Date of Degree
Access restricted until 07/03/2020
MS (Master of Science)
First Committee Member
Steven D. Marshall
Second Committee Member
Thomas E. Southard
Third Committee Member
Fourth Committee Member
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.
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.
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.
viii, 71 pages
Includes bibliographical references (pages 68-71).
Copyright © 2018 Samuel James Christensen
Christensen, Samuel James. "Adolescent skeletal and dental changes with rapid maxillary expansion." MS (Master of Science) thesis, University of Iowa, 2018.
Available for download on Friday, July 03, 2020