Differential Growth among Components of the Palate in Rhesus Monkeys (Macaca mulatta)

Abstract

To understand the etiology of maxillary hypoplasia better, which is common in individuals with cleft palate and other cranlofacial anomalies, the relative growth and contribution of the maxillary and palatine segments to enlargement of the hard palate was examined in rhesus monkeys. The purpose of the study was to identify and evaluate sites of differential growth of the palatine and maxillary segments as they contribute to the development of the midface and facial prognathism. One hundred and eight male and 107 female skulls ranging from 1.0 to 7.0 years of age were examined. Measurements of the maxillary and palatine lengths, palatal width, midface depth, canine length, and molar surface areas in the ontogenetic sample were collected. Univariate and bivariate statistics were used to describe dimensional changes and evaluate region-specific sex differences. The relative growth of palatal dimensions was evaluated using allometric analysis methods. Significant sex differences were observed (t-test, p ≤ .05) for all palatal dimensions by 4 years of age. However, proportions of the maxillary and palatine segments to overall palate length appeared to be similar throughout growth for both sexes. The results suggest that sutures of the midface, in particular the transverse palatine suture, may be important in the bony development of the palate during growth. These sutures may contribute to the overall modulation of palatal development. These findings suggest that the greater midfacial prognathism seen in adult rhesus males than in females may be associated with increased relative growth of the palatine segment during puberty, and that small growth differentials in the transverse palatine suture region can have a significant effect on the overall sagittal dimensions of the midface.