Does surgical volume correlate with outcomes in TMJ replacement surgery?

OBJECTIVE: To survey oral and maxillofacial surgeons (OMS) who perform temporomandibular joint replacement (TMJR) to determine whether length of surgery, specific TMJR protocols, or the incidence of complications are related to experience and case volume. STUDY DESIGN: An anonymous electronic survey was emailed to 407 surgeon members of the American Association of Oral and Maxillofacial Surgeons, American Society of Temporomandibular Joint Surgeons, and European Society of Temporomandibular Joint Surgeons known to have TMJR experience via publications or reputation. The descriptive survey contained multiple choice and open-ended questions. Descriptive statistics were computed for each variable for data analysis. RESULTS: Forty-nine surgeons completed the survey. The average stock TMJR cases included 54.6% unilateral and 50.5% bilateral cases. The average custom TMJR cases included 50.5% unilateral and 49.5% bilateral cases. Average procedure time for stock TMJR was 2.86 hours for unilateral, and 5.30 hours for bilateral cases. The average procedure time for a custom TMJR was 2.75 hours for unilateral, and 4.87 hours for bilateral cases. Average duration of hospital stay for stock and custom TMJR cases was 1.49 and 1.41 days (unilateral), and 1.98 and 1.95 days (bilateral). CONCLUSIONS: This study provides some pilot data that demonstrates that the length of surgery, specific TMJR surgical protocols, and the incidence of complications may be related to surgeon TMJR experience and case volume.

Alloplastic TMJ replacement in the skeletally immature patient - A systematic review.

This study assessed the current evidence for the use of TMJR reconstruction in skeletally immature patients. A systematic review was conducted according to PRISMA guidelines. An electronic search in PubMed and Embase was performed. Meta-analysis randomized controlled trials (RCTs), cohort studies, observational studies, case series, and case reports were eligible for inclusion. Case reports were also included due to the limited number of publications identified with the predefined terms. Exclusion criteria were: (1) studies written in a language other than English; (2) full-text unavailability (i.e., posters and conference abstracts). The selected studies were assessed for risk of bias. A meta-analysis was not performed as it necessitates a substantial between-study design homogeneity; hence, a descriptive synthesis of data was performed. There were 9 TMJR device reconstruction studies involving 14 subjects 13 years of age or younger. Follow-up ranged from 7 months to 120 months. All papers reported significant decrease in pain and improvement of diet. All prostheses were functional. No material failures of the prosthesis components were observed. The mandible continued to show limited growth following TMJR and most of the cases required no secondary or revision surgery even when the patient reached skeletal maturity. This systematic review had some limitations. The studies included had a low level of evidence and a high risk of bias. Most of the studies had a small patient sample, and no study had a control group. The literature reviewed supports the use of TMJR devices in the restoration of mandibular function and form in skeletally immature patients.

Alloplastic temporomandibular joint replacement - past, present, and future: "Learn from the past, prepare for the future, live in the present." Thomas S. Monson.

Based on evidence from the orthopaedic, biomedical engineering, and oral and maxillofacial surgical literature, this paper discusses reported successes and failures of past alloplastic temporomandibular joint (TMJ) devices that have led to the development of present total temporomandibular joint replacement (TMJR) devices. The paper concludes with discussion of the ongoing research that will lead to future embodiment (materials, designs, and manufacture) advances in TMJR management of severe and debilitating end-stage TMJ disease, further improving patients' mandibular function, form, and overall quality of life.

Recommendations on the Use of Oral Orthotic Occlusal Appliance Therapy for Temporomandibular Joint Disorders: Current Evidence and Clinical Practice.

