The role of environmental versus genetic factors on tooth and dental arch dimensions in a twin sample


Background: Genetic variability and heritability were estimated for mesiodistal tooth diameters and dental arch dimensions to evaluate the relative influence of genetics and environment on them and to determine if monozygotic and dizygotic twin can be differentiated on the basis of comparison between these parameters.
Materials and methods: A sample of 32 pairs of monozygotic twin (13 males and 19 females) and 30 pairs of dizygotic twin (12 males and 18 females), both groups age range was 13-23, were selected. Both mesiodistal crown dimension and dental arch parameter were identified and the data was analyzed through two main quantitative genetic approaches, simple variance analysis (f ratio) and classical correlation analysis (falconer's formula).
Results: the maxillary left central incisors was the common tooth which has high genetic variability and strong heritability estimate in total twin sample and in male and female twin pairs, A potential source of common environment contribution to tooth size was found in male twin pairs while females were appeared to have an impact on dental arch dimension.
Conclusions: the maxillary left central incisors may be useful as an additional tool for zygosity determination along with other trait, while dental arch dimensions are not recommended for zygosity diagnosis. Common environment revealed an effect on teeth in males and on dental arch dimension in females.
Keywords: twin, genetics, tooth diameter and dental arch. (J Bagh Coll Dentistry 2008; 20(1)87-94)