Hall technique crowns and children's masseter muscle activity: A surface electromyography pilot study

Hall technique crowns (HTCs) alter the occlusion temporarily, potentially affecting jaw muscles, particularly the masseter - the primary jaw-closing muscle.

To assess masseter muscle activity (MMA) in children treated with a unilateral HTC.

In 12 children treated with a single HTC, bilateral MMA was recorded with surface electromyography (sEMG) for ten cycles of Rest Position (RP) and Maximum Voluntary Clenching (MVC) over 20 seconds immediately pre-HTC cementation (P_base ), immediately post-HTC cementation (P_immed ), at 2 weeks post-HTC cementation (P_2w ) and at 6 weeks post-HTC cementation (P_6w ). t test, ANOVA and post hoc statistics were used (P < .05).

As expected, MMA was low at rest and increased during maximal jaw clenching (P < .0001). MMA (mean ± SD) increased significantly (P < .001) between RP and MVC at: P_base [from 1.60 μV·s (±0.96) to 5.40(±2.30)]; P_immed [1.57(±1.15) to 3.75(±1.87)]; P_2w [1.39(±0.54) to 5.54(±1.45)] and finally P_6w [1.46(±0.56) to 6.45(±2.56)]. Rest MMA at P_base , P_immed , P_2w and P_6w remained unchanged (P = .18) whereas P_base clench MMA reduced by a third at P_immed (P < .001), returned to and exceeded baseline levels at P_2w (P = .822) and P_6w (P < .001), respectively.

This pilot study showed that Hall technique crowns may affect masseter muscle activity in children. Clench MMA was reduced immediately post-treatment but returned to and later exceeded baseline levels at 2 and 6 weeks, respectively. Rest MMA remained unchanged.