Prediction of transverse width changes of dental arches during maxillomandibular sagittal movement using a geometric model

Background:The present study was done to determine the transverse intermolar and intercanine width in normal occlusion and to predict the changes in width at fixed anatomic landmarks on the mandibular arch when the opposing arches were moved in sagittal direction.Aims & Objectives: To determine the average transverse intermolar and intercanine width in normal occlusion using a digital geometric arch form.To predict the changes in intermolar and intercanine width at fixed anatomic landmarks on the maxillary dental arch when the mandibular arch was moved sagittally at 3 mm, 6 mm, and 9 mm, respectively.Materials and Methods: 48 subjects between 18 and 30 years with class I occlusion having a pleasing profile were selected, and geometric arch forms of ellipses were obtained on their digital models.The transverse intermolar and intercanine width and the changes were measured by simulating sagittal movement of mandibular arches at 3, 6, and 9 mm, respectively.Results: The average transverse intermolar width in maxilla and mandible in normal occlusion was 50.51 2.54 mm and 43.44 2.28 mm, and 33.67 2.12 mm and 26.28 2.07 mm, respectively, in the canine region.The mean transverse width changes for molars at 3, 6, and 9 mm were 1.97 0.59 mm and for canines at 3 and 6 mm were 4.03 1.18 mm, which was statistically significant (p< 0.001).The relationship of the transverse width at the molar and canine regions and the sagittal movement of dental arches showed that the variables were not significant (p0.05). Conclusion:An average intermolar and intercanine transverse width difference exists between maxillary and mandibular arches in normal occlusion.There was an increase in transverse width in the intermolar and intercanine regions when the mandibular arches moved at 3mm, 6mm, and 9mm, respectively, and a predicted ratio can be formulated.