Background and objective

Bruxism (BRX) is defined as grinding or clenching of teeth, involuntarily and intensely, due to hypertrophy and/or contraction of muscles related to chewing, with particular involvement of masseters. It can happen during sleep or wakefulness indistinctly. Treatments are intended to limit destructive effects of BRX on different biological structures, especially the temporomandibular joint; are variable and range from irreversible occlusion, interposition of splints, pharmacological therapies, cognitive-behavioral approaches and the use of botulinum toxin type A (BoNT-A).

The aim of this study was to investigate the relaxation effect of BoNT-A injection in masseter muscles and its relation to relief of symptoms in patients with BRX.

Methods

This study is a clinical, prospective and longitudinal trial on 25 adult female patients between age ranges 24 to 67 (3.,2 +/- 10.7), carried out from September 2018 to March 2019.Evaluation controls were done before, 2 weeks and 4 months after treatment with BoNT-A. Examination protocol in the trial included digital photography, Smith and Knight tooth wear index, orthopantomography and magnetic resonance imaging. Measurements of bigonial diameters were taken by calliper, at rest and during contraction, and the thickness of each masseter muscle was also evaluated in the same conditions, by ultrasound at every control.

Results

As a result, after BoNT-A treatment, 24% of the patients were free of BRX, while the remaining 76% obtained a significant improvement, with few and transient adverse effects.

Conclusions

BoNT-A can be used to protect oral-facial structures (such as teeth, jaw muscles, temporomandibular joint), from excessive forces and harmful damage caused by BRX, and to relieve accompanying pain and related complaints by decreasing the muscle forces exerted during contraction.

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