Adolescent Skeletal and Dental Changes With Rapid Maxillary Expansion

Objectives: Maxillary skeletal expansion by rapid maxillary expansion (RME) becomes more difficult with age due to increasing facial, mid-palatal, and skeletal resistance. Object of this study is to evaluate the age and maturation at which a successful split of the maxillary midpalatal suture (MPS) split can be achieved, and to assess the skeletal vs. dental changes that are associated with a MPS split or no split.
Methods: Thirty nine consecutively treated subjects exhibiting maxillary skeletal constriction (13 M, 26 F) underwent RME. Subjects were divided into pre- and post-pubertal groups based on maturation, determined as age of menarche in females and age of visible secondary sexual characteristics in males. Evidence of a MPS split was confirmed by developed diastema and using a maxillary occlusal radiograph. Pre and post-expansion maxillary models were scanned using 3 Shape Ortho Analyzer Software^© to assess changes in arch perimeter, crowding, intercanine width, intermolar width, arch length, inclination of the alveolus, and inclination of molars.
Results: The 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). The differences in all dental movements was statistically significant with-in both the pre-pubertal and post-pubertal groups. The mean difference in the inclination of the alveolus was 4.94° in the pre-pubertal group compared with 10.13° in the post-pubertal group, although this difference was not statistically significant (p= 0.0924). No significant differences were seen in dental movements between the pre-pubertal and post-pubertal groups.
Conclusions: These results demonstrate that MPS separation with RME 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.