Temporomandibular Joint Movement Research Articles

Pengembangan Terapi Regeneratif pada Osteoartritis Sendi Temporomandibula : Telaah Pustaka

Temporomandibular joint osteoarthritis (TMJ OA) is a degenerative condition that affects the temporomandibular joint, causing pain, stiffness, and limited jaw movement. Conventional therapies such as medications, physical therapy, and surgery often only provide temporary solutions and cannot permanently restore joint function. Therefore, regenerative therapy has emerged as a promising approach to address TMJ OA by harnessing the body's natural healing potential. This literature review aims to provide a comprehensive overview of the development of regenerative therapies for TMJ OA, including therapeutic strategies, challenges, and future opportunities. Regenerative therapies for TMJ OA encompass various strategies, such as stem cell injections, biomaterial scaffolds, growth factors, gene therapy, and combination therapies. Although regenerative therapies have shown promising results in preclinical studies, several challenges remain, such as safety, efficacy, and translation into clinical applications. It can be concluded that regenerative therapy offers an innovative and potential approach to addressing TMJ OA by utilizing the body's natural healing capabilities, with the hope of restoring joint function and improving the quality of life for TMJ OA patients in the future.

Reliability of landmark identification for analysis of the temporomandibular joint in real-time MRI

BackgroundReal-time magnetic resonance imaging (rtMRI) is essential for diagnosing and comprehending temporomandibular joint (TMJ) movements. Current methods for tracking and analysis require manual landmark placement on each acquisition frame. Therefore, our study aimed to assess the inter- and intra-rater reliability of placing cephalometric landmarks in frames from a dynamic real-time TMJ MRI.Material and methodsFour real-time MRIs of the right TMJ were taken during mandibular movement at ten frames per second. Seven dentists identified ten landmarks on two frames (intercuspal position—ICP—and maximum mouth opening—MMO) twice at a two-week interval, yielding 112 tracings. Six typical cephalometric measurements (angles and distances) were derived from these landmarks. The reliabilities of landmarks and measurements were evaluated using distance-based (dbICC), linear mixed effect model intraclass correlation (lmeICC), and standard ICC.ResultsThe average inter-rater reliability for the landmarks stood at 0.92 (dbICC) and 0.93 (lmeICC). The intra-rater reliability scores were 0.97 and 0.98. Over 80% of the landmarks showed an ICC greater than 0.98 (inter-rater) and over 0.99 (intra-rater). The lowest landmark ICC was observed for the orbitale and the oblique ridge of the mandibular ramus. However, the cephalometric angle and distance measurements derived from these landmarks showed only moderate to good reliability, whereas the reliability in the frames with ICP was better than those with MMO. Measurements performed in the ICP frame were more reliable than measurements in the MMO frame.ConclusionWhile dentists reliably localize isolated landmarks in real-time MRIs, the cephalometric measurements derived from them remain inconsistent. The better results in ICP than MMO are probably due to a more familiar jaw position. The higher error rate of the TMJ measurements in MMO could be associated with a lack of training in real-time MRI analysis in dentistry.

Evaluation of condylar and mandibular movements on the upper airway during the use of mandibular advancement device for obstructive sleep apnea treatment.

To evaluate the temporomandibular joint (TMJ), condylar and mandibular movements in obstructive sleep apnea (OSA) patients treated with mandibular advancement device (MAD) and to identify the influence of these anatomic factors on upper airway (UA) volume and polysomnographic outcomes after treatment. Twenty OSA patients were prospectively treated with MAD. Clinical examinations, cone-beam computed tomography, and polysomnography were performed before MAD treatment and after achieving therapeutic protrusion. Polysomnographic variables and three-dimensional measurements of the TMJ, mandible, and upper airway were statistically analyzed. Condylar rotation, anterior translation, and anterior mandibular displacement were directly correlated with total UA volume, while vertical mandibular translation was inversely correlated with the volume of the inferior oropharynx. MAD treatment resulted in an increase in the volume and area of the superior oropharynx. There was no statistically significant correlation between condylar rotation and translation and polysomnographic variables. With MAD, there was a significant increase in vertical dimension, changes in condylar position (rotation and translation), and mandibular displacement. The central and medial lengths of the articular eminence were inversely correlated with condylar rotation and translation, respectively. The lateral length of the eminence was directly correlated with condylar translation, and the lateral height was directly correlated with condylar rotation and translation. Condylar and mandibular movements influenced UA volume. The articular eminence played a role in the amount of condylar rotation and translation. Individualized anatomical evaluation of the TMJ proves to be important in the therapy of OSA with MAD.

