath Elangovan
- Periodontology, School of Dentistry, University of Rwanda, Kigali, RWA
| | - Dinesh C Maganti
- Periodontology, School of Dentistry, University of Rwanda, Kigali, RWA
| | - Danilo Milanes Zambrano
- Pediatric Dentistry and Orthodontics, School of Dentistry, University of Rwanda, Kigali, RWA
| | - Collins N Agholor
- Prosthodontics and Restorative Dentistry, School of Dentistry, University of Rwanda, Kigali, RWA
| | - Anwesha Das
- Periodontology, Sri Aurobindo College of Dentistry, Indore, IND
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A Mutation in CACNA1S Is Associated with Multiple Supernumerary Cusps and Root Maldevelopment. Diagnostics (Basel) 2023; 13:diagnostics13050895. [PMID: 36900039 PMCID: PMC10000453 DOI: 10.3390/diagnostics13050895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/21/2023] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
BACKGROUND Enamel knots and Hertwig epithelial root sheath (HERS) regulate the growth and folding of the dental epithelium, which subsequently determines the final form of tooth crown and roots. We would like to investigate the genetic etiology of seven patients affected with unique clinical manifestations, including multiple supernumerary cusps, single prominent premolars, and single-rooted molars. METHODS Oral and radiographic examination and whole-exome or Sanger sequencing were performed in seven patients. Immunohistochemical study during early tooth development in mice was performed. RESULTS A heterozygous variant (c. 865A>G; p.Ile289Val) in CACNA1S was identified in all the patients, but not in an unaffected family member and control. Immunohistochemical study showed high expression of Cacna1s in the secondary enamel knot. CONCLUSIONS This CACNA1S variant seemed to cause impaired dental epithelial folding; too much folding in the molars and less folding in the premolars; and delayed folding (invagination) of HERS, which resulted in single-rooted molars or taurodontism. Our observation suggests that the mutation in CACNA1S might disrupt calcium influx, resulting in impaired dental epithelium folding, and subsequent abnormal crown and root morphology.
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Stuhlträger J, Kullmer O, Wittig RM, Kupczik K, Schulz-Kornas E. Variability in molar crown morphology and cusp wear in two Western chimpanzee populations. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023; 181:29-44. [PMID: 36807569 DOI: 10.1002/ajpa.24707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 01/11/2023] [Accepted: 01/24/2023] [Indexed: 02/23/2023]
Abstract
OBJECTIVES Chimpanzees (Pan troglodytes) possess a relatively generalized molar morphology allowing them to access a wide range of foods. Comparisons of crown and cusp morphology among the four subspecies have suggested relatively large intraspecific variability. Here, we compare molar crown traits and cusp wear of two geographically close populations of Western chimpanzees, P. t. verus, to provide further information on intraspecific dental variability. MATERIALS AND METHODS Micro-CT reconstructions of high-resolution replicas of first and second molars of two Western chimpanzee populations from Ivory Coast (Taï National Park) and Liberia, respectively were used for this study. First, we analyzed projected tooth and cusp 2D areas as well as the occurrence of cusp six (C6) on lower molars. Second, we quantified the molar cusp wear three-dimensionally to infer how the individual cusps alter with advancing wear. RESULTS Both populations are similar in their molar crown morphology, except for a higher appearance rate of a C6 in Taï chimpanzees. In Taï chimpanzees, lingual cusps of upper molars and buccal cusps of lower molars possess an advanced wear pattern compared to the remaining cusps, while in Liberian chimpanzees this wear gradient is less pronounced. DISCUSSION The similar crown morphology between both populations fits with previous descriptions for Western chimpanzees and provides additional data on dental variation within this subspecies. The wear pattern of the Taï chimpanzees are in concordance with their observed tool rather than tooth use to open nuts/seeds, while the Liberian chimpanzees may have consumed hard food items crushed between their molars.
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Affiliation(s)
- Julia Stuhlträger
- Former Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Group Animal Husbandry and Ecology, Group Animal Breeding, Institute of Agricultural and Nutritional Sciences, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Ottmar Kullmer
- Division of Paleoanthropology, Senckenberg Research Institute and Natural History Museum Frankfurt, Frankfurt am Main, Germany
- Department of Paleobiology and Environment, Institute of Ecology, Evolution, and Diversity, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Roman M Wittig
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, CSRS, Abidjan, Ivory Coast
- Institute for Cognitive Sciences, CNRS UMR5229 University Claude Bernard Lyon 1, Bron, France
| | - Kornelius Kupczik
- Former Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Department of Anthropology, Faculty of Social Sciences, University of Chile, Santiago de Chile, Chile
| | - Ellen Schulz-Kornas
- Former Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Department of Cariology, Endodontics and Periodontology, University of Leipzig, Leipzig, Germany
- Section Mammalogy and Palaeoanthropology, Leibniz Institute for the Analysis of Biodiversity Change and University of Hamburg, Hamburg, Germany
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Hardin AM, Knigge RP, Duren DL, Williams-Blangero S, Subedi J, Mahaney MC, Sherwood RJ. Genetic influences on dentognathic morphology in the Jirel population of Nepal. Anat Rec (Hoboken) 2022; 305:2137-2157. [PMID: 34981668 PMCID: PMC9250551 DOI: 10.1002/ar.24857] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022]
Abstract
Patterns of genetic variation and covariation impact the evolution of the craniofacial complex and contribute to clinically significant malocclusions in modern human populations. Previous quantitative genetic studies have estimated the heritabilities and genetic correlations of skeletal and dental traits in humans and nonhuman primates, but none have estimated these quantitative genetic parameters across the dentognathic complex. A large and powerful pedigree from the Jirel population of Nepal was leveraged to estimate heritabilities and genetic correlations in 62 maxillary and mandibular arch dimensions, incisor and canine lengths, and post-canine tooth crown areas (N ≥ 739). Quantitative genetic parameter estimation was performed using maximum likelihood-based variance decomposition. Residual heritability estimates were significant for all traits, ranging from 0.269 to 0.898. Genetic correlations were positive for all trait pairs. Principal components analyses of the phenotypic and genetic correlation matrices indicate an overall size effect across all measurements on the first principal component. Additional principal components demonstrate positive relationships between post-canine tooth crown areas and arch lengths and negative relationships between post-canine tooth crown areas and arch widths, and between arch lengths and arch widths. Based on these findings, morphological variation in the human dentognathic complex may be constrained by genetic relationships between dental dimensions and arch lengths, with weaker genetic correlations between these traits and arch widths allowing for variation in arch shape. The patterns identified are expected to have impacted the evolution of the dentognathic complex and its genetic architecture as well as the prevalence of dental crowding in modern human populations.
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Affiliation(s)
- Anna M. Hardin
- Biology Department, Western Oregon University
- Craniofacial Research Center, Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine
- Department of Orthopaedic Surgery, University of Missouri School of Medicine
| | - Ryan P. Knigge
- Craniofacial Research Center, Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine
- Department of Orthopaedic Surgery, University of Missouri School of Medicine
- Department of Integrative Biology and Physiology, University of Minnesota Medical School
| | - Dana L. Duren
- Craniofacial Research Center, Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine
- Department of Orthopaedic Surgery, University of Missouri School of Medicine
| | - Sarah Williams-Blangero
- South Texas Diabetes and Obesity Institute, School of Medicine, University of Texas Rio Grande Valley
| | | | - Michael C. Mahaney
- South Texas Diabetes and Obesity Institute, School of Medicine, University of Texas Rio Grande Valley
- Department of Human Genetics, School of Medicine, University of Texas Rio Grande Valley
| | - Richard J. Sherwood
- Craniofacial Research Center, Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine
- Department of Orthopaedic Surgery, University of Missouri School of Medicine
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Tamborini M. A Plea for a New Synthesis: From Twentieth-Century Paleobiology to Twenty-First-Century Paleontology and Back Again. BIOLOGY 2022; 11:1120. [PMID: 35892976 PMCID: PMC9394316 DOI: 10.3390/biology11081120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/22/2022] [Accepted: 07/24/2022] [Indexed: 11/16/2022]
Abstract
In this paper, I will briefly discuss the elements of novelty and continuity between twentieth-century paleobiology and twenty-first-century paleontology. First, I will outline the heated debate over the disciplinary status of paleontology in the mid-twentieth century. Second, I will analyze the main theoretical issue behind this debate by considering two prominent case studies within the broader paleobiology agenda. Third, I will turn to twenty-first century paleontology and address five representative research topics. In doing so, I will characterize twenty-first century paleontology as a science that strives for more data, more technology, and more integration. Finally, I will outline what twenty-first-century paleontology might inherit from twentieth-century paleobiology: the pursuit of and plea for a new synthesis that could lead to a second paleobiological revolution. Following in the footsteps of the paleobiological revolution of the 1960s and 1970s, the paleobiological revolution of the twenty-first century would enable paleontologists to gain strong political representation and argue with a decisive voice at the "high table" on issues such as the expanded evolutionary synthesis, the conservation of Earth's environment, and global climate change.
