A photogrammetric technique for the analysis of palatal three-dimensional changes during rapid maxillary expansion

The aim of the study was to assess, by a digital photogrammetric technique, the relative dimensional changes before and after rapid maxillary expansion. The transverse diameters and volumetric variations of the palate were measured by photogrammetry on study casts taken at three different phases of therapy: at the beginning of the treatment (T1), on removal of the rapid expander, after expansion and retention for three months (T2), and six months after appliance removal (T3). The sample consisted of 30 children, (age range 7-8 years), all with a crossbite; 15 were Angle class I, 6 class II and 9 class III. The findings demonstrated a significant relapse (P<0.001) in the dental transverse diameter in all patients six months after appliance removal, although the palatal volume remained stable.