The heritability of palatal rugae amongst siblings: geometric morphometric method

Abstract

Palatal rugae are irregular ridges present on the anterior part of the palate. Due to their stability and uniqueness to everyone, they have been proposed as a stable reference area for orthodontic superimposition to quantify tooth movement and anchorage loss, and as a diagnostic tool for human identification. Evidence showed some similarities in the palatal rugae amongst family members, which suggested the influence of hereditary in palatal rugae. Heritability estimates (h2) express the proportion due to nature or nurture. Therefore, this study amongst the sibling groups aimed to i) investigate palatal rugae morphology variation, ii) determine the association of shape and size (allometry) of palatal rugae, iii) investigate palatal rugae shape variation and iv) determine the heritability amongst siblings. This cross-sectional study involved an archive of 3- dimensional (3D) digital images of the maxillary arches of 150 subjects, consisting of three groups of siblings (female-male, male-male, and female-female). Six palatal rugae (first, second, and third) of the right and left of the palatine raphe were assessed across the sample using Stratovan Checkpoint software (Stratovan Corp, USA). The result postulated a wide morphology variation of palatal rugae, with 71.3% of the shape variation covered in the first nine principal component analyses (PCA). Statistically significant allometry accounted for 2.46% (p < 0.05). Besides, three of six palatal rugae shapes could be differentiated between sibling groups (p < 0.05), they were right first, right second, and left third rugae. The genetic influence was observed in all siblings in seven palatal rugae landmarks (h2 > 0.7), transverse distance of left second rugae (h2 > 0.6), intermedial distance of third rugae (h2 > 0.8), and the interlateral distance of second rugae (h2 > 1). The female-male siblings showed h2 > 0.5 in the three variables of anteroposterior distance. In conclusion, palatal rugae show individual characteristics and are influenced by genetic factors. Therefore, palatal rugae can be theorised for orthodontic superimposition and forensic odontology.