Adolescent skeletal and dental changes with rapid maxillary expansion

• Main Author: Christensen, Samuel James
• Other Authors: Shin, Kyungsup
• Format: Others
• Language: English
• Published: University of Iowa 2018
• Online Access: https://ir.uiowa.edu/etd/6075; https://ir.uiowa.edu/cgi/viewcontent.cgi?article=7770&context=etd

Introduction A constricted maxilla can be associated with a unilateral or bilateral posterior cross bite, CR-CO shift, maxillary or mandibular growth asymmetry, and dental crowding. Correction of adolescent maxillary constriction typically includes rapid maxillary expansion (RME). However, maxillary skeletal expansion becomes more difficult with age due to increasing facial, and mid-palatal, skeletal resistance. The purpose of this study is to evaluate the age and maturation at which a successful split of the maxillary midpalatal suture (MPS) can be achieved. A secondary aim is to assess the dental arch changes that are associated with a MPS split or no split. Material and Methods In this retrospective study, 39 (13 M, 26 F) consecutively treated subjects exhibiting maxillary skeletal constriction underwent orthodontic treatment with RME to alleviate unilateral or bilateral posterior cross bites. Subjects were divided into pre-pubertal and post-pubertal groups based on maturation. Evidence of a MPS split was confirmed by development of a diastema between upper central incisors and using a maxillary occlusal radiograph. Measurements were made on initial and post-expansion maxillary models to assess dental changes. Results Average age of pre-pubertal and post-pubertal subjects was 11.9± 1.1 years (n=13) and 14.6 ± 1.4 years (n=26) respectively. A MPS split occurred for 100% of pre-pubertal group compared with 65% of the post-pubertal group (p < 0.05). No significant differences were seen in dental movements between the pre-pubertal and post-pubertal groups while significant differences were seen for arch perimeter, crowding, intercanine width, and intermolar width in the split and no-split groups. There was a significantly strong negative correlation between age and percent ability to get a MPS split. Conclusions These results demonstrate that MPS separation is more likely to occur pre-pubertally than post-pubertally but that MPS separation after puberty is still possible. This finding supports the importance of appropriate timing in the use of rapid maxillary expanders.