Mandibular movements at maximum mouth opening and EMG activity of masticatory and neck muscles in patients rehabilitated after a mandibular condyle fracture

Exercise therapy in postoperative patients with temporomandibular joint internal derangement: A systematic review

OBJECTIVE

Postoperative patients with temporomandibular joint internal derangement (ID) often have problems such as limited mouth opening and pain. Exercise therapy can be advantageous for improving the recovery of patients following surgery. However, there is continuing discussion on the precise aspects of the exercise program, including the optimal timing, length, intensity, and use of assistive equipment. Hence, this study aimed to incorporate pre-existing exercise treatment regimens and investigate their impact.

METHODS

Publications that detailed the clinical treatment of patients with temporomandibular joint ID who received postoperative exercise therapy interventions were included. Nine databases were searched until October 1st, 2023. The JBI critical appraisal tools were used to assess the methodological quality of the included studies.

RESULTS

Five studies were finally included for subsequent analysis; two were randomised controlled studies, and three were quasi-experimental. Exercises suitable for such patients encompass vertical, transverse, and horizontal stretching, among which vertical stretch can be divided into active and passive movements. The start time ranged from the first to the fifth week after surgery, with a duration of 1-6 months. Although the data in the studies could not be integrated and further analysed, preliminary results showed that maximum mouth opening and pain in patients improved significantly. The therapeutic effect of combining three exercise methods was best and was related to patient compliance.

CONCLUSION

Exercise therapy positively affects postoperative rehabilitation in patients with temporomandibular joint ID. It is proposed that targeted, comprehensive studies be conducted to provide a basis for designing more sophisticated exercise therapy regimens and further confirm its curative effect.

Complete mouth rehabilitation in a patient with condylar fracture malunion: A clinical report

Mandibular condyle fracture malunion and tooth loss can cause functional and esthetic problems. A patient with restricted mouth opening associated with muscle atrophy required prosthetic rehabilitation. Since the remaining teeth had a poor prognosis and the patient had difficulty adapting to the interim denture, complete mouth rehabilitation with implants was chosen. The implants were placed by using nerve lateralization and an autogenous bone graft. Prosthetic rehabilitation combines digital diagnosis and conventional prosthetic restorations. The definitive prosthesis was fabricated to ensure adequate oral hygiene and functional adaptation of the orofacial structures. Treatment resulted in stable masticatory function, occlusion, and esthetics and restored the function of the atrophied lips and restricted mouth opening.

Analysis of Mandibular Muscle Variations Following Condylar Fractures: A Systematic Review

This review analyzes muscle activity following mandibular condylar fracture (CF), with a focus on understanding the changes in masticatory muscles and temporomandibular joint (TMJ) functioning.

MATERIALS AND METHODS

The review was conducted following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. A search was performed on online databases using the keywords "masticatory muscles" AND ("mandibular fracture" OR "condylar fracture"). The eligibility criteria included clinical trials involving human intervention and focusing on muscle activity following a condylar fracture.

RESULTS

A total of 13 relevant studies were reviewed. Various studies evaluated muscle activity using clinical evaluation, bite force measurement, electromyography (EMG), magnetic sensors and radiological examinations to assess the impact of mandibular fractures on masticatory muscles.

CONCLUSIONS

Mandibular condylar fractures can lead to significant changes in muscle activity, affecting mastication and TMJ functioning. EMG and computed tomography (CT) imaging play crucial roles in assessing muscle changes and adaptations following fractures, providing valuable information for treatment planning and post-fracture management. Further research is required to explore long-term outcomes and functional performance after oral motor rehabilitation in patients with facial fractures. Standardized classifications and treatment approaches may help improve the comparability of future studies in this field.

