Electromyographic analysis of anterior temporalis and superficial masseter muscles in mandibular angle fractures--a pilot study

Comparison of bite force evaluation for mandibular angle fracture fixation by conventional miniplates versus new design miniplates: a clinical study

PURPOSE

To evaluate postoperative masticatory efficacy of a new design non-compression titanium miniplate compared to conventional non-compression titanium miniplate on the basis of bite force for treatment of mandibular angle fractures.

METHODOLOGY

The prospective study included 20 patients with mandibular angle fractures randomly categorized into 2 groups: Group I, fixation of angle fractures by conventional miniplates, and Group II, fixation of angle fractures by new design miniplates. Evaluation was done for clinical outcome, primarily bite force; radiological outcome; and associated postoperative morbidities at different time intervals.

RESULTS

The results showed to be highly significant in terms of mean operating time for plate adaptation and fixation and bite force adaptation (p = 0.003 at follow-up of 6 months) for the newer miniplate compared to the conventional miniplate. No statistically significant difference was seen for postoperative paresthesia, malunion, non-union, occlusal discrepancy, or hardware failure.

CONCLUSION

Within the limits of the study, it appears that the single, monocortical, non-compression, superior border new design miniplate proved to be a successful procedure for treating non-comminuted mandibular angle fractures specifically in terms of enhanced postoperative masticatory efficiency as compared to conventional miniplates. Further clinical studies with larger sample size can derive a more comprehensive conclusion.

Masticatory muscles activity in patients with mandibular angle fractures: A literature review on which procedure to use to reverse the best masticatory muscles functionality

Introduction

Mandible is the first or the second most fractured bone of facial skeleton. Fractures of the angle account for 23-43% of all mandibular fractures. Soft and hard tissue are affected in a traumatized mandible. Bite forces are an essential factor in masticatory muscles activity. An improved function is a result of improvement in the bite force.

Aim

The objective of this research was to conduct a systematic review of all available literature regarding the masticatory muscles' activity and bite forces in patients with mandibular angle fractures.

Methods

PubMed, and Google Scholar databases have been searched with the following keywords: "mandibular angle fractures" AND "bite forces "OR "masticatory muscles activity".

Results

This research methodology provided 402 articles. Of which 33 were selected for analysis if they were pertinent to the topic. Then only 10 results have been identified and included in this review.

Conclusions

We can conclude that bite force decreased significantly after trauma, specifically during the first month after injury, and then increases gradually over time. More randomized clinical trial studies and the incorporation of more methods such as electromyography (EMG) for measuring the electrical activity of muscles and bite force recorder could be considered in the future.

Fracture Fixation Technique and Chewing Side Impact Jaw Mechanics in Mandible Fracture Repair

Lower jaw (mandible) fractures significantly impact patient health and well‐being due to pain and difficulty eating, but the best technique for repairing the most common subtype—angle fractures—and rehabilitating mastication is unknown. Our study is the first to use realistic in silico simulation of chewing to quantify the effects of Champy and biplanar techniques of angle fracture fixation. We show that more rigid, biplanar fixation results in lower strain magnitudes in the miniplates, the bone around the screws, and in the fracture zone, and that the mandibular strain regime approximates the unfractured condition. Importantly, the strain regime in the fracture zone is affected by chewing laterality, suggesting that both fixation type and the patient's post‐fixation masticatory pattern—ipsi‐ or contralateral to the fracture— impact the bone healing environment. Our study calls for further investigation of the impact of fixation technique on chewing behavior. Research that combines in vivo and in silico approaches can link jaw mechanics to bone healing and yield more definitive recommendations for fixation, hardware, and postoperative rehabilitation to improve outcomes. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Electromyographic Changes in the Masseter and Temporalis Muscles Before and After Orthognathic Surgery in Patients With Mandibular Prognathism

OBJECTIVE

Evaluate the electromyographic changes in the Masseter (MM) and Temporalis (TM) muscles during voluntary clenching of the teeth both before and after orthognathic surgery in patients aged 18 years and older and diagnosed with mandibular prognathism.

METHODS

Eleven patients with prognathism were included in the study, in all of whom the initial phase of orthodontic treatment had been completed. The orthognathic procedure to reduce prognathism comprised intraoral oblique sliding (or subsigmoid) osteotomy, after which intermaxillary fixation with ligaments in the maxilla and mandible was undertaken in all patients for 6 weeks post-surgery. Electromyographic activity was recorded during the baseline maximum voluntary contraction of the teeth, with the same measurement taken 3 and then 6 months after orthognathic surgery.