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Affiliation(s)
- Marco Tamborini
- Department of Philosophy, Technische Universität Darmstadt, Marktplatz 15 (Residenzschloss), 64283 Darmstadt, Germany
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Morita W, Morimoto N, Otsu K, Miura T. Stripe and spot selection in cusp patterning of mammalian molar formation. Sci Rep 2022; 12:9149. [PMID: 35701484 PMCID: PMC9197828 DOI: 10.1038/s41598-022-13539-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/25/2022] [Indexed: 11/09/2022] Open
Abstract
Tooth development is governed largely by epithelial-mesenchymal interactions and is mediated by numerous signaling pathways. This type of morphogenetic processes has been explained by reaction-diffusion systems, especially in the framework of a Turing model. Here we focus on morphological and developmental differences between upper and lower molars in mice by modeling 2D pattern formation in a Turing system. Stripe vs. spot patterns are the primary types of variation in a Turing model. We show that the complexity of the cusp cross-sections can distinguish between stripe vs. spot patterns, and mice have stripe-like upper and spot-like lower molar morphologies. Additionally, our computational modeling that incorporates empirical data on tooth germ growth traces the order of cusp formation and relative position of the cusps in upper and lower molars in mice. We further propose a hypothetical framework of developmental mechanism that could help us understand the evolution of the highly variable nature of mammalian molars associated with the acquisition of the hypocone and the increase of lophedness.
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Affiliation(s)
- Wataru Morita
- Department of Anthropology, National Museum of Nature and Science, Ibaraki, Japan.
| | - Naoki Morimoto
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Keishi Otsu
- Division of Developmental Biology and Regenerative Medicine, Department of Anatomy, Iwate Medical University, Iwate, Japan
| | - Takashi Miura
- Department of Anatomy and Cell Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Paul KS, Stojanowski CM, Hughes T, Brook AH, Townsend GC. Genetic Correlation, Pleiotropy, and Molar Morphology in a Longitudinal Sample of Australian Twins and Families. Genes (Basel) 2022; 13:genes13060996. [PMID: 35741762 PMCID: PMC9222655 DOI: 10.3390/genes13060996] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 01/01/2023] Open
Abstract
This study aims to expand our understanding of the genetic architecture of crown morphology in the human diphyodont dentition. Here, we present bivariate genetic correlation estimates for deciduous and permanent molar traits and evaluate the patterns of pleiotropy within (e.g., m1–m2) and between (e.g., m2–M1) dentitions. Morphology was observed and scored from dental models representing participants of an Australian twin and family study (deciduous n = 290, permanent n = 339). Data collection followed Arizona State University Dental Anthropology System standards. Genetic correlation estimates were generated using maximum likelihood variance components analysis in SOLAR v.8.1.1. Approximately 23% of deciduous variance components models and 30% of permanent variance components models yielded significant genetic correlation estimates. By comparison, over half (56%) of deciduous–permanent homologues (e.g., m2 hypocone–M1 hypocone) were significantly genetically correlated. It is generally assumed that the deciduous and permanent molars represent members of a meristic molar field emerging from the primary dental lamina. However, stronger genetic integration among m2–M1/M2 homologues than among paired deciduous traits suggests the m2 represents the anterior-most member of a “true” molar field. The results indicate genetic factors act at distinct points throughout development to generate homologous molar form, starting with the m2, which is later replaced by a permanent premolariform crown.
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Affiliation(s)
- Kathleen S. Paul
- Department of Anthropology, University of Arkansas, Fayetteville, AR 72701, USA
- Correspondence: ; Tel.: +1-479-718-1352
| | - Christopher M. Stojanowski
- Center for Bioarchaeological Research, School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287, USA;
| | - Toby Hughes
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia; (T.H.); (A.H.B.)
| | - Alan H. Brook
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia; (T.H.); (A.H.B.)
- Barts and the London Dental Institute, Queen Mary University of London, London EC1M 6AX, UK
| | - Grant C. Townsend
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia; (T.H.); (A.H.B.)
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Bermúdez de Castro JM, García-Campos C, Sarmiento S, Martinón-Torres M. The protoconid: a key cusp in lower molars. Evidence from a recent modern human population. Ann Hum Biol 2022; 49:145-151. [PMID: 35521995 DOI: 10.1080/03014460.2022.2074539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
BACKGROUND The molar (M) size sequence in the genus Homo is decreasing and the general pattern in Homo sapiens is M1 > M2 > M3. AIM To gain a better understanding of the reduction patterns of molar components (cusps), we aim to assess the area of the protoconid, the phylogenetically oldest cusp of the lower molars. SUBJECT AND METHODS We measured the protoconid and the total crown area in the scaled photographs of a recent modern human sample of lower molars (76 males and 39 females). The values were statistically analysed. RESULTS The absolute size of the protoconid increases significantly between M1 and M2/M3, whereas the relative size of this cusp increases significantly from M1 to M3. In the latter, reduction or disappearance of the cusps of the talonid is common. CONCLUSIONS The results can be explained in the framework of the patterning cascade model. As the first cusp to appear developmentally, the protoconid forms in response to signals from the primary enamel knot, likely contributing to its stability. Inhibitory signals emitted during the protoconid formation may lead to the reduction or disappearance of the talonid cusps, if these do not have enough time to form before the end of the molar morphogenetic process.
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Affiliation(s)
- José María Bermúdez de Castro
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH). Paseo de la Sierra de Atapuerca 3, 09002, Burgos, Spain.,Anthropology Department, University College London, London, UK
| | - Cecilia García-Campos
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH). Paseo de la Sierra de Atapuerca 3, 09002, Burgos, Spain
| | - Susana Sarmiento
- Universidad Isabel I, Calle de Fernán González, 76, 09003 Burgos, Spain
| | - María Martinón-Torres
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH). Paseo de la Sierra de Atapuerca 3, 09002, Burgos, Spain.,Anthropology Department, University College London, London, UK
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11
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The biological significance of tooth identification based on developmental and evolutional viewpoints. J Oral Biosci 2022; 64:287-302. [DOI: 10.1016/j.job.2022.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 11/22/2022]
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12
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Lafuma F, Corfe IJ, Clavel J, Di-Poï N. Multiple evolutionary origins and losses of tooth complexity in squamates. Nat Commun 2021; 12:6001. [PMID: 34650041 PMCID: PMC8516937 DOI: 10.1038/s41467-021-26285-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/27/2021] [Indexed: 11/21/2022] Open
Abstract
Teeth act as tools for acquiring and processing food, thus holding a prominent role in vertebrate evolution. In mammals, dental-dietary adaptations rely on tooth complexity variations controlled by cusp number and pattern. Complexity increase through cusp addition has dominated the diversification of mammals. However, studies of Mammalia alone cannot reveal patterns of tooth complexity conserved throughout vertebrate evolution. Here, we use morphometric and phylogenetic comparative methods across fossil and extant squamates to show they also repeatedly evolved increasingly complex teeth, but with more flexibility than mammals. Since the Late Jurassic, multiple-cusped teeth evolved over 20 times independently from a single-cusped common ancestor. Squamates frequently lost cusps and evolved varied multiple-cusped morphologies at heterogeneous rates. Tooth complexity evolved in correlation with changes in plant consumption, resulting in several major increases in speciation. Complex teeth played a critical role in vertebrate evolution outside Mammalia, with squamates exemplifying a more labile system of dental-dietary evolution.
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Affiliation(s)
- Fabien Lafuma
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, FI-00014, Helsinki, Finland.
| | - Ian J Corfe
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, FI-00014, Helsinki, Finland.
- Geological Survey of Finland, FI-02150, Espoo, Finland.
| | - Julien Clavel
- Department of Life Sciences, The Natural History Museum, London, SW7 5BD, UK
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Nicolas Di-Poï
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, FI-00014, Helsinki, Finland.
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Kataoka K, Fujita H, Isa M, Gotoh S, Arasaki A, Ishida H, Kimura R. The human EDAR 370V/A polymorphism affects tooth root morphology potentially through the modification of a reaction-diffusion system. Sci Rep 2021; 11:5143. [PMID: 33664401 PMCID: PMC7933414 DOI: 10.1038/s41598-021-84653-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 02/15/2021] [Indexed: 01/31/2023] Open
Abstract
Morphological variations in human teeth have long been recognized and, in particular, the spatial and temporal distribution of two patterns of dental features in Asia, i.e., Sinodonty and Sundadonty, have contributed to our understanding of the human migration history. However, the molecular mechanisms underlying such dental variations have not yet been completely elucidated. Recent studies have clarified that a nonsynonymous variant in the ectodysplasin A receptor gene (EDAR 370V/A; rs3827760) contributes to crown traits related to Sinodonty. In this study, we examined the association between the EDAR polymorphism and tooth root traits by using computed tomography images and identified that the effects of the EDAR variant on the number and shape of roots differed depending on the tooth type. In addition, to better understand tooth root morphogenesis, a computational analysis for patterns of tooth roots was performed, assuming a reaction-diffusion system. The computational study suggested that the complicated effects of the EDAR polymorphism could be explained when it is considered that EDAR modifies the syntheses of multiple related molecules working in the reaction-diffusion dynamics. In this study, we shed light on the molecular mechanisms of tooth root morphogenesis, which are less understood in comparison to those of tooth crown morphogenesis.
