The use of pseudo-dynamic magnetic resonance imaging for evaluating the relationship between temporomandibular joint anterior disc displacement and joint pain

The relationship between temporomandibular joint (TMJ) pain and the magnetic resonance imaging (MRI) finding of articular disc displacement is debated. The purpose of this study is to investigate the correlation between TMJ pain and anterior disc displacement (ADD) using pseudo-dynamic MRI. A retrospective review of MRI studies was carried out on 130 TMJs in 65 patients presenting unilateral TMJ pain. The contralateral asymptomatic joints served as the control group. Bilateral oblique sagittal and coronal MRIs as well as pseudo-dynamic studies in the oblique sagittal plane were obtained. The disc–condyle relationship was divided into three subtypes (normal disc position, ADD with reduction, and ADD without reduction), based on the pseudo-dynamic MRI findings. Fisher's exact test was used to determine whether the TMJ pain was linked to ADD. The results showed that TMJ pain was significantly related to ADD (with and without reduction) compared to the group with a normal disc position (P = .0001). A significant correlation was found between TMJ pain and the ADD subtype without reduction, as compared to the ADD subtype with reduction (P = .0156). These data suggest that a displaced disc, particularly in the subtype without reduction, is an important source of pain.     

Groningen temporomandibular total joint prosthesis: An 8-year longitudinal follow-up on function and pain

Total temporomandibular joint replacement is a surgical procedure for patients with severe temporomandibular joint afflictions affecting quality of life, which have not responded beneficially to previous conventional surgery. The aim of this study was to assess the long-term outcome of the Groningen temporomandibular joint (TMJ) prosthesis in patients with chronic pain and mutilated temporomandibular joints following multiple surgical procedures, with respect to prosthesis failure, the patient's postoperative level of satisfaction and longitudinal changes in maximum mouth opening, functional mandibular impairment and pain. Eight female patients were studied in whom Groningen TMJ prostheses were inserted, two unilaterally and six bilaterally.The Groningen TMJ prosthesis was mechanically successful during 8 years of follow-up in seven out of eight patients with a disc dislocation being seen in one patient (7%). Patients were satisfied, despite the limited improvement of the maximum mouth opening, and pain scores.Although the decline of MFIQ scores during 8 years of follow-up was significant compared to baseline (p = 0.027), the effects of the prosthesis on maximum mouth opening, function and pain were limited. This may be due to persistent chronic pain and the adverse effects of multiple previous surgical procedures.     

Effects of four treatment strategies for temporomandibular joint closed lock

A previous randomized controlled trial (RCT) by Schiffman et al. (2007)¹⁵ compared four treatments strategies for temporomandibular joint (TMJ) disc displacement without reduction with limited mouth opening (closed lock). In this parallel group RCT, 106 patients with magnetic resonance imaging (MRI)-confirmed TMJ closed lock were randomized between medical management, non-surgical rehabilitation, arthroscopic surgery, and arthroplasty. Surgical groups also received rehabilitation post-surgically. The current paper reassesses the effectiveness of these four treatment strategies using outcome measures recommended by the International Association of Oral and Maxillofacial Surgeons (IAOMS). Clinical assessments at baseline and at follow-up (3, 6, 12, 18, 24, and 60 months) included intensity and frequency of TMJ pain, mandibular range of motion, TMJ sounds, and impairment of chewing. TMJ MRIs were performed at baseline and 24 months, and TMJ tomograms at baseline, 24 and 60 months. Most IAOMS recommended outcome measures improved significantly over time (P ≤ 0.0003). There was no difference between treatment strategies relative to any treatment outcome at any follow-up (P ≥ 0.16). Patient self-assessment of treatment success correlated with their ability to eat, with pain-free opening ≥35 mm, and with reduced pain intensity. Given no difference between treatment strategies, non-surgical treatment should be employed for TMJ closed lock before considering surgery.     