Background: 'Temporomandibular joint disorders (TMDs)' denote an umbrella term that includes arthritic, musculoskeletal and neuromuscular conditions involving the temporomandibular joint, the masticatory muscles, and the associated tissues. Occlusal devices are one of the common treatment modalities utilized in the conservative management of TMDs. The indications for the available 'oral splints' or 'oral orthotic occlusal devices' remain ambiguous. Methods: A joint international consortium was formulated involving the subject experts at TMJ Foundation, to resolve the current ambiguity regarding the use of oral orthotic occlusal appliance therapy for the temporomandibular joint disorders based on the current scientific and clinical evidence. Results: The recommendations and the conclusion of the clinical experts of the joint international consort has been summarized for understanding the indications of the various available oral orthotic occlusal appliances and to aid in the future research on oral occlusal orthotics. Conclusion: The use of the oral orthotic occlusal appliances should be based on the current available scientific evidence, rather than the archaic protocols.

Does Emotional State Improve Following Temporomandibular Joint Total Joint Replacement?

BACKGROUND: Temporomandibular joint total joint replacement (TMJTJR) offers patients the opportunity for improved function and reduced pain. TMJTJR also has the potential to affect a patient's emotions in a positive or negative manner. PURPOSE: The purpose of this study was to evaluate changes in emotional state for subjects undergoing TMJTJR. STUDY DESIGN, SETTING, SAMPLE: The authors implemented a retrospective cohort study. Subjects who received TMJTJR were identified from the TMJ Inter Network, which is a study group comprising more than 130 temporomandibular joint surgeons. Subjects between the ages of 18 and 65 years with complete medical records and pre/post TMJTJR video/audio recordings were enrolled in the study. PREDICTOR VARIABLE: The predictor variable was time (preoperative and postoperative). MAIN OUTCOME VARIABLES: The primary outcome variable is change in the emotional state. All subjects had preoperative (T0) recorded interview as well as a postoperative (T1) interview at 3 to 6 months. The eight-category emotional state was classified as neutral, happy, sad, angry, fearful, disgusted, surprised, and bored. The three-category emotional state was classified as neutral, positive, and negative. The emotional state was measured using artificial intelligence at T0 and T1. The secondary outcome variable was pain score and maximal interincisal opening. COVARIATES: The covariates are gender, age, diagnosis, prosthetic side, TMJTJR design, and TMJTJR type. ANALYSES: The relationship between emotional state change and covariates was examined using both the χ2 test and the Kruskal-Wallis H test. The significance of the change in categorical data after surgery was examined using the McNemar-Bowker test. P values < .05 were considered statistically significant. RESULTS: Thirty-three subjects were included in the study. The mean age was 30.09 ± 8.69 with 15 males (45%) and 18 females (55%). The percentage of subjects with preoperative neutral, happy, sad, angry, and fearful emotional states was 24, 15, 24, 9, and 27%, respectively. The percentage of subjects with postoperative neutral, happy, sad, angry, and fearful emotional states was 21, 39, 21, 12, and 6%, respectively. The change in emotional state was statistically significant (P = .037). There was no statistically significant relationship between covariates and emotional state changes (P > .05). CONCLUSION: According to the assessment of artificial intelligence, TMJTJR improves the emotional state of patients.

Chemokine Regulation in Temporomandibular Joint Disease: A Comprehensive Review.

Temporomandibular joint disorders (TMDs) are conditions that affect the muscles of mastication and joints that connect the mandible to the base of the skull. Although TMJ disorders are associated with symptoms, the causes are not well proven. Chemokines play an important role in the pathogenesis of TMJ disease by promoting chemotaxis inflammatory cells to destroy the joint synovium, cartilage, subchondral bone, and other structures. Therefore, enhancing our understanding of chemokines is critical for developing appropriate treatment of TMJ. In this review, we discuss chemokines including MCP-1, MIP-1α, MIP-3a, RANTES, IL-8, SDF-1, and fractalkine that are known to be involved in TMJ diseases. In addition, we present novel findings that CCL2 is involved in ß-catenin-mediated TMJ osteoarthritis (OA) and potential molecular targets for the development of effective therapies. The effects of common inflammatory factors, IL-1ß and TNF-α, on chemotaxis are also described. In conclusion, this review aims to provide a theoretical basis for future chemokine-targeted therapies for TMJ OA.

RE: Biomechanical comparative analysis of temporomandibular joint, glenoid fossa and head of the condyle of conventional models prothesis with new PEEK design.

