Treatment of muscle spasticity in patients with cerebral palsy using BTX-A: a pilot study

This study was designed to verify the safety and efficacy of botulinum toxin type A (BTX-A) used as a neuromuscular block on spastic masticatory musculature of children with cerebral palsy. Six patients who had spastic-tetraplegic cerebral-palsy, aged 5 to 20 years were selected. All patients had spasticity of the jaw muscles, bruxism, lower lip trauma, limited mouth opening, and difficulties in cleaning the oral cavity. The patients were sedated under general anesthesia, while the dentist injected the masseter and temporalis muscles bilaterally with 150 and 75 units of BTX-A each. Clinical examinations were conducted at 7, 14, 30, and 90 days after the initial appointment. We found statistically significant decreases in muscle spasticity and bruxism ( p = 0.002), improved inter-incisal opening ( p = 0.002), improved oral hygiene ( p = 0.031), and less lower lip trauma ( p = 0.060) after the neuromuscular blocking.     

Anterior and posterior neck muscle activation during a variety of biting tasks

Bruxism may be involved in the aetiology of myofascial neck pain. The objective of this study was to test the hypothesis that anterior and posterior neck muscles co-contract during jaw clenching. Ten test subjects developed different feedback-controlled submaximum bite forces in a variety of bite-force directions by means of bite-force transducers. The electromyographic activity of the sternocleidomastoid and supra/infrahyoidal muscles, and of the semispinalis capitis, semispinalis cervicis, and multifidi muscles was recorded by use of surface electrodes and intramuscular wire electrodes, respectively. For normalization of electromyography data, maximum voluntary contraction tasks of the neck muscles were conducted in eight different loading directions. The results confirmed co-contraction of the neck muscles in the range of 2-14% of the maximum voluntary contraction at a bite force ranging from 50 to 300 N. Significant activity differences were observed as a result of the different force levels and force directions exerted by the jaw muscles. Long-lasting tonic activation of specific neck muscles triggered by the jaw-clenching tasks was also detected. These findings support the assumption of a relationship between jaw clenching and the activity of the neck muscles investigated. The low level of co-contraction activity, however, requires further study to elucidate possible pathophysiological interactions at the level of single motor units.     

Occlusal splint for sleep bruxism: an electromyographic associated to Helkimo Index evaluation

This study aims to evaluate long-term effects of using an occlusal splint in patients with sleep bruxism (SB), using surface electromyography (EMG) of masseter and temporalis muscles, as well as the Helkimo Index. The subjects were 15 individuals aged from 19 to 29 years, bearers of SB, with presence of signs and symptoms of temporomandibular disorders (TMD), which never have used occlusal splints. The subjects answered the Helkimo's Index and underwent EMG before and after 60 days of occlusal splints use. There was no indication of a significant decrease in mean EMG levels over the therapy in the muscles. A significant decrease in TMD signs and symptoms were observed in SB patients after 60 days of occlusal splints therapy.     

开张式双殆垫与塑料殆垫治疗磨牙症的对比研究

目的：比较开张式双胎垫在治疗磨牙症中与塑料殆垫的临床疗效。方法：分别用自制的开张式双殆垫与塑料殆垫对48例磨牙症患者进行治疗,随访9个月。统计治疗结束1个月和9个月时的停止磨牙病例和平均减少的磨牙时间。结果：戴用1个月停止磨牙病例数比为6：12,戴用9个月时停止磨牙病例数比为10：21。其差异具有显著性（P〈0．01）。结论：开张式双殆垫治疗磨牙症优于塑料殆垫。     

Possible sleep bruxism,circadian preference,and sleep-related characteristics and behaviors among dental students

Objective: To assess sleep bruxism prevalence and its association with circadian preference and sleep-related characteristics among dental students.

Methods: Dental students of the Federal University of Minas Gerais participated in this cross-sectional study. Participants answered a scale assessing individuals' circadian preference, and a questionnaire regarding sleep-related characteristics and behaviors, history of muscle ache in the temporomandibular area, and history of bruxism.

Results: One hundred fifty-two students participated in the study. Sleep bruxism was reported by 11.3%. Most students (63.2%) were classified as intermediary, 34.9% as morningness, and 1.3% as eveningness. Individuals who reported muscle ache in the temporomandibular area in the morning (PR = 3.5; 95% CI = 1.1–11.5) were more likely to be in the group with sleep bruxism.

Conclusion: Muscle ache in the temporomandibular area is an important associated factor with sleep bruxism among dental students. Special attention should be paid to dental students’ circadian preference.     

Comparison of ambulatory and polysomnographic recording of jaw muscle activity during sleep in normal subjects

Clinicians and investigators need a simple and reliable recording device to diagnose or monitor sleep bruxism (SB). The aim of this study was to compare recordings made with an ambulatory electromyographic telemetry recorder (TEL-EMG) with those made with standard sleep laboratory polysomnography with synchronised audio-visual recording (PSG-AV). Eight volunteer subjects without current history of tooth grinding spent one night in a sleep laboratory. Simultaneous bilateral masseter EMG recordings were made with a TEL-EMG and standard PSG. All types of oromotor activity and rhythmic masseter muscle activity (RMMA), typical of SB, were independently scored by two individuals. Correlation and intra-class coefficient (ICC) were estimated for scores on each system. The TEL-EMG was highly sensitive to detect RMMA (0·988), but with low positive predictive value (0·231) because of a high rate of oromotor activity detection (e.g. swallowing and scratching). Almost 72% of false-positive oromotor activity scored with the TEL-EMG occurred during the transient wake period of sleep. A non-significant correlation between recording systems was found (r = 0·49). Because of the high frequency of wake periods during sleep, ICC was low (0·47), and the removal of the influence of wake periods improved the detection reliability of the TEL-EMG (ICC = 0·88). The TEL-EMG is sensitive to detect RMMA in normal subjects. However, it obtained a high rate of false-positive detections because of the presence of frequent oromotor activities and transient wake periods of sleep. New algorithms are needed to improve the validity of TEL-EMG recordings.     

Is there a trend of decreasing prevalence of TMD-related symptoms with ageing among the elderly?

Objective. Older adults have not been studied as much as younger ones regarding prevalence of TMD-related symptoms. The aim was to assess the prevalence of TMD-related symptoms in two population samples, 70 and 80 years old. Materials and methods. Identical questionnaires were in 2012 sent to all subjects born in 1932 and 1942 living in two Swedish counties. The response rate was 70.1%, resulting in samples of 5697 70- and 2922 80-year-old subjects. The questionnaire comprised 53 questions. Answers to questions on problems regarding TMD-related symptoms and awareness of bruxism were analysed. Results. Twelve per cent of the women and 7% of the men in the 70-year-old group reported some, rather great or severe problems regarding TMD pain. In the 80-year-olds the prevalence was 8% and 7%, respectively. Subjects who had problems with TMJ sounds reported difficulty to open the jaw wide 6-times and TMJ pain 10–13-times more frequently than subjects without such problems. Changes of taste and awareness of bruxism were the only variables significantly associated with TMD symptoms in both age groups. Number of teeth was not significantly associated with any of the TMD-related symptoms. Conclusions. Most of the elderly subjects had no severe problems with TMD-related symptoms, but 12% of the 70-year-old women reported some, rather great or severe problems. The marked gender difference at age 70 had disappeared in the 80-year-old group. The prevalence was lower among the 80- compared with the 70-year-old subjects of both sexes. The results support the comorbidity between TMD-related symptoms and general health problems.