Deviation Of Mandible Research Articles

Mandibular Deviation With Longstanding Temporomandibular Joint Dislocation Caused by Lateral Pterygoid Muscle Hyaline Degeneration.

The present report described a rare case of mandible deviation with longstanding unilateral temporomandibular joint dislocation caused by lateral pterygoid muscle hyaline degeneration. A 28-year-old male was referred for mandible deviation for 2 years. It was found that the left condyle was dislocated just below the articular eminence with the dilated capsule in magnetic resonance imaging images. After surgical dissection of the lateral pterygoid muscle, which was excessively attached to the condyle, the left condyle was reduced, and the patient's mandibular deviation was greatly improved. The pathologic results showed lateral pterygoid muscle hyaline degeneration.

Recording the maxillomandibular relationship with the Aqualizer system prior to occlusal splint therapy for treating temporomandibular disorders: a randomized controlled trial

Temporomandibular disorders (TMD) present a public health issue and are one of the most common musculoskeletal conditions causing chronic pain. This study compares the outcomes of occlusal splint therapy in patients with TMD following two different maxillomandibular relationship (MMR) registration techniques. 40 TMD patients were randomly allocated to MMR registration with the Aqualizer system (AQU) or with chin point guidance (CPG) prior to fabricating occlusal splints. TMD symptoms, subjective pain intensity, and quality of life (QoL) were recorded at baseline and after 3 and 6 months. The treatment led to an overall reduction of TMD symptoms in both groups (Conover test, p < 0.00001). TMJ sounds, TMJ pain with palpation and muscle pain with palpation subsided regardless of the type of MMR registration method used (Cohen’s d > 0.8). AQU-based occlusal splints led to a better improvement of TMJ pain with maximum opening compared to CPG-based occlusal splints (Cohen’s d = 0.9; CPG d = 0.13). In both groups, occlusal splint treatment had little to no effect on correcting lateral mandible deviation or improving restricted jaw opening. After 6 months occlusal splints in both groups had a large effect on improving subjective pain intensity (Cohen’s d > 0.8), however, patients reported a higher QoL in the AQU group compared to the CPG group (Mann–Whitney-U-test, p < 0.05). The results of this study support the premise that occlusal splints are effective in relieving pain-related TMD symptoms. The Aqualizer can be considered for determining MMR in cases, where guided registration techniques are not possible.Trial registration: DRKS00031998.

Assessment of jaw muscles and cervical spine muscles isometric force using a hand-held dynamometer in young adults

Our study aims to investigate the jaw and cervical spine muscle isometric forces in healthy young adults. Fifty-four subjects (21.2 ± 4.82 years) met the inclusion criteria and agreed to par-ticipate in the study. Muscle forces were assessed with a hand-held dynamometer. A significant positive correlation was found between jaw opening forces and cervical flexors forces (r=0.62, p0.0001) and between lateral mandible deviation forces and cervical spine lateral flexion forces, both for right and left side (r=0.65, p&lt;0.0001; r=0.69, p&lt;0.0001, respectively. In healthy young adults, using a hand-held dynamometer for muscle strength testing, significant positive correla-tion was found between jaw opening forces and cervical flexors forces and between lateral mo-uth deviation force and cervical spine lateral flexion forces, both for right and left side. The rela-tionship between jaw muscles forces and cervical spine muscles forces is a topic that needs to be further studied, also together with posture and balance.

Concomitant Microvascular Aided Extended Temporo-Mandibular Joint Replacement (ME-TJR) and Stock Temporo-Mandibular Joint Replacement (MS-TJR) During Mandibular Reconstruction.