This is a Letter to the Editor that describes some of the biomechanical concerns with the statements made in This is a LTE that raises some biomechanical statements made in Genovesi W, Comenale IC, Genovesi Filho W, Veloso Fernandes M. Biomechanical comparative analysis of temporomandibular joint, glenoid fossa and head of the condyle of conventional models prothesis with new PEEK design. J Oral Biol Craniofac Res. 2022 Sep-Oct; 12(5):529-541.

Is Heterotopic Ossification Removal From Alloplastic Temporomandibular Joint Prosthesis Using Er,Cr:YSGG Laser Superior to Conventional Methods?

PURPOSE: Heterotopic ossification (HO) formed over the major components and fixation screw heads of an alloplastic temporomandibular joint replacement (TMJR) prosthesis can result in decreased quality of life, limited function, prosthesis failure, and hinder prosthesis revision, replacement, or removal. This study simulated HO removal from the major components and fixation screw heads of alloplastic TMJR prostheses using an erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser and compared the results to conventional methods of HO removal. The surface morphology and chemical structure of the exposed components were analyzed. The investigators hypothesize that HO removal with an Er,Cr:YSGG laser causes less damage to TMJR prosthesis components compared to conventional HO removal methods. METHODS: This multiple test descriptive analysis simulated HO removal from TMJR prostheses mounted to stereolithic models. Simulated HO removal was completed using a novel Er,Cr:YSGG laser method and conventional methods which utilized a fissure carbide bur in a high-speed rotary instrument, a standard osteotome, and an ultrasonic aspirator. Surfaces exposed on the TMJR prostheses were analyzed for morphological or chemical change using scanning electron microscopy, energy dispersive X-ray spectroscopy, and Raman spectroscopy. RESULTS: The Er,Cr:YSGG laser did not adversely affect the titanium screws or titanium components of the TMJR prostheses, while conventional methods of HO removal did. HO removal using the Er,Cr:YSGG laser and conventional methods both inflicted surface damage to the fossa ultrahigh molecular weight polyethylene component of the TMJR prostheses. CONCLUSION: Damage inflicted to titanium alloy or commercially pure titanium components of TMJR prostheses by conventional HO removal methods can be avoided by instead removing HO with an Er,Cr:YSGG laser. However, long exposure of the Er,Cr:YSGG laser to ultrahigh molecular weight polyethylene surfaces should be avoided. Additional research to expand on applications to other procedures and in other surgical fields is encouraged.

A novel approach to establishing a temporomandibular joint fibrocartilage cell line.

Background/purpose: The temporomandibular joint (TMJ) is a bi-arthrodial joint that is composed of the temporal bone glenoid fossa and the condylar head of the mandible both having fibrocartilaginous articular surfaces. Functional overloading of the TMJ is the main cause of TMJ osteoarthritis (TMJ OA) disease. The aim of this study was to establish immortalized TMJ fibrocartilage cell clones to provide enough cells to adequately investigate the molecular mechanisms studies of TMJ OA. Materials and methods: We have isolated temporomandibular condyle chondrocytes from adult Sprague Dawley rat. The cells were cultured and immortalized by treating with Y-27632, a well-characterized inhibitor of Rho-Associated Kinase (ROCK). Clones were characterized on the basis of cell morphology and analyses of marker gene expression through 45 passages. Results: Cells from the condylar fibrocartilage of the TMJ were successfully immortalized by ROCK inhibitor, retaining a consistent cuboidal cell morphology and the expression of several cell markers of polymorphic cell fate. In addition, they retained phenotype features similar to the primary parental TMJ fibrocartilage cells when the cells were challenged with different cytokines and growth factors. Conclusion: These studies establish a novel immortalized cell line through ROCK inhibitor Y-27632, that retains the polymorphic phenotype of primary cell lines from TMJ fibrocartilage chondrocyte cell through a high number of passages, serving as a valuable preclinical resource for mechanistic in vitro assessment of TMJ health, disease, and regeneration.

Modification of an extended total temporomandibular joint replacement (eTMJR) classification system.

