No effect of conscious clenching on simple arithmetic task in healthy participants

Abstract

Purpose: This study aimed to investigate whether clenching aids performance in a task requiring mental concentration in healthy participants.
Materials and methods: Twenty healthy participants (an average of 26.8 ± 2.0 years, nine females and 11 males) were recruited from our department. Participants performed four sets of hundred-square calculations as a mental arithmetic task. Among these sets, the third and the fourth sets were randomly divided into two conditions: one condition where participants made an effort to not allow their teeth to touch (‘no tooth-contact’ condition), and another where they made a conscious effort to rhythmically clench their teeth (‘clenching’ condition) during the task. Surface EMG was recorded from the left masseter muscle. Arithmetic performance was compared between the tooth-contact and clenching conditions using paired t-tests. In addition, we computed Pearson product–moment coefficients of the correlations between the difference in EMG activity and arithmetic performance in the two conditions.
Results: No significant change in arithmetic score was found between the no tooth-contact (68.8 ± 12.2) and clenching conditions (66.5 ± 12.7; P = 0.27). No significant correlation was found between the difference in EMG activity and changes in arithmetic performance (r = 0.32, P = 0.17).
Conclusion: In healthy participants, conscious clenching was not associated with any benefit in arithmetic performance. Although our study was limited by only measuring the short-term effects of clenching on a simple arithmetic task, the results indicate that it may not be harmful for clinicians to encourage their patients to refrain from clenching their teeth.