Disarticulation is indicated when pathologic process involves the condyle or when a body/ramus lesion extends into condylar process. The goal of reconstruction is to reinstate joint mechanism for function and also to restore facial symmetry. Retrospective evaluation of functional and aesthetic outcomes in patients with disarticulation defects of mandible treated with concomitant alloplastic temporomandibular joint replacement and microvascular free flap reconstruction. Nine patients (8 benign pathologies and 1 secondary reconstruction for malignant neoplasm), who underwent mandibular resection with condylar disarticulation and reconstruction with Free microvascular flap and Alloplastic total joint replacement between 2015 and 2022 were included in the study. A modified functional intra-oral Glasgow scale(FIGS)2 was used for quality of life (QOL) scoring. Speech, mastication, swallowing, VAS pain score, mouth-opening, occlusion, facial symmetry and overall patient satisfaction were assessed. 8 patients with benign pathology reported excellent outcome with a QOL score of 13-15 in terms of speech, chewing and swallowing. Pre-operative occlusion of native mandible was maintained in all dentulous patients. VAS score of 0-1 was reported. Mouth opening was adequate in all patients. 2 patients reported mild ipsilateral deviation of mandible. Mild facial asymmetry was reported by 2 patients with an overall satisfaction of 8-9. There were no significant intra/post-operative complications in patients with benign pathology. Failure of stock joint was observed in secondary reconstruction for malignant neoplasm. Microvascular free flap aided stock or custom alloplastic replacement of temporomandibular joint (MS-TJR, ME-TJR) restores function and aesthetics following mandibular resection with disarticulation of condyle.

Evaluation of treatment with unilateral mandibular sagittal split ramus osteotomy and maxillary osteotomy in patients with condylar osteochondroma and mandibular asymmetry: A retrospective case series

The aim of the study was to describe an approach where condylar resection with condylar neck preservation was combined with Le Fort I osteotomy and unilateral mandibular sagittal split ramus osteotomy (SSRO).Patients with a unilateral condylar osteochondroma combined with dentofacial deformity and facial asymmetry who underwent surgery between January 2020 and December 2020 were enrolled. The operation included condylar resection, Le Fort I osteotomy and contralateral mandibular sagittal split ramus osteotomy (SSRO). Simplant Pro 11.04 software was used to reconstruct and measure the preoperative and postoperative craniomaxillofacial CT images. The deviation and rotation of the mandible, change in the occlusal plane, position of the “new condyle” and facial symmetry were compared and evaluated during follow-up. Three patients were included in the present study. The patients were followed up for 9.6 months on average (range, 8–12). Immediate postoperative CT images showed that the mandible deviation and rotation and occlusion plane canting decreased significantly postoperatively; facial symmetry was improved but still compromised. During the follow-up, the mandible gradually rotated to the affected side, the position of the “new condyle” moved further inside toward the fossa, and both the mandible rotation and facial symmetry were more significantly improved.Within the limitations of the study it seems that for some patients a combination of condylectomy with condylar neck preservation and unilateral mandibular SSRO can be effective in achieving facial symmetry.

To Assess the Effect of Trauma on the Temporomandibular Joint in Postoperative Cases of Zygomaticomaxillary Complex Fractures.

The study aims to assess the incidence and features of temporomandibular joint(TMJ) dysfunction in post-surgical treatment of unilateral zygomaticomaxillary complex(ZMC) fractures.The objectives are:To assess severity of TMJ dysfunction in postoperative cases of ZMC fractures.To create awareness of the same among clinicians. Patients presenting with zygomaticomaxillary complex fractures were evaluated prospectively. Evaluation of TMJ dysfunction was done by different parameters via questionnaire, clinical and radiographic examination preoperatively and a follow-up period of 1week, 3months and 6months. The parameters were, clicking of joint, pain on opening /closing, pain on biting, deviation of mandible, pain in the preauricular region, ringing sound and mouth opening. Statistical analysis was done by the Friedman test and Post Hoc analysis. On presentation, 69.1% patients diagnosed with ZMC fractures presented with symptoms related to TMJ dysfunction. Post-surgery 1week majority findings persisted, with 21 patients complained of pain on opening or closing and 2 patients with a persistent opening click. These symptoms, however, decreased over the 3month and 6month follow up period. 5 patients presented with decreased mouth opening which was attributed to lack of adequate physiotherapy. Patients presented with mild symptoms of TMJ dysfunction until 6months post-surgery, however these symptoms weren't significant as the pain score assessed was found to decrease in the following post-operative periods. And the symptoms present were'nt exclusive to conclude a TMJ dysfunction. Early treatment and a close follow up are key to prevent progression of symptoms.