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Affiliation(s)
- Keiichi Kataoka
- Department of Human Biology and Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa, 903-0215, Japan
- Department of Oral and Maxillofacial Functional Rehabilitation, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Hironori Fujita
- Astrobiology Center, National Institutes of Natural Sciences, Tokyo, Japan
- National Institute for Basic Biology, National Institutes of Natural Sciences, Aichi, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate School for Advanced Studies), Aichi, Japan
| | - Mutsumi Isa
- Department of Human Biology and Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa, 903-0215, Japan
| | - Shimpei Gotoh
- Department of Human Biology and Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa, 903-0215, Japan
- Department of Oral and Maxillofacial Functional Rehabilitation, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Akira Arasaki
- Department of Oral and Maxillofacial Functional Rehabilitation, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Hajime Ishida
- Department of Human Biology and Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa, 903-0215, Japan
| | - Ryosuke Kimura
- Department of Human Biology and Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa, 903-0215, Japan.
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Malik Z, Roth DM, Eaton F, Theodor JM, Graf D. Mesenchymal Bmp7 Controls Onset of Tooth Mineralization: A Novel Way to Regulate Molar Cusp Shape. Front Physiol 2020; 11:698. [PMID: 32719613 PMCID: PMC7350786 DOI: 10.3389/fphys.2020.00698] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 05/28/2020] [Indexed: 01/14/2023] Open
Abstract
Investigating the molecular basis for tooth shape variation provides an important glimpse into the evolution of tooth function. We recently showed that loss of mesenchymal BMP7 is sufficient to alter morphology and function of the toothrow. Here we report on the underlying mechanism. Expression of mesenchymal Bmp7 is observed at sites where mineralization is initiated, in tooth cusps of developing molars. Neural crest-specific deletion of Bmp7 (Bmp7ncko) resulted in a complete lack of dentin/enamel formation at birth, the time when mineralization is normally initiated in the upper molars, similar to what was observed in Bmp2ncko mice. Unlike loss of Bmp2, loss of Bmp7 did not affect odontoblast polarization and did not significantly alter the levels of pSmad1/5/8, but almost completely abolished canonical Wnt signaling in (pre)-ameloblasts. Tooth mineralization resumed with a 48-h delay allowing for additional mesenchymal proliferation. Enamel volume was still reduced at P4 and P8, but was comparable in erupted teeth, which were broader and had altered cusp shapes. Tooth eruption was also delayed. Overall, enamel appeared inconspicuous, although some structural changes along with reduced mineral density could be observed. Loss of Bmp7 led to an increase in mesenchymal Bmp6 suggesting an interplay between Bmp6 and Bmp7 in the regulation of mineralization initiation. Our findings show that regulation of the onset of tooth mineralization is a hitherto unsuspected mechanism controlling tooth shape variation. Initiation of tooth mineralization is regulated by a complex epithelial-mesenchymal Bmp/Wnt-signaling network to which Bmp7 contributes. This network is separate and independent of the Bmp2-signaling network regulating odontoblast cell polarization. From an evolutionary perspective, addition of Bmp7 as initiator of tooth mineralization might be akin to an upgrade of an existing computer operating system. While not essential, it provides obviously sufficient advantage warranting its evolutionary incorporation.
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Affiliation(s)
- Zeba Malik
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Daniela M Roth
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Farah Eaton
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Jessica M Theodor
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Daniel Graf
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.,Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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15
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Brocklehurst N. Morphological evolution in therocephalians breaks the hypercarnivore ratchet. Proc Biol Sci 2020; 286:20190590. [PMID: 30966993 DOI: 10.1098/rspb.2019.0590] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Large carnivorous mammals have been suggested to show a ratchet-like mode of morphological evolution. A limited number of specializations for hypercarnivory evolve repeatedly in multiple clades, with those lineages evolving such specialities being unable to retreat back along their evolutionary trajectory or jump between adaptive peaks. While it has been hypothesized that such mechanisms should have applied to the evolution of other terrestrial carnivores, the non-mammalian synapsid clade Therocephalia appears to defy this expectation. The earliest, basalmost members of this clade are large macropredators, and it is later that small carnivores appear, seemingly evolving from top-predator ancestors. In order to test this reading of therocephalian evolution, variation in rates of body size evolution were tested for and incorporated into an ancestral reconstruction. Similar studies were made of the evolution of discrete characters related to carnivory. All analyses indicate the ancestral therocephalian was a large macro-predator, with serrated teeth, elongated canines and robust lower jaws. Small sizes apparently evolve later. It is therefore suggested that the hypercarnivore ratchet is a feature of mammalian evolution.
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Affiliation(s)
- Neil Brocklehurst
- Department of Earth Sciences, University of Oxford , 3 South Parks Road, Oxford OX1 3AN , UK
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16
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Morita W, Morimoto N, Kono RT, Suwa G. Metameric variation of upper molars in hominoids and its implications for the diversification of molar morphogenesis. J Hum Evol 2019; 138:102706. [PMID: 31785453 DOI: 10.1016/j.jhevol.2019.102706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 10/20/2019] [Accepted: 10/20/2019] [Indexed: 11/18/2022]
Abstract
Metameric variation of molar size is in part associated with the dietary adaptations of mammals and results from slight alterations of developmental processes. Humans and great apes exhibit conspicuous variation in tooth morphology both between taxa and across tooth types. However, the manner in which metameric variation in molars emerged among apes and humans via evolutionary alterations in developmental processes remains largely unknown. In this study, we compare the enamel-dentine junction of the upper molars of humans-which closely correlates with morphology of the outer enamel surface and is less affected by wear-with that of the other extant hominoids: chimpanzees, bonobos, gorillas, orangutans, and gibbons. We used the morphometric mapping method to quantify and visualize three-dimensional morphological variation, and applied multivariate statistical analyses. Results revealed the following: 1) extant hominoids other than humans share a common pattern of metameric variation characterized by a largely linear change in morphospace; this indicates a relatively simple graded change in metameric molar shape; 2) intertaxon morphological differences become less distinct from the mesial to distal molars; and 3) humans diverge from the extant ape pattern in exhibiting a distinct metameric shape change trajectory in the morphospace. The graded shape change and lower intertaxon resolution from the mesial to distal molars are consistent with the concept of a 'key' tooth. The common metameric pattern observed among the extant nonhuman hominoids indicates that developmental patterns underlying metameric variation were largely conserved during ape evolution. Furthermore, the human-specific metameric pattern suggests considerable developmental modifications in the human lineage.
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Affiliation(s)
- Wataru Morita
- Developmental Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland; Department of Oral Functional Anatomy, Faculty of Dental Medicine, Hokkaido University, Hokkaido, Japan.
| | - Naoki Morimoto
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan.
| | - Reiko T Kono
- Faculty of Letters, Keio University, Kanagawa, Japan
| | - Gen Suwa
- The University Museum, The University of Tokyo, Tokyo, Japan
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Bai B, Meng J, Mao FY, Zhang ZQ, Wang YQ. A new early Eocene deperetellid tapiroid illuminates the origin of Deperetellidae and the pattern of premolar molarization in Perissodactyla. PLoS One 2019; 14:e0225045. [PMID: 31703104 PMCID: PMC6839866 DOI: 10.1371/journal.pone.0225045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/28/2019] [Indexed: 11/19/2022] Open
Abstract
Deperetellidae is a clade of peculiar, Asian endemic tapiroids from the early and middle Eocene. The previously published material mainly comprises maxillae, mandibles, and some postcranial elements. However, the absence of cranial materials and primitive representatives of the deperetellids obscures their phylogenetic relationships within Tapiroidea. Furthermore, derived deperetellids have completely molarized premolars, but the pattern of their evolution remains unclear. Here, we report a nearly complete skull and some carpals of a new basal deperetellid tapiroid, Irenolophus qii gen. et sp. nov., from the late early Eocene of the Erlian Basin, Inner Mongolia, China. We suggest that deperetellids (along with Tapiridae) probably also arose from some basal 'helaletids', based on the reduced, flat, lingually depressed metacones on the upper molars, the trend towards the bilophodonty on the lower molars, and a shallow narial notch with the premaxilla in contact with the nasal. The molarization of the premolars in Deperetellidae from Irenolophus through Teleolophus to Deperetella was initiated and gradually enhanced by the separation between the paraconule and the protocone. That pattern differs from the protocone-hypocone separation in helaletids, tapirids, and most rhinoceroses, and the metaconule-derived pseudohypocone in amynodontids. However, the specific relationship of deperetellids within Tapiroidea and the roles of different patterns of premolar molarization in perissodactyl evolution need further and comprehensive study.
