Does orthodontic treatment provide a real functional improvement? a case control study

Evaluation of the bioelectrical activity of the masticatory muscles in patients with narrowed maxillary transverse dimension compared to the occlusal norm

OBJECTIVE

The aim of the study was to determine how the electrical activity of the temporalis, masseter and sternocleidomastoid muscles differs in children with reduced transverse jaw dimension compared to children with normal occlusion.

DESIGN

It was a experimental study. Thirty-seven patients were included in the study. 18 in the study group received orthodontic treatment with removable appliances and 19 subjects were classified as normal occlusion subjects in the control group. A panoramic X-ray and digital intraoral scan were taken, followed by an surface electromyography of three muscle pairs (temporalis muscles, masseter muscles, sternocleidomastoid muscles) in resting position, while clenching and clenching on cotton rollers.

RESULTS

There was significantly greater activity in the experimental group than in the control group comparing muscles: temporalis muscles and masseter muscles in the resting position. Additionally, significantly greater activity of muscles in the control group was found during clenching. However, the asymmetry index of muscles indicates that there is significantly greater asymmetry of muscles activity in the experimental group. Compared to children with normal occlusion, children with a narrowed transverse dimension of the jaw have statistically significant differences in the bioelectrical activity of the temporalis, masseter and sternocleidomastoid muscles, as well as greater asymmetry in the bioelectrical voltage of the masseter muscles.

CONCLUSIONS

Patients with reduced transverse dimension of the jaw are characterized by increased resting activity of the masticatory muscles and reduced functional activity of the masticatory muscles. These patients have increased asymmetry in the bioelectrical tension of the masticatory muscles.

Electromyographic Assessment of Muscle Activity in Children Undergoing Orthodontic Treatment-A Systematic Review

Background: Surface electromyography (sEMG) can provide an objective and quantitative image of the functional state of neuromuscular balance in the stomatognathic system. The objective of this systematic review is to examine current scientific evidence regarding the effects of orthodontic treatment on muscle electromyographic (EMG) activity in children. Methods: The search strategy included the PubMed, PubMed Central, Web of Science, Scopus, and Embase databases. The inclusion criteria were studies assessing EMG muscle activity in children undergoing orthodontic treatment compared with untreated children. The Cochrane risk-of-bias tool (RoB2) and the Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of the studies. The quality of evidence assessment was performed using GRADE analysis. The PRISMA diagram visually represented the search strategy, as well as screening and inclusion process. Results: The search strategy identified 540 potential articles. Fourteen papers met the inclusion criteria. Six studies were judged at a low risk of bias. The certainty of evidence was rated as moderate to low, according to the GRADE criteria. Studies showed alterations in EMG muscle activity in children undergoing orthodontic treatment. Conclusions: Orthodontic treatment appears to affect muscle activity in children undergoing orthodontic treatment. However, the quality of evidence is low and, therefore, it is not possible to definitively state this effect. Further long-term studies are needed to confirm the findings of this review. Study protocol number in PROSPERO database: CRD42023491005.

Effects of class II intermaxillary elastics on masticatory muscle activity balance, occlusal contact area and masticatory performance: A multicenter randomised controlled trial

BACKGROUND

Bilateral Class II intermaxillary elastics (CII elastics) are commonly used in orthodontics; however, the effects of CII elastics on masticatory muscle activity and the occlusal contact area have not been studied.

OBJECTIVES

To evaluate the short-term effects of CII elastics on masticatory muscle activity balance, occlusal contact area and masticatory performance in a group of adult orthodontic patients after 3 months.

MATERIALS AND METHODS

Forty-three patients with a <3 mm Class II molar relationship receiving ongoing treatment with fixed appliances were recruited. The experimental group (n = 21) wore CII elastics (100-150 g/side) full time; the control group (n = 22) did not wear CII elastics. Surface electromyography, the areas of occlusal contact and near contact (ACNC) and the median particle size of a test food were assessed prior to (T0) and after one (T1) and 3 months (T2). Within- and between-group differences were analysed and the relationships between changes in dependent variables were examined (α = 0.05).

RESULTS

At T2, the experimental group showed better masticatory muscle activity balance (p < .001) and masticatory performance (p < .05) than controls. Both masticatory muscle activity balance (p < .001) and masticatory performance (p < .001) significantly improved in the experimental group between T0 and T2. The changes in masticatory muscle activity balance and masticatory performance were significantly related (p < .05). No significant changes in cumulative ACNC or ACNC balance were observed (p > .05).

CONCLUSION

After 3 months, CII elastics improved masticatory muscle activity balance, which led to better masticatory performance.

