Bruxism is a prevalent condition that differentially burdens individuals. The overall objective of this pilot study is to measure the effects of BTX-A (Xeomin®) injections into bilateral masseter muscles for the management of sleep bruxism and associated symptoms. The hypothesis is that BTX-A reduces masticatory muscle activity. The aim of this study is to instrumentally monitor subjects closely over an extended time period of three months before and after application of BTX-A.~Botulinum toxin type A ( BTX A; Xeomin ® ) temporarily blocks neuromuscular synapses. It is successfully and safely used therapeutically in various types of movement disorders and in chronic migraineurs. The mechanism of action of this treatment is related to a reduction of neurotransmitter release leading to reduced muscle activity.~The following Null hypothesis will be tested:~Injections of Xeomin® into the masseter muscles bilaterally (25 Units per muscle applied with 2 injections in each muscle) have no effect on bruxism measured by A) Masticatory muscle activity (1° objective) B) Subjects' well-being (2° objective) C) Sensitivity of masticatory muscles and jaw joints (2° objective) D) Anxiety over tooth wear (2° objective) E) Disturbed sleep by bed partner (2° objective)~Following instruments will be used:~WISE questionnaires. A comprehensive web-based interdisciplinary symptom evaluation tool.~Algometer for sensitivity measure of masticatory muscles and jaw joints.~Bio-signal recorder. Parallel to the Electromyography (EMG) of the masseter muscles, other bio-signals such as a number of electroencephalographic (EEG) derivations, electrooculogram (EOG ) as well as an electrocardiogram (ECG) will be recorded, in order to detect sleep stages and better identify bruxism episodes. The device used in this study has been approved for projects NIH #2R01DE016417-05A1 and #1 R01DE028548-01.~Ultrasound for masseter muscle thickness measure~Dual-color chewing gum for chewing efficiency measure.
The purpose of this study is to test whether severe masticatory muscle spasms during sleep (e.g. teeth clenching and grinding, known as bruxism in technical jargon) demonstrably decrease after application of botulinum toxin type A (Xeomin®). Xeomin® has so far been used to relieve spasms of other muscles and is an approved drug in Switzerland. This study is now intended to test the suitability of this drug for relaxation of the masseter muscle.