Evaluation of female facial attractiveness with different skeletal asymmetry. A cross-sectional study

Introduction: Facial asymmetry is a common problem that varies in severity between individuals depending on several factors and origins and affects facial beauty. Therefore, the two objectives of this study are to first determine the level of facial attractiveness in an adult woman with different degrees of deviation of the chin and mandible. The second is to measure the difference in perception of the degrees of asymmetry and to judge the facial attractiveness between several evaluator groups. Material and Methods: An adult woman with a symmetrical face was photographed. The image was then modified using Adobe Photoshop into two series. The first was with deviation of the chin to the right generating 5 photographs. The second one was with deviation of the mandible to the right resulting in 5 other photos.After that, the images were presented in a questionnaire to 180 evaluators. Finally only 135 rated the attractiveness of each face using the VAS scale; divided into 38 dentists, 35 orthodontists and 57 laypeople. Results: In both series, orthodontists determined facial asymmetry from 2 mm deviation of the chin and mandible. On the other hand, dentists noticed the asymmetry starting from 4 mm of chin deviation and 2 mm of mandibular deviation and laypeople from 4 mm of chin deviation and 2 mm of mandible deviation. For the two series, the difference was not significant between the two sexes. Conclusion: Orthodontists were the most sensitive to detecting asymmetry and there was no significant difference between the results of dentists and laypeople.

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The clinical case presents an orthodontic treatment of a 8.5-year old patient through cooperation between an orthodontist and an kinesiologist. The aim of the treatment was to reach the maximum aesthetical result without the future orthognathic surgery intervention. The patient had skeletal crossbite with the deviation of mandible in combination with the skeletal mesial occlusion. Parents were deeply worried about the facial asymmetry of their child. Of course, when they referred to an orthodontist, they didn’t notice a general skeletal asymmetry. During the consultation, the connection between the general skeletal and facial asymmetries was explained to them in details. The patient was directed to an kinesiological consultation, after which parallel to orthodontic treatment, the patient got 10 kinesiological procedures during the first year of treatment, and 7 more procedures later. During that period the orthopedic expansion of maxilla in horizontal plane was performed. After 17 kinesiological procedures and an orthopedic expansion, the mandible was replaced by up to 90%, and the deflection was corrected. After that the facial mask was combined for the orthopedic growth of maxilla in sagittal plane. By the way, mesial occlusion had bilateral genetic predisposition in the patient. The mesial occlusion was corrected in that stage, but it was planned to do the second part of permanent occlusion.

Efficacy of Low-Level Laser Therapy in Management of Temporomandibular Joint Pain: A Double Blind and Placebo Controlled Trial.

Stomatognathic system is an interaction of the muscles of mastication, dentition, neural component, and temporomandibular joint. Any dysfunction in this system may lead to temporomandibular disorders (TMDs). Various non-surgical modalities have been employed for treating TMDs. The aim of the study was to objectively evaluate the effects of low-level laser therapy (LLLT) in treatment of patients with TMDs. Sixty individuals diagnosed with TMDs were divided randomly into two groups (Group I-placebo and Group II -LLLT). A series of 20 sessions of LLLT applied both in closed mouth and maximum mouth opening position were given over a period of 08weeks. Assessment was done in terms of improvement in mouth opening, pain, clicking, and deviation of mandible. The data collected were analyzed statistically. The results showed improvement in the pain reduction, improvement in the maximum mouth opening, reduction in deviation, and clicking in both groups but better treatment outcome in the low-level laser group. Though conservative measures improved the symptoms in TMD but LLLT has shown better results in comparison with the placebo group. Being non-surgical can be employed in combination with other modes for effectively treating such disorders. Keywords: Pain, Dysfunction, Temporomandibular joint disorders (TMDs), Low-level laser therapy (LLLT).

