LAUSR

BACKGROUND Hall technique crowns (HTCs) alter the occlusion temporarily, potentially affecting jaw muscles, particularly the masseter -the primary jaw-closing muscle. AIM To assess masseter muscle activity (MMA) in children treated with a unilateral HTC. METHODS 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 (Pbase ), immediately-post (Pimmed ), at two weeks-post (P2w ) and at six weeks-post (P6w ) HTC cementation. T-test, ANOVA and post hoc statistics were used (p<0.05). RESULTS As expected, MMA was low at rest and increased during maximal jaw clenching (p<0.0001). MMA (mean+SD) increased significantly (p<0.001) between RP and MVC at: Pbase [from 1.60 μV.s (+0.96) to 5.40(+2.30)]; Pimmed [1.57(+1.15) to 3.75(+1.87)]; P2w [1.39(+0.54) to 5.54(+1.45)] and finally P6w [1.46(+0.56) to 6.45(+2.56)]. Rest-MMA at Pbase , Pimmed , P2w & P6w remained unchanged (p=0.18) while Pbase clench-MMA reduced by a third at Pimmed (p<0.001), returned to and exceeded baseline levels at P2w (p=0.822), and P6w (p<0.001) respectively. CONCLUSIONS 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 two and six weeks, respectively. Rest-MMA remained unchanged.