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Affiliation(s)
- Bin Bai
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenviroment, Beijing, China
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China
| | - Jin Meng
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- Division of Paleontology, American Museum of Natural History, New York, United States of America
- Earth and Environmental Sciences, Graduate Center, City University of New York, New York, United States of America
| | - Fang-Yuan Mao
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenviroment, Beijing, China
- Division of Paleontology, American Museum of Natural History, New York, United States of America
| | - Zhao-Qun Zhang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenviroment, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yuan-Qing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenviroment, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
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18
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Pillai JP, Patel D. Novel application of the ‘Hardy-Weinberg equilibrium’ in the analysis of cusp patterning phenotype in Gujarati Population. FORENSIC SCIENCE INTERNATIONAL: REPORTS 2019. [DOI: 10.1016/j.fsir.2019.100046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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19
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Maier C, Dumančić J, Brkić H, Kaić Z, Savić Pavičin I, Poje Z, Scott GR. Tooth Crown Morphology in Turner and Klinefelter Syndrome Individuals from a Croatian Sample. Acta Stomatol Croat 2019; 53:106-118. [PMID: 31341318 PMCID: PMC6604557 DOI: 10.15644/asc53/2/2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 06/01/2019] [Indexed: 10/31/2022] Open
Abstract
OBJECTIVE Turner syndrome (TS) and Klinefelter syndrome (KS) represent the two most common X chromosome aneuploidies, each associated with systemic disruptions to growth and development. Effects of these conditions on tooth crown morphology are explored in a sample of Croatian individuals. MATERIALS AND METHODS The sample included 57 TS, 37 KS and 88 control individuals. Dental crown morphology was scored on dental casts according to the Turner-Scott Dental Anthropology System. RESULTS Incisor shoveling and the hypocone were significantly different between TS individuals and both control and KS individuals. Individuals with TS exhibit lower grades of expression than either group. Furthermore, the number of lingual cusps on the mandibular premolars, the hypoconulid on the mandibular second molar, and cusp 7 on the mandibular first molar were significantly different, though pair-wise comparisons did not elucidate these differences. Tuberculum dentale, distal accessory ridge, and Carabelli's trait were expressed similarly to the control. KS individuals were not significantly different from control individuals for any trait, though this may be related to sample size. CONCLUSIONS Previous studies suggest the loss of an X chromosome has a reducing effect on dental crown morphology, which is confirmed in this research. TS individuals exhibit generally simpler dental morphology compared to the control sample, though some traits are expressed comparably to the control sample. The effects of KS are less clear. Though previous studies suggest that the presence of an extra X chromosome increases dental crown dimensions, there was no notable effect on crown morphology in this study.
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Affiliation(s)
- Christopher Maier
- Eckerd College, Department of Anthropology, 4200 54 Ave. S. St. Petersburg, FL 33711, USA
| | - Jelena Dumančić
- University of Zagreb School of Dental Medicine, Department of Dental Anthropology, Zagreb, Croatia
- Department of Dental Medicine, University Hospital Centre Zagreb, Croatia
| | - Hrvoje Brkić
- University of Zagreb School of Dental Medicine, Department of Dental Anthropology, Zagreb, Croatia
- Department of Dental Medicine, University Hospital Centre Zagreb, Croatia
| | - Zvonimir Kaić
- Croatian Dental Chamber, Zagreb, Croatia
- Croatian Academy of Medical Sciences, Zagreb, Croatia
| | - Ivana Savić Pavičin
- University of Zagreb School of Dental Medicine, Department of Dental Anthropology, Zagreb, Croatia
| | - Zvonko Poje
- Croatian Dental Chamber, Zagreb, Croatia
- Croatian Academy of Medical Sciences, Zagreb, Croatia
| | - G. Richard Scott
- University of Nevada, Reno, Department of Anthropology, 1664 N. Virginia St., Reno, NVUSA
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20
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Barbière F, Ronez C, Ortiz PE, Martin RA, Pardiñas UFJ. A new nomenclatural system for the study of sigmodontine rodent molars: first step towards an integrative phylogeny of fossil and living cricetids. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz021] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Franck Barbière
- Instituto Superior de Correlación Geológica (INSUGEO), Yerba Buena, Tucumán, Argentina
| | - Christophe Ronez
- Instituto de Diversidad y Evolución Austral (IDEAus-CONICET), Puerto Madryn, Chubut, Argentina
| | - Pablo E Ortiz
- Instituto Superior de Correlación Geológica (INSUGEO), Yerba Buena, Tucumán, Argentina
- Cátedra de Paleontología, Facultad de Ciencias Naturales e Instituto Miguel Lillo, San Miguel de Tucumán, Argentina
| | - Robert A Martin
- Department of Biological Sciences, Murray State University, Murray, KT, USA
| | - Ulyses F J Pardiñas
- Instituto de Diversidad y Evolución Austral (IDEAus-CONICET), Puerto Madryn, Chubut, Argentina
- Instituto Nacional de Biodiversidad (INABIO), Quito, Ecuador
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21
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Insulin-like growth factor 1 modulates bioengineered tooth morphogenesis. Sci Rep 2019; 9:368. [PMID: 30675004 PMCID: PMC6344556 DOI: 10.1038/s41598-018-36863-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/21/2018] [Indexed: 11/08/2022] Open
Abstract
Regenerative therapy to replace missing teeth is a critical area of research. Functional bioengineered teeth have been produced by the organ germ method using mouse tooth germ cells. However, these bioengineered teeth are significantly smaller in size and exhibit an abnormal crown shape when compared with natural teeth. The proper sizes and shapes of teeth contribute to their normal function. Therefore, a method is needed to control the morphology of bioengineered teeth. Here, we investigated whether insulin-like growth factor 1 (IGF1) can regulate the sizes and shapes of bioengineered teeth, and assessed underlying mechanisms of such regulation. IGF1 treatment significantly increased the size of bioengineered tooth germs, while preserving normal tooth histology. IGF1-treated bioengineered teeth, which were developed from bioengineered tooth germs in subrenal capsules and jawbones, showed increased sizes and cusp numbers. IGF1 increased the number of fibroblast growth factor (Fgf4)-expressing enamel knots in bioengineered tooth germs and enhanced the proliferation and differentiation of dental epithelial and mesenchymal cells. This study is the first to reveal that IGF1 increases the sizes and cusp numbers of bioengineered teeth via the induction of enamel knot formation, as well as the proliferation and differentiation of dental epithelial and mesenchymal cells.
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22
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Nakayama M, Kondo O, Pesonen P, Alvesalo L, Lähdesmäki R. Influence of long and short arms of X chromosome on maxillary molar crown morphology. PLoS One 2018; 13:e0207070. [PMID: 30439977 PMCID: PMC6237344 DOI: 10.1371/journal.pone.0207070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 10/24/2018] [Indexed: 12/03/2022] Open
Abstract
Although genes on the human X chromosome reportedly influence tooth crown morphology, little is known about X chromosome activation or inactivation systems relevant to morphological variations. We assessed the relationships between tooth crown size and crown morphological traits in females with Turner syndrome, the variants of which include complete absence of one X chromosome, lack of the short arm (Xp), or duplication of the long arms (Xq), and then estimated the functions of Xp and Xq in the process of unilateral X chromosome inactivation during tooth crown development. The mesiodistal and buccolingual diameters in the maxillary first (M1) and second (M2) permanent molars were compared among X chromosome karyotypes by multiple regression analyses, and their relationships with the development of Carabelli’s cusp and the distolingual cusp were analyzed using logistic regression analysis. The crown sizes increased in the order of the 46,X,i(Xq) karyotype, 45,X and 45,X/46,XX karyotypes, and control group. A lower frequency of Carabelli’s cusp and higher frequency of a reduced distolingual cusp in M1 were characteristics of Turner syndrome. The overall M1 and M2 crown sizes differed among the X chromosome karyotypes, whereas a smaller crown size was associated with a reduced distolingual cusp but not with Carabelli’s cusp. Considering the differences in chromosome arrangement among females with Turner syndrome and the process of unilateral X chromosome inactivation, the observed results can be considered in terms of quantity or number of promoters/inhibitors during tooth crown development. The X chromosome karyotypes have a strong influence on the overall crown sizes of the M1 and M2 molars because those karyotypes with variable numbers of active gene regions directly influence tooth germ development in an early stage of human odontogenesis. The later forming cusps, such as the distolingual cusp and Carabelli’s cusp, may be affected by this developmental prerequisite.