Temporomandibular joint biomechanics and equine incisor occlusal plane maintenance.

In equine dentistry, the physiological incisor occlusal surface is visually perceived as a plane with a distinct inclination to the head's coronal plane, extending rostro-ventrally to caudo-dorsally. To better understand the formation of this inclined plane and its connection to dental wear, we investigated the hypothesis that it arises from masticatory movements and the considerable distance between mandibular articular heads and the incisor occlusal surfaces, acting as the three points of support for the mandibles. Leveraging data from a large-scale clinical study involving static and dynamic orthodontic measurements in horses, we approximated the mandibular movement range where incisor occlusion and dental wear occur. By introducing and testing a segment coordinate system, we explored possible angular deviations from the occlusal plane caused by mandibular roll and pitch rotations during two lateral mandibular movement patterns, protrusion and retrusion. Theoretical biomechanical calculations and simulations confirmed the visual perception of the incisor occlusal surface as a plane. To further examine our assumptions, we employed a simple mechanical simulator to assess incisor normal occlusion and provoked malocclusions (diagonal, smile, and frown bite) by modifying temporomandibular joint (TMJ) movement patterns. The results from clinical investigations were corroborated by both the theoretical analysis and mechanical simulations, strengthening our understanding of the biomechanical basis behind the physiological incisor occlusal plane maintenance in horses. These findings have significant implications for equine dental health and contribute to a thorough understanding of TMJ dynamics.

Correlation between orthodontic treatment and temporomandibular joint disorders

Orthodontic treatment aims to regulate the growth and development of the jaw and teeth. The temporomandibular joint (TMJ) is a hinge joint that connects the upper and lower jaw bones between the temporal bone and the head of the mandibular con-dyle. Orthodontic treatment of patients with a history of restriction of TMJ movement experienced statistically significant re-sults and reduction of TMJ pain. The results of the analysis of 6 journals stated that orthodontic treatment had a significant re-lationship with temporomandibular joint disorders. Orthodontic treatment can cause TMD such as structural disorders of the TMJ and functional disorders. Orthodontic treatment can also help overcome TMD such as reducing pain in the TMJ and pro-viding balance to the occlusion.

MATHEMATICAL ANALYSIS OF FRONTAL AREA BITE HEIGHT SEPARATION USING DENTAL SCANNER INDICATORS IN LOCALIZED PATHOLOGICAL TOOTH WEAR

The issue of occlusion changes resulting from tooth loss or wear requires prompt early identification and effective resolution. Alterations in the physiological position of the lower jaw can have cascading effects on facial muscles, articulation, chewing biomechanics, and patient’s aesthetics and comfort. It also poses challenges for orthodontic procedures. Correcting occlusion height is a significant concern for both patients and dental specialists, necessitating the use of appropriate techniques and informed decision-making.
 This review aims to examine primary literature sources concerning the causes and consequences of pathological tooth wear, its impact on bite changes in patients, and the relevance of mathematical calculations in orthodontic interventions.
 An electronic search and analysis of publications from prominent scientific databases (ScienceDirect, Research Gate, NCBI, PubMed, Ovid MEDLINE, Willey, Web of Science, EBSCO, Scopus, Google Scholar) were conducted. Emphasis was given to articles published after 2018. The presence of additional informative references in the analyzed text materials was also assessed.
 Mathematical equation models were identified as useful tools for quantitatively assessing temporomandibular joint movement during the restoration of the initial occlusion height. Such calculations are most effective in the early stages of orthodontic intervention, particularly when temporomandibular joint mobility is limited. However, it is crucial for dental specialists to approach each orthodontic procedure with precision and rationale, considering the existing temporomandibular structure. The accuracy of the method can be evaluated by calculating the proportion of true positives and true negatives in all assessed cases. While mathematical calculations can provide general guidelines, individual patient criteria should remain the primary consideration for the specialist.

