The Effects of the Placement of Prefabricated Metal Crowns Utilizing the Hall Technique on Masseter Muscle Activity: A Surface Electromyography Study in Children
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Background: Hall technique crowns, used to restore non-pulpal carious primary molars, change the occlusal apparatus temporarily, of which the masseters muscles are part of. Surface-electromyography (sEMG) is used to assess masseter muscle activity (MMA). Aim: To assess the effect of Hall technique crownson MMA in children by measuring sEMG. Methods: Bilateral MMA was recorded (mean integrated sEMG expressed in μV.s) for ten cycles of Rest Position (RP) and Maximum Voluntary Clenching(MVC) over 20 seconds immediately-pre (P₁) and immediately-post (P₂) cementing a single HTC in 12 healthy children withcaries. Further post op results at two weeks (P₃) and six weeks (P₄) results were obtained for 9 and 7 out of the 12 children respectively. T-test, ANOVA and post hoc statistical analyses were used. Significance was set at (p<0.05). Results: Bilateral MMA was low at rest and increased during clenching in children. MMA increased significantly (p<0.001) between RP and MVC at P₁ from 1.85(+0.96) to 5.49(+2.30) μV.s; at P₂ from 1.77(+1.15) to 3.75(+1.81); at P₃ from 1.39(+0.54) to 5.54(+1.45) and finally at P₄ from 1.46(+0.56) to 6.6(+2.56). While there were no significant differences between all RP-MMA readings at P₁, P₂, P₃& P₄(p=0.18), the MVC-MMA readings differed significantly (p<0.001) as MVC-MMA at P₁(baseline) reduced by a third at P₂, returning to (p=0.822) and increasing above (p<0.001) MVC-MMA baseline levels at P₃ and P₄ respectively. Conclusions: Children’s masseter muscle clenching activity, as measured by sEMG, reduced immediately after cementing a single HTPMC. The activity returned to, and later exceeded, baseline levels at two and six weeks respectively. HTPMCs had minimal effect on masseter muscle rest activity.