Three-dimensional comparison of tooth-borne and tooth-bone-borne RME appliances: a randomized controlled trial with 5-year follow-up

Objectives To compare the long-term skeletal effects of tooth-borne (TB) and tooth-bone-borne (TBB) rapid maxillary expansion in growing children, using 3D imaging. Materials and methods In total, 52 consecutive patients who met the eligibility criteria were recruited and allocated to either the TB group, mean age 9.3 years (SD 1.3), or the TBB group, mean age 9.5 years (SD 1.2). Cone-beam computed tomography records and plaster models were taken before (T-0), directly after (T-1), 1 year after (T-2), and 5 years after expansion (T-3). Randomization Participants were randomly allocated in blocks of different sizes, using the concealed allocation principle in a 1:1 ratio. The randomization list was also stratified by sex to ensure homogeneity between groups. Blinding Due to clinical limitations, only the outcome assessors were blinded to the groups to which the patients were allocated. Results At T-1, the midpalatal suture at its anterior part showed a statistically significant difference between the groups with a mean of 0.6 mm (CI 0.2-1.1) more expansion in the TBB group (P < 0.01). This difference was also more evident in boys at T-1 with a mean of 0.8 mm (CI 0.2-1.4) (P < 0.01). These differences, however, blotted out at T-2 and T-3. The nasal width also showed similar differences between the groups, with a significantly larger expansion in the TBB group by a mean of 0.7 mm (CI 0.1-1.4) (P = 0.03). This group difference in favour of the TBB group was maintained at T-2 (1.6 mm) and T-3 (2.1 mm) (P < 0.01 T-2 and T-3, respectively). Conclusions Skeletal expansion in the midpalatal suture was significantly higher in the TBB group; however, the magnitude of this expansion was around 0.6 mm more and may not be clinically significant. Skeletal expansion at the level of the nasal cavity was significantly higher in the TBB group. There were no differences between boys and girls with regard to skeletal expansion.