Assessment of Various Complains after Non-Surgical Treatment of Condylar Fracture

Objective: To assess various complains of patients after non-surgical treatment of condylar fracture. Methodology: A cross-sectional study was performed from October 2021 to October 2022 at the Department of Oral and Maxillofacial Surgery, Nishtar Institute of Dentistry, Multan. The sample size collected was 34 patients using a consecutive non-probability sampling. Using pertinent clinical examination, the patient was assessed for disturbed occlusion, limited mouth opening, deviation of the mouth, pain, and clicking sound. The mean follow-up period was six months. Results: The male-to-female ratio was 1.8: 1, with male predominance. The leading cause of fracture was attributed to incidents involving road traffic accidents (RTAs) (n—26, 76.5%).Twenty-three patients had a positive post-opt complaint after treatment, from which the most complaints presented were with unilateral condylar fracture n=15. The most common complaint presented was TMJ Pain with limited mouth opening n=8(23.5%). Conclusion: Conservative care for unilateral mandibular condyle fractures is a safe treatment approach. However, it can cause a few post-treatment functional complaints, the most frequent of which is TMJ pain. To further evaluate the improvement in function and discomfort, more research and consistent long-term follow-ups are required. Keyword: Temporomandibular joint movement (TMJ), TMJ Pain, Maxillomandibular Fixation (MMF)

Reeducarea tulburărilor specifice de articulare a vorbirii determinate de dezechilibru muscular orofacial cu ajutorul terapiei logopedice miofuncționale

Phonetic disorders are errors of articulation and resonance of phonemes, which, in the presence or absence of organic changes in the phonoarticulatory organs, persist beyond the acquisition of perceptual and articulatory skills. For the correct production of each vowel/consonant, the structures of the articulatory apparatus come into contact in a variable way, following finely coordinated movements, and adopt a certain position to allow the correct emission of the sound. Orofacial muscle imbalances and disorders are disorders of the muscles and functions of the face and mouth. These can directly and/or indirectly affect breastfeeding, growth and development of the facial skeleton, mastication, swallowing, resting position of the tongue, speech- phonemic articulation, occlusion, temporomandibular joint (TMJ) movements, oral hygiene, stability of orthodontic treatment, facial aesthetics and others. The correct swallowing mechanism depends on the correct relationship between the muscles of the face, mouth and pharyngo-laryngeal region, but also on a balance of the entire body system. Another important element that must be taken into account, in particular, is the resting position of the tongue. Dysfunctional swallowing - refers to a condition in which there is an alteration of the mouth-lingual movements in the act of swallowing. Balancing the oro-facial musculature through education - re-education of deviant swallowing, breathing and mastication difficulties, phonatory verbal articulation alterations, malocclusion and painful symptoms of the temporomandibular joint, in different age groups is done through TMF (Myofunctional Therapy). Myofunctional therapy can lead to stable correction of swallowing abnormalities, with positive effects for correcting speech articulation disorders.

Surgical treatment of pseudoankylosis of the temporomandibular joint in a dog

AbstractPseudoankylosis of the temporomandibular joint is infrequent in veterinary practice and mostly seen secondary to trauma. This case report describes the surgical treatment of a 1‐year old, male, entire lurcher that presented with progressive lateral deviation of the muzzle to the left and decreased vertical mandibular range of motion of 6‐month duration. There was no history of trauma, no pain on palpation and complete loss of temporomandibular joint movement, even under sedation. Computed tomography investigation showed a left‐sided temporomandibular pseudoankylosis with osseous fusion between the zygomatic arch and mandible. Surgical excision of the ankylosed bone was performed and achieved an initial 5 cm interincisal gap. The surgical site healed, with no complications reported. Re‐examination at 4 weeks revealed good vertical mandibular range of motion with interincisal gap of approximately 5 cm. At 9 months post‐operatively, the dog had maintained good vertical mandibular range of motion and was able to eat normally, pant and hold large toys.

