Evaluation of Botulinum Toxin Injection in Masseter Muscle on Subjective Reports of Nocturnal Bruxism

Abstract

Background & Aim: Nocturnal bruxism is defined as a functional disorder of the masticatory system that includes unconscious gnashing and clenching of the teeth during sleep, which may cause fractures of dental restorations and damage to the teeth and incitement to temporal headache and temporomandibular disorders. Several studies showed the effectiveness of botulinum toxin injection into the masseter muscle at different doses depending on each study (20U, 25U, and 30U) for reducing nocturnal bruxism in patients who did not respond to conservative treatments, Most of these studies did not take into account the change in the size of the masseter muscle and the shape of the lower third of the face at the angle of the jaw when injecting a high dose of botulinum toxin, so this study aims to evaluate the effectiveness of injecting 10U of botulinum toxin into the masseter muscle to reduce nocturnal bruxism and its accompanying symptoms.

Materials and Methods: The sample consisted of 20 patients who suffer from pain in the masseter muscle and sensitivity of the teeth as a result of its wear due to nocturnal bruxism. The sample was randomly divided into 2 groups, group A included 10 patients who were injected with 10U of botulinum toxin into the masseter muscle on both sides and group B included 10 patients who were given a placebo in the masseter muscle on both sides, The self-assessment of nocturnal bruxism was done by means of a questionnaire distributed to patients and observing the change in the answers after the injection for a period of one, three and six months.

Results: Student's T-test was conducted for independent samples, the significance level is much smaller than the value 0.05, meaning that at the 95% confidence level there are statistically significant differences in the average values of patients' answers to the questionnaire items between the two study groups, this indicates a decrease in nocturnal bruxism events and morning masseter muscle spasm in the study sample compared with the control sample.

Conclusions: Effectiveness of injecting 10U of botulinum toxin into the masseter muscle to reduce nocturnal bruxism and the accompanying symptoms of pain and spasm of the masseter muscle in the morning.