The aims of this paper were to validate a modification of an extended total temporomandibular joint replacement (eTMJR) classification system and develop a classification schematic for ease of reference. High-volume TMJ surgeons were asked to score 20 separate eTMJR devices using the updated classification system, and inter-rater variability was calculated. Using the modified classification system developed, a Conger's kappa (κ) coefficient of 0.53 was returned, suggesting moderate to good levels of agreement. The final classification system was then developed in a series of standardised graphic illustrations as visual representations of the different subcategories of eTMJR devices.

Characteristics of Medical Malpractice Claims Involving Temporomandibular Joint Surgery in the United States.

PURPOSE: Medical malpractice claims contribute to the practice of defensive medicine which exposes patients to unnecessary tests and limits access to care. The purpose of this study is to characterize medical malpractice claims involving temporomandibular joint (TMJ) operations by oral and maxillofacial surgeons in the United States. MATERIALS AND METHODS: Retrospective cross-sectional study of closed medical malpractice claims against oral and maxillofacial surgeons in the Unites States insured by OMS National Insurance Company, RRG (OMSNIC), from January 1, 2016, through December 31, 2020. All claims were obtained from the OMSNIC claims database and classified by procedure type. The primary outcome measure was closed claims involving a TMJ operation. Claims regarding postoperative TMJ complications from non-TMJ operations were excluded. Predictor variables included alleged error and type of TMJ procedure performed. Claim outcome was reported as a secondary outcome measure. Additional outcomes measured included claims involving dentoalveolar or dental implant procedures. Descriptive statistics were performed, and risk ratios were calculated for TMJ claim settlement by alleged error and procedure. Significance was set at P < .05. RESULTS: A total of 1455 closed claims occurred during the study period. There were 14 closed claims involving a TMJ operation (0.96% of all claims). "Improper performance" was the most common alleged error for TMJ claims. Two claims (1 TMJ arthroscopy and 1 TMJ replacement) were settled with payment, and the alleged error for these claims was improper performance. No TMJ claim received a court-adjudicated payout. Dentoalveolar and dental implant-related claims made up 68.73% (n = 1,000) and 15.53% (n = 226) of all OMSNIC claims, respectively. The risk of a settlement was not significantly influenced by alleged error or TMJ procedure performed. CONCLUSIONS: Medical malpractice claims against oral and maxillofacial surgeons for TMJ operations are very uncommon. Medical malpractice risk should not factor into a surgeon's decision to exclude TMJ operations from their practice.

Alloys Used in Different Temporomandibular Joint Reconstruction Replacement Prostheses Exhibit Variable Microstructures and Electrochemical Properties.

PURPOSE: Metallic temporomandibular joint replacement (TMJR) systems vary depending on design, material composition, and manufacturing methods such as casting, forging, and additive manufacturing. Therefore, the purpose of this study was to measure the association between manufacturing process of TMJR systems in terms of microstructure and electrochemical properties. MATERIALS AND METHODS: The sample was composed of new or surgically retrieved TMJ replacement devices of either titanium alloy (Ti6Al4V) or cobalt-chromium-molybdenum (CoCrMo) alloy from 8 different manufacturers. The primary predictor variable was alloy type, according to its manufacturing process (wrought, cast, additively manufactured [AM]). The primary outcome variables were 1) microstructure (grain size, aspect ratio, and phase content) and 2) corrosion potential and current, polarization resistance, and capacitance. Differences between alloy groups were determined by t tests, Kruskal-Wallis, and Mann-Whitney tests. RESULTS: We demonstrated that the TMJR CoCrMo and Ti6Al4V alloy microstructures can vary broadly within American Society for Testing and Materials specifications, where the components made of Ti6Al4V had 3 types of microstructures (equiaxial, bimodal, and martensitic) out of 10 samples, and the components made of CoCrMo had 2 types of microstructure (equiaxial and dendritic) out of 16 samples. Some CoCrMo alloys exhibited preferential corrosion sites, while wrought Ti6Al4V alloys trended toward a superior corrosion behavior (corrosion rate: 2 × 10-9 A/cm2, polarization resistance: 5,000,000 kΩcm2, and capacitance: 10 µSsa/cm2) compared with AM alloys (39 × 10-9 A/cm2, 1676 kΩcm2, 36 µSsa/cm2, respectively), where 4 samples of each group were tested and repeated 5 times. Among four AM devices, two exhibited a significantly inferior corrosion behavior. CONCLUSIONS: Although AM is an exciting emerging new technology that allows manufacturing of custom-made TMJR, their corrosion behavior is still inferior in comparison to that of traditional wrought alloys. Preventing corrosion is crucial because it can cause surface defects that may lead to implant fracture.

