An investigation of cephalometric and morphological predictors of successful twin block therapy.

OBJECTIVE: To identify predictors of overjet reduction, changes in mandibular length (Co-Me) and antero-posterior changes in mandibular position (Pog-Vert) during Twin Block therapy. METHODS: Pre- and post-treatment cephalograms of 131 participants were analysed (Mean age 12.73 years +/- 1) following Twin Block therapy. RESULTS: Mean annualised overjet reduction was 7.29 mm (+/- 2.99) with chin projection improving by 2.66 mm (+/- 5.37). The magnitude of the initial overjet was a strong predictor (95% CI: 0.30, 0.77, p < 0.01) of overjet reduction and change in chin position (95% CI: 0.08, 0.77, p = 0.02). Greater forward movement of Pogonion occurred if there was greater retrusion of Pogonion at the outset (95% CI: 0.15, 0.45, p < 0.01). No prognostic relationship was noted for other potential cephalometric predictors including pretreatment mandibular lower border morphology and Co-Go-Me angle. CONCLUSION: No relationship between mandibular morphology, vertical skeletal pattern and favourable dentoalveolar and skeletal responses to Twin Block therapy could be found. These results require confirmation on an external sample.