The severity and direction prevalence rate of patients with a mandible deviation compared to Cobb’s angle

Background: Patients with mandible deviation often have idiopathic scoliosis, which might affect the result of orthodontic and orthopaedic treatment. Orthodontic treatment not only focuses on aesthetic and functional but also orthopaedic stability. A thorough examination is needed to obtain orthopaedic stability by evaluating the occlusion and posture to establish the best strategy of treatment and interdisciplinary approach. Purpose: This study was conducted to assess the correlation between mandible deviation and idiopathic scoliosis. Methods: This is a descriptive-analytic study with a cross-sectional approach. From 60 samples, 35 patients were chosen based on the inclusion criteria of the total sampling technique. Patients were referred to have skull posteroanterior (PA) and a thoracolumbar PA radiograph taken. Skull PA radiographs were analysed with Grummon’s method using the Orthovision program. Cobb’s angle analysis was used by the radiologist to analyse the thoracolumbar PA radiographs. The data gathered was then further analysed using the Spearman test and the Crosstabs test, using SPSS 23.0. Results: Correlation between mandible deviation and the severity of idiopathic scoliosis is not significant (p=0.866). The direction prevalence of mandible deviation towards Cobb’s angle is 54.3% to the right and 45.7% to the left. All patients with mandible deviation have Cobb’s angle. Conclusion: There is no correlation between mandible deviation and the severity of idiopathic scoliosis. However, many cases showed that the direction of mandible deviation and of idiopathic scoliosis is the same.

Is Open Reduction and Internal Fixation Sacrosanct in the Management of Subcondylar Fractures: A Comparative Study.

Purpose:This paper is intended to compare and evaluate the better treatment option in the management of subcondylar fractures of the mandible.Materials and Methods:This study included 20 patients who were diagnosed clinically and radiologically to have sustained an isolated subcondylar fracture of the mandible. They were divided into two groups randomly. Group I included 10 patients who underwent treatment by intermaxillary fixation alone followed by active physiotherapy in the form of conservative management. Group II included 10 patients who underwent treatment by surgical intervention for open reduction and internal fixation under general anesthesia following elastic guidance. Factors such as maximal mouth opening, pain scores, and deviation of mandible on mouth opening were taken into consideration and evaluated.Results:It is observed that the patients in Group I had weight loss and restrictions in their social well-being in the early recovery phase, in addition to delay in return to function. In spite of the early return to function, patients in Group II were subjected to all kinds of surgical complications such as transient facial nerve injury, infection, and unesthetic scar. The maximal mouth opening and deviation of the mandible on mouth opening remained almost the same in both groups.Conclusion:A regular follow up of operated patients post trauma is essential to obtain morphological and functional recovery. When the respective advantages and disadvantages of both treatment options were compared and evaluated, it was observed that patients treated by closed reduction had a better clinical and psychological outcome.

Efficiency of treatment of patients with muscular and joint dysfunction of the TMJ

The prevalence of dysfunction of the temporomandibular joint (TMJ), especially in people aged 18-65 years, reached 95-98% among all dental applications. The course of the pathology is usually hidden, with periodic recurrences, and has a long nature, which is accompanied by a decrease in overall quality of life. Treatment of this pathology of the TMJ is a set of complex therapeutic, orthopedic and psychological measures. The literature describes many ways to treat TMJ dysfunction, and one of the modern ones is the use of occlusal splints, which enables to change the position of the mandible, diagnose and eliminate musculoskeletal dysfunction of the TMJ. The aim of the study was to determine the effectiveness of treatment of musculoskeletal dysfunction of the TMJ with occlusal splints according to axiography. Material and methods. 274 patients aged 18 to 65 years were diagnosed with temporomandibular joint (TMJ) pain syndrome before and after treatment.Results. All patients with signs of TMJ dysfunction before treatment had a violation of the trajectory of the mandible (deviation – 68.7%, dyslexia – 31.3%). When opening and closing the mouth, asymmetrical shifts of the lower jaw to the sides of more than 2 mm (deviation from the midline – more than 2 mm) were observed. After treatment with occlusal splints there was an improvement in the trajectory of opening and closing the mouth: the number of patients with a violation of the trajectory decreased by 89.1%, and the displacement of the mandible during opening and closing the mouth in 92.4% of patients decreased on average to 0, 9 mm. When analyzing the movements of the mandible in the sagittal plane in 79 % of cases, deviations of the trajectory of the mandible were detected. After treatment with occlusive muscle relaxation splints, elimination of violations of the trajectory of the mandible in the transverse plane was noted in 93.4% of cases, reduction of displacement to 0.9 mm in 78.1% of patients. Сonclusions. The trajectory of the mandible in the sagittal plane improved in 80.1% of patients, normalization of the position of the mandible relative to the neuromuscular trajectory was achieved in 93.4% of clinical cases. According to the analysis of parameters, such treatment should be considered effective.

