Three-dimensional condyle and glenoid fossa alterations after class II treatment with twin block and herbst functional appliances – a randomized clinical trial

BACKGROUND: Functional appliances, such as Twin Block and Herbst, produce dental and skeletal effects to correct Class II division 1 malocclusion. Although widely studied, there are no prospective randomized studies in the literature evaluating the effects of these appliances on the condyle (CO) and glenoid fossa (GF). OBJECTIVE: To evaluate the differences in the CO and GF after treatment using Twin Block (TB) and Herbst (HB) functional appliances for skeletal Class II malocclusions. TRIAL DESIGN: A single-center, two-arm, parallel-group randomized controlled trial. MATERIALS AND METHODS: The sample consisted of 24 patients (12 in the TB group, 11.9 ± 1 year; 12 in the HB group, 12.5 ± 1.8 years) with Class II division 1 malocclusion. Cone beam computed tomography (CBCT) scans were recorded before (T0) and after (T1) treatment (12 months). Superimpositions were performed on Dolphin Imaging software, and partial 3D models of CO and GF were segmented in ITK-SNAP software. A coordinate system (X, Y, and Z axes) was created using Geomagic Qualify software in each 3D T0 model. CO and GF models were aligned in the 3D T0 and T1 models. A 3D centroid point was generated between T0 and T1 in each CO and GF. RESULTS: The TB group showed posterior growth in the right CO (1.3 mm), left CO (1.3 mm), right GF (0.8 mm), and left GF (0.4 mm). The HB group showed posterior growth in the right CO (1.4 mm), left CO (1.7 mm), right GF (0.1 mm), and left GF (0.1 mm). LIMITATIONS: As the operator and patients were aware of the type of functional appliance, blinding could be performed only to assess and measure the CBCT exams. CONCLUSIONS: In both groups, CO and GF grew posteriorly; CO grew vertically in the superior direction, and GF in the inferior direction. The effects on CO and GF were similar when using TB or HB. TRIAL REGISTRATION: ClinicalTrials.gov (ID: NCT02411812). It was registered before commencement.