Soft tissue changes in the orofacial region after rapid maxillary expansion : A cone beam computed tomography study.

OBJECTIVE: Rapid maxillary expansion (RME) is usually used for expanding the maxillary bony segments. Many studies have assessed the dental and skeletal effects of the expansion treatment but few studies evaluated soft tissue changes using cone beam computed tomography (CBCT) images. This study aims to compare soft tissue changes after RME in prepubertal and postpubertal subjects using CBCT images. The null hypothesis of this study is there is no difference between prepubertal and postpubertal patients in soft tissue changes after RME treatment.

MATERIALS AND METHODS: A total of 28 patients (10 males, 18 females) with a bonded type of rapid maxillary expander were included in this study. The patients were divided into two subgroups according to cervical vertebral maturation stage. Prepubertal and postpubertal groups were obtained. Following the selection of CBCT images from the archive, pretreatment (T0) and postretention measurements (T1) were performed. Nine linear and one angular measurement for a total of 10 measurements were evaluated on each CBCT image. The mean differences between T0 and T1 measurements were compared by using the paired-samples t test and significance was set at P < 0.05.

RESULTS: The largest median increase was found in cheek projection of the prepubertal group. Changes in soft tissue nasal base, philtrum width, upper lip length, columella width, columella height, and cheek projection were statistically significant (P < 0.001) in both groups. No significant differences were observed in soft tissue alar base, nostril width, nostril height, and nasolabial angle.

CONCLUSION: Some significant changes in facial soft tissues were observed after RME treatment but there were no significant differences between prepubertal and postpubertal subjects. The null hypothesis is accepted because there were no significant differences between the groups.