Wearable Orofacial Technology and Orthodontics

Wearable technology to augment traditional approaches are increasingly being added to the arsenals of treatment providers. Wearable technology generally refers to electronic systems, devices, or sensors that are usually worn on or are in close proximity to the human body. Wearables may be stand-alone or integrated into materials that are worn on the body. What sets medical wearables apart from other systems is their ability to collect, store, and relay information regarding an individual's current body status to other devices operating on compatible networks in naturalistic settings. The last decade has witnessed a steady increase in the use of wearables specific to the orofacial region. Applications range from supplementing diagnosis, tracking treatment progress, monitoring patient compliance, and better understanding the jaw's functional and parafunctional activities. Orofacial wearable devices may be unimodal or incorporate multiple sensing modalities. The objective data collected continuously, in real time, in naturalistic settings using these orofacial wearables provide opportunities to formulate accurate and personalized treatment strategies. In the not-too-distant future, it is anticipated that information about an individual's current oral health status may provide patient-centric personalized care to prevent, diagnose, and treat oral diseases, with wearables playing a key role. In this review, we examine the progress achieved, summarize applications of orthodontic relevance and examine the future potential of orofacial wearables.

Efficacy of Kinematic Parameters for Assessment of Temporomandibular Joint Function and Disfunction: A Systematic Review and Meta-Analysis

The aim of this review was to answer the following PICO question: “Do TMJ kinematic parameters (intervention and comparison) show efficacy for assessment of mandibular function (Outcome) both in asymptomatic and TMD subjects? (Population)”. PubMed, Scopus, Web of Science, Embase, Central databases were searched. The inclusion criteria were (1) performed on human, (2) English only, (3) on healthy, symptomatic or surgically altered TMJ, (4) measured dynamic kinematics of mandible or TMJ (5) with six degrees of freedom. To assess the Risk of Bias, the Joanna Briggs Institute tool for non-randomised clinical studies was employed. A pairwise meta-analysis was carried out using STATA v.17.0 (Stata). The heterogeneity was estimated using the Q value and the inconsistency index. Ninety-two articles were included in qualitative synthesis, nine studies in quantitative synthesis. The condylar inclination was significantly increased in female (effect size 0.03°, 95% CI: −0.06, 0.12, p = 0.00). Maximum mouth opening (MMO) was increased significantly in female population in comparison with males (effect size 0.65 millimetres (0.36, 1.66). Incisor displacement at MMO showed higher values for control groups compared with TMD subjects (overall effect size 0.16 millimetres (−0.37, 0.69). Evidence is still needed, considering the great variety of devices and parameters used for arthrokinematics. The present study suggests standardising outcomes, design, and population of the future studies in order to obtain more reliable and repeatable values.

Alterations in kinematics of temporomandibular joint associated with chronic neck pain

BACKGROUND

Temporomandibular disorder (TMD) is an umbrella term for pain and dysfunction of the temporomandibular joint (TMJ) and its associated structures. Patients with TMD show changes in TMJ kinematics and masticatory muscle activation. TMD is commonly comorbid with non-specific chronic neck pain (NCNP), which may be one of the risk factors for TMD.

OBJECTIVES

This study aimed to investigate whether patients with NCNP have altered TMJ kinematics and masticatory muscle activity.

METHODS

This was a cross-sectional exploratory study including 19 healthy participants and 20 patients with NCNP but without TMD symptoms. TMJ kinematics was measured during mouth opening and closing, jaw protrusion and jaw lateral deviation. Surface electromyography was used to record the muscle activity of the anterior temporalis, masseter, sternocleidomastoid and upper trapezius while clenching. Furthermore, cervical posture, cervical range of motion (ROM) and pressure-pain threshold of the neck and masticatory muscles were measured.

RESULTS

Compared with the healthy group, the NCNP group showed significantly reduced upper cervical rotation ROM (p = .041) and increased condylar path length (p = .02), condylar translation (opening p = .034, closing p = .011) and mechanical pain sensitivity of the upper trapezius (p = .018). Increased condylar translation was significantly correlated with reduced upper cervical mobility and poor cervical posture (r = -0.322 to -0.397; p = .012-.046).

