Is maxillary protraction the earlier the better? A retrospective study on early orthodontic treatment of Class III malocclusion with maxillary deficiency.

Abstract

To investigate the optimal timing of maxillary protraction in children with Class III malocclusion to aid comprehension of this still non-consensual topic. In all, the data of 97 children with Class III malocclusion treated by using the Delaire facemask with maxillary expansion were collected retrospectively and divided into three groups according to their dentition stages; those subjects in the mixed dentition group were further divided into three subgroups. All patients were regrouped by the cervical vertebral maturation index (CVMI) and observed closely by cephalograms at the beginning of treatment (T0) and after facemask removal (T1). Comparisons between subgroups, within groups, and the final evaluation of the increment of maxillary length were performed by different statistical methods. Similar favorable maxillary traction effects were achieved in all stages. Intragroup comparisons showed changes without significance in aspect ratio during the mixed dentition stage, while there was a significant decrease during the deciduous and permanent dentition stages. The largest increment of maxillary length was obtained when the maxillary protraction began at Cervical Stage (CS)2. However, no significant difference was found in all skeletal measurements among the three groups (deciduous, mixed and permanent dentition stages) and the three subgroups with mixed dentition. The univariable linear regression analysis also showed that CVMI and dentition stage at T1 did not have a significant impact on the increment of maxillary length. In our center, Class III malocclusion patients treated with the Delaire facemask achieved similar skeletal changes in short term, when they began the treatment at different dentition stages or CVMI stages. Starting the maxillary protraction at CS2 was likely a reliable choice for those who desired more maxillary advancement.