43 research outputs found
VMG II transport medium stabilises oral microbiome samples for Next-Generation Sequencing
No full textAbstract not availableChristina J. Adler, Abbe White, Michelle Bockmann, Gina V. Browne, Grant Townsend, Toby Hughe
Tooth Exfoliation Timing and Patterning in a Cohort of Australian Twins
No full textFinal Presentation ID: 1169.
Interactive Talk Session. Late Breaking Abstracts: Craniofacial Biology and Mineralized Tissue. Saturday, 06/24/2023 , 02:00PM - 03:30PMChye, Leila, Bockmann, Michelle, Hughes, Tob
Genetic, environmental and epigenetic influences on variation in human tooth number, size and shape
No full textThe aim of this review is to highlight some key recent developments in studies of tooth number, size and shape that are providing better insights into the roles of genetic, environmental and epigenetic factors in the process of dental development. Advances in molecular genetics are helping to clarify how epigenetic factors influence the spatial and temporal regulation of the complex processes involved in odontogenesis. At the phenotypic level, the development of sophisticated systems for image analysis is enabling new dental phenotypes to be defined. The 2D and 3D data that are generated by these imaging systems can then be analysed with mathematical approaches, such as geometric morphometric analysis. By gathering phenotypic data and DNA from twins, it is now possible to use ‘genome-wide’ association studies and the monozygotic co-twin design to identify important genes in odontogenesis and also to clarify how epigenetic and environmental factors can affect this process. Given that many of the common dental anomalies affecting the human dentition are interrelated, apparently reflecting pleiotropic genetic effects, the discoveries and new directions described in this paper should have important implications for clinical dental practice in the future.Grant Townsend, Michelle Bockmann, Toby Hughes and Alan Broo
Do feeding practices, gestation length, and birth weight affect the timing of emergence of the first primary tooth?
No full textRecent studies of twins have confirmed that there is a strong genetic constribution to variation in timing of primary tooth emergence. Although environmental factors, such as severe nutritional deficiency of the infant, may affect primary tooth emergence, the roles of other environmental factors remain unclear. This study aimed to determine whether newborn feeding practices, gestation length, and birth weight affect the emergence time of the first primary tooth. Data were collected from questionnaires and parental records as part of an ongoing longitudinal study of Australian twins and their families. The sample comprised 217 twin pairs. Most commonly, a mandibular central incisor was the first tooth to emerge, with the next being a maxillary central incisor. F- and t-tests were performed, comparing variables and mean values between groups, and statistical significance was set at p2500g) (10.1mo compared with 7.9mo). These findings indicated that the development of primary dentition is well 'protected' against environmental disturbances, with only extreme prematurity or very low birth weight leading to significant delays in emergence.Emmanual Chan, Michelle Bockmann, Toby Hughes, Suzanna Mihailidis and Grant Townsen
Genetic and environmental influences on human dental variation: A critical evaluation of studies involving twins
No full textUtilising data derived from twins and their families, different approaches can be applied to study genetic and environmental influences on human dental variation. The different methods have advantages and limitations and special features of the twinning process are important to consider. Model-fitting approaches have shown that different combinations of additive genetic variance (A), non-additive genetic variance (D), common environmental variance (C), and unique environmental variance (E) contribute to phenotypic variation within the dentition, reflecting different ontogenetic and phylogenetic influences. Epigenetic factors are also proposed as important in explaining differences in the dentitions of monozygotic co-twins. Heritability estimates are high for most tooth size variables, for Carabelli trait and for dental arch dimensions, moderate for intercuspal distances, and low for some occlusal traits. In addition to estimating the contributions of unmeasured genetic and environmental influences to phenotypic variation, structural equation models can also be used to test the effects of measured genetic and environmental factors. Whole-genome linkage analysis, association analysis of putative candidate genes, and whole genome association approaches, now offer exciting opportunities to locate key genes involved in human dental development.Grant Townsend, Toby Hughes, Michelle Luciano, Michelle Bockmann and Alan Brookhttp://www.elsevier.com/wps/find/journaldescription.cws_home/203/description#descriptio
Genetic modeling of primary tooth emergence: A study of Australian twins
No full textThe aim of this study was to quantify contributions of genetic and environmental factors to variation in timing of emergence of the primary teeth in a sample of monozygotic and dizygotic twins, using univariate model-fitting approaches. The sample comprised 94 pairs of monozygotic twins and 125 pairs of dizygous twins, all of European ancestry, aged from 2–6 years. Tooth emergence timing was based on parental report, with a subset of data validated by clinical assessment. Heritability estimates for tooth emergence timing were generally high, around 90%, however estimates for the lower right lateral incisor and the lower canines were around 50%. These findings confirm a strong genetic influence on observed variation in the timing of emergence of the human primary teeth.Michelle R. Bockmann, Toby E. Hughes and Grant C. Townsen
Heritability of dental arches and occlusal characteristics: a systematic review and meta-analysis
