Effect of the dental arches morphology on the masticatory muscles activities in normal occlusion young adults.

ABSTRACT

OBJECTIVES: The aim of this study was to assess the relationship between the morphology of dental arches and the activity of the masticatory muscles activities in healthy volunteers with full natural dentition. METHODS: Two-hundred youthful Class I volunteers (113 females, 87 males) were clinically investigated. Alginate impressions of dental arches were taken, and plaster casts were prepared and measured. EMG data from eight masticatory muscles was recorded to assess their activities in central occlusion, lateral and protrusive movements. RESULTS: Clinical measurements and plaster casts analyses confirmed normal values of parameters investigated. Most of the arch measurements were significantly larger in the males than in the females. Weak positive correlations were found between overbite and masseter activity in centric occlusion (the right Mm R = 0.151, P ≤ 0.05; the left Mm R = 0.191, P ≤ 0.05). Also, the range of protrusive movement positively correlated with masseter activities in central occlusion (the right Mm R = 0.194, P ≤ 0.05; the left R = 0.201, P ≤ 0.05). CONCLUSIONS: The null hypothesis that morphology of dental arches does not affect the masticatory muscles' activities was rejected. The findings of this investigation indicate that systemic, longitudinal analyses of morphology of occlusion and muscular response, even in normal subjects, are needed.