The effects of torque control spurs in twin-block appliances.

The study compared the effects of torque control spurs on upper incisor retroclination and extrusion with two designs of a twin-block functional appliance in Class II/1 cases. The two designs were also compared with respect to anchorage loss in the lower arch and for patient compliance rates. Consecutively started cases were chosen - 90 patients with a design incorporating a labial bow (CTB group) and 110 with upper incisor 'torquing' spurs (STB group) and used to calculate failure rates. Thirty consecutive patients with satisfactory records from each group were analysed cephalometrically. The STB group experienced substantially less upper incisor retroclination, reduced upper incisor extrusion and slightly more favourable mandibular growth. The labial movement of lower incisors and the patient compliance were not significantly different in the two groups. Overall, 82.5% of patients fully reduced their overjet with 9% failing to reduce the overjet below 6 mm.Fig. 1f