Effect of abnormal occlusal contact on temporomandibular joint

Occlusion, temporomandibular joint and masticatory muscle are in a functional system, which cooperate and influence each other. When any one of these elements is abnormal, it will affect the function of other elements. The normal occlusal relationship is the convex-concave relationship of apical fossa contact, and the masticatory movement trajectory is teardrop-like, which is helpful to promote the normal mandibular functional movement. The abnormal occlusal contact relationship changes the convex-concave relationship of apical fossa contact into convex relationship, which will form abnormal masticatory movement trajectory, and may even cause abnormal movement and stress of temporomandibular joint and abnormal contractile activity of masticatory muscle. The longer the duration of this abnormal occlusal relationship, the greater the damage to bone and soft tissue. scissors bite, openbite and crossbite are common occlusal abnormalities in clinic, so this article will focus on the effects of these three abnormal occlusal contacts on the temporomandibular joint.

The use of platelet-rich plasma, hyaluronic acid, and botulinum toxin for the treatment of TMJ disorders

The temporomandibular joint (TMJ) is a synovial joint that connects the mandibular to the skull. Its main function is to facilitate the movement of the jaw and when it suffers any type of damage or injury, it leads to a decrease in mobility and pain in the area. This localized pain is called temporomandibular joint disorders (TMJD), and it can be caused by intraarticular or extraarticular disorders. The most common symptoms include acute pain, decreased mouth opening, tightening of the muscle, headache, and loss of joint function. Nowadays, there are treatments for temporomandibular joint dysfunction from surgical procedures up to less invasive methods, such as the use of splints. Platelet rich plasma (PRP), hyaluronic acid (HA) and botulinum toxin (BTX) injections have been categorized as a complement of primary treatment in TMJD, as well as decrease drug excess in patients. Due to their natural origin, PRP and HA can regenerate tissue in cases of cartilage degeneration, inhibit inflammation, slow down the progression of osteoarthritis and increase the production of natural lubricating fluid in the joint. Its intra-articular application reduces pain due to lubrication and nutrition to the avascular areas of the disc and condylar cartilage. Botulinum toxin (BTX) has been used for years in the medical and cosmetic field, but its use in TMJD refers to injections specifically within masseter muscle, with the objective to reduce the muscular tension TMJ overload, therefore, pain decreases, and movement increases. Over the years these less invasive methods have been increasing in the medical area due to the great pain management in the neuro-muscular and articular complex.

Evaluation of Temporomandibular Joint Dysfunction in Patients with Chronic Neck Pain

Objective: The aim of this study was to compare the presence of temporomandibular joint dysfunction (TMD) in individuals with and without chronic neck pain (CNP).
 Materials-Methods: The study included 41 subjects with neck pain and 41 subjects without neck pain. Temporomandibular Disorders were evaluated according to the Research Diagnostic Criteria (TMR). The amount of mouth opening was measured with a ruler (cm). Presence of voice in TMJ movements was evaluated. Pain intensity (Visual Analog Scale (VAS)) was evaluated on palpation of chewing muscles. Active joint motion of the cervical region was evaluated with a goniometer. Pain-related disability was assessed with the Neck Disability Indicator/NDI.
 Results: The results of our study showed that the pain intensity of the temporomandibular joint (TMJ) was significantly higher than the control group. The severity of pain felt during rest, activity (active mouth opening) and chewing in the study group was significantly higher than the control group (p

Evaluation the relationship between polymorphism of galactose mutarotase gene by creating jaw sound in patients with temporomandibular disorder (TMD)

