Sleep bruxism associated with obstructive sleep apnoea syndrome - A pilot study using a new portable device.

Sleep bruxism (SB) and obstructive sleep apnoea syndrome (OSAS) share common pathophysiologic pathways. We aimed to study the presence and relationship of SB in a OSAS population. Patients referred with OSAS suspicion and concomitant SB complains were evaluated using a specific questionnaire, orofacial evaluation and cardio-respiratory polygraphy that could also monitor audio and EMG of the masseter muscles. From 11 patients studied 9 had OSAS. 55.6% were male, mean age was 46.3±11.3 years, and apnea hypopnea index of 11.1±5.7/h. Through specific questionnaire 55.6% had SB criteria. Orofacial examination (only feasible in 3) confirmed tooth wear in all. 77.8% had polygraphic SB criteria (SB index>2/h). Mean SB index was 5.12±3.6/h, phasic events predominated (72.7%). Concerning tooth grinding episodes, we found a mean of 10.7±9.2 per night. All OSAS patients except two (77.8%) had more than two audible tooth-grinding episodes. These two patients were the ones with the lowest SB index (1.0 and 1.4 per hour). Only in one patient could we not detect tooth grinding episodes. There was a statistically significant positive correlation between tooth grinding episodes and SB index and phasic event index (R=0.755, p=0.019 and R=0.737, p=0.023 respectively, Pearson correlation). Mean apnoea to bruxism index was 0.4/h, meaning that only a minority of SB events were not secondary to OSAS. We could not find any significant correlation between AHI and bruxism index or phasic bruxism index (R=-0.632 and R=-0.611, p>0.05, Pearson correlation). This pilot study shows that SB is a very common phenomenon in a group of mild OSAS patients, probably being secondary to it in the majority of cases. The new portable device used may add diagnostic accuracy and help to tailor therapy in this setting.

Application of Infrared Thermal Imaging in a Violinist with Temporomandibular Disorder.

Temporomandibular disorders (TMD) consist of a group of pathologies that affect the masticatory muscles, temporomandibular joints (TMJ), and/or related structures. String instrumentalists, like many orchestra musicians, can spend hours with head postures that may influence the biomechanical behavior of the TMJ and the muscles of the craniocervicomandibular complex (CCMC). The adoption of abnormal postures acquired during performance by musicians can lead to muscular hyperactivity of the head and cervical muscles, with the possible appearance of TMD. Medical infrared thermography is a non-invasive procedure that can monitor the changes in the superficial tissue related to blood circulation and may serve as a complement to the clinical examination. The objective of this study was to use infrared thermography to evaluate, in one subject, the cutaneous thermal changes adjacent to the CCMC that occur before, during, and after playing a string instrument.

Changes in EMG activity during clenching in chronic pain patients with unilateral temporomandibular disorders.

The study assessed the differences in electromyographic (EMG) activity recorded during clenching in women with chronic unilateral temporomandibular disorders (TMDs) as compared to control subjects. Seventy-five full dentate, normo-occlusion, right-handed, similarly aged female subjects were recruited. Twenty five subjects presented with right side TMD, 25 presented with left side TMD and 25 pain-free control subjects participated. Using integrated surface EMG over a 1 s contraction, the anterior temporalis and masseter muscles were evaluated bilaterally while subjects performed maximum voluntary clenching. Lower EMG activation was observed in patients with TMD as compared to control subjects (temporalis: 195.74+/-18.57 vs. 275.74+/-22.11, P=0.011; masseters: 151.09+/-17.37 vs. 283.29+/-31.87, P<0.001). An asymmetry index (SAI) was calculated to determine ratios of right to left sided activation. Patients with right-sided TMD demonstrated preferential use of their left-sided muscles (SAI -5.35+/-4.02) whereas patients with left-sided TMD demonstrated preferential use of their right-sided muscles (SAI 6.95+/-2.82), (P=0.016). This unilateral reduction in temporalis and masseter activity could be considered as a specific protective functional adaptation of the neuromuscular system due to nociceptive input. The asymmetry index (SAI) may be a useful measure in discriminating patients with right vs. left-sided TMD.

Electromyographic activity in patients with temporomandibular disorders.

Evaluation of masticatory muscle activity by surface electromyography (EMG) is a valuable tool for diagnosing dysfunction of the masticatory apparatus. However, controversy exists with regard to the usefulness of the EMG for patients with temporomandibular disorders (TMD). Forty patients with TMD were subjected to surface EMG of the masticatory muscles. These patients had consulted because of temporomandibular pain and clicks. In most cases (75%), the symptoms affected the patient's left side. Overall mean resting activity was 2.52 microV+/-1.25 microV (s.d.), which is slightly higher than in comparable healthy subjects (1.92+/-1.20 microV). Mean resting activity was highest in the anterior digastric muscle (3.49 microV) on the left side. Overall mean activity during clenching was 66.77+/-35.22 microV, which is about half that observed in healthy subjects (110.30+/-82.97 microV). During leftward movement of the jaw, activity was on average highest in the left digastric, while during rightward movement, activity was on average highest in the right anterior temporal (AT). Our results thus indicate that patients with temporomandibular joint (TMJ) disorder show: (1) a slight increase in basal tone; (2) a significantly reduced capacity for clenching; and (3) an apparently paradoxical inhibition of the dysfunctional-side AT during movement of the mandible towards that side.