Dentoskeletal effects of class II malocclusion treatment with the modified Twin Block appliance.

Background: The purpose of this study was to prospectively assess the dentoskeletal effect of a modified Twin Block appliance for treatment of class II malocclusions.

Material And Methods: Lateral cephalograms of 25 Class II malocclusion patients were compared to evaluate skeletal, dentoalveolar and soft tissue changes pre- and post-treatment with a modified Twin Block appliance. A total of 33 angular and linear variables were used for analysis. The differences were calculated at the start and end of treatment. The paired T test was performed to compare the cephalometric measurements before and after treatment.

Results: Compared the pre- and post- treatment measurements, there was a significant increase in SNB (<0.001), CO-Gn (<0.001), ANS-Me (=0.001), Mandibular base (<0.001), Lower 1 to NB (°) (=0.004), Lower 1 to NB (mm) (<0.001), and Z-angle (=0.001) following functional therapy with modified Twin Block appliance. On the other hand, a significant decrease was observed in ANB (<0.001), NA-Pog (<0.001), overjet (<0.001), and overbite (=0.007), Upper 1 to palatal plane (=0.007), UL-E-line (<0.001), LL-E-line (=0.001), and H-angle (=0.002) after treatment with modified Twin Block appliance.

Conclusions: The modified Twin-Block improves facial esthetics in Class II malocclusion by a combination of changes in skeletal as well as dentoalveolar structures. The increase of mandibular unit length was observed to be due to a true mandibular growth not just a repositioning of the mandible. The modified appliance, however, did not show any superior effects in terms of less dental compensation compared to the conventional Twin-Block appliance. Dentoskeletal effect, Modified Twin Block, Class II malocclusion.