Morphometric analysis of palatal rugae in different malocclusions

Studies of the association between palatal rugae (PR) and malocclusion are scarce. While unstable following treatment such as rapid maxillary expansion, we hypothesized that PR differ among malocclusions because of genetic determination but also different environmental conditions during development. Our goal was to assess the possible association between PR morphometric measurements and both sagittal and vertical characteristics of malocclusion.

Maxillary pretreatment dental casts of 243 nongrowing individuals (115 males, 128 females, age 25.5 ± 7.5 years) were laser scanned (Perceptron ScanWorks® V5, Hallam VIC, Australia); angular and linear measurements of the first three PR were recorded in transverse and anteroposterior directions. Cephalometric measurements were obtained from corresponding digitized lateral cephalograms. Statistics included analyses of variance to compare PR measurements among sagittal (class I, class II divisions 1 and 2, class III) and vertical (hypodivergent, normodivergent, hyperdivergent) malocclusion groups and the Pearson correlations among PR dimensions and cephalometric measurements.

PR measurements were statistically different between malocclusions, especially with respect to vertical patterns. A majority of transverse and anteroposterior rugae measurements were greatest in class II division 2 subjects. PR were more anteriorly directed in hypodivergent than hyperdivergent groups; the transverse separation between opposing rugae points was smaller. Correlations were generally low.

The findings suggest the possibility for PR to adapt to environmental effects in developing malocclusions, mostly in the class II division 2 phenotype. This premise reinforces the need to explore in longitudinal studies the long-term environmental influences on rugae superimposed on their genetically determined morphological pattern.