To discuss the genetic basis of occlusal traits through analysis of the effects of inbreeding in a subdivided isolated community.
Subjects and methods
The sample comprised dental casts of 224 children, aged 7–14 years, from 15 villages of the Island of Hvar, Croatia.
Main outcome measures
Studied traits were Angle class, overjet, vertical bite, overbite, and crowding/spacing.
Design
Children with complete grandparental endogamy (all four grandparents born in the village of residence of the examinee) were compared to children with incomplete grandparental endogamy. In addition, children resident in the group of villages with a high prevalence of inbreeding were compared to children resident in the groups of villages with moderate and low prevalence of inbreeding.
Results
In both designs, inbreeding seemed to increase the mean values of overjet, overbite, and vertical bite, while it had little or no effect on crowding/spacing. Angle classes were correlated to inbreeding at the individual level, but this was not supported at the population level. The effects were stronger in the subsample with bilaterally concordant Angle classes.
Conclusion
The observed inbreeding effects imply that the genetic basis of some occlusal traits is polygenic and, in considerable part, influenced by rare and recessive genetic variants.
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