Evaluation of alveolar bone loss following rapid maxillary expansion using cone-beam computed tomography

Objective: To evaluate the changes in cortical bone thickness, alveolar bone
height, and the incidence of dehiscence and fenestration in the surrounding
alveolar bone of posterior teeth after rapid maxillary expansion (RME) treatment
using cone-beam computed tomography (CBCT). Methods: The CBCT records of
20 subjects (9 boys, mean age: 13.97 ± 1.17 years; 11 girls, mean age: 13.53 ±
2.12 year) that underwent RME were selected from the archives. CBCT scans had
been taken before (T1) and after (T2) the RME. Moreover, 10 of the subjects had
6-month retention (T3) records. We used the CBCT data to evaluate the buccal
and palatal aspects of the canines, first and second premolars, and the first
molars at 3 vertical levels. The cortical bone thickness and alveolar bone height
at T1 and T2 were evaluated with the paired-samples t-test or the Wilcoxon
signed-rank test. Repeated measure ANOVA or the Friedman test was used to
evaluate the statistical significance at T1, T2, and T3. Statistical significance was
set at p < 0.05. Results: The buccal cortical bone thickness decreased gradually
from baseline to the end of the retention period. After expansion, the buccal
alveolar bone height was reduced significantly; however, this change was not
statistically significant after the 6-month retention period. During the course
of the treatment, the incidence of dehiscence and fenestration increased and
decreased, respectively. Conclusions: RME may have detrimental effects on the
supporting alveolar bone, since the thickness and height of the buccal alveolar
bone decreased during the retention period.