Cephalometric evaluation of skeletal and dentoalveolar effects of Twin-Block appliance and van Beek headgear-activator (vBHGA) in the correction of class II malocclusion

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Kirtane, Rohan
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Objective: To evaluate the cephalometric skeletal and dentoalveolar short-term effects of Twin Block (TB) and van Beek Headgear Activator (vBHGA) appliances, in the correction of skeletal Class II malocclusion (ANB≥5) in growing patients as determined by the CVM method, in comparison with a growing untreated control. Materials and Methods: Pre (T1) and post-functional appliance (T2) lateral cephalograms were retrospectively obtained for the vBHGA (n=46), TB (n=45), and control (n=45) groups. The groups were also stratified into horizontal or vertical using Jarabak ratio values. A customized cephalometric analysis and superimposition-based measurements were performed. Analysis of Covariance (ANCOVA) regression models at the 5% level of significance were used. Results: Both appliances equally improved the jaw relationship. For vBHGA, they were: ANB (1.590; p=0.00) and Harvold Difference (2.51mm; p<0.0001) and for TB, they were ANB: 1.700; p=0.01, Wits: 3.59mm; p<0.001 and Harvold Difference: 2.65mm; p<0.0001). While this mostly occurred due to forward positioning of the mandible (SNB: 0.960; p=0.01) for TB; maxillary restriction with counterclockwise rotation of the palatal plane (SNA: 1.590; p=0.00 and PP-SN: 0.180; p=0.64) was seen with vBHGA. Dentoalvelolar changes were more pronounced with TB. Only U1-SN0, U1-NA0, and U1-PP0 values were affected by the growth pattern. The TB horizontal growers experienced more maxillary incisor retroclination than their vBHGA counterparts (U1/NA0: 3.620; p=0.0067) The overbite reduced more in the TB group (OB: 1.83mm; p<0.001), but this was due to greater relative intrusion of the lower incisors as they proclined (0.80mm; p=0.05). Conclusions: Both appliances were effective to correct skeletal Class II malocclusions in growing patients regardless of growth pattern. The mechanism by which this occurred differed between the groups and can be used in favor of specific patients’ needs. Key Words: Class II malocclusion, vBHGA, TB.
Twin-Block, van Beek Headgear-Activator, Class II malocclusion, functional appliances, orthopedic correction in growing children, CVM stages, pubertal peak