A prospective,single-centre study on patient outcomes following temporomandibular joint replacement using a custom-made Biomet TMJ prosthesis

This study describes the clinical variables in 61 patients following total alloplastic temporomandibular joint reconstruction (TJR) in which the Biomet Microfixation Patient-Patient-Matched TMJ Implant was used. All patients were classified using the Wilkes classification. The visual analogue scale score for jaw pain intensity, the maximum inter-incisal opening (MIO), and the frequency of adverse events were recorded during follow-up; the mean follow-up was 14.2 ± 8.6 months. Significant improvements were found in the MIO (P < 0.0005), except at the 3-year follow-up. Additionally, a significant reduction in pain was observed both short and long term (P < 0.0005). The incidence of adverse events was low (seven of the 81 alloplastic joints); two joints needed revision. TJR appears to be a relevant treatment option in patients with a broad range of temporomandibular joint disorders in whom none of the joint components are salvageable because of significant disease. Our patients gained an almost normal range of mouth opening and experienced a significant reduction in pain. Our results are promising, however TJR is associated with some side effects. TJR should be considered when less invasive procedures fail and a comprehensive presurgical work-up has been performed. Ongoing prospective studies are needed to consolidate the possible significant treatment outcomes.     

Effectiveness of treatment with viscosupplementation in temporomandibular joints with or without effusion

The objective of this study was to determine whether the effectiveness of viscosupplementation with hyaluronic acid (HA) in patients with temporomandibular joint (TMJ) degenerative disorders depends on the presence of intra-articular effusion. In this study of case–control design, two groups of 25 patients were recruited: patients with a clinical diagnosis of painful chronic TMJ osteoarthritis and magnetic resonance imaging (MRI) signs of TMJ degeneration, with (effusion group) or without (no effusion group) MRI evidence of TMJ effusion. All patients underwent five weekly single-needle arthrocenteses plus medium molecular weight HA and 6 months of follow-up. Several clinical outcome parameters were assessed. For all variables, analysis of variance (ANOVA) for repeated measures was performed to assess the existence of significant within-group and between-group treatment effects. Over time, both groups showed significant improvements in all outcome parameters, which were maintained at the 6-month follow-up (P < 0.05). Between-group comparisons showed that the treatment effects did not differ significantly for either the primary outcome variable (pain levels: F = 0.849, P = 0.548) or secondary outcome variables (chewing efficiency: F = 0.854, P = 0.544; functional limitation: F = 1.35, P = 0.226; mouth opening: F = 0.658, P = 0.707). The null hypothesis that there are no differences in treatment effectiveness between patients with and without effusion could not be rejected.     

Predictive factors in temporomandibular joint arthroscopy: a prospective cohort short-term outcome study

Improving the outcomes of surgical treatment of the temporomandibular joint (TMJ) is beneficial from a patient and health-economy perspective. Optimizing conditions for a successful result can be reached using validated, strict diagnostic criteria and by identifying patient-specific factors predicting the outcome. The aim of this study was to investigate possible predictive factors in TMJ arthroscopy. A prospective cohort study including 93 patients undergoing arthroscopy was conducted. The outcome was graded as successful (53%, n = 49), good (25%, n = 23), intermediate (20%, n = 19), or deteriorated (2%, n = 2) using a predefined set of objective and subjective outcome measures. The outcome was correlated with preoperative and perioperative variables and the diagnosis. Preoperative bilateral masticatory muscle tenderness on palpation was the only variable significantly correlated with a negative outcome in the adjusted regression analysis (odds ratio (OR) 2.56, P = 0.048). Low age (OR 1.03, P = 0.05) and bilateral joint surgery/operated side (OR 0.24, P = 0.05) were found to correlate with an unsuccessful outcome in the unadjusted analysis. Eighty-nine percent of the patients with osteoarthritis benefited from arthroscopy, while corresponding figures were 80% for disc displacement without reduction and 64% for chronic inflammatory arthritis. Preoperative bilateral masticatory tenderness might be a useful predictive factor suggesting the consideration of revised non-invasive therapy before surgery.     

Ultrasonography of the temporomandibular joint: a literature review

This review summarizes knowledge on the accuracy and clinical usefulness of ultrasonography (US) for the diagnosis of temporomandibular joint (TMJ) disorders. A systematic search in the National Library of Medicine's Database was performed to identify all peer-reviewed papers in the English literature that assessed the accuracy of US with respect to magnetic resonance (MR), computerized tomography (CT), clinical assessment or autopsy specimens for the diagnosis of TMJ disk displacement, effusion and osteoarthrosis. The combined search words “ultrasonography” and “temporomandibular joint”, “temporomandibular disorders”, “effusion”, “disk displacement”, “condyle”, yielded 20 papers. Most studies (N = 17) focused on detecting disk displacement, with less emphasis on assessing joint effusion (N = 6) and osteoarthrosis (N = 7). US accuracy was 54–100% for diagnosing disk displacement, 72–95% for joint effusion and 56–93% for osteoarthrosis. US is operator-dependent. Better standardization of the technique is required and normal parameters must be set. Standardization is also required for the taxonomic aspects of pathologies. Despite these limitations, US remains potentially useful as an alternative imaging technique for monitoring TMJ disorders, particularly the presence of intrarticular effusion.     

