This prospective, non-profit study aims to better understand how occlusal splints (gnathological splints) affect daytime and nighttime bruxism (teeth grinding) and clenching in adults with chronic myofascial pain of the jaw muscles, a common form of temporomandibular disorder (TMD). Bruxism and clenching are repetitive or sustained jaw muscle activities that can contribute to jaw pain and dysfunction, and their accurate diagnosis requires instrumental assessment of muscle activity. In this study, muscle activity will be objectively measured using a portable device (dia-BRUXO®) worn for 24 hours, which records the electrical activity of the chewing muscles during both wakefulness and sleep. Adult patients with TMD who are prescribed a night-time occlusal splint will undergo three 24-hour recordings: before using the splint, two weeks after starting treatment, and two months later. During each recording, participants will also report their facial pain levels and awareness of clenching or grinding during the day. Their results will be compared with those of a matched control group without TMD. The main goal is to compare jaw muscle activity between patients and healthy individuals, while secondary goals include analyzing how long the muscles are active and how these patterns relate to symptoms. By combining objective measurements and patient-reported experiences, this study seeks to clarify how occlusal splints influence muscle activity and symptoms, helping clinicians improve diagnosis and treatment of bruxism and TMD.

This prospective, non-profit interventional study is designed to evaluate the effects of a gnathological occlusal splint on masticatory muscle activity in adults with temporomandibular disorders (TMD) and chronic myofascial pain. Bruxism and clenching, occurring during both wakefulness and sleep, are recognized contributors to TMD symptoms and are best assessed through instrumental measurement. For this purpose, the study uses a validated portable device (dia-BRUXO®) capable of recording the electromyographic (EMG) activity of the masseter muscles continuously over a 24-hour period, allowing objective assessment of muscle activity during daily life and sleep.

Participants with TMD who have a clinical indication for nocturnal occlusal splint therapy will undergo three 24-hour EMG recordings: at baseline (before splint use), two weeks after splint delivery, and two months after initiation of treatment. During each recording period, participants will also self-report facial pain intensity and awareness of parafunctional activities at regular intervals during wakefulness. EMG outcomes will include average signal amplitude, muscle activation time, and the presence of abnormal co-contraction patterns. These data will be used to assess changes in muscle activity over time and in relation to splint use.

A control group of age- and sex-matched adults without TMD will undergo two 24-hour EMG recordings, two months apart, following the same recording and self-report procedures. Comparisons between the TMD group and controls will allow identification of functional differences in masticatory muscle activity. The primary endpoint is the comparison of masseter muscle EMG activity between participants with TMD and healthy controls, while secondary endpoints include analysis of muscle activation duration and correlations between EMG patterns and reported symptoms. This integrated approach aims to improve understanding of the functional impact of occlusal splints and support more objective diagnosis and management of bruxism and TMD.

Inclusion Criteria:

• Adult subjects aged ≥ 18 years
• Subjects willing to provide written informed consent
• Patients with temporomandibular disorders who have an indication for treatment with a gnathological occlusal splint

Exclusion Criteria:

• Patients who change their pharmacological regimen during the monitoring period, as drug therapy may affect facial pain and/or muscle activity.