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Affiliation(s)
- Mitsuko Nakayama
- Oral Development and Orthodontics, Research Unit of Oral Health Sciences, Medical Faculty, University of Oulu, Oulu, Finland
- Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland
- Department of Anatomy I, Nihon University, School of Dentistry at Matsudo, Matsudo, Japan
- * E-mail:
| | - Osamu Kondo
- Department of Biological Science, Graduate School of Science, University of Tokyo, Tokyo, Japan
| | - Paula Pesonen
- Northern Finland Birth Cohorts, Faculty of Medicine, University of Oulu, Oulu, Finland
| | - Lassi Alvesalo
- Oral Development and Orthodontics, Research Unit of Oral Health Sciences, Medical Faculty, University of Oulu, Oulu, Finland
| | - Raija Lähdesmäki
- Oral Development and Orthodontics, Research Unit of Oral Health Sciences, Medical Faculty, University of Oulu, Oulu, Finland
- Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland
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23
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Billet G, Bardin J. Serial Homology and Correlated Characters in Morphological Phylogenetics: Modeling the Evolution of Dental Crests in Placentals. Syst Biol 2018; 68:267-280. [DOI: 10.1093/sysbio/syy071] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 10/22/2018] [Indexed: 01/24/2023] Open
Affiliation(s)
- Guillaume Billet
- CR2P, UMR 7207, Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, 8 rue Buffon 75005 Paris, France
| | - Jérémie Bardin
- CR2P, UMR 7207, Sorbonne Université, MNHN, CNRS, T.46-56, E.5, case 104, 4 place Jussieu, 75252 Paris cedex 05, France
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24
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Weiss KM. The tales genes tell (or not): A century of exploration. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 165:741-753. [PMID: 29574847 DOI: 10.1002/ajpa.23333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 09/13/2017] [Accepted: 09/20/2017] [Indexed: 12/19/2022]
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25
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Guatelli-Steinberg D. Dental anthropology in the AJPA: Its roots and heights. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 165:879-892. [PMID: 29574842 DOI: 10.1002/ajpa.23352] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/12/2017] [Accepted: 10/18/2017] [Indexed: 11/06/2022]
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26
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Constantino PJ, Bush MB, Barani A, Lawn BR. On the evolutionary advantage of multi-cusped teeth. J R Soc Interface 2017; 13:rsif.2016.0374. [PMID: 27558851 DOI: 10.1098/rsif.2016.0374] [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: 05/12/2016] [Accepted: 07/28/2016] [Indexed: 11/12/2022] Open
Abstract
A hallmark of mammalian evolution is a progressive complexity in postcanine tooth morphology. However, the driving force for this complexity remains unclear: whether to expand the versatility in diet source, or to bolster tooth structural integrity. In this study, we take a quantitative approach to this question by examining the roles of number, position and height of multiple cusps in determining sustainable bite forces. Our approach is to use an extended finite-element methodology with due provision for step-by-step growth of an embedded crack to determine how fracture progresses with increasing occlusal load. We argue that multi-cusp postcanine teeth are well configured to withstand high bite forces provided that multiple cusps are contacted simultaneously to share the load. However, contact on a single near-wall cusp diminishes the strength. Location of the load points and cusp height, rather than cusp number or radius, are principal governing factors. Given these findings, we conclude that while complex tooth structures can enhance durability, increases in cusp number are more likely to be driven by the demands of food manipulation. Structural integrity of complex teeth is maintained when individual cusps remain sufficiently distant from the side walls and do not become excessively tall relative to tooth width.
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Affiliation(s)
- Paul J Constantino
- Department of Biology, Saint Michael's College, Colchester, VT 05439, USA
| | - Mark B Bush
- School of Mechanical and Chemical Engineering, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Amir Barani
- School of Mechanical and Chemical Engineering, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Brian R Lawn
- Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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27
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Ortiz A, Bailey SE, Hublin JJ, Skinner MM. Homology, homoplasy and cusp variability at the enamel-dentine junction of hominoid molars. J Anat 2017; 231:585-599. [PMID: 28718921 PMCID: PMC5603786 DOI: 10.1111/joa.12649] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2017] [Indexed: 12/25/2022] Open
Abstract
Evolutionary studies of mammalian teeth have generally concentrated on the adaptive and functional significance of dental features, whereas the role of development on phenotypic generation and as a source of variation has received comparatively little attention. The present study combines an evolutionary biological framework with state-of-the-art imaging techniques to examine the developmental basis of variation of accessory cusps. Scholars have long used the position and relatedness of cusps to other crown structures as a criterion for differentiating between developmentally homologous and homoplastic features, which can be evaluated with greater accuracy at the enamel-dentine junction (EDJ). Following this approach, we collected digital models of the EDJ and outer enamel surface of more than 1000 hominoid teeth to examine whether cusp 5 of the upper molars (UM C5) and cusps 6 and 7 of the lower molars (LM C6 and LM C7) were associated each with a common developmental origin across species. Results revealed that each of these cusps can develop in a variety of ways, in association with different dental tissues (i.e. oral epithelium, enamel matrix) and dental structures (i.e. from different cusps, crests and cingula). Both within and between species variability in cusp origin was highest in UM C5, followed by LM C7, and finally LM C6. The lack of any species-specific patterns suggests that accessory cusps in hominoids are developmentally homoplastic and that they may not be useful for identifying phylogenetic homology. An important and unanticipated finding of this study was the identification of a new taxonomically informative feature at the EDJ of the upper molars, namely the post-paracone tubercle (PPT). We found that the PPT was nearly ubiquitous in H. neanderthalensis and the small sample of Middle Pleistocene African and European humans (MPAE) examined, differing significantly from the low frequencies observed in all other hominoids, including Pleistocene and recent H. sapiens. We emphasize the utility of the EDJ for human evolutionary studies and demonstrate how features that look similar at the external surface may be the product of different developmental patterns. This study also highlights the importance of incorporating both developmental and morphological data into evolutionary studies in order to gain a better understanding of the evolutionary significance of dental and skeletal features.
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Affiliation(s)
- Alejandra Ortiz
- Institute of Human Origins, School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, USA
| | - Shara E Bailey
- Department of Anthropology, Center for the Study of Human Origins, New York University, New York, NY, USA
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Matthew M Skinner
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- School of Anthropology and Conservation, University of Kent, Canterbury, UK
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28
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Paul KS, Stojanowski CM. Comparative performance of deciduous and permanent dental morphology in detecting biological relatives. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2017. [DOI: 10.1002/ajpa.23260] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Kathleen S. Paul
- Center for Bioarchaeological Research, School of Human Evolution and Social Change; Arizona State University; Tempe AZ 85287
| | - Christopher M. Stojanowski
- Center for Bioarchaeological Research, School of Human Evolution and Social Change; Arizona State University; Tempe AZ 85287
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29
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Solé F, Ladevèze S. Evolution of the hypercarnivorous dentition in mammals (Metatheria,Eutheria) and its bearing on the development of tribosphenic molars. Evol Dev 2017; 19:56-68. [DOI: 10.1111/ede.12219] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Floréal Solé
- Evo-Devo of Vertebrate Dentition; Institut de Génomique Fonctionnelle de Lyon; Ecole Normale Supérieure de Lyon; Université de Lyon; UCBL 1 CNRS, Lyon France
| | - Sandrine Ladevèze
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P, UMR 7207); Sorbonne Universités MNHN CNRS UPMC-Paris6; Muséum national d'Histoire naturelle; 57 rue Cuvier CP 38 F-75005 Paris France
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30
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Martin RM, Hublin JJ, Gunz P, Skinner MM. The morphology of the enamel–dentine junction in Neanderthal molars: Gross morphology, non-metric traits, and temporal trends. J Hum Evol 2017; 103:20-44. [DOI: 10.1016/j.jhevol.2016.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 12/15/2022]
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31
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Nova Delgado M, Galbany J, Pérez-Pérez A. Molar shape variability in platyrrhine primates. J Hum Evol 2016; 99:79-92. [PMID: 27650581 DOI: 10.1016/j.jhevol.2016.07.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 07/18/2016] [Accepted: 07/22/2016] [Indexed: 11/26/2022]
Abstract
Recent phylogenetic analyses suggest that platyrrhines constitute a monophyletic group represented by three families: Cebidae, Atelidae, and Pitheciidae. Morphological variability between and within these three families, however, is widely discussed and debated. The aim of this study was to assess molar shape variability in platyrrhines, to explore patterns of interspecific variation among extant species, and to evaluate how molar shape can be used as a taxonomic indicator. The analyses were conducted using standard multivariate analyses of geometric morphometric data from 802 platyrrhine lower molars. The results indicated that the interspecific variation exhibited a highly homoplastic pattern related to functional adaptation of some taxa. However, phylogeny was also an important factor in shaping molar morphological traits, given that some phenotypic similarities were consistent with current phylogenetic positions. Our results show that the phylogenetic and functional signals of lower molar shape vary depending on the taxa and the tooth considered. Based on molar shape, Aotus showed closer similarities to Callicebus, as well as to some Cebidae and Ateles-Lagothrix, due to convergent evolutionary trends caused by similar dietary habits, or due to fast-evolving branches in the Aotus lineage, somewhat similar to the shape of Callicebus and Cebidae.
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Affiliation(s)
- Mónica Nova Delgado
- Secció de Zoologia i Antropologia Biològica, Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
| | - Jordi Galbany
- Secció de Zoologia i Antropologia Biològica, Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain; Center for the Advanced Study of Human Paleobiology, Department of Anthropology, George Washington University, 800 22nd Street NW, Ste 6000, Washington, D.C. 20052, USA
| | - Alejandro Pérez-Pérez
- Secció de Zoologia i Antropologia Biològica, Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain.