RESULTS

Significant differences were found in the mean amplitude (17.0 vs 14.7, P = 0.020) and peak-to-peak amplitude (left [761.6 vs 457.0, P = 0.003] and right [676.9 vs 357.4, P = 0.007]) for the MM between the baseline score and 6 months after surgery. Likewise, significant differences were found in the mean amplitude (18.2 vs 25.6, P = 0.009) and peak-to-peak amplitude (left [856.4 vs 1594.2, P = 0.004] and right [804.4 vs 1813.4, P = 0.004]) for the TM between the baseline score and that taken 6 months post-surgery. Only 18.2% (2/11) presented orthodontic appliances problem in the 3 months post-surgery.

CONCLUSION

Electromyographic activity was restored 6 months after the orthognathic surgery. From a clinical perspective, the results obtained confirm that orthognathic surgery has not only an esthetic but also a functional objective in terms of achieving equilibrium and occlusal harmony.

Electromyography assessment in zygomaticomaxillary complex fractures

OBJECTIVE

The aim of this study was to assess the activity of the masseter and temporalis muscles using surface electromyography (EMG) in patients with zygomaticomaxillary complex (ZMC) fractures.

PATIENTS AND METHODS

This prospective study was carried out on 25 patients who had ZMC fractures. Fifteen patients were managed by open reduction and rigid fixation (ORIF) using titanium miniplates. This study, using surface electromyography, analyzed the activity of the masseter and temporalis muscles of 25 patients with ZMC fractures; 15 of them were surgically treated under general anesthesia (GA). Evaluations were made before surgery and 6 weeks after surgery by recording the mean of muscle contraction of 20 motor unit action potential (MUAP) against resistance, and statistical analyses were performed.

RESULTS

A significant EMG difference between the normal and ZMC fracture sides was found (P < 0.0001) for both masseter and temporalis muscles and was significantly improved after ORIF. However, postoperative EMV values of the repaired side was significantly less than measured postoperatively in the normal side (P < 0.0001) for both muscles.

CONCLUSION

ZMC fractures significantly diminish muscular activity of the masseter and temporalis and even though significant recovery of muscle activity was revealed after 6 weeks, it is still less than normal activity, highlighting the importance of postoperative rehabilitation.

Effect of surgical treatment of mandibular fracture: electromyographic analysis, bite force, and mandibular mobility

This study aimed to examine individuals undergoing surgery for the treatment of the fractured mandibular angle, using bite force, mandibular mobility, and electromyographic (EMG) analysis in many different clinical conditions, after 2 months postoperatively. Bite force was recorded with a digital dynamometer, model IDDK. The EMG activity (Myosystem-Br1) included the analysis of the masseter and temporal muscles. Mandibular mobility was measured using a digital pachymeter. The subjects were divided into 3 groups: G1, mandibular angle fracture (n = 7); G2, condylar process fracture (n = 5); and G3, control (n = 12). Data were tabulated and submitted to statistical analysis using the repeated-measure test carried out over time and the Student's t-test (P < 0.05), using the Statistical Package for the Social Sciences software, version 19 (SPSS Inc, Chicago, IL). G1 and G2 had an increase in bite force. In G1, there was a regular decrease in the EMG activity in the second postoperative month. G2 presented an irregular pattern in EMG data during the period tested. Regarding the mandibular mobility, both groups obtained amplitude of all mandibular movements with a high percentage, when compared with control. A good functional recovery was achieved by the individuals who had a mandible angle fracture or condylar process fracture, after 2 postoperative months.

Does Prolonged Reconstruction of Disarticulation Defect With Bone Plate Affect the Electromyography Records of Masticatory Muscles?

OBJECTIVES

For medical or socioeconomic reasons, the primary reconstruction of disarticulation defects with bone plates stays for many years. This study was performed to assess the effect of this delay on electromyography (EMG) records of masticatory muscles.

MATERIALS AND METHODS

Twenty-five patients treated by insertion of reconstruction plates in disarticulation defects were prospectively included in this study. Electromyography records for masticatory muscles were obtained before surgery and 3 months, 6 months, 1 year, 2 years, and 3 years afterward. Paired t-test was used to determine whether there was significant difference between the EMG values.

RESULTS

At 3 years after surgery, the amplitude values of the masseter and temporalis muscles, on the resected side, have decreased by 39% and 60%, respectively, whereas on the nonoperated side, they have increased by 35% and 29%. The peak decrease, on the resected sides, has occurred at 3 months for the temporalis and 2 years for the masseter. On the nonoperated side, the peak increase has occurred at 6 months for both the temporalis and the masseter.

CONCLUSIONS

A prolonged use of bone plates to reconstruct disarticulation defects leads to alterations in EMG values of masticatory muscles. These alterations present clinically as muscle atrophy on the operated side and hypertrophy on the nonoperated side.