Comparison of Jaw Muscle Activity, Masticatory Performance, and Salivation Across Three Chewing Patterns: A Within-Subjects Experimental Study.

BACKGROUND

The effects of simultaneous bilateral chewing are not well understood. Jaw muscle activity, masticatory performance, and salivary production during strictly unilateral, alternate unilateral, and bilateral chewing were investigated.

MATERIALS AND

METHODS

Twenty healthy dental students (aged 20-24 years) with complete natural dentition participated in this repeated-measures study. Each participant chewed a standardized piece of raw carrot for 20 chewing cycles using three chewing patterns: strictly unilateral on the preferred side, alternate unilateral with side switching every five cycles, and simultaneous bilateral chewing. Masseter and anterior temporalis muscle activity was recorded using surface electromyography. Masticatory performance was assessed by image analysis of the total area of chewed particles, and salivary volume and flow rate were measured gravimetrically. Repeated-measures ANOVA or Friedman tests were used to compare differences among the three chewing patterns.

RESULTS

Masticatory performance and the masseter asymmetry index (AI) did not differ significantly among chewing patterns. However, the anterior temporalis AI was significantly lower, chewing duration was significantly longer, and subsequently, salivary volume was significantly higher during alternate unilateral and simultaneous bilateral chewing compared with strictly unilateral.

CONCLUSION

Alternate unilateral and simultaneous bilateral chewing promote more symmetrical jaw muscle activity and prolong chewing time without compromising masticatory performance, suggesting that these patterns may serve as alternative chewing strategies for individuals with strictly unilateral chewing habits.