Changes in canine inclination after rapid and slow maxillary expansion compared to untreated controls

Objects: Palatally displaced canines (PDC) might represent condition causing several clinical problems, such as roots resorption and malocclusion, and can develop palatal canine impaction. Some interceptive treatments such as rapid maxillary expansion were suggested in order to foster maxillary canine eruption. Among expansion protocols, no data are available about differences between rapid and slow maxillary expansion on maxillary canine eruption. The aim of this study was therefore to evaluate α-angle changes in palatally displaced canines using rapid and slow maxillary expansion compared to untreated control patients. Setting and sample population: The final sample comprised 19 patients treated with rapid maxillary expansion (RME group), 17 treated with slow maxillary expansion (SME group) and 22 control patients (Control group). Materials and methods: α-angle was measured on panoramic films to detect canine inclination at the beginning, and at the end of maxillary expansion treatment or observation, time and changes over time were compared. Results: In the comparisons among groups, RME group was the only group showing a decrease in α-angle measurements that was statistically significant also when compared to the other groups, except for the left side when compared to SME group. Conclusion: RME treatment significantly and positively affected canine position when compared to SME treatment and control group.