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32
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Le Luyer M, Coquerelle M, Rottier S, Bayle P. Internal Tooth Structure and Burial Practices: Insights into the Neolithic Necropolis of Gurgy (France, 5100-4000 cal. BC). PLoS One 2016; 11:e0159688. [PMID: 27447183 PMCID: PMC4957824 DOI: 10.1371/journal.pone.0159688] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 07/05/2016] [Indexed: 02/01/2023] Open
Abstract
Variations in the dental crown form are widely studied to interpret evolutionary changes in primates as well as to assess affinities among human archeological populations. Compared to external metrics of dental crown size and shape, variables including the internal structures such as enamel thickness, tissue proportions, and the three-dimensional shape of enamel-dentin junction (EDJ), have been described as powerful measurements to study taxonomy, phylogenetic relationships, dietary, and/or developmental patterns. In addition to providing good estimate of phenotypic distances within/across archeological samples, these internal tooth variables may help to understand phylogenetic, functional, and developmental underlying causes of variation. In this study, a high resolution microtomographic-based record of upper permanent second molars from 20 Neolithic individuals of the necropolis of Gurgy (France) was applied to evaluate the intrasite phenotypic variation in crown tissue proportions, thickness and distribution of enamel, and EDJ shape. The study aims to compare interindividual dental variations with burial practices and chronocultural parameters, and suggest underlying causes of these dental variations. From the non-invasive characterization of internal tooth structure, differences have been found between individuals buried in pits with alcove and those buried in pits with container and pits with wattling. Additionally, individuals from early and recent phases of the necropolis have been distinguished from those of the principal phase from their crown tissue proportions and EDJ shape. The results suggest that the internal tooth structure may be a reliable proxy to track groups sharing similar chronocultural and burial practices. In particular, from the EDJ shape analysis, individuals buried in an alcove shared a reduction of the distolingual dentin horn tip (corresponding to the hypocone). Environmental, developmental and/or functional underlying causes might be suggested for the origin of phenotypic differences shared by these individuals buried in alcoves.
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Affiliation(s)
- Mona Le Luyer
- Unité Mixte de Recherche 5199, de la Préhistoire à l’Actuel: Culture, Environnement, Anthropologie (UMR 5199 PACEA), Université de Bordeaux, Pessac, France
- * E-mail:
| | | | - Stéphane Rottier
- Unité Mixte de Recherche 5199, de la Préhistoire à l’Actuel: Culture, Environnement, Anthropologie (UMR 5199 PACEA), Université de Bordeaux, Pessac, France
| | - Priscilla Bayle
- Unité Mixte de Recherche 5199, de la Préhistoire à l’Actuel: Culture, Environnement, Anthropologie (UMR 5199 PACEA), Université de Bordeaux, Pessac, France
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33
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Nova Delgado M, Galbany J, Pérez-Pérez A. Morphometric variation of extant platyrrhine molars: taxonomic implications for fossil platyrrhines. PeerJ 2016; 4:e1967. [PMID: 27190704 PMCID: PMC4867715 DOI: 10.7717/peerj.1967] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/04/2016] [Indexed: 12/25/2022] Open
Abstract
The phylogenetic position of many fossil platyrrhines with respect to extant ones is not yet clear. Two main hypotheses have been proposed: the layered or successive radiations hypothesis suggests that Patagonian fossils are Middle Miocene stem platyrrhines lacking modern descendants, whereas the long lineage hypothesis argues for an evolutionary continuity of all fossil platyrrhines with the extant ones. Our geometric morphometric analysis of a 15 landmark-based configuration of platyrrhines' first and second lower molars suggest that morphological stasis may explain the reduced molar shape variation observed. Platyrrhine lower molar shape might be a primitive retention of the ancestral state affected by strong ecological constraints throughout the radiation of the main platyrrhine families. The Patagonian fossil specimens showed two distinct morphological patterns of lower molars, Callicebus-like and Saguinus-like, which might be the precursors of the extant forms, whereas the Middle Miocene specimens, though showing morphological resemblances with the Patagonian fossils, also displayed new, derived molar patterns, Alouatta-like and Pitheciinae-like, thereby suggesting that despite the overall morphological stasis of molars, phenotypic diversification of molar shape was already settled during the Middle Miocene.
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Affiliation(s)
- Mónica Nova Delgado
- Department of Evolutionary Biology, Ecology and Environmental Sciences, Zoology and Physical Anthropology Section, Universitat de Barcelona , Barcelona , Spain
| | - Jordi Galbany
- Department of Evolutionary Biology, Ecology and Environmental Sciences, Zoology and Physical Anthropology Section, Universitat de Barcelona, Barcelona, Spain; Center for the Advanced Study of Human Paleobiology, Department of Anthropology, George Washington University, Washington DC, United States of America
| | - Alejandro Pérez-Pérez
- Department of Evolutionary Biology, Ecology and Environmental Sciences, Zoology and Physical Anthropology Section, Universitat de Barcelona , Barcelona , Spain
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34
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Morita W, Morimoto N, Ohshima H. Exploring metameric variation in human molars: a morphological study using morphometric mapping. J Anat 2016; 229:343-55. [PMID: 27098351 DOI: 10.1111/joa.12482] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2016] [Indexed: 12/01/2022] Open
Abstract
Human molars exhibit a type of metameric variation, which is the difference in serially repeated morphology within an organism. Various theories have been proposed to explain how this variation is brought about in the molars. Actualistic data that support the theories, however, are still relatively scarce because of methodological limitations. Here we propose new methods to analyse detailed tooth crown morphologies. We applied morphometric mapping to the enamel-dentine junction of human maxillary molars and examined whether odontogenetic models were adaptable to human maxillary molars. Our results showed that the upper first molar is phenotypically distinct among the maxillary molars. The average shape of the upper first molar is characterized by four well-defined cusps and precipitous surface relief of the occlusal table. On the other hand, upper third molar is characterized by smooth surface relief of the occlusal table and shows greater shape variation and distinct distribution patterns in morphospace. The upper second molar represents an intermediate state between first and third molar. Size-related shape variation was investigated by the allometric vector analysis, and it appeared that human maxillary molars tend to converge toward the shape of the upper first molar as the size increases. Differences between the upper first molar and the upper second and third molar can thus be largely explained as an effect of allometry. Collectively, these results indicate that the observed pattern of metameric variation in human molars is consistent with odontogenetic models of molar row structure (inhibitory cascade model) and molar crown morphology (patterning cascade model). This study shows that morphometric mapping is a useful tool to visualize and quantify the morphological features of teeth, which can provide the basis for a better understanding of tooth evolution linking morphology and development.
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Affiliation(s)
- Wataru Morita
- Department of Oral Functional Anatomy, Hokkaido University Graduate School of Dental Medicine, Sapporo, Japan.,Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Naoki Morimoto
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Hayato Ohshima
- Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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35
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Couzens AMC, Evans AR, Skinner MM, Prideaux GJ. The role of inhibitory dynamics in the loss and reemergence of macropodoid tooth traits. Evolution 2016; 70:568-85. [DOI: 10.1111/evo.12866] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 12/22/2015] [Accepted: 01/02/2016] [Indexed: 12/21/2022]
Affiliation(s)
- Aidan M. C. Couzens
- School of Biological Sciences; Flinders University; Bedford Park, South Australia 5042 Australia
| | - Alistair R. Evans
- School of Biological Sciences; Monash University; Victoria 3800 Australia
- Geosciences; Museum Victoria; Melbourne Victoria 3001 Australia
| | - Matthew M. Skinner
- School of Anthropology and Conservation; University of Kent; Kent CT2 7NZ United Kingdom
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig 04103 Germany
| | - Gavin J. Prideaux
- School of Biological Sciences; Flinders University; Bedford Park, South Australia 5042 Australia
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36
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Yamamoto N, Oshima M, Tanaka C, Ogawa M, Nakajima K, Ishida K, Moriyama K, Tsuji T. Functional tooth restoration utilising split germs through re-regionalisation of the tooth-forming field. Sci Rep 2015; 5:18393. [PMID: 26673152 PMCID: PMC4682098 DOI: 10.1038/srep18393] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 11/17/2015] [Indexed: 12/11/2022] Open
Abstract
The tooth is an ectodermal organ that arises from a tooth germ under the regulation of reciprocal epithelial-mesenchymal interactions. Tooth morphogenesis occurs in the tooth-forming field as a result of reaction-diffusion waves of specific gene expression patterns. Here, we developed a novel mechanical ligation method for splitting tooth germs to artificially regulate the molecules that control tooth morphology. The split tooth germs successfully developed into multiple correct teeth through the re-regionalisation of the tooth-forming field, which is regulated by reaction-diffusion waves in response to mechanical force. Furthermore, split teeth erupted into the oral cavity and restored physiological tooth function, including mastication, periodontal ligament function and responsiveness to noxious stimuli. Thus, this study presents a novel tooth regenerative technology based on split tooth germs and the re-regionalisation of the tooth-forming field by artificial mechanical force.