Neurosensory assessment in patients with total reconstruction of the temporomandibular joint

Somatosensory sensitivity and postoperative endogenous pain modulation have not been investigated in temporomandibular joint (TMJ) prosthesis patients. The objectives of this study were to assess somatosensory function at the TMJ and examine possible differences in conditioned pain modulation (CPM) between patients with total TMJ prostheses (n = 7) and a reference group of healthy controls (n = 20). Somatosensory abnormalities were assessed using quantitative sensory testing (QST), which encompasses thermal and mechanical testing procedures. CPM was tested by comparing pressure pain thresholds (PPT) before (baseline), during, and after the application of painful and non-painful cold stimuli. PPTs were measured at the TMJ and thenar eminence (control). The effect of CPM on PPT values was tested with analysis of variance. Three patients exhibited mixed somatosensory loss (i.e., decreased thermal and mechanical detection) with mixed hyperalgesia (i.e., increased sensitivity to thermal and mechanical pain) and two patients exhibited mixed loss with only mechanical hyperalgesia. There was a significant decrease in pressure pain sensitivity at both sites during painful cold application in healthy controls (P < 0.001) but not in patients (P = 0.476). In conclusion, QST measures demonstrated somatosensory abnormalities in patients with total TMJ prostheses. Noxious conditioning cold stimuli evoked CPM-like effects in healthy subjects but not in patients with TMJ reconstruction.     

Relationships between disk displacement,joint effusion,and degenerative changes of the TMJ in TMD patients based on MRI findings

This study was performed to investigate the relationships between disk displacement, joint effusion, and degenerative changes in patients with temporomandibular disorders using MRI. Randomly selected MRIs of 508 temporomandibular joints of 254 patients (92 males and 162 females, mean age was 30.5 ± 12.0 years) were reviewed retrospectively. Seventy-eight percent (198 out of 254) of the patients complained of joint pain. Compared with joints with a normal disk position, the joints with anterior disk displacement with reduction showed a 2.01 odds ratio (P < 0.01) of degenerative changes and a 2.85 odds ratio (P < 0.001) of joint effusions. The joints with anterior disk displacement without reduction showed a 4.43 odds ratio (P < 0.001) of degenerative changes and a 4.61 odds ratio (P < 0.001) of joint effusions. These results clearly show that the risk of degenerative changes and joint effusions increase with displacement of the disk position in patients with temporomandibular disorders. Although all disk displacement situations do not progress to painful joints and/or degenerative joint diseases, the possibility of an increased risk of progression by a breakdown in the balance between a patient’s adaptive capacity and functional loading of the TMJ should be assessed in each and every patient through comprehensive evaluation of various contributing factors.     

The relationship between temporomandibular joint effusion and pain in patients with internal derangement

ObjectivesThe purpose of this study was to evaluate the relationship between temporomandibular joint (TMJ) effusion and joint pain in patients with internal derangement based on the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD).MethodsA total of 240 TMJs from 120 patients with unilateral painful joints (103 females and 17 males, mean age 29.9 ± 12 years) were evaluated. Clinical assessments were carried out according to the DC/TMD guidelines. Magnetic resonance imaging (MRI) was used to evaluate the degree of effusion in each joint. The radiological and clinical findings were analysed for statistically significant correlations.ResultsAlthough the results indicated a statistically significant association between moderate joint effusion and disc displacement (p < 0,05), there was no statistically significant association between moderate effusion and joint pain (p > 0,05). There were, however, statistically significant associations between marked effusion and both disc displacement and joint pain (p < 0,05).ConclusionTMJ effusion is associated with both disc displacement and joint pain: the effusion increased in direct proportion to the severity of pain and disc displacement. The possibility that there are various aetiologies for the condition should also be considered.     