The ESTMJS (European Society of Temporomandibular Joint Surgeons) Consensus and Evidence-Based Recommendations on Management of Condylar Dislocation.

Although condylar dislocation is not uncommon, terminology, diagnostics, and treatment concepts vary considerably worldwide. This study aims to present a consensus recommendation based on systematically reviewed literature and approved by the European Society of TMJ Surgeons (ESTMJS). Based on the template of the evidence-based German guideline (register # 007-063) the ESTMJS members voted on 30 draft recommendations regarding terminology, diagnostics, and treatment initially via a blinded modified Delphi procedure. After unblinding, a discussion and voting followed, using a structured consensus process in 2019. An independent moderator documented and evaluated voting results and alterations from the original draft. Although the results of the preliminary voting were very heterogenous and differed significantly from the German S3 guideline (p < 0.0005), a strong consensus was achieved in the final voting on terminology, diagnostics, and treatment. In this voting, multiple alterations, including adding and discarding recommendations, led to 24 final recommendations on assessment and management of TMJ dislocation. To our knowledge, the ESTMJS condylar dislocation recommendations are the first both evidence and consensus-based international recommendations in the field of TMJ surgery. We recommend they form the basis for clinical practice guidelines for the management of dislocations of the mandibular condyle.

Does Maximum Voluntary Clenching Force Pose a Risk to Overloading Alloplastic Temporomandibular Joint Replacement?-A Prospective Cohort Study.

PURPOSE: The amount of maximum voluntary clenching (MVC) force may influence functional loading at the polyethylene/metal bearing surfaces in alloplastic total temporomandibular joint replacement (TMJR). The aim of this study was to measure ipsilateral MVC and estimate the risk for revision due to overloading of the TMJR. METHODS: A prospective cohort study design was used to study patients who underwent alloplastic TMJR. The primary predictor was time after TMJR, the secondary predictors were age at TMJR placement, coronoidectomy, prior ipsilateral TMJ surgeries, TMJR design (custom, stock), and bite location. The primary outcome variable was MVC, the secondary outcome was need for TMJR revision. Data were collected preoperatively (T0), and 1 year (T1), 2 to 3 years (T2) and ≥4 years postoperatively (T3). Analysis of variance (ANOVA) with post hoc Tukey-HSD and regression analysis was used for statistical analysis. P < .05 was considered significant. RESULTS: Thirty-seven patients (58 TMJR) with unilateral (n = 16) and bilateral (n = 21) TMJR were enrolled; 8 males (12 TMJR) and 29 females (46 TMJR). Average age was 46.4 ± 14.9 years. MVC increased significantly over the observation period (P = .000). At all observation time points, age at TMJR placement and bite location significantly influenced MVC (P = .000). Coronoidectomy and prior ipsilateral TMJ surgeries did not demonstrate a significant influence on MVC. TMJR design influenced MVC significantly at T3 (P = .006). Regression analysis identified age as a significant factor for higher MVC. No TMJR required revision or replacement. CONCLUSIONS: Based on this study, ipsilateral MVC increases significantly after TMJR. However, since MVC is significantly lower than in healthy test-patients, a considerably lower functional loading at the polyethylene/metal bearing surfaces can be assumed. Lower loading at the TMJR bearing surfaces and at the cortical screw fixation sites suggest a potential longer lifespan compared to other artificial joints like hip and knee prostheses.