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Affiliation(s)
- Naomi Yamamoto
- Department of Maxillofacial Orthognathics, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, 113-8510, JAPAN.,Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, JAPAN
| | - Masamitsu Oshima
- Department of Oral Rehabilitation and Regenerative Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 700-8525, JAPAN.,Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, JAPAN
| | - Chie Tanaka
- Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, JAPAN
| | - Miho Ogawa
- Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, JAPAN.,Organ Technologies Inc., Tokyo, 108-0074, JAPAN.,RIKEN Center for Developmental Biology, Kobe, Hyogo, 650-0047, JAPAN
| | - Kei Nakajima
- Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, JAPAN.,Department of Clinical Pathophysiology, Tokyo Dental College, Chiyoda-ku, Tokyo, 101-0061, JAPAN
| | - Kentaro Ishida
- Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, JAPAN.,Department of Physics and Mathematics, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, Kanagawa, 252-5258, JAPAN
| | - Keiji Moriyama
- Department of Maxillofacial Orthognathics, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, 113-8510, JAPAN
| | - Takashi Tsuji
- Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, JAPAN.,Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, JAPAN.,Organ Technologies Inc., Tokyo, 108-0074, JAPAN.,RIKEN Center for Developmental Biology, Kobe, Hyogo, 650-0047, JAPAN
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37
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Delgado MN, Galbany J, Górka K, Pérez-Pérez A. Taxonomic Implications of Molar Morphology Variability in Capuchins. INT J PRIMATOL 2015. [DOI: 10.1007/s10764-015-9850-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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38
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Tapaltsyan V, Charles C, Hu J, Mindell D, Ahituv N, Wilson GM, Black BL, Viriot L, Klein OD. Identification of novel Fgf enhancers and their role in dental evolution. Evol Dev 2015; 18:31-40. [PMID: 26086993 DOI: 10.1111/ede.12132] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Mammalian dental morphology is under strong evolutionary pressure because of its importance for mastication and diet. While the mechanisms underlying tooth development have been widely studied in model organisms, the role of genetic regulatory elements in patterning the different elements of the occlusal surface and crown height across species is not well understood. Previous studies showed that Fibroblast Growth Factor (FGF) genes are important regulators of tooth development that influence morphological variation. We hypothesized that inter-specific variation in rodent dental morphology could be governed by nucleotide variation in genetic regulatory elements that modulate the spatial and temporal expression of the genes encoding FGF signaling molecules. In this study, we compared the variation in dental morphology across nine taxa of rodents to the variation in sequences of non-coding evolutionary conserved regions (ECRs) of Fgf3, 4, 8, 9, and 10. We correlated the variation in molar tooth cusp shape and the evolution of high molar crowns (hypsodonty) to the patterns of sequence variation in two ECRs, Fgf10ECR3, and Fgf9ECR1, respectively. By conducting luciferase and electrophoretic mobility shift assays, we determined that these ECRs could function as enhancers. These data suggest that emergence of hypsodonty and occlusal cusp patterning may have happened through the evolutionary changes in enhancers, such as Fgf9ECR1 and Fgf10ECR3, which affected the expression of major signaling molecules involved in tooth development.
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Affiliation(s)
- Vagan Tapaltsyan
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California San Francisco, San Francisco, CA 94143, USA
| | - Cyril Charles
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California San Francisco, San Francisco, CA 94143, USA.,Team Evo-Devo of Vertebrate Dentition, Institut de Génomique Fonctionnelle de Lyon, ENS de Lyon, Université de Lyon, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Jianxin Hu
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - David Mindell
- Division of Environmental Biology, National Science Foundation, Arlington, VA 22230, USA
| | - Nadav Ahituv
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA.,Institute for Human Genetics, University of California San Francisco, San Francisco, CA 94143, USA
| | - Gregory M Wilson
- Department of Biology, University of Central Oklahoma, Edmond, OK 73034, USA
| | - Brian L Black
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Laurent Viriot
- Team Evo-Devo of Vertebrate Dentition, Institut de Génomique Fonctionnelle de Lyon, ENS de Lyon, Université de Lyon, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Ophir D Klein
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California San Francisco, San Francisco, CA 94143, USA.,Institute for Human Genetics, University of California San Francisco, San Francisco, CA 94143, USA.,Department of Pediatrics, University of California San Francisco, San Francisco, CA 94143, USA
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39
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Nakayama M, Lähdesmäki R, Niinimaa A, Alvesalo L. Molar morphology and the expression of Carabelli's trait in 45,X females. Am J Hum Biol 2015; 27:486-93. [DOI: 10.1002/ajhb.22674] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 11/16/2014] [Accepted: 12/04/2014] [Indexed: 11/08/2022] Open
Affiliation(s)
- Mitsuko Nakayama
- Oral Development and Orthodontics; Oral Health Research Unit; Medical Faculty; University of Oulu; Finland
| | - Raija Lähdesmäki
- Oral Development and Orthodontics; Oral Health Research Unit; Medical Faculty; University of Oulu; Finland
- Medical Research Center; University hospital of Oulu; Finland
| | - Ahti Niinimaa
- Oral Development and Orthodontics; Oral Health Research Unit; Medical Faculty; University of Oulu; Finland
| | - Lassi Alvesalo
- Oral Development and Orthodontics; Oral Health Research Unit; Medical Faculty; University of Oulu; Finland
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40
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Hubbard AR, Guatelli-Steinberg D, Irish JD. Do nuclear DNA and dental nonmetric data produce similar reconstructions of regional population history? An example from modern coastal Kenya. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 157:295-304. [DOI: 10.1002/ajpa.22714] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 01/19/2015] [Accepted: 01/28/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Amelia R. Hubbard
- Department of Sociology and Anthropology; Wright State University; Dayton OH
| | - Debbie Guatelli-Steinberg
- Department of Anthropology; Department of Evolution; Ecology; and Organismal Biology; The Ohio State University; Columbus OH
| | - Joel D. Irish
- Research Centre in Evolutionary Anthropology and Palaeoecology; Liverpool John Moores University; Liverpool UK
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41
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Kimura R, Watanabe C, Kawaguchi A, Kim YI, Park SB, Maki K, Ishida H, Yamaguchi T. Common polymorphisms in WNT10A affect tooth morphology as well as hair shape. Hum Mol Genet 2015; 24:2673-80. [DOI: 10.1093/hmg/ddv014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 01/16/2015] [Indexed: 11/14/2022] Open
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42
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Polychronis G, Halazonetis DJ. Shape covariation between the craniofacial complex and first molars in humans. J Anat 2014; 225:220-31. [PMID: 24916927 PMCID: PMC4111929 DOI: 10.1111/joa.12202] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2014] [Indexed: 12/31/2022] Open
Abstract
The occurrence of mutual genetic loci in morphogenesis of the face and teeth implies shape covariation between these structures. However, teeth finalize their shape at an early age, whereas the face grows and is subjected to environmental influences for a prolonged period; it is therefore conceivable that covariation might modulate with age. Here we investigate the extent of this covariation in humans by measuring the 3D shape of the occlusal surface of the permanent first molars and the shape of the craniofacial complex from lateral radiographs, at two maturations stages. A sample of Greek subjects was divided into two groups (110 adult, 110 prepubertal) with equally distributed gender. The occlusal surfaces of the right first molars were 3D scanned from dental casts; 265 and 274 landmarks (including surface and curve semilandmarks) were digitized on the maxillary and mandibular molars, respectively. The corresponding lateral cephalometric radiographs were digitized with 71 landmarks. Geometric morphometric methods were used to assess shape variation and covariation. The vertical dimension of the craniofacial complex was the main parameter of shape variation, followed by anteroposterior deviations. The male craniofacial complex was larger (4.0-5.7%) and was characterized by a prominent chin and clockwise rotation of the cranial base (adult group only). Allometry was weak and statistically significant only when examined for the sample as a whole (percent variance explained: 2.1%, P = 0.0002). Covariation was statistically significant only between the lower first molar and the craniofacial complex (RV = 14.05%, P = 0.0099, and RV = 12.31%, P = 0.0162, for the prepubertal and adult groups, respectively). Subtle age-related covariation differences were noted, indicating that environmental factors may influence the pattern and strength of covariation. However, the main pattern was similar in both groups: a class III skeletal pattern (relative maxillary retrusion and mandibular protrusion), hyperdivergency, forward rotation of the posterior cranial base and upward rotation of the anterior cranial base were associated with mesiodistal elongation of the lower molars and height reduction of their distal cusps. This pattern mimics phylogeny in humans, where flexion and counterclockwise rotation of the cranial base, considered advantageous to survival, co-occur with tooth reductions that cannot be easily explained in evolutionary terms. The similarity of the phylogenetic and covariation patterns seems to support the pleiotropic gene hypothesis.
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Affiliation(s)
- Georgios Polychronis
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
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43
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Morita W, Yano W, Nagaoka T, Abe M, Ohshima H, Nakatsukasa M. Patterns of morphological variation in enamel-dentin junction and outer enamel surface of human molars. J Anat 2014; 224:669-80. [PMID: 24689536 PMCID: PMC4025894 DOI: 10.1111/joa.12180] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2014] [Indexed: 11/29/2022] Open
Abstract
Tooth crown patterning is governed by the growth and folding of the inner enamel epithelium (IEE) and the following enamel deposition forms outer enamel surface (OES). We hypothesized that overall dental crown shape and covariation structure are determined by processes that configurate shape at the enamel-dentine junction (EDJ), the developmental vestige of IEE. This this hypothesis was tested by comparing patterns of morphological variation between EDJ and OES in human permanent maxillary first molar (UM1) and deciduous second molar (um2). Using geometric morphometric methods, we described morphological variation and covariation between EDJ and OES, and evaluated the strength of two components of phenotypic variability, canalization and morphological integration, in addition to the relevant evolutionary flexibility, i.e. the ability to respond to selective pressure. The strength of covariation between EDJ and OES was greater in um2 than in UM1, and the way that multiple traits covary between EDJ and OES was different between these teeth. The variability analyses showed that EDJ had less shape variation and a higher level of morphological integration than OES, which indicated that canalization and morphological integration acted as developmental constraints. These tendencies were greater in UM1 than in um2. On the other hand, EDJ and OES had a comparable level of evolvability in these teeth. Amelogenesis could play a significant role in tooth shape and covariation structure, and its influence was not constant among teeth, which may be responsible for the differences in the rate and/or period of enamel formation.