Surface Electromyography (sEMG) Activity of Masticatory Muscle (Masseter and Temporalis) with Three Different Types of Orthodontic Bracket

Objective

This pre-post study is aimed at determining the effects of masticatory muscle activity (masseter and temporalis) measured via sEMG between conventional, self-ligating, and ceramic bracket after six months of orthodontic treatment.

Methods

A total of eighteen (18) malocclusion patients were identified. Malocclusion patients were subdivided into 3 groups based on the bracket selection (conventional, self-ligating, and ceramic bracket) with 6 patients for each group. sEMG of muscles were done using a two-channel electromyography device, where pregelled and self-adhesive electrodes (bilateral) were applied. Chewing and clenching of masseter and temporalis muscle activity were recorded for 20 s pre and 6 months of orthodontic treatment using sEMG (frequency 60 Hz). The data were analysed by using repeated measures ANOVA in IBM SPSS Statistics Version 24.0.

Results

Chewing and clenching for masseter muscle showed no significant difference (P > 0.05) in sEMG activity of three types of the brackets. However, for temporalis muscle, there was a significant difference found in sEMG activity during chewing (P < 0.05) and clenching (P < 0.05) between these three brackets.

Conclusion

The activity of temporalis muscle showed significant changes in chewing and clenching, where the conventional group demonstrated better muscle activity pre and at six months of fixed appliances.

Computerized Assessment of Occlusion and Muscle Activity during Use of a Multilayer Clear Retainer: A Preliminary Study

The aim of this preliminary study was to evaluate the short-term changes of occlusal contacts and muscle activity after orthodontic treatment during the use of a multi-layer clear retainer. Evaluation was done with the T-scan and BioEMG systems. A total of 18 subjects were included, who were evaluated at three time intervals-T0 at debonding, T1 at one month after retainer delivery, and T2 at four months after retainer delivery. The T-scan and electromyography (EMG) data were recorded simultaneously. The T-scan system recorded the occlusion time, disclusion time and force distribution. The EMG waves were quantified by calculating the asymmetry index and activity index. The time variables changed but not significantly. Occlusal force decreased in the anterior dentition and increased in the posterior dentition during T0-T2. There was no clear evidence of a relationship between unbalanced occlusal forces and muscle activity. In most subjects, the temporalis anterior muscle was more dominant than the masseter muscle. From this preliminary computerized study, there were no significant changes in the state of the occlusion or muscle activity during the short-term retention period.

Electromyographic evaluation in children orthodontically treated for skeletal Class II malocclusion: Comparison of two treatment techniques

OBJECTIVE

To compare the clinical efficacy of two techniques for fabricating a Bimler device by assessing the patient's surface electromyography (sEMG) activity at rest before treatment and six months after treatment.

METHODS

Twenty-four patients undergoing orthodontic treatment were enrolled in the study; 12 formed the test group and wore a Bimler device fabricated with a Myoprint impression using neuromuscular orthodontic technique and 12 formed the control group and were treated by traditional orthodontic technique with a wax bite in protrusion. The "rest" sEMG of each patient was recorded prior to treatment and six months after treatment.

RESULTS

The neuromuscular-designed Bimler device was more comfortable and provided better treatment results than the traditional Bimler device.

CONCLUSION

This study suggests that the patient group subjected to neuromuscular orthodontic treatment had a treatment outcome with more relaxed masticatory muscles and better function versus the traditional orthodontic treatment.

Effects of intervertebral disc disorders of low back on the mandibular kinematic: kinesiographic study

Background

Intervertebral disc disorders are one of the most common causes of low back pain. Neuromuscular dysfunction frequently is present in patients with lumbar disc herniation.

When considering joint dysfunction, it is important to remember that the spine functions as a unit. Dysfunction on one level can trigger compensatory changes in other spinal levels or in other areas of the musculoskeleton. Findings demonstrated the relationship between stomatognathic and postural systems justifying the hypothesis that muscular-skeletal impairment in one system could affect the other one. However, evidence that a lumbar intervertebral disc herniation could influence the mandibular kinematics is still lacking. Aim of this study was to analyse the effects that intervertebral disc herniation of low back could have on the mandibular kinematics.

Findings

Kinesiographic evaluations of the mandibular dynamics of 23 adult patients suffering L4/L5 and L5/S1 lumbosacral disc hernation were compared with a non pathological control group. A statistically significant difference of maximal mouth opening (p < .05) and of maximal mouth opening velocity (p < .03) was found comparing the study patients with the control subjects.

Conclusion

Lumbosacral disc herniation appears to be associated with changes in the activity of mandibular kinematics both in rate and quality of movement. The study suggests the existence of connections between masticatory system and lumbar disk herniation.