Electromyographic evaluation of masticatory muscles at rest and maximal intercuspal positions of the mandible in children with sleep bruxism

Comparative study of surface electromyography of masticatory muscles in patients with different types of bruxism

BACKGROUND

Bruxism is a rhythmic masticatory muscle activity that occurs involuntarily in a non-physiologically functional state. There is a lack of research classifying the functional status of masticatory muscles in patients with different mandibular movement types (centric clenching or eccentric grinding) of bruxism.

AIM

To assess the differences of the masticatory muscle activity in patients with different types of bruxism.

METHODS

A total of 21 subjects with centric bruxism (CB) and 21 subjects with eccentric bruxism (ECB) were screened from college students according to a questionnaire and their tooth wear features. Sixteen subjects with no bruxism were also recruited. The surface electromyography (EMG) signals of the temporalis anterior (TA) and superficial masseter muscle (MM) were measured in different mandibular positions and during the chewing task. The EMG amplitude and chewing cycle duration parameters were then analyzed.

RESULTS

The CB group showed fewer muscle maximal motor units, with the MM being more pronounced, a higher proportion of muscle contractions to be recruited for the same load of chewing activity, and a longer chewing cycle. The ECB group showed more TA maximal motor units and higher MM activity on the non-working side in unilateral chewing.

CONCLUSION

CB mainly affects the MM, and patients with CB show reduced masticatory muscle contraction efficiency and chewing cycle efficiency. ECB mainly affects the TA, and patients with ECB show enhanced contraction of non-functional lateral muscle bundles.

Immediate Evaluation of the Effect of Infrared LED Photobiomodulation on Childhood Sleep Bruxism: A Randomized Clinical Trial

The gold standard for the management of sleep bruxism (SB) is the use of a rigid occlusal splint; however, there are limitations for its use in children and alternatives to the management of SB are needed. Photobiomodulation therapy has been used with positive results in temporomandibular disorders. This study aimed to evaluate the effects of photobiomodulation therapy with infrared LED in children with SB. Thirty children were divided into three groups: Group 1: control/absence of bruxism (n = 10); Group 2: SB treated with infrared LED (n = 10); Group 3: SB treated with occlusal splint (n = 10). Electromyographic evaluation of masseter, anterior temporalis, and upper trapezius, and salivary dopamine levels were assessed before and after treatments. Data were statistically analyzed using two-way mixed model ANOVA. An increase in the temporalis and right masseter EMG activity at rest was observed in Group 3, with large effect size (p < 0.05). Left masseter and temporalis EMG activity did not differ over time in the LED group, similar to the control group. Moreover, the EMG activity of masticatory muscles during chewing and upper trapezius muscle did not differ over time in all groups. The results also pointed to a difference in the levels of dopamine between children with and without SB, with Group 3 showing higher levels in the pre-treatment time compared to controls (p < 0.025). In conclusion, an increase in the masticatory muscles activity at rest was observed in children undergoing splint therapy. Moreover, a difference in the levels of salivary dopamine was found between children with and without SB.

Prevalence of clinical signs and symptoms of the masticatory system and their associations in children with sleep bruxism: A systematic review and meta-analysis

Sleep bruxism (SB) is a behavior of central origin that is related to different factors. This systematic review aimed to determine the prevalence of clinical signs and symptoms of the masticatory system and their association in children with SB. A structured search in ten databases were taken. Two authors independently selected studies, extracted the data, study quality assessment and graded the evidence. A meta-analysis of proportion and association was performed under random-effect model, confidence interval of 95% and p < 0.05 for pulled values. Were included 22 studies, and their overall quality was poor. The more common clinical signs and symptoms of the masticatory system in children with SB were primary canine wear (P:84.13, 95% CI:78.13-89.32; p = 0.248; I² 25.05), dental wear (P:73.76, 95% CI:38.73-96.91; p < 0.001; I² 97.62) and headache (P:52.85, 95% CI:38.92-66.56; p < 0.001; I² 93.65). The prevalence of SB in children was 31.16% (P:31.16, 95% CI:22.18-40.92; p < 0.001; I² 98.56). There was no significant risk of dental wear and headache in children with SB. There is low to very low certainty of the evidence. The more prevalent clinical signs and symptoms of the masticatory system presented in children with SB were primary canine wear, dental wear and headache. Further studies of high quality are still needed to elucidate these important questions.

Effects of Rapid Palatal Expansion on Chewing Biomechanics in Children with Malocclusion: A Surface Electromyography Study

Malocclusion during childhood may affect both morphology and masticatory function and could greatly affect the subsequent growth and development of the jaws and face. The purpose of this study was to evaluate the efficiency of surface electromyography in describing the effects of the rapid palatal expansion (RPE) on Masseter (M) and Temporalis Anterior (T) muscles' activity in 53 children with different types of malocclusion: bilateral posterior crossbite (BPcb), underdeveloped maxillary complex without crossbite (NOcb) and unilateral posterior crossbite on the right (UPCBr) and on the left (UPCBl). The muscular activities during chewing tasks were assessed bilaterally before and after RPE application and three months after removal. Both the envelope's peak (µV) and its occurrence (% of chewing task) were extracted from the surface electromyography signal. Our results showed the presence of statistically significant differences (p < 0.05) on temporomandibular joint muscles, across different assessments, in all the tested populations of subjects. Surface electromyography demonstrated a relationship between the correction of a maxillary transverse discrepancy and the restoration of a muscle's activation patterns comparable to healthy subjects for both T and M.

Knowledge of parents/guardians about nocturnal bruxism in children and adolescents

BACKGROUND

Bruxism is a repetitive jaw-muscle activity characterized by the clenching or grinding of teeth and/or the bracing or thrusting of the mandible.

OBJECTIVE

This study assessed parents/guardians' knowledge of nocturnal bruxism in children/adolescents.

METHOD

A cross-sectional study using a validated questionnaire was carried out on 134 Brazilian guardians. Data were analyzed descriptively and through the chi-square test to assess the association if guardians reported bruxism and the causes and consequences of nocturnal bruxism.

RESULTS

Mothers (68.7%) were the main contributors; 23.1% said their child had bruxism. Although most participants (73.9%) had no opinion, some believe bruxism is linked to emotional stress (13.4%), mysticism/religiosity (3.7%), health (3.7%) or dental problems (3.0%), and presence of parasites (2.2%). Among the parents/guardians of children without bruxism, 81.9% were unaware of some possible cause versus 18.1% of those with bruxism (p=0.011). There was no association between children with bruxism and the type of sleep (p=0.191) or sleep duration (p=0.377). The majority (90.3%) of guardians whose children have bruxism believe the condition affects their health (p=0.006).

CONCLUSION

Guardians have a widespread ignorance about the causes and consequences of sleep bruxism.