Objective: One of the concerns of dentists is the referral of patients with temporomandibular prob- lems. Temporomandibular joint disorders (TMD) is a complex multifactorial clinical problem that involves masticatory muscles, temporomandibular joint and related structures. This complication is one of the three common chronic pains after headache and low back pain, which can manifest as pain in the temporoman- dibular region and limitation in joint movements, or even as clicking, crepitus, and popping sounds during temporomandibular joint movements. For the first time, the american association for oral pain (AAOP) proposed the role of genetic factors in the development of TMD. It is thought that a complex disorder such as TMD is multidimensional and can be subjected to environmental conditions as well as multiple gene polymorphisms. Identification of single nucleotide polymorphisms in the human genome can play an important role in clinical setting for diagnosis, prognosis and therapeutic interventions in various diseases including TMD. The aim of this study was to evaluate the relationship between polymorphism of galactose mutarotase gene by creating jaw sound in patients with temporomandibular disorder in a population with high similarity to the whole Iranian population and using the results in prevention and targeted treatment of affected patients.
 Study Design: 101 patients with TMD using DC/TMD criteria among those referred to Tehran University School of Dentistry and 103 healthy subjects for TMD that have age and gender matched were selected to control groupfrom those referring to the Oral and Maxillofacial Diseases and Oral and Maxillo- facial Pain departments. Blood samples were taken in 5cc and DNA extracted from the blood of both groups by applying the technique PCRARMS in terms of polymorphism rs4776783 in Galm gene were Compared.
 Results: 101 patients with TMD along with 103 healthy individuals without a history of TMD were evaluated to investigate rs4776783 polymorphism in GALM gene. The average age of the patients was 35.92, and 21 were men and 80 were women. According to the questionnaire, 61 people felt the sound in their jaw while moving. On the other hand, according to the TMD/DC criterion, the number of people who have crepitus in the right and left jaws is equal. The average age of the patients was 35.92, and 21 were men and 80 were women. According to the questionnaire, 61 people felt the sound in their jaw while moving. On the other hand, according to the TMD/DC criterion, the number of people who have crepitus in the right and left jaws is equal. The low prevalence of crepitation with p=0.734 has a significant relationship with the genotype of people.
 Conclusion: This study showed that there is a significant relationship between the rs4776783 poly- morphism in Galm gene and the occurrence of temporomandibular disorder (TMD), jaw sound and pain in many masticatory muscles such as lateral pterygoid and temporal. Therefore, it can be concluded that TMD has a genetic basis.

Estimation of Temporomandibular Joint Dysfunction in Oral Cancer Survivors.

The Objective of this study was estimation of Temporomandibular joint dysfunction in oral cancer survivors. The hundred patients with oral cancer who had undergone radiotherapy or chemotherapy were randomly selected as per inclusion criteria. Range of motion of temporomandibular joint(TMJ), visual analogue scale (VAS), Manual muscle testing (MMT), Auscultation test, Chvostek test and swelling over orofacial muscles were used as the Outcome measures. The findings of this study revealed that the Temporomandibular joint was significantly dysfunctional. The group analysis demonstrated statistically significant impairments in all the Outcome measures. VAS (p<0.0001), ROM for all four motions (p<0.0001), Manual muscle testing (p<0.0001), Provocation test (52%), Auscultation test (92%), Chvostek Test (4%), and swelling (56%) were all shown significant dysfunction of TMJ. This study showed that pain was increased during activity than at rest based on the findings of VAS pain rating scale. It was found that the range of motion of TMJ was significantly reduced; however muscular strength was minimally affected. Majority of survivors were tested positive for the provocation test and auscultation test and few for Chvostek test which indicated the involvement of facial nerve.

Puricelli biconvex arthroplasty as an alternative for temporomandibular joint reconstruction: description of the technique and long-term case report

BackgroundThere are several indications for partial or total replacement of the temporomandibular joint (TMJ), including neoplasms and severe bone resorptions. In this regard, several techniques have been suggested to increase the functionality and longevity of these prosthetic devices. This case report describes the treatment of a TMJ ankylosis patient with the Puricelli biconvex arthroplasty (ABiP) technique, with a long-term follow-up.Case presentationIn 1978, a 33-year-old male polytraumatised patient developed painful symptoms in the right preauricular region, associated with restricted movement of the ipsilateral TMJ. Due to subcondylar fracture, an elastic maxillomandibular immobilisation (EMMI) was applied. Subsequently, the patient was referred for treatment when limitations of the interincisal opening (10 mm) and the presence of spontaneous pain that increased on palpation were confirmed. Imaging exams confirmed the fracture, with anteromedial displacement and bony ankylosis of the joint. Exeresis of the compromised tissues and their replacement through ABiP was indicated. The method uses conservative access (i.e., preauricular incision), partial resection of the ankylosed mass, and tissue replacement using two poly(methyl methacrylate) components, with minimal and stable contact between the convex surfaces. At the end of the procedure, joint stability and dental occlusion were tested. The patient showed significant improvement at the postoperative 6-month follow-up, with no pain and increased mouth opening range (30 mm). At the 43-year follow-up, no joint noises, pain or movement restrictions were reported (mouth opening of 36 mm). Imaging exams did not indicate tissue degeneration and showed the integrity of prosthetic components.ConclusionsThe present case report indicates that ABiP enables joint movements of the TMJ, allowing the remission of signs and symptoms over more than 40 years of follow-up. These data suggest that this technique is a simple and effective alternative when there is an indication for TMJ reconstruction in adult patients with ankylosis.

