The effects of torque control spurs in twin‐block appliances

Abstract

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

Midpalatal implants vs headgear for orthodontic anchorage—a randomized clinical trial: Cephalometric results

“…All patients who had failed implants requested further implant placement. This failure rate is very similar to those quoted for other studies, including early treatment with a twin block functional appliance 17 , a prospective cohort study of the twin block appliance 18 and for the Herbst appliance 11 but much less that later treatment with a twin block 11 .…”

Use of the Clark Twin Block functional appliance with and without an upper labial bow: a randomized controlled trial

“…One of the main problems with removable functional appliances is poor patient cooperation, with discontinuation rates between different appliances primarily reflecting design. One of the main advantages of the CTB is the fact that it is well tolerated and has a low discontinuation rate, which varies between 9% and 33% 4,10 and compares favorably with that of other functional appliances, including the Bass appliance (28%), 10 the bionator (25%), 17,18 and the functional regulator (up to 42%). 19 In this study, the overall discontinuation rate was 6.25%.…”

“…1,[4][5][6][9][10][11][12] The main aim of this study was to compare the effect on treatment response of incorporating a maxillary labial bow in the core CTB appliance design in a matched sample of Class II division 1 subjects. Both appliance designs were effective in producing complete or partial correction of the overjet during the period of observation.…”

“…3 However, in an attempt to reduce incisor retroclination and to maximize skeletal effects of the appliance, many clinicians choose to omit this component. Alternative modifications have been investigated in an attempt to promote skeletal change and limit dentoalveolar movements, including torquing spurs on the upper incisors, 4 Southend clasps, 5 and the addition of headgear. 6 To date, no direct investigations have explored the overall effects of the upper labial bow on the outcome of CTB therapy.…”

Twin Block appliance with acrylic capping does not have a significant inhibitory effect on lower incisor proclination

“…5 On the contrary, when a labial bow or torquing springs had been incorporated in the upper plate, no statistically significant differences in the angular position of incisors were observed between the two alternative designs. 6,7 Acrylic capping was previously recommended to prevent labial tipping of the lower incisors in functional appliance treatment. 8 Such TB modification proved to minimize lower incisor proclination compared with untreated matched historical control subjects.…”