Evaluation of the effects of monoblock functional appliance therapy on masseter muscles in skeletal class II patients using ultrasonography and ultrasonographic elastography

OBJECTIVES: This study aimed to evaluate changes in masseter muscle morphology and elasticity after monoblock functional appliance therapy in skeletal Class II patients using ultrasonography and elastography, with elasticity as the primary outcome. METHODS: 30 skeletal Class II and 30 skeletal Class I individuals received monoblock therapy and bilateral ultrasonographic and elastographic assessments were performed at T0 and T1; masseter elasticity (kPa) was the primary outcome, with thickness, length, and area as secondary outcomes, analyzed using mixed-design ANOVA with Bonferroni correction. RESULTS: = 0.026), indicating decreased resting and slightly increased clenching values over time. CONCLUSION: Masseter elasticity was mainly influenced by functional condition, being higher during clenching. Left-side stiffness was greater. Muscle response remained stable and mainly depended on functional activity rather than treatment-related differences.