Tooth-borne versus tooth-bone-borne rapid maxillary expanders according to a stereophotogrammetric evaluation of facial soft tissues: A randomized clinical trial.

Abstract

To evaluate the effects of tooth-borne and tooth-bone-borne rapid maxillary expansion (RME) on soft tissue with stereophotogrammetry. Thirty two patients (15 males and 17 females) who met inclusion criteria were divided into two groups. In the first group, tooth-borne RME appliance (hyrax) was applied to 16 patients (9 males and 7 females mean age 13.4±1.3years), and in the second group, tooth-bone-borne RME appliance (hybrid hyrax) was applied to 16 patients (6 males and 10 females, mean age 13.05±1.24years). Changes in soft tissues before RME (T0) and post-retention (T1) period were evaluated by stereophotogrammetry. Linear and angular measurements were performed. Independent- and dependent-sample t tests were used to compare intra- and inter-group differences at P<.05 significance level. The data revealed statistically significant changes in nasal width, mid-face width, upper lip vermillion length/lower lip vermillion length ratio and upper lip angle in hyrax group. (P<.05) Also nasal width, lower lip length, lower lip vermillion length, anterior face height, lower face height, convexity angle and mandibular angle showed statistically significant changes in hybrid hyrax group. (P<.05) In the inter-group evaluation, no significant differences were found except upper lip and mandible angle. (P<.05). Both hyrax and hybrid hyrax expanders had effects on soft tissue profile. Anterior face height and lower face height increased in both groups. Upper lip length increased by 0.36mm in the hybrid group and 0.10mm in the hyrax group. This trial was registered at Clinicaltrials.gov (Identifier: NCT04828213).