Cone-beam Computed Tomography Evaluation of Skeletal and Dentoalveolar Alteration Following Twin Block versus Fixed Functional Appliance in Mandibular Advancement.

INTRODUCTION Mandibular retrognathism is commonly managed during growth modification using functional appliances. Cone-beam computed tomography (CBCT) allows accurate evaluation of skeletal and dentoalveolar changes. This study compared the skeletal, dentoalveolar, and temporomandibular joint (TMJ) alterations in growing patients after receiving twin block and fixed functional appliance therapy.

Materials And Methods

Thirty participants, aged 11-15 years, diagnosed with Class II malocclusion due to mandibular retrognathism were included in this comparative clinical investigation. Two groups of patients were split equally as twin block and fixed functional appliance therapy groups. CBCT evaluations were performed at baseline (T0) and posttreatment (T1). Skeletal, dentoalveolar, and TMJ parameters were assessed and compared between the groups.

Results

Skeletal analysis showed significantly greater mandibular advancement in the twin block group, with increased SNB and Co-Gn measurements. There was a greater reduction in ANB angle compared to the fixed functional group, indicating superior orthopedic effects. Dentoalveolar changes revealed controlled maxillary incisor retroclination in both the groups. However, mandibular incisor proclination (IMPA) was significantly higher in the fixed functional group. TMJ evaluation demonstrated adaptive remodeling in both the groups, with the twin block appliance showing more favorable anterior and posterior joint space changes.

Conclusion

Both twin block and fixed functional appliances are efficient in treating Class II malocclusion in growing patients. Twin block therapy produces more favorable skeletal advancement and TMJ remodeling, whereas fixed functional appliances rely more on dentoalveolar corrections.