Temporomandibular disorders in North Indian population visiting a tertiary care dental hospital.

Background:The terminology “temporomandibular disorders” (TMDs) encompasses a wide spectrum of conditions. Several hypothesized causes are occlusal disharmony, muscle hyperactivity, central pain mechanisms, psychological distress, and trauma. In day-to-day practice, TMDs had become more prevalent in Indian population due to changed dietary pattern and food habits, excessive stress of modern life, and other environmental causes. This study is an attempt to find the prevalence of TMDs in North Indian population.Aims:The present study is taken into account to determine the prevalence of TMDs on the basis of signs and symptoms based on the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD).Materials and Methods:The present cross-sectional study was conducted in the Department of Oral Medicine and Radiology. A total of 1009 patients aged between 6 and 80 years with a mean age of 42.04 ± 16.8 years seeking dental treatment from January 2016 to June 2017 were included in the study. All the patients were screened for TMD sign and symptoms. The demographic data and the signs and symptoms of TMDs were recorded in designed structured questionnaires which were based on the RDC/TMD criteria.Results:The study population consisted of 1009 patients aged between 6 and 80 years. In the present study population, based on RDC/TMD criteria, the incidence of clicking sound (42.5%) was highest in TMD joint followed by deviation of mandible on mouth opening (40.8%), internal derangement (36.8%), myofacial pain dysfunction syndrome (33.7%), osteoarthritis (29.5%), crepitus (25.8%), joint tenderness (5.8%), and pain on mouth opening (4.8%).Conclusion:Clicking sound was the most common sign of TMD disorders in Indian population.

THE CONDITION OF SKELETAL SYSTEM IN PUPILS WITH HEARING IMPAIRMENT

Pathogenic link of dentofacial abnormalities with posture disturbance and vertebra deformation causes interest in researchers, because the problem of the disorder of skeletal system has an important role. Orthodontic correction of dentofacial abnormalities without treatment of skeletal apparatus is incorrect and it leads to the large number of relapses and complications and also including temporo-mandibular joint. The aim of the research was to study correlation between injuries of hard tissues of teeth, posture disorders, bite abnormalities (malocclusion) in schoolchildren with hearing disorders. The condition of hard tissues of teeth, muscoskeletal system, dentofacial system in pupils with hearing impairment was done and evaluated. The age of examined is 6-19 years old, bite formation: 1st – presents the period of mixed bite (6-13 years old), 2nd – presents the period of permanent bite (14-19 years old). Results and conclusions: During dental examination it was detected that 58 pupils with hearing disorders (81,8%) have carious lesions of the teeth, the level of caries intensity contains 3,36. The condition of skeletal system was investigated in 56 pupils (36 boys and 20 girls). Disturbances of skeletal system in schoolchildren with hearing disorders presented 94,74%; 5,26% of pupils were almost healthy. The condition of the bite was examined in 58 pupils (32 boys and 26 girls). Different types of disorders of dentofacial apparatus were detected in 100% of pupils with hearing disorders. The most widespread pathology of bite was Angle’s bite (the first class) 68,97%, the second class – in 27,58%, the third class – 3,45%. Orthognathic bite among pupils with hearing disorders was not observed. In 31,15% of pupils during temporo-mandibular joint, deviation of mandible is observed.

