The Influence of Sex and Ancestry on Three-Dimensional Palate Shape.

ABSTRACT: Modern human palate shape has been reported to vary by sex and ancestry, but limitations in the methods used to quantify shape and in population coverage have led to inconsistent findings. In the present study, the authors aim to characterize the effects of sex and ancestry on normal-range three-dimensional palate shape through landmark-based morphometrics.Three-dimensional digital dental casts were obtained and landmarked from 794 adults of European (n = 429), African (n = 295), and East Asian (n = 70) ancestry. Principal component analysis was conducted to identify patterns of shape variation present in our cohort, and canonical variates analysis was performed to test for shape differences between sexes and ancestries.Principal component analysis showed that 3 principal components, explaining 76.52% of variance, linked higher palatal vault with either a relative reduction in anteroposterior or mediolateral dimensions. Canonical variates analysis showed that males had wider and shorter palates with more posteriorly located maximum vault depth than females. Individuals of African ancestry, having higher vaults with more posteriorly located maximal depths, also had wider and shorter palates, whereas individuals of European ancestry had narrower and longer palates with more anteriorly located maximum vault depths. Individuals of East Asian ancestry showed the shallowest vaults.It was found that both sex and ancestry influence palate shape, suggesting a possible genetic component underlying this variation. Additionally, our findings indicate that vault height tends to co-vary with anteroposterior or mediolateral dimensions. Further investigation of these morphological patterns may shed light on possible links to common congenital anomalies such as orofacial clefting.

Parents of Children With Nonsyndromic Orofacial Clefting Show Altered Palate Shape.

OBJECTIVE: The unaffected relatives of individuals with nonsyndromic orofacial clefts have been shown to exhibit subtle craniofacial differences compared with the general population. Here, we investigate whether these morphological differences extend to the shape of the palate. DESIGN: We conducted a geometric morphometric analysis to compare palate shape in the clinically unaffected parents of children with nonsyndromic cleft lip with or without cleft palate and adult controls of European, Asian, and African ancestry. We conducted pairwise group comparisons using canonical variates analysis, and then confirmed and characterized findings of shape differences using Euclidean distance matrix analysis. RESULTS: Significant differences in palate shape were detected in unaffected mothers (but not fathers) compared to demographically matched controls. The differences in shape were ancestry-specific; mothers of Asian-derived and African-derived ancestry showed wider and shorter palates with higher posterior palatal vaults, while mothers of European-derived ancestry showed narrower palates with higher anterior palatal vaults. CONCLUSIONS: Our findings suggest that altered palate shape is a subclinical phenotypic feature, which may be indicative of elevated orofacial cleft risk. The risk phenotype varied by sex and ancestry, suggesting possible etiologic heterogeneity among demographic groups. Understanding the genetic basis of these informative palate shape traits may reveal new genes and pathways relevant to nonsyndromic orofacial clefting.

Prevalence of Torus Palatinus and association with dental arch shape in a multi-ethnic cohort.

Objectives: Torus Palatinus (TP) is a bony projection located on the oral surface of the hard palate. The trait is typically benign, has an unknown etiology, and varies widely in phenotypic expression. Prior studies suggest differences in TP prevalence by sex and ancestry, but the reported rates vary, even within a single ancestral group. We assessed the prevalence of TP and its association with palatal shape in a large multi-ethnic cohort of normal individuals. Methodology: 1102 adults were included (625 with European ancestry, 377 with West African anscestry, and 100 with East Asian ancestry). 3D digital dental casts were obtained and rated. TP frequencies were compared between sexes and/or ethnicities using Chi-squared tests. Dental cast models were then landmarked, and canonical variates analysis was performed to test for shape differences between those with and without TP. Results: Females had a significantly higher rate of TP than males across all three ancestral groups (p≤0.004). In males, no significant differences were found among ethnicities. Ancestral differences in TP frequency were driven by females, with East Asians having the highest rate (34.69%), followed by Europeans (24.88%) and West Africans (15.22%). Shape differences were found only in Asians and Africans, indicated a shorter and wider palate in presence of TP. Conclusions: Ethnic differences in TP frequency were present only in females. Further, females have considerably higher rates of TP than males in each population tested. Further studies of TP at earlier time-points and in connection to other aspects of craniofacial growth may shed light on these sex and ethnic differences.