Comparison of the outcomes of three surgical treatments for end-stage temporomandibular joint disease

The aim of this study was to determine whether there are any differences between condylectomy, rib grafts, and prosthetic joints (Biomet TMJ stock prosthesis) with regard to outcomes for patients with end-stage temporomandibular joint (TMJ) disease. Fifty-six of a total 127 patients who presented with category 5 end-stage TMJ disease over 3 years (2010–2013) agreed to participate in this retrospective, comparative, cohort study. Patients were divided into four groups: preoperative (n = 16), condylectomy (n = 8), rib graft (n = 16), and prosthetic joint (n = 16). They were assessed for major postoperative complications (i.e., return to theatre) and maximum range of mandibular motion, and all completed a specific quality of life (QOL) questionnaire. Whilst the condylectomy group demonstrated the best mandibular range of motion (P < 0.01), rib graft patients were more likely to experience complications (43.8%) necessitating a return to theatre. The prosthesis group recorded the best mean aggregate QOL score, but the difference compared to the rib graft and condylectomy groups was not statistically significant. The results of this study suggest that for dentate patients, prosthetic joints are highly dependable with no returns to theatre and favourable QOL outcomes. For edentulous patients, condylectomies alone also appear to work well. Future TMJ prosthetic designs should focus on improving mandibular range of motion, as the current stock prosthesis allows only a restricted range, no better than that achieved with rib graft (P > 0.05) and far less than that achieved with condylectomy (P < 0.01).     

Transformation of temporomandibular joint disc configuration in internal derangement patients using magnetic resonance imaging

PurposeThe normal disc configuration is biconcave; however, the deformed disc can be found in internal derangement (ID) of the temporomandibular joint (TMJ). The purpose of this study was to evaluate the relationship between the transformation patterns of TMJ disc configuration during mouth opening and disc displacement status, disc reduction ability and TMJ clinical symptoms.MethodsTMJ MR images from volunteers and ID patients were analyzed for closed and open mouth positions. MR images of ID patients were classified into 4 groups: symptomatic joint with anterior disc displacement with or without reduction (ADW or ADWo) and asymptomatic joint with ADW or ADWo. The disc configurations in both positions were categorized as biconcave, biplanar, convex or folded; then the patterns of transformation were observed.ResultsFor the ADW group, the most common disc configuration for closed and open mouth positions were biplanar (66.7%) and biconcave (86.3%). The transformation pattern was significantly related to disc reduction ability (p < 0.05).ConclusionsThe transformation patterns of disc configuration during opening were related to anterior disc displacement and disc reduction ability.     

Irrigation fluid volume requirement for conventional arthrocentesis of the temporomandibular joint: a cadaver study

Temporomandibular joint (TMJ) arthrocentesis is considered an effective and minimally invasive procedure for certain conditions related to temporomandibular disorders. The ideal irrigation volume for arthrocentesis lavage has not yet been defined. Therefore, the aim of this study was to evaluate the efficacy of different saline solution volumes in removing methylene blue from the TMJ space of fresh human cadavers. Nineteen cadavers were selected and 1 ml of 10 μM methylene blue solution was injected into the upper joint space unilaterally. Conventional arthrocentesis was then conducted by infusion of 300 ml of 0.9% saline solution, collecting a 1-ml sample from the drained quantity for every 25 ml injected. Finally, the samples were assayed by measuring photo absorbance of the methylene blue solution. There was a statistically significant difference between the irrigation volumes regarding the removal of methylene blue solution from the joint space (P < 0.001), specifically between the first 25 ml and 200 ml (P = 0.014), 225 ml (P = 0.001), 250 ml (P < 0.001), and 275 ml (P = 0.001). Based on this ex vivo study, a 25-ml perfusion volume appears to be sufficient for joint lavage in conventional arthrocentesis of the TMJ.     

Association between hypoplastic condyles and temporomandibular joint disc displacements: a cone beam computed tomography and magnetic resonance imaging metrical analysis

This study investigated the association between hypoplastic condyles and disc displacements without reduction (DDw/oR). Consecutive patients with non-syndromic unilateral condylar hypoplasia were recruited and clinical, cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI) data were acquired. Linear measurements including condylar head width, depth, height and condyle length were determined with CBCT while MRI was used to assess disc position, morphology and displacement. A total of 43 patients were enrolled of which 93.02% had a history of temporomandibular disorders (TMDs) and 83.72% presented with TMD signs and symptoms. Depth and height of the condylar head along with condyle length of hypoplastic joints (6.68 ± 1.67 mm, 4.97 ± 1.25 mm and 14.49 ± 3.02 mm, respectively) were significantly lesser than normal joints (7.77 ± 1.26 mm, 6.35 ± 1.45 mm and 18.20 ± 3.18 mm) (P < 0.001). The prevalence of DDw/oR was significantly higher in hypoplastic joints (79.07% versus 13.95%) (P < 0.001). Joints with hypoplastic condyles had shorter disc lengths (6.99 ± 2.16 mm vs, 8.45 ± 2.26 mm) (P = 0.007). Furthermore, disc displacements were significantly more advanced (8.52 ± 2.84 mm) and severe (76.74% with severe translations) when compared to the contralateral side (4.77 ± 2.97 mm and 32.56%) (P < 0.05). A significant association was observed between condylar hypoplasia and temporomandibular joint DDw/oR with hypoplastic joints exhibiting more severely displaced and deformed discs. DDw/oR coupled with repaired degenerative joint disease may mimic condylar hypoplasia radiographically.     

