Method for evaluation of transverse dimension in self-ligating orthodontic treatment. A comparative study

Knowledge of the best way to evaluate changes in transverse dimension produced by orthodontic treatment enables the estimation of potential space that may be generated and optimizes planning. The aim of this study was to compare two methods for measuring changes in transverse dimension following tooth alignment by passive self-ligating system: Method 1 (M1) considering palatal landmarks and Method 2 (M2) considering dental landmarks. Subjects were 12 patients of both sexes, aged 15 to 24 years old, with moderate crowding (Nance discrepancy -4 to -6 mm), who were treated with the Damon System at the Department of Orthodontics of the School of Dentistry, Buenos Aires University. Their pre- and posttreatment maxillary casts were analyzed (24 casts altogether). Five measurements were taken on each cast: intercanine width, first and second inter-premolar width and first and second inter-molar width, using the two measurement methods (M1 and M2). Both methods found average width to have increased, though this increase was smaller as measured by Ml than by M2, with statistically significant difference between values (p<0.05). Ml and M2 provided significantly different measurements for first and second inter-premolar and first intermolar distances (p< 0.05). The values obtained using Ml (palatal landmarks for teeth) present less variation and provide information on the changes in the dental arches without adding tooth tipping. Considering Ml, the greatest gain in transverse dimension occurred in first and second inter-premolar distance, there was a slight increase in inter-canine and first inter-molar distance, and a decrease in second inter-molar distance.