Changes in orthodontic occlusal indices after semi-rapid maxillary expansion

ObjectivesTo quantify malocclusion complexity changes after semi-rapid maxillary expansion.Materials and methodThe study sample consisted of pre- and postexpansion dental models and frontal intraoral photographs of 195 consecutive patients treated for maxillary expansion using a removable plate and a semi-rapid screw activation protocol. Differences between the pre- and posttreatment scores of the weighted Peer Assessment Rating Index (PAR), dental health component (DHC), aesthetic component (AC) of Index of Orthodontic Treatment Need (IOTN), and Discrepancy Index (DI) were analyzed.ResultsThe intraclass correlation coefficient test to assess the intraobserver error in PAR index and DI was performed and the value was found to be more than 0.80. The kappa score of 0.923 and 0.926 was observed in DHC and AC indices of IOTN, respectively, suggesting a good intraobserver agreement of scores. The pre- and postexpansion mean values in all the indices showed a significant reduction (P < 0.001). The IOTN-DHC, PAR, IOTN-AC, and DI scores showed improvements in 87.2%, 81.6%, 80.5%, and 72.8% of the subjects, respectively. The percentage change in the scores was maximum for IOTN-DHC (−27.8%) followed by PAR (−23.3%). IOTN-AC and DI showed approximately 20% improvement each. More than 25% improvement in scores was seen in 47% to 82% of the subjects.ConclusionThe study suggests that there is a significant decrease in orthodontic treatment need and treatment complexity after semi-rapid maxillary expansion treatment.