No full textBackground and objective: The genetic basis of dentoalveolar characteristics has been investigated by several studies, however, the findings are equivocal. The objective of this systematic review and meta-analysis was to evaluate the heritability of dental arches and occlusal parameters in different stages of human dentition. Search methods: Electronic databases PubMed, Embase, Scopus, Web of Science, and Dentistry and Oral Science Source were searched up to August 2023 without the restriction of language or publication date. Selection criteria: Empirical studies investigating the heritability of dentoalveolar parameters among twins and siblings were included in the review. Data collection and analysis: Study selection, data extraction, and risk of bias assessment were performed independently and in duplicate by two authors and a third author resolved conflicts if needed. Joanna Briggs Institute’s critical appraisal tool was used to evaluate the risk of bias among studies and the certainty of evidence was assessed using the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria. Results: Twenty-eight studies were included in the systematic review, of which 15 studies reporting heritability coefficients in the permanent dentition stages were deemed suitable for the meta-analysis. Random-effects meta-analyses showed high heritability estimates for maxillary intermolar width (0.52), maxillary intercanine width (0.54), mandibular intermolar width (0.55), mandibular intercanine width (0.55), maxillary arch length (0.76), mandibular arch length (0.57), and palatal depth (0.56). The heritability estimates for the occlusal parameters varied considerably, with relatively moderate values for crossbite (0.46) and overbite (0.44) and low values for buccal segment relationship (0.32), overjet (0.22), and rotation and displacement of teeth (0.16). However, the certainty of evidence for most of the outcomes was low according to the GRADE criteria. Conclusions: Based on the available evidence, it can be concluded that the dental arch dimensions have a high heritability while the occlusal parameters demonstrate a moderate to low heritability.Jamal Giri, Michelle Bockmann, Alan Brook, Taseef Hasan Farook, Maurice Meade and Toby Hughe
How studies of twins can inform our understanding of dental morphology.
No full textTwo metaphors are presented to highlight concepts that could lead to a paradigm shift in dental studies of twins. The first, derived from the Song of Solomon in the Bible, refers to teeth as being twins. This viewpoint emphasises that each tooth should be viewed as a paired structure, not only with its antimere (within the same arch) but also with its isomer (in the opposing arch). The other metaphor provided by Waddington in 1957 is visual and involves 'an epigenetic landscape' that represents the processes of decision-making by cells during development. It likens the different stages of cellular decision-making to a ball rolling down an undulating landscape of interconnecting hills and valleys. This viewpoint helps to explain how distinct differences in dental phenotypes may arise both within and between monozygotic (MZ) co-twins due to relatively minor temporospatial effects during development. Measurements of maximum mesiodistal diameters of teeth in a pair of MZ twins, using calipers and also 2D and 3D imaging systems, have demonstrated that differences in dental crown size occur between antimeric pairs and between corresponding teeth of MZ co-twins. By defining new dental phenotypes that provide more comprehensive descriptions of tooth size and shape, and by drawing on the metaphors described, we are confident of providing new insights into the reasons for observed similarities and differences within, and between, the dentitions of twins. Our approaches will focus on multivariate analyses that take into account the paired arrangement of teeth and also explore epigenetic, as well as genetic and environmental, sources of variation.Grant Townsend, Toby Hughes, Michelle Bockmann, Richard Smith and Alan Broo
An overview of dental genetics
No full textRapid developments in the fields of molecular genetics and genetic modeling, together with advances in the phenotyping of dental features, are leading to improved understanding of the nature and causes of variation within the human dentition, with implications for anthropologists and clinicians. Major advances are occurring in the field of epigenetics and in studies of twins, and these discoveries are adding support to the view that dental development is a complex process that is influenced by a combination of genetic, epigenetic, and environmental factors.Toby Hughes, Grant Townsend, and Michelle Bockman
New approaches to dental anthropology based on the study of twins
No full textStudies of twins carried out over the past 25 years by the Craniofacial Biology Research Group at the University of Adelaide have provided insights into the roles of genetic, environmental and epigenetic influences on human dento-facial growth and development. The aim of this paper is to review some of the main findings of these studies and to highlight the value of using different twin models, including the monoqygotic (MZ) co-twin design. We also introduce the concept of 'dental phenomics' whereby modern 2D and 3D imaging systems are now enabling biologically-meaningful, dental phenotypes to be quantified in order to provide detailed descriptions of the size and shape of teeth. We propose that developments in the field of 'dental phenomics', with linking of the data generated to large-scale genome sequencing approches, should enable us to further unravel the msyteries of how genetic, environmental and epigenetic factors interact to produce the extensive range of morphological variations evident within the human dentition and face.Grant Townsend, Michelle Bockmann, Toby Hughes, Suzanna Mihailidis, W. Kim Seow and Alan Broo
