Vertical growth-related changes in the positions of palatal rugae and maxillary incisors

With 3-dimensional scanning, the image of 1 digital dental cast can be superimposed on another to observe growth or treatment changes; however, this requires stable references. The palatal rugae were considered reliable points for detecting dental changes on the cast's occlusal plane, but is this the case in the vertical plane? Our aims were to assess the long-term stability of the palatal rugae in the vertical dimension, relate them to possible maxillary incisor posteruptive movements, and validate them as references for the evaluation of longitudinal dental changes.

Four-year longitudinal lateral cephalograms and dental casts of 10 adults and 13 adolescents were used. The median palatal contour of each cast and marks corresponding to each ruga were superimposed on the palate of the cephalograms. Changes in rugae positions during the observation period were measured with respect to the palatal plane.

Vertical changes were greater for the first rugae (closest to the incisors), less for the second, and even less for the third (farthest from the incisors). The adolescents showed greater vertical changes in rugae position than the adults. There were no statistically significant differences in the anteroposterior changes between the groups. The maxillary central incisor and the first ruga had vertical displacements proportional to the increase of the subject's lower anterior facial height.

We found vertical displacement of the maxillary incisor and the rugae during the 4 years of observation in adolescents and adults. The third ruga, the farthest from the incisors, can be used as a reliable reference to assess longitudinal dental changes mainly when growth changes are less prominent.