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

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.

Cone-beam computed tomography assessment of mandibular asymmetry in unilateral cleft lip and palate patients / 대한치과교정학회지

OBJECTIVE: To determine whether there is any difference between the cleft and non-cleft sides of the mandible in unilateral cleft lip and palate (UCLP) patients, or the right and left sides in control patients; and to determine if there is any difference between the mandibular asymmetry of UCLP patients and that of control patients. METHODS: We examined cone-beam computed tomography (CBCT) scans of 15 patients with UCLP and 15 age- and gender-matched control patients. We evaluated 8 linear, 3 surface, and 3 volumetric measurements and compared the cleft/non-cleft sides of UCLP patients and the right/left sides of controls. RESULTS: There were no statistically significant gender differences in any linear, surface, or volumetric measurement. The single significant side-to-side difference in UCLP patients was a longer coronoid unit on the cleft side than on the non-cleft side (p = 0.046). Body volume was significantly lower in the UCLP group than in the control group (p = 0.008). CONCLUSIONS: In general, UCLP patients have symmetrical mandibles, although the coronoid unit length is significantly longer on the cleft side than on the non-cleft side. UCLP patients and controls differed only in body volume.

Changes in mandibular transversal arch dimensions after rapid maxillary expansion procedure assessed through cone-beam computed tomography / 대한치과교정학회지

OBJECTIVE: This study aimed at evaluating the changes in mandibular arch widths and buccolingual inclinations of mandibular posterior teeth after rapid maxillary expansion (RME). METHODS: Baseline and post-expansion cone-beam computed tomographic (CBCT) images of patients who initially had bilateral posterior cross-bite and underwent RME with a banded-type expander were assessed in this study. The patients included 9 boys (mean age: 13.97 +/- 1.17 years) and 11 girls (mean age: 13.53 +/- 2.12 years). Images obtained 6 months after retention were available for 10 of these patients. Eighteen angular and 43 linear measurements were performed for the maxilla and mandible. The measurements were performed on frontally clipped images at the following time points; before expansion (T1), after expansion (T2), and after retention (T3). Statistical significance was assessed with paired sample t-test at p < 0.05. RESULTS: T1-T2 comparisons showed statistically significant post-RME increases for all measurements; similarly, T2-T1 and T3-T1 comparisons showed statistically significant changes. The maxillary linear and angular measurements showed decreases after expansion, and mandibular linear and angular measurements increased after retention. CONCLUSION: All mandibular arch widths increased and mandibular posterior teeth were uprighted after RME procedure.