Lateral Pterygoid Muscle Ossification After Intraoral Condylectomy.

Lateral pterygoid muscle ossification has not been reported in condylectomy patients. This study aimed to explore the incidence, risk factors, and imaging characteristics of 38 cases with lateral pterygoid muscle ossification among 54 patients after condylectomy via intraoral approach. This retrospective study included 54 patients following simultaneous orthognathic surgery and condylectomy with coronoid process resection via intraoral approach. The authors evaluated the preoperative, 1 week, 6 months, and 1 year or more postoperative computed tomographic (CT) scans for the presence of lateral pterygoid muscle ossification and its characteristics. Sex, age at the time of surgery, disease course, affected side, preoperative alkaline phosphatase, pathology diagnosis, the height of the removed condyle, condylar shape, operator, preoperative temporomandibular joint movement, and clinical symptoms were assessed as risk factors for ossification. No incidence of lateral pterygoid muscle ossification was found on preoperative CT images. Various small-size osseous masses were observed in the lateral pterygoid muscles on postoperative 6 months CT images in 38/54 patients (70.37%) after condylectomy. But no apparent enlargement of the osseous masses was found. No patients complained of clinical discomfort or functional disorder during the follow-up period (23.11 ± 13.16 months). No significant risk factors for ossification were found. Lateral pterygoid muscle ossification is relatively common in patients after condylectomy via intraoral approach. However, its enlargement is self-limited and remains stable 6 months after surgery. it has no adverse effects on the temporomandibular joint functional movement.

Clinical application of 3D-printed PEEK implants for repairing mandibular defects

The aim of this study was to investigate and discuss the efficacy of 3D-printed PEEK implants in personalized reconstruction of mandibular segmental defects.This study was a single-center case series. Six patients who underwent mandibular reconstruction with a custom-made 3D-printed PEEK implant were enrolled. Patient demographics, photographs, computed tomography (CT), and other clinical data were collected and analyzed pre- and postoperatively. The average patient age was 60.0 ± 15.09 years. The mean operative time was 213.33 ± 30.77 min, and the postoperative follow-up time ranged from 10 to 24 months. Mandibular segmental defects ranged from the symphysis to the condyle. Five patients did not have any postoperative complications and were satisfied with the cosmetic and functional results. One patient had to undergo removal of the PEEK implant because of implant exposure at 10 months after surgery.PEEK implants can repair different forms of defect in the mandible, maintaining the original shape of the mandible, whilst not affecting mandible functions, such as mastication and temporomandibular joint movement. However, PEEK implantation requires the strict selection of appropriate indications, especially with regard to the evaluation of soft-tissue conditions in the implanted area.

Influence of demographic characteristics, tooth loss, and tooth wear on condylar movements: Cross-sectional study