PREVALENCE OF TEMPOROMANDIBULAR DISORDERS AMONG NEPALESE POPULATION

Background: Temporomandibular disorders (TMDs) comprise of a variety of clinical signs and symptoms such as joint sounds, muscle tenderness, joint tenderness, deviation, deflection, pain on mouth opening, protrusive, lateral movement and limited mouth opening which can be the result of trauma, stress, gum chewing, hard food biting habits, bruxism, long dental appointment. This study was aimed to determine the prevalence of temporomandibular disorders in Nepalese population in Eastern Nepal.&#x0D; Methods: The study was performed from May 2018 to Oct 2018. All the patients who came to the Department of Oral Medicine and Radiology, Nobel Medical College and Teaching Hospital (NMCTH) and health camps in Eastern part of Nepal were included. The self-administered questions were asked to the subjects about demographic data, different signs and symptoms of TMDs and etiological factors responsible to it.&#x0D; Results: More than two thirds of the study sample (83.96%) in the present study had one or more clinical signs and symptoms of TMDs. Deviation of mandible on mouth opening and clicking sound made up the highest percentage. Females were reported to have significantly higher prevalence of TMDs signs and symptoms than male. Disc displacement was the most prevalent disorder followed by myofascial pain and degenerative joint disorder.&#x0D; Conclusion: The results of this study show that a significant percentage of the population has signs and symptoms of TMDs. Measures should be taken to prevent and treat TMDs in this part of the world.

Prevalence of Temporomandibular Disorders among Nepalese Population

Background: Temporomandibular disorders (TMDs) comprise of a variety of clinical signs and symptoms such as joint sounds, muscle tenderness, joint tenderness, deviation, deflection, pain on mouth opening, protru­sive, lateral movement and limited mouth opening which can be the re­sult of trauma, stress, gum chewing, hard food biting habits, bruxism, long dental appointment. This study was aimed to determine the prevalence of temporomandibular disorders in Nepalese population in Eastern Nepal.&#x0D; Methods: The study was performed from May 2018 to Oct 2018. All the patients who came to the Department of Oral Medicine and Radiology, Nobel Medical College and Teaching Hospital (NMCTH) and health camps in Eastern part of Nepal were included. The self-administered questions were asked to the subjects about demographic data, different signs and symptoms of TMDs and etiological factors responsible for it.&#x0D; Results: More than two thirds of the study sample (83.96%) in the present study had one or more clinical signs and symptoms of TMDs. Deviation of mandible on mouth opening and clicking sound made up the highest per­centage. Females were reported to have significantly higher prevalence of TMDs signs and symptoms than male. Disc displacement was the most prevalent disorder followed by myofascial pain and degenerative joint dis­order.&#x0D; Conclusions: The results of this study show that a significant percentage of the population has signs and symptoms of TMDs. Measures should be taken to prevent and treat TMDs in this part of the world.

Complete dentures for a patient after a stroke by means of orofacial myofunctional therapy: A clinical report

After a stroke, patients frequently show compromised swallowing, mastication, and speech, as well as unfavorable motion and deviation of the tongue and mandible. The dentist can improve the oral rehabilitation of a patient with deteriorated facial and oral muscles after a stroke by incorporating orofacial myofunctional therapy. This report describes a method for tongue exercises and correction of mandible deviation in an edentulous patient after a stroke by using a pearl on a wire in the anteriomedian palatal part of the maxillary denture.

Three-dimensional printing of patient-specific surgical plates in head and neck reconstruction: A prospective pilot study

BackgroundSurgical plates have been extensively used in head and neck reconstruction and conventional plates are mass-produced with universal configurations. To overcome disadvantages of conventional surgical plates, we have been exploring patient-specific surgical plates using the three-dimensional (3D) printing technology. We hypothesized that the application of 3D-printed patient-specific surgical plates in head and neck reconstruction is feasible, safe and precise. MethodsWe are conducting a prospective clinical trial to assess the feasibility, safety and accuracy of applying 3D-printed patient-specific surgical plates in head and neck reconstruction. The primary endpoint was the intraoperative success rate. Secondary endpoints included the incidence and severity of postoperative adverse events within six months postoperatively. The accuracy of surgical outcomes was also explored by comparing the planned and final positions of the maxilla, mandible and grafted bone segments. ResultsFrom December 2016 to October 2017, ten patients were enrolled and underwent head and neck reconstruction using 3D-printed patient-specific surgical plates. The patient-specific surgical plates adapted to bone surface precisely and no plate-bending was performed. The intraoperative success rate was 100%. The average follow-up period was 6.5 months. No major adverse events were observed. The mean absolute distance deviation of integral mandible or maxilla was 1.40 ± 0.63 mm, which showed a high accuracy of reconstruction. ConclusionsThe 3D printing of patient-specific surgical plates could be effective in head and neck reconstruction. Surgical procedures were simplified. The precise jaw reconstruction was achieved with high accuracy. Long-term results with a larger sample size are warranted to support a final conclusion.The study protocol has been registered in ClinicalTrials.gov with a No. of NCT03057223.