Mechanical Loading Disrupts Focal Adhesion Kinase Activation in Mandibular Fibrochondrocytes During Murine Temporomandibular Joint Osteoarthritis.

PURPOSE: Mechanical overloading is a key initiating condition for temporomandibular joint (TMJ) osteoarthritis (OA). The integrin-focal adhesion kinase (FAK) signaling axis is implicated in the mechanobiological response of cells through phosphorylation at Tyr397 (pFAK) but poorly defined in TMJ health and disease. We hypothesize that mechanical overloading disrupts TMJ homeostasis through dysregulation of FAK signaling. MATERIALS AND METHODS: To assess if FAK and pFAK are viable clinical targets for TMJ OA, peri-articular tissues were collected from patients with TMJ OA receiving a total TMJ replacement. To compare clinical samples with preclinical in vivo studies of TMJ OA, the joints of c57/bl6 mice were surgically destabilized and treated with and without inhibitor of pFAK (iFAK). FAK signaling and TMJ OA progression was evaluated and compared using RT-PCR, western blot, immunohistochemistry, and histomorphometry. To evaluate mechanical overloading in vitro, primary murine mandibular fibrochondrocytes were seeded in a 4% agarose-collagen scaffold and loaded in a compression bioreactor with and without iFAK. RESULTS: FAK/pFAK was mostly absent from the articular cartilage layer in the clinical sample and suppressed on the central condyle and elevated on the lateral and medial condyle in murine TMJ OA. In vitro, compressive loading lowered FAK/pFAK levels and elevated the expression of TGFß, NG2, and MMP-13. iFAK treatment suppressed MMP13 and Col6 and elevated TGFß, NG2, and ACAN in a load independent manner. In vivo, iFAK treatment moderately attenuated OA progression and increased collagen maturation. CONCLUSION: These data illustrate that FAK/pFAK is implicated in the signaled dysfunction of excessive mechanical loading during TMJ OA and that iFAK treatment can moderately attenuate the progression of cartilage degeneration in the mandibular condyle.

Unilateral, Alloplastic Temporomandibular Joint Reconstruction, Biomechanically What Happens to the Contralateral Temporomandibular Joint?-A Prospective Cohort Study.

PURPOSE: Unilateral alloplastic total temporomandibular joint reconstruction (TMJR) might influence the contralateral side joint function. This study's purpose was to estimate the risk for contralateral TMJR and the jaw function of the contralateral untreated temporomandibular joint (TMJ). PATIENTS AND METHODS: A prospective cohort study design was used for patients who underwent unilateral alloplastic TMJR. The primary predictor was time after TMJR, and the secondary predictors were pre-TMJR mandibular angle resection, prior ipsilateral TMJ surgeries, and TMJR design (custom, stock). The primary outcome variable was the need for contralateral TMJR. The secondary outcome variables were the results of jaw function-jaw tracking, maximum voluntary clenching, surface electromyography, and pressure pain thresholds (PPT) and patient's quality-of-life (oral health-related quality-of-life [OHrQoL]). Data were collected preoperatively (T0), and 1 year (T1), 2-3 years (T2), and ≥ 4 years postoperatively (T4). Analysis of variance with post hoc Tukey -HSD test and multiple linear regression analysis were used for statistical analysis. P < .05 was considered significant. RESULTS: Thirty-nine patients were enrolled, 15 males and 24 females, with an average age of 48.9 ± 16.2 years. Two patients (5.1%) required a contralateral TMJR. Contralateral condylar motion, incisal laterotrusion, and protrusion slightly decreased, while incisal opening (P = .003), rotation angle (P = .013), opening deflection, surface electromyography activity, maximum voluntary clenching (P = .01), PPTs, and OHrQoL all increased. Pre-TMJR mandibular angle resection had an impact on PPTs and subjective outcomes and prior ipsilateral TMJ surgeries on the opening rotation angle. CONCLUSIONS: Based on this study, bilateral TMJR does not appear necessary when the contralateral TMJ is healthy. Unilateral alloplastic TMJR is associated with improved contralateral jaw function and OHrQoL.