[Three-dimensional evaluation of sagittal-guidance Twin-block appliance on mandibular growth remodeling in adolescents with skeletal Class Ⅱ malocclusion].

PURPOSE: To three-dimensionally evaluate the effects of sagittal-guidance Twin-block (SGTB) appliance on mandibular growth in adolescents with skeletal Class Ⅱmalocclusion.

METHODS

Forty-three adolescents with skeletal Class Ⅱ malocclusion were divided into SGTB treatment group [n=22, treatment duration (13.26±1.71) months] and untreated control group [n=21, observation period (12.72±0.59) months]. CBCT scans were obtained pre- and post-intervention for 3D cephalometric analysis.

RESULTS

The treatment group showed significantly greater vertical ramus growth (left (3.16±1.63) mm vs. (1.49±1.13) mm; right (3.18±1.23) mm vs. (1.15±0.76) mm, P＜0.001) with no intergroup difference in mandibular body length (P＞0.05). ANB angle decreased by 1.87°±1.06° in SGTB group, significantly greater than 0.41°±0.20° in controls (P＜0.001). In the treatment group, the maxillary incisors were lingually inclined by 6.12°, and the mandibular incisors were labially inclined by 2.48°, no significant changes were observed in the control group. Three-dimensional measurements showed that the mandible exhibits a combined growth pattern of forward and downward direction.

CONCLUSIONS

SGTB effectively enhances vertical ramus development and improves sagittal jaw relationship through combined skeletal adaptation and dentoalveolar compensation.