Changes in condylar and joint disc positions after bilateral sagittal split ramus osteotomy for correction of mandibular prognathism

The effect of combined orthodontic and orthognathic treatment was studied retrospectively in 24 patients with skeletal class III malocclusions with mandibular hyperplasia, particularly the effect on temporomandibular joint (TMJ) disc position. The patients underwent preoperative orthodontic treatment, orthognathic surgery, and postoperative orthodontic treatment. The patients were studied clinically, radiographically with lateral cephalometric radiograph and MRI to locate the position of the TMJ disc in relation to the glenoid fossa. One patient had less pain after treatment, one lost abnormal joint clicking sounds after treatment. There were no TMJ symptoms in 20 of the 24 preoperatively and postoperatively. 48 sagittal MRI images showed that the disc length before treatment was 3.040–12.928 (mean 8.289 ± 2.028) and after treatment was 3.699–11.589 (mean 8.097 ± 1.966); results were not significant (p > 0.05). Maximum disc displacement before treatment was 6.090 (mean 1.383), after treatment it was 11.931 (mean 2.193); results were not significant (p > 0.05). The results suggest that combined orthodontic and orthognathic treatment (including bilateral SSRO and rigid internal fixation) can be used safely to correct skeletal class III malocclusion with mandibular hyperplasia without causing additional TMJ symptoms.     

Magnetic resonance imaging predictors of temporomandibular joint pain

BACKGROUND: The authors conducted a study to evaluate whether temporomandibular joint, or TMJ, disorder subgroups are related to magnetic resonance imaging, or MRI, diagnoses of TMJ internal derangement, or ID; osteoarthrosis, or OA; effusion; and bone marrow edema. METHODS: The TMJ disorder group was composed of 118 subjects with TMJ pain who were assigned a clinical unilateral single diagnosis of a specific TMJ disorder. The control group consisted of 46 subjects who did not have TMJ pain. Sagittal and coronal magnetic resonance images were obtained to establish the prevalence of ID, OA, effusion and bone marrow edema. The authors used a multiple logistic regression analysis to compute the odds ratios, or OR, for MRI features for control subjects versus four groups of subjects who had TMJ pain: ID type I (n = 35), ID type III (n = 39), capsulitis/synovitis (n = 26) and degenerative joint disease, or DJD, (n = 18). RESULTS: MRI diagnoses that did not contribute to the risk of TMJ pain included disk displacement, or DD, with reduction and effusion. Significant increases in the risk of experiencing TMJ pain occurred selectively with DD without reduction (OR = 10.2:1; P = .007) and bone marrow edema (OR = 15.6:1, P = .003) for the ID type III group and with DD without reduction (OR = 11.7:1, P = .054) for the DJD group. Subjects in the group with ID type I were less likely to be associated with an MRI finding of OA than were control subjects (OR = 1:5.6). CONCLUSIONS: While the contribution of MRI variables to the TMJ pain subgroups was not zero, most of the variation in each TMJ pain population was not explained by MRI parameters. Thus, MRI diagnoses may not be considered the unique or dominant factor in defining TMJ disorder populations. CLINICAL IMPLICATIONS: Therapy for subjects with TMJ based on the evaluation of concomitant morphological abnormalities, whether prophylactically or as treatment for TMJ disorders, may be unwarranted.     