CONCLUSION

Increased condylar translation and path length in patients with NCNP may indicate poor control of TMJ articular movement, which may result from neck pain or may be a compensation for limited neck mobility. Evaluation of excessive TMJ translation may be considered in patients with NCNP.

Measurement of normal and pathological mandibular and temporomandibular joint kinematics: A systematic review

Motion of the mandible and temporomandibular joint (TMJ) plays a pivotal role in the function of the dentition and associated hard and soft tissue structures, and facilitates mastication, oral communication and access to respiratory and digestive systems. Quantification of TMJ kinematics is clinically relevant in cases of prosthetic rehabilitations, TMJ disorders, osteoarthritis, trauma, tumour resection and congenital abnormalities, which are known to directly influence mandibular motion and loading. The objective of this systematic review was to critically investigate published literature on historic and contemporary measurement modalities used to quantify in vivo mandibular and TMJ kinematics in six degrees of freedom. The electronic databases of Scopus, Web of Science, Medline, Embase and Central were searched and 109 relevant articles identified. Publication quality was documented using a modified Downs and Black checklist. Axiography and ultrasonic tracking are commonly employed in the clinical setting due to their simplicity and capacity to rapidly acquire low-fidelity mandibular motion data. Magnetic and optoelectronic tracking have been used in combination with dental splints to produce higher accuracy measurements while minimising skin motion artefact, but at the expense of setup time and cost. Four-dimensional computed tomography provides direct 3D measurement of mandibular and TMJ motion while circumventing skin motion artefact entirely, but employs ionising radiation, is restricted to low sampling frequencies, and requires time-consuming image processing. Recent advances in magnetic tracking using miniature sensors adhered to the teeth in combination with intraoral scanning may facilitate rapid and high precision mandibular kinematics measurement in the clinical setting. The findings of this review will guide selection and application of mandibular and TMJ kinematic measurement for both clinical and research applications.

A mechanical study of novel additive manufactured modular mandible fracture fixation plates - Preliminary Study with finite element analysis.✰

The paper presents an innovative osteofixation system designed for bone fracture stabilization. Its special feature, which makes it different from other similar systems, is the possibility to precisely adjust the implant to the shape of the bone. Such a precise adjustment is particularly important in the case of multiple fractures, where proper stabilization is a condition for restoring bone geometry and thus obtaining the biomechanical function of a given segment of the body lost due to fracture. Based on the tested properties of the implant material, the presented system structure was verified for loading, stress, and share forces in multi-site fractures of the mandible. Numerical tests were performed for three different fracture models: unilateral double fracture of the body of mandible, unilateral double fracture of the body and the angle of mandible, and bilateral fracture of the mandible at the angle and body of the mandible. The results indicate that the proposed system may be used to stabilize broken bone fragments successfully, and the obtained stabilization would allow unrestricted use of the chewing function during bone healing and remodeling. The authors point out the advantages of the proposed implantation method thanks to which it is possible to obtain any shape of the implant and thus stabilize bone fragments in any case.

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.

Analysis of Masticatory Muscle Activity Based on Presence of Temporomandibular Joint Disorders

Background

This study was conducted to analyze the activity of masticatory muscles depending on the presence of temporomandibular joint disorders (TMD) when foods of various hardness are masticated.

Material/Methods

We enrolled 20 subjects (13 men and 7 women) who met our selection criteria, and they were divided into 3 groups (the Disorder Group, the Malalignment Group, and the Control Group) based on surveys and screening inspection. The average of reference voluntary contraction (RVC) was used to measure masticatory muscle activity. Using surface electromyography (SEMG) for each group during masticatory activity, the activities of the masseter muscle and temporalis muscle were measured based on the hardness of 3 different foods (soft, sticky, and hard).