Comparative evaluation of signs of temporomandibular joint dysfunction and occlusal discrepancies in asymptomatic men and women: A cross-sectional study

Context: Temporomandibular joint (TMJ) disorders represent a multifactorial disease process manifesting with various combination of signs and symptoms. Several studies have shown that there is an increased prevalence of TMJ dysfunction among females; however, there has been no conclusive explanation for this increased occurrence. Occlusal discrepancies have been identified as a causative factor in several cases. Aims: The present study was designed to identify the presence of three signs of occlusal discrepancy, namely the presence of anterior and/or lateral slide from centric relation to centric occlusion, occlusal contact on the nonworking side, and disclusive contact distal to canine on working side on purposeful lateral movement of mandible, in among the population with no signs of TMJ dysfunction. Methods and Materials: A sample population of 620 patients consisting of 313 females and 307 males with no signs of TMJ dysfunction were included in this study. Individual patients were examined for maximum inter-incisal opening, deviation of mandible on opening and closing, presence of joint sounds, and the three abovementioned signs of occlusal discrepancies. Results and Conclusion: The results revealed that there was no statistically significant difference in the occurrence of signs of TMJ dysfunction and of occlusal discrepancies among symptom-free men and women.

The Effect of Functional Mandibular Shift on the Muscle Spindle Systems in Head-Neck Muscles and the Related Neurotransmitter Histamine.

The aim of this study is to explore the effects of abnormal occlusion and functional recovery caused by functional mandible deviation on the head and neck muscles and muscle spindle sensory-motor system by electrophysiological response and endogenous monoamine neurotransmitters’ distribution in the nucleus of the spinal tract. Seven-week-old male Wistar rats were randomly divided into 7 groups: normal control group, 2W experimental control group, 2W functional mandible deviation group, 2W functional mandible deviation recovery group, 4W experimental control group, 4W functional mandible deviation group, 4W functional mandible deviation recovery group. Chewing muscles, digastric muscle, splenius, and trapezius muscle spindles electrophysiological response activities at the opening and closing state were recorded. And then the chewing muscles, digastric, splenius, trapezius, and neck trigeminal nucleus were taken for histidine decarboxylase (HDC) detection by high performance liquid chromatography (HPLC), immunofluorescence, and reverse-transcription polymerase chain reaction (RT-PCR). Histamine receptor proteins in the neck nucleus of the spinal tract were also examined by immunofluorescence and RT-PCR. Electromyography activity of chewing muscles, digastric, and splenius muscle was significantly asymmetric; the abnormal muscle electromyography activity was mainly detected at the ipsilateral side. After functional mandibular deviation, muscle sensitivity on the ipsilateral sides of the chewing muscle and splenius decreased, muscle excitement weakened, modulation depth decreased, and the muscle spindle afferent impulses of excitation transmission speed slowed down. Changes for digastric muscle electrical activity were contrary. The functions recovered at different extents after removing the deflector. However, trapezius in all the experimental groups and recovery groups exhibited bilateral symmetry electrophysiological responses, and no significant difference compared with the control group. After functional mandibular deviation, HDC protein and messenger ribonucleic acid (mRNA) levels on the ipsilateral sides of the chewing muscle and splenius increased significantly. HDC level changes for digastric muscle were contrary. After the removal of the mandibular position deflector, HDC protein and mRNA levels decreased on the ipsilateral sides of the chewing muscle and splenius while they increased in the digastric muscle. The difference of histamine decarboxylase content in the bilateral trapezius in each experimental group was small. After functional mandibular deviation, the temporomandibular joint mechanical receptors not only caused the fusimotor fiber hypoallergenic fatigue slow response on the ipsilateral sides of splenius, but also increased the injury neurotransmitter histamine release. The authors’ results further support the opinion that the temporomandibular joint receptors may be involved in the mechanical theory of the head and neck muscles nervous system regulation.