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1.
Aust Dent J ; 59 Suppl 1: 101-16, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24117977

RESUMO

The continuing studies of the teeth and faces of Australian twins and their families in the Craniofacial Biology Research Group in the School of Dentistry at the University of Adelaide began 30 years ago. Three main cohorts of twins have been recruited, enabling various objectives and specific hypotheses to be addressed about the roles of genetic, epigenetic and environmental influences on human dentofacial growth and development, as well as oral health. This paper highlights some key findings arising from these studies, emphasizing those of direct relevance to practising oral health professionals. We also draw on published literature to review the significant developments in relation to the use of precision 2D and 3D imaging equipment, the application of modern molecular techniques, and the development of sophisticated computer software for analysing genetic relationships and comparing complex shapes. Such developments are valuable for current and future work. Apart from the classical or traditional twin model, there are several other twin models that can be used in research to clarify the relative contributions of genetic, epigenetic and environmental contributions to phenotypic variation. The monozygotic (MZ) co-twin model is one particularly valuable method, given that examination of only one pair of MZ twins can provide considerable insights into underlying causes of observed variation. This model can be used in a dental practice environment, with oral health professionals having the opportunity to explore differences in orofacial structures between MZ co-twins who are attending as patients. As researchers have become more aware of the complexities of the interactions between the genome, the epigenome and the environment during development, there is the need to collect more phenotypic data and define new phenotypes that will better characterize variations in growth processes and health status. When coupled with powerful new genetic approaches, including genome-wide association studies and linkage analyses, exciting opportunities are opening up to unravel the causes of problems in craniofacial growth and common oral diseases in human populations.


Assuntos
Desenvolvimento Maxilofacial/fisiologia , Dente/crescimento & desenvolvimento , Gêmeos Monozigóticos , Adolescente , Coeficiente de Natalidade , Criança , Pré-Escolar , Cárie Dentária/genética , Epigenômica , Face/anatomia & histologia , Assimetria Facial/diagnóstico , Feminino , Estudo de Associação Genômica Ampla , Humanos , Imageamento Tridimensional , Estudos Longitudinais , Masculino , Saúde Bucal , Fenótipo , Fotografação , Irmãos , Austrália do Sul , Gemelaridade Monozigótica/fisiologia
2.
Front Oral Biol ; 13: 110-115, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19828980

RESUMO

AIMS: This study is part of a larger investigation of genetic and environmental influences on primary tooth emergence in Australian twins. Our aims were to describe patterns of emergence asymmetry, including directional and fluctuating components (DA, FA), and to test for a genetic basis to observed asymmetry. METHODS: The study sample consisted of 131 twin pairs. Using one randomly-selected twin from each pair, dental asymmetry was examined by analysing the number of days between emergence of antimeres (Delta), with dates of emergence provided through parental recording. Scatterplots were used for assessment of DA and FA, followed by paired t-tests to detect significant differences in mean Delta from zero (evidence of DA). FA was assessed by calculating means and variances of the absolute value of Delta. A range of intervals (0, 7, 14, 21, 28 days) was used to define symmetrical emergence of antimeres. RESULTS: Although a trend in left-side advancement for tooth emergence was detected, this was not statistically significant. Relatively low levels of FA were noted through -out the primary dentition, with maxillary and mandibular lateral inisors displaying the highest values, but no evidence of a genetic influence on FA was noted. Around 50% of all antimeric pairs of primary teeth were found to emerge within 14 days of each other, although time differences of more than 50 days were noted in some cases. CONCLUSION: Studies of dental asymmetry provide insights into the biological basis of lateralisation in humans and the results can also assist clinicians to discriminate between normal and abnormal developmental patterns.


Assuntos
Lateralidade Funcional , Odontogênese/fisiologia , Erupção Dentária/fisiologia , Dente Decíduo/fisiologia , Meio Ambiente , Feminino , Humanos , Lactente , Masculino , Fatores Sexuais , Estatísticas não Paramétricas , Fatores de Tempo , Erupção Dentária/genética , Dente Decíduo/crescimento & desenvolvimento , Gêmeos Dizigóticos , Gêmeos Monozigóticos
3.
J Dent Res ; 86(12): 1160-5, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18037648

RESUMO

Our understanding of tooth eruption in humans remains incomplete. We hypothesized that genetic factors contribute significantly to phenotypic variation in the emergence of primary incisors. We applied model-fitting to data from Australian twins to quantify contributions of genetic and environmental factors to variation in timing of the emergence of human primary incisors. There were no significant differences in incisor emergence times between zygosity groups or sexes. Emergence times of maxillary central incisors and mandibular lateral incisors were less variable than those of maxillary lateral incisors and mandibular central incisors. Maxillary lateral incisors displayed significant directional asymmetry, the left side emerging earlier than the right. Variation in timing of the emergence of the primary incisors was under strong genetic control, with a small but significant contribution from the external environment. Estimates of narrow-sense heritability ranged from 82 to 94% in males and 71 to 96% in females.


Assuntos
Incisivo/fisiologia , Característica Quantitativa Herdável , Erupção Dentária/genética , Dente Decíduo/fisiologia , Austrália , Pré-Escolar , Feminino , Lateralidade Funcional , Humanos , Lactente , Masculino , Mandíbula , Maxila , Modelos Genéticos , Fatores de Tempo , Gêmeos Dizigóticos , Gêmeos Monozigóticos
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