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Affiliation(s)
- Wataru Morita
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto UniversityKyoto, Japan
| | - Wataru Yano
- Department of Oral Anatomy, Division of Oral Structure, Function and Development, Asahi University School of DentistryMizuho, Gifu, Japan
| | - Tomohito Nagaoka
- Department of Anatomy, St. Marianna University School of MedicineKawasaki, Kanagawa, Japan
| | - Mikiko Abe
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City UniversityOsaka, Japan
| | - Hayato Ohshima
- Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental SciencesNiigata, Japan
| | - Masato Nakatsukasa
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto UniversityKyoto, Japan
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Lai WF, Lee JM, Jung HS. Molecular and engineering approaches to regenerate and repair teeth in mammals. Cell Mol Life Sci 2014; 71:1691-701. [PMID: 24270857 PMCID: PMC11113857 DOI: 10.1007/s00018-013-1518-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 12/16/2022]
Abstract
Continuous replacement of teeth throughout the lifespan of an individual is possibly basal for most of the vertebrates including fish and reptiles; however, mammals generally have a limited capacity of tooth renewal. The ability to induce cellular differentiation in adults to replace lost or damaged cells in mammals, or to tissue-engineer organs in vitro, has hence become one of the major goals of regenerative medicine. In this article, we will revisit some of the important signals and tissue interactions that regulate mammalian tooth development, and will offer a synopsis of the latest progress in tooth regeneration and repair via molecular and engineering approaches. It is hoped that this article will not only offer an overview of recent technologies in tooth regeneration and repair but will also stimulate more interdisciplinary research in this field to turn the pursuit of tooth regeneration and repair into practical reality.
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Affiliation(s)
- Wing-Fu Lai
- Division in Anatomy and Developmental Biology, Department of Oral Biology, BK21 PLUS Project, Oral Science Research Institute, College of Dentistry, Yonsei Center of Biotechnology, Yonsei University, 50 Yonsei-ro Seodaemum-gu, Seoul, 120-752 Korea
| | - Jong-Min Lee
- Division in Anatomy and Developmental Biology, Department of Oral Biology, BK21 PLUS Project, Oral Science Research Institute, College of Dentistry, Yonsei Center of Biotechnology, Yonsei University, 50 Yonsei-ro Seodaemum-gu, Seoul, 120-752 Korea
| | - Han-Sung Jung
- Division in Anatomy and Developmental Biology, Department of Oral Biology, BK21 PLUS Project, Oral Science Research Institute, College of Dentistry, Yonsei Center of Biotechnology, Yonsei University, 50 Yonsei-ro Seodaemum-gu, Seoul, 120-752 Korea
- Oral Biosciences, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China
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45
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Cook RA, Aubry BS. Aggregation, interregional interaction, and postmarital residence patterning: A study of biological variation in the late prehistoric middle Ohio Valley. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 154:270-8. [DOI: 10.1002/ajpa.22503] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 02/23/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Robert A. Cook
- Department of Anthropology; The Ohio State University; Columbus OH
| | - B. Scott Aubry
- Department of Anthropology; The Ohio State University; Columbus OH
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46
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Bailey SE, Benazzi S, Hublin JJ. Allometry, merism, and tooth shape of the upper deciduous M2 and permanent M1. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 154:104-14. [DOI: 10.1002/ajpa.22477] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 01/14/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Shara E. Bailey
- Department of Anthropology; Center for the Study of Human Origins, New York University; New York NY 10003
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig D-04103 Germany
| | - Stefano Benazzi
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig D-04103 Germany
| | - Jean-Jacques Hublin
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig D-04103 Germany
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47
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Morita W, Yano W, Nagaoka T, Abe M, Nakatsukasa M. Size and Shape Variability in Human Molars during Odontogenesis. J Dent Res 2014; 93:275-80. [DOI: 10.1177/0022034513519268] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Under the patterning cascade model (PCM) of cusp development inspired by developmental genetic studies, it is predicted that the location and the size of later-forming cusps are more variable than those of earlier-forming ones. Here we assessed whether differences in the variability among cusps in total and each particular crown component (enamel-dentin junction [EDJ], outer enamel surface [OES], and cement-enamel junction [CEJ]) could be explained by the PCM, using human maxillary permanent first molars (UM1) and second deciduous molars (um2). Specimens were µCT-scanned, and 3D models of EDJ and OES were reconstructed. Based on these models, landmark-based 3D geometric morphometric analyses were conducted. Size variability in both tooth types was generally consistent with the above prediction, and the differences in size variation among cusps were smaller for the crown components completed in later stages of odontogenesis. With a few exceptions, however, the prediction was unsupported regarding shape variability, and UM1 and um2 showed different patterns. Our findings suggested that the pattern of size variability would be caused by temporal factors such as the order of cusp initiation and the duration from the beginning of mineralization to the completion of crown formation, whereas shape variability may be affected by both topographic and temporal factors.
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Affiliation(s)
- W. Morita
- Laboratory of Physical Anthropology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - W. Yano
- Department of Oral Anatomy, Division of Oral Structure, Function and Development, Asahi University School of Dentistry, Gifu 501-0296, Japan
| | - T. Nagaoka
- Department of Anatomy, St. Marianna University School of Medicine, Kanagawa 216-8511, Japan
| | - M. Abe
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan
| | - M. Nakatsukasa
- Laboratory of Physical Anthropology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Riga A, Belcastro MG, Moggi-Cecchi J. Environmental stress increases variability in the expression of dental cusps. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 153:397-407. [DOI: 10.1002/ajpa.22438] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 11/08/2013] [Indexed: 12/24/2022]
Affiliation(s)
- Alessandro Riga
- Department of Biological; Geological and Environmental Sciences, University of Bologna; 40126 Bologna Italy
| | - Maria Giovanna Belcastro
- Department of Biological; Geological and Environmental Sciences, University of Bologna; 40126 Bologna Italy
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Abstract
Human jaws and teeth display a high degree of morphological individuality as they represent personal, family and population characteristics. A protostylid is a supernumerary or accessory cusp located on the mesial half of the buccal surface on the molars that may seldom pose problems while its presence may not be a cause for alarm in most instances. This case report presents a rare finding of protostylid on the buccal surface of the primary molars in 4 children. From the perspective of forensic dentistry, this morphological feature, though uncommon, may be useful for classification and identification of victims in mass causalities and bite marks on bodies or inanimate objects.
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Affiliation(s)
- S V S G Nirmala
- Department of Pedodontics and Preventive Dentistry, Narayana Dental College, Nellore, Andhra Pradesh, India
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50
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Polychronis G, Christou P, Mavragani M, Halazonetis DJ. Geometric morphometric 3D shape analysis and covariation of human mandibular and maxillary first molars. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 152:186-96. [PMID: 24009105 DOI: 10.1002/ajpa.22340] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 06/20/2013] [Accepted: 06/20/2013] [Indexed: 12/31/2022]
Abstract
Dental casts of 160 Greek subjects (80 males, 80 females) were scanned by a structured-light scanner. The upper and lower right first molar occlusal surface 3D meshes were processed using geometric morphometric methods. A total of 265 and 274 curve and surface sliding semilandmarks were placed on the upper and lower molar surfaces, respectively. Principal component analysis and partial least square analysis were performed to assess shape parameters. Molars tended to vary between an elongated and a more square form. The first two principal components (PCs), comprising almost 1/3 of molar shape variation, were related to mesiodistal-buccolingual ratios and relative cusp position. Distal cusps displayed the greatest shape variability. Molars of males were larger than those of females (2.8 and 3.2% for upper and lower molars respectively), but no shape dimorphism was observed. Upper and lower molar sizes were significantly correlated (r(2) = 0.689). Allometry was observed for both teeth. Larger lower molars were associated with shorter cusps, expansion of the distal cusp, and constriction of the mesial cusps (predicted variance 3.25%). Upper molars displayed weaker allometry (predicted variance 1.59%). Upper and lower molar shape covariation proved significant (RV = 17.26%, P < 0.0001). The main parameter of molar covariation in partial least square axis 1, contributing to 30% of total covariation, was cusp height, in contrast to the primary variability traits exhibited by PC1 and PC2. The aim of this study was to evaluate shape variation and covariation, including allometry and sexual dimorphism, of maxillary and mandibular first permanent molar occlusal surfaces.
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Affiliation(s)
- Georgios Polychronis
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, 11527, Greece
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