Genetic and environmental determinants of dental occlusal variation in twins of different nationalities.
ABSTRACT We have compared 10 occlusal traits in 358 monozygous and dizygous twin pairs in 4 different samples and estimated genetic variances for these features. Variable and frequently nonsignificant genetic variance was noted across samples for incisal overbite and overjet, sagittal molar relationship, posterior crossbite, and rotations and displacements of anterior teeth. Heritability estimates (when appropriately calculated) were low in magnitude (0-40%) and erratic, emphasizing the importance of environmental influences on occlusal variation and the variability of apparent genetic determinants with respect to the environment or population in which they are measured.
Article: Dental crowding.[Show abstract] [Hide abstract]
ABSTRACT: Abstract Objective: To evaluate the role of genetics and tooth wear in the etiology of dental crowding through the analysis of a split indigenous Amazon population. Materials and Methods: Dental crowding prevalence (n = 117), tooth wear (n = 117), and inbreeding coefficient (n = 288) were compared for both villages. A biometric investigation was performed by dental cast analysis of 55 individuals with no tooth loss. Mann-Whitney statistics, independent t-tests, and Fisher exact tests were used at P < .05. Results: A high coefficient of inbreeding was confirmed in the resultant village (F = 0.25, P < .001). Tooth wear was not significantly different (P = .99), while a significantly higher prevalence of dental crowding was confirmed in the original village (PR = 6.67, P = 0.02). Forty dental arches (n = 20) were examined in the new group, and only one (2.5%) had a dental crowding ≥5 mm. In the original villages, we found 20 arches (28.6%) with dental crowding. No difference was observed for tooth size, while larger dental arch dimensions explained a lower level of dental crowding in the resultant village. Conclusions: Our findings downplay the widespread influence of tooth wear, a direct evidence of what an individual ate in the past, on dental crowding and emphasize the role of heredity, exacerbated through inbreeding, in the etiology of this malocclusion.The Angle Orthodontist 07/2012; · 1.18 Impact Factor
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ABSTRACT: Studies examining human and nonhuman primates have supported the hypothesis that the recent increase in the occurrence of misalignment of teeth and/or incorrect relation of dental arches, named dental malocclusion, is mainly attributed to the availability of a more processed diet and the reduced need for powerful masticatory action. For the first time on live human populations, genetic and tooth wear influences on occlusal variation were examined in a split indigenous population. The Arara-Iriri people are descendants of a single couple expelled from a larger village. In the resultant village, expansion occurred through the mating of close relatives, resulting in marked genetic cohesion with substantial genetic differences. Dental malocclusion, tooth wear and inbreeding coefficient were evaluated. The sample examined was composed of 176 individuals from both villages. Prevalence Ratio and descriptive differences in the outcomes frequency for each developmental stage of the dentition were considered. Statistical differences between the villages were examined using the chi-square test or Fisher's exact statistic. Tooth wear and the inbreeding coefficient (F) between the villages was tested with Mann-Whitney statistics. All the statistics were performed using two-tailed distribution at p≤0.05. The coefficient inbreeding (F) confirmed the frequent incestuous unions among the Arara-Iriri indigenous group. Despite the tooth wear similarities, we found a striking difference in occlusal patterns between the two Arara villages. In the original village, dental malocclusion was present in about one third of the population; whilst in the resultant village, the occurrence was almost doubled. Furthermore, the morphological characteristics of malocclusion were strongly different between the groups. Our findings downplay the widespread influence of tooth wear, a direct evidence of what an individual ate in the past, on occlusal variation of living human populations. They also suggest that genetics plays the most important role on dental malocclusion etiology.PLoS ONE 01/2011; 6(12):e28387. · 3.73 Impact Factor
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ABSTRACT: Successful treatment of any orthodontic problem depends on an appropriate diagnosis of its etiology. It is well known that the genetics, as well as environmental factors, play an important role on the etiology of skeletal anomalies. Recent studies and advances in genetic sciences allowed the orthodontists to better understand the effects of genetics on the etiology of dentofacial characteristics and pathologies which in turn supported the effects of the genes in the development of dentofacial complex. In orthodontic practice, the genetic basis of a skeletal anomaly should also be considered during the diagnosis. Therefore orthodontic treatment plan should be chosen accordingly. However, further genetic studies are required to clearly determine all the specific genes leading to a particular skeletal variability caused by the polygenic nature of craniofacial traits. This article includes the current information on the association between orthodontics and genetics, an outline of the evidence based impact of heredity on dentofacial development as a review of the etiological factors of skeletal anomalies from the genetic point of view.European journal of dentistry. 07/2012; 6(3):340-5.