Results

Characteristics of these 3 groups prior to the experiment were identical, and subsequent findings were as follows: First, when masticating sticky food, the Disorder Group and Malalignment Group showed significant differences from the Control Group in activities of the masseter muscle and temporalis muscle (p<0.05). Second, when masticating hard food, the Malalignment Group and Control Group showed significant differences from the Disorder Group in the masseter muscle and temporalis muscle activities (p<0.05). Based on these findings, the study showed that malalignment affects movement of the temporomandibular joint during mastication of sticky food, and the temporomandibular joint movement was affected by the presence of pain during mastication of hard food.

Conclusions

Our results provide basic data useful in the diagnosis of temporomandibular joint disorder, as well as guiding future studies on this topic.

Nonsurgical management of temporomandibular joint autoimmune disorders

Introduction

Temporomandibular disorders (TMD) are observed in a number of autoimmune diseases but limited studies have assessed the effect of autoimmune diseases on TMD. Therefore, the present review article was conducted to determine the effect of autoimmune diseases on TMD.

Methods

International databases, including Web of Sciences, PubMed and Scopus, were searched in order to find related articles. The search key words were; temporomandibular joint (TMJ) autoimmune disorders, TMJ, TMD, medical therapy and non-invasive, local and systemic management. Published articles from June, 2010 to June, 2019 were included in the review.

Results

A total of 11 related articles including rheumatoid arthritis (RA), lupus erythematosus and systemic sclerosis were found. All articles noted that TMJ has unique features that distinguishes it from other human body joints. Cases of TMJ injury and TMD require specific treatments. Therefore, early diagnosis of TMD is essential. It was also mentioned in the articles that the collagen-induced arthritis (CIA) method is a suitable method for investigating TMD and its relationship with RA. Treatment methods included oral steroids, Disease-modifying antirheumatic drugs, nonsteroidal anti-inflammatory drugs, methotrexate 75 mg, and combination therapy with methotrexate.

Conclusion

Based on the results of this study, TMD exists in some autoimmune diseases, including RA, lupus erythematosus and systemic sclerosis. Therefore, there should be an interdisciplinary collaboration between physicians and dentists in order to choose the best conservative treatment and medication therapy for TMD to reduce the progression and pain associated with this type of disorder.

Dynamic Stability Assessment of the Temporomandibular Joint as a Sequela of Open Reduction and Internal Fixation of Unilateral Condylar Fracture

PURPOSE

Dynamic stability of the temporomandibular joint (TMJ) is the characteristic of the joint to achieve normal function by harmonious, balanced, synchronized interactions of the various functional subunits of the stomatognathic system. The aim of this study was to evaluate changes in the mechanics and dynamics of the TMJ during recovery from surgical treatment of an isolated condylar fracture.

PATIENTS AND METHODS

This is a prospective cohort study involving 30 patients who underwent open reduction and internal fixation for an isolated unilateral condylar fracture and were clinically asymptomatic at 6 months after surgery. The dynamics of the TMJ were assessed by bite-force analysis, both static and dynamic, to assess masticatory efficiency. Surface electromyography was recorded to assess changes in muscle dynamics. Joint vibration analysis was performed to evaluate the internal functioning of the TMJ. All the assessments were carried out bilaterally to allow comparison of the injured and uninjured joints, and the data were analyzed with the paired t test and independent-samples t test. Statistical significance was considered at P < .05.

RESULTS

The study included 18 male and 12 female patients aged between 20 and 40 years. Bite-force analyses showed significantly higher bite forces on the uninjured side at 6 months after surgery. Similarly, surface electromyography analysis showed increased muscle activity on the affected side pointing toward some compensatory hyperactivity in the masticatory muscles. Joint vibration analysis showed that there was increased friction during function in both the injured and uninjured joints.

CONCLUSIONS

The observations in this study suggest that residual imbalances are present in the TMJ at 6 months after open reduction and internal fixation of condylar fractures. Therefore, long-term studies are required to establish a complete timeline of adaptive changes occurring in the TMJ after condylar fractures, especially in comparison with other treatment modalities.