ObjectivesThe study’s aim was to assess and compare the values of the sagittal condylar angle (SCA), the Bennett angle (BA), and the immediate side shift (ISS) between fully dentate and partially dentate patients, male and female patients, and Saudi and non-Saudi patients. The study also aimed to statistically analyze the correlation of the different condylar movements with tooth loss and tooth wear. Materials and MethodsUsing the electronic pantograph (Cadiax Compact II), the SCA, BA, and ISS were recorded at a 10-mm condylotrack distance in dentate and partially dentate patients, from both genders, older than 20 years, medically stable, and with normal temporomandibular joint movements and normal activity of masticatory muscles. The recorded average values were compared between the groups using an unpaired t-test. ResultsThe average condylar movements between dentate (n = 57) and partially dentate (n = 39) groups revealed no significant differences concerning right SCA, left SCA, right BA, right ISS, and left ISS. However, the left BA showed significant differences (P = 0.011) in the dentate compared with the partially dentate group. Gender (male: n = 24, female: n = 72) showed no statistical significance between groups when measuring SCA, BA, or ISS. When comparing Saudi (n = 78) with non-Saudi patients (n = 18), it was found that the mean right SCA was significantly higher in Saudi than in non-Saudi patients (P = 0.024). Condylar inclination values in relation to tooth wear showed no statistical significance (P > 0.05), except left ISS, which was significantly higher among those who had tooth wear (P = 0.040). ConclusionTooth loss had a major impact on the left BA, while patients with tooth wear had a significantly increased ISS on the left side.

200 A Scoring System for Equine Dental Health

Abstract Scoring systems have been implemented in veterinary practice to indicate the severity of pathologies, such as lameness and gastric ulceration. The need for a scoring system of equine dentition in relation to digestive health has been identified. A scoring system would allow veterinarians, owners, and researchers to more accurately assess dental health and the resulting impact it may have on chewing ability. A proposed system, the Equine Dental Scoring System (EDSS), was developed via collaboration of a team of veterinarians and equine nutritionists familiar with equine dental abnormalities. The EDSS was designed to assign higher scores corresponding to increasing severity of dental abnormalities that would impede proper chewing. The proposed scoring system ranges from 0 to 5 as follows: 0) no sharp enamel points, soft tissue damage, or malocclusion, (1) sharp enamel points, but no soft tissue damage or malocclusion, (2) sharp enamel points and soft tissue damage, but no malocclusion, (3) mild malocclusion with all aligned teeth meeting level (ex. ramps, hooks), (4) moderate malocclusion with all teeth meeting but not level (ex. wave, smile, diagonal, frown), (5) major malocclusion with one or more teeth not meeting or inhibited temporomandibular joint movement (ex. step, shear, retained cap), and/or infection, and/or pain while chewing. The EDSS was validated by assessing agreement via the Cohen’s kappa statistic between four trained professionals scoring ten images of horse dentition. Both the weighted (к = 0.62) and unweighted (к = 0.73) kappa statistics indicated substantial agreement between scorers, signifying reliable repeatability of the EDSS. Presenting dental health in the form of a score would indicate severity of dental pathologies and allow for quantitative and statistical evaluation of dental health in nutrition research and veterinary medicine.

Biomechanical analysis of temporomandibular joints during mandibular protrusion and retraction motions: A 3d finite element simulation

Background and ObjectiveTemporomandibular disorders (TMDs) represent a wide range of musculoskeletal disorders associated with the maxillofacial system, which negatively affect the daily activities of patients. TMD symptoms are caused by the temporomandibular joint (TMJ) overloading. TMJ motions are frequent and can trigger overloading and imbalanced loads on the TMJs, which are assumed to be dangerous. The condyles move forward a lot during mandibular protrusion, which is possibly harmful to the biomechanical environment of the TMJs. The aim of this study was to investigate the biomechanical behavior of TMJs during mandibular protrusion and retraction. MethodsSix three-dimensional maxillofacial system models from asymptomatic subjects were established through computed tomography (CT) and magnetic resonance imaging (MRI). The mandibular protrusion and retraction were recorded using an optical tracking system. Finite element analysis was used to simulate the biomechanical behaviors of the TMJs during the movements. ResultsThe simulation results were validated to be effective by comparison with the MRIs. The results indicated that the stresses during the protrusion and retraction were approximately equal at the same condylar displacement. Meanwhile the discal stresses, relatively correlated with the condylar displacement, increased as the condylar displacement increased during the protrusion and decreased as the condylar displacement decreased in the retraction. In addition, the average peak maximum and minimum principal stresses of the discs were 0.186 and -0.192 MPa, respectively. ConclusionsThe models were reasonable for the investigation of the TMJs motion. Based on the results, three quadratic polynomials were proposed to describe the relationship between the stresses and the condylar displacements. In clinical diagnosis, the functions are helpful in the prediction of the discal stresses by measuring the condylar displacement.