Correlation of twin-block appliance efficacy and wear duration as assessed with a compliance indicator.

BACKGROUND: The aim of this study was to investigate the association between objective wear time and treatment efficacy of a twin block (TB) appliance. METHODS: A TB appliance incorporating a compliance indicator was delivered to 44 children in the age group of 11-14 years (25 boys and 19 girls). Participants were instructed to wear the appliance full time and were recalled at 3-4- week intervals. Cephalograms and study models were taken at baseline and after 6 months of appliance therapy. RESULTS: Data from 41 of the 44 participants were analyzed. A wide variation in daily wear time among participants was observed. Based on wear time, they were divided into full time (FT >17 h/d) and part time (PT < 12 h/d) wear groups. Mean wear durations were 20.86 hours in the FT-wear group and 9.55 hours in the PT-wear group. In skeletal changes, the ANB (A point, nasion, B point) angle was reduced by 2.69 degrees in the FT-wear group, and 1.33 degrees in the PT-wear group, and statistically significant increases were seen for the mandibular base measurement (Pg/OLp) in the FT-wear group (2.22mm), compared with those in the PT-wear group (0.44mm). . In dental changes, overjet were reduced by 3.91 mm and 2.0 mm in the FT-wear and PT-wear group, respectively. This difference was statistically significant. CONCLUSIONS: Skeletal effects were pronounced in the FT-wear group, and dentoalveolar changes were comparable in the 2 wear groups. The maximum skeletal treatment effect of a TB appliance was found to occur with FT wear over a 6-month treatment period.