Impact of midface and upper face fracture on bite force, mandibular mobility, and electromyographic activity

This study evaluated the bite force, electromyographic activity, and mandibular mobility in patients undergoing surgery for facial fracture treatment that required a coronal approach. Ten men were divided into two groups: group I, coronal approach with pre-auricular extension (n=4, average age 34.5 years); group II, coronal approach (n=6, average age 24.8 years). The maximum bite force was measured using a dynamometer and mandibular mobility using a calliper. The electromyographic activity of the right masseter (RM), left masseter (LM), right temporal (RT), and left temporal (LT) muscles was evaluated using a Myosystem-Br1 apparatus. Patients were evaluated at 1, 2, 3, and 6 months after surgery. Data were analysed using the repeated measures test (SPSS 21.0; P≤0.05). Statistically significant differences were found for electromyographic activity at rest (group II: LM P=0.00), left laterality (group I: RT P=0.02; group II: RT P=0.04), and maximum voluntary contraction (group I: RM P=0.04 and RT P=0.04; group II: RM P=0.05, LM P=0.00, and LT P=0.01 and for maximum molar bite force in the right (group I, P=0.00; group II, P=0.01) and left (group II, P=0.01) molar regions. The subjects regained electromyographic activity, maximum bite force, and mandibular mobility throughout the period evaluated.

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.

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.

Three-dimensional mandibular motion after closed and open reduction of unilateral mandibular condylar process fractures

OBJECTIVE

To detect the changes in 3D mandibular motion after two types of condylar fracture therapies.

MATERIALS AND METHODS

Using a 3D motion analyzer, free mandibular border movements were recorded in 21 patients successfully treated for unilateral fractures of the mandibular condylar process (nine patients: open reduction, rigid internal fixation, and functional treatment; 12 patients: closed reduction and functional treatment; follow-up: 6-66 months), and in 25 control subjects.

RESULTS

No differences were found among the groups at maximum mouth opening (MO), protrusion and in lateral excursions. During opening, the patients had a larger maximal deviation to the fractured side than the controls (controls 2.3 mm, open treatment 3.9 mm, closed treatment 4.2 mm; Kruskal-Wallis test, p=0.014; closed treatment vs. controls, p=0.004), with a larger coronal plane angle (controls 2.4°, open treatment 3.6°, closed treatment 4.4°; p=0.016; closed treatment vs. controls, p=0.013). In the closed treatment patients, a longer follow-up was related to increased maximum MO (p=0.04), sagittal plane angle (p=0.03), and reduced lateral mandibular deviation during MO (p=0.03).

CONCLUSION

Mandibular condylar fractures can recover good function; some kinematic variables of mandibular motion were more similar to the norm in the open treatment patients than in closed treatment patients.

A three-dimensional study of facial mimicry in healthy young adults

To assess sex-related characteristics in facial movements, and to define a set of reference normal values, 20 healthy young adults (10 men, 10 women) performed six standardized facial movements (maximum smile; free smile; "surprise" with closed mouth; "surprise" with open mouth; right- and left-side eye closures). The three-dimensional coordinates of 21 soft-tissue facial landmarks were recorded by an optoelectronic motion analyzer, their movements computed, and standardized for facial dimensions. Asymmetry indices were calculated. The mouth area had the largest movements. Sex-related differences were found only for the superciliare landmark (men had larger movements than women, p<0.001). Asymmetries in the eyes, mouth and nose were similar in both sexes (p>0.01), with a significant effect of movement (p<0.001): eye and mouth asymmetry was larger during the asymmetric eye closures than during the symmetric movements. The right-side asymmetric movements were somewhat larger than the left-side ones. The total facial movement did not differ between sexes; the "surprise with mouth open" movement had the largest landmark displacements (p<0.001). In conclusion, normal young adult men and women had similar standardized facial movements, except in the forehead. Some individual asymmetry was found in symmetric facial animations; some synkinesis was found even in normal adults.