Quantitative bone imaging biomarkers to diagnose temporomandibular joint osteoarthritis

Bone degradation of the condylar surface is seen in temporomandibular joint osteoarthritis (TMJ OA); however, the initial changes occur in the subchondral bone. This cross-sectional study was performed to evaluate 23 subchondral bone imaging biomarkers for TMJ OA. The sample consisted of high-resolution cone beam computed tomography scans of 84 subjects, divided into two groups: TMJ OA (45 patients with TMJ OA) and control (39 asymptomatic subjects). Six regions of each mandibular condyle scan were extracted for computation of five bone morphometric and 18 grey-level texture-based variables. The groups were compared using the Mann–Whitney U-test, and the receiver operating characteristics (ROC) curve was determined for each variable that showed a statically significance difference. The results showed statistically significant differences in the subchondral bone microstructure in the lateral and central condylar regions between the control and TMJ OA groups (P <  0.05). The area under the ROC curve (AUC) for these variables was between 0.620 and 0.710. In conclusion, 13 imaging bone biomarkers presented an acceptable diagnostic performance for the diagnosis of TMJ OA, indicating that the texture and geometry of the subchondral bone microarchitecture may be useful for quantitative grading of the disease.     

Surgical complications related to temporomandibular joint arthroscopy: a prospective analysis of 39 single-portal versus 43 double-portal procedures

Temporomandibular joint (TMJ) arthroscopy is a minimally invasive surgical procedure proposed for diverse TMJ intra-articular disorders. A prospective study was designed with the aim of investigating intraoperative and postoperative surgical complications for single and double-portal TMJ arthroscopy. All interventions were performed by one surgeon with the same surgical protocol. A total of 55 patients were enrolled, resulting in 82 TMJ arthroscopies (28 unilateral and 27 bilateral). A total of 39 single portal (47.57%) and 43 double-portal (52.43%) arthroscopies were performed. No severe and irreversible complications were observed. Most complications were resolved after 4 weeks. Double-portal was associated with more complications (n = 23) compared with single-portal TMJ arthroscopy (n = 14), with a statistically significant difference found between single and double-portal TMJ arthroscopy in two intraoperative complications: intra-articular bleeding (P = 0.044) and oedema of the preauricular area (P = 0.042). This study confirms the safety of TMJ arthroscopy for single and double-portal procedures, with the authors suggesting a multicentre study, in an effort to minimize any possible bias.     

Endoscopically assisted fixation of the custom-made total temporomandibular joint prosthesis in TMJ Yang’s system through a modified preauricular approach

This article describes the experience with the endoscopically assisted fixation of the customized total temporomandibular joint (TMJ) prosthesis in TMJ Yang’s system only through a modified preauricular approach. Twenty patients (23 joints) treated with the custom-made total TMJ prosthesis were retrospectively recruited. An endoscopically assisted technique was used through a modified preauricular approach to fix the mandibular component for all these patients. These reconstructions were evaluated by surgical records, clinical examinations, and radiographic observations. All patients had successful fixation of the prosthesis. No patient had permanent weakness of the facial nerve and malocclusion or any other severe complications. The mean operative time was 111 min per joint (range, 85–133 min). The average surgical bleeding was 195 ml per side. The mean follow-up period was 16.2 months (range, 5–32 months). The mean scores were 8.3 for surgical satisfaction and 9.2 for scar healing evaluation. All patients experienced positive clinical outcomes, with a mean 75.2% reduction in pain and 53.7% increase in mouth opening with significant differences (P < 0.05). The endoscopically assisted TMJ reconstruction with the customized prosthesis in TMJ Yang’s system through the modified preauricular approach could produce good aesthetic and functional results.     

Prospective study of five-year outcomes and postoperative complications after total temporomandibular joint replacement with two stock prosthetic systems

To evaluate and compare outcomes and complications associated with reconstruction of the temporomandibular joint (TMJ), we prospectively analysed the data of 70 patients who had their joints replaced with stock prostheses during the period 2004-14 and who had been followed up for five years. We used two types of stock prostheses: the metal-on-metal Christensen system (CS), and the ultra-high-molecular-weight-polyethylene-on-metal Biomet® system (BS). Data were collected at 3, 6, 12, 24, 36, 48, and 60 months postoperatively and compared with preoperative measurements. Five years after the replacement there was an increase in mean (SD) mouth opening from 2.0 (0.6) to 4.0 (0.5 cm) (p = 0.012) in the CS, and from 2.5 (1.0) cm to 4.1 (0.6) cm (p = 0.018) in the BS. The mean (SD) reductions in visual analogue pain scores were from 6.9 (1.6) to 2.0 (1.4) (p = 0.001) in the CS, and 6.5 (1.4) to 1.5 (1.1) (p = 0.001) in the BS. There were no significant differences in improvements in mouth opening or reduction in pain between the two groups. However, there were differences in the number of implants that failed, which led to removal and replacement of 2/14 prostheses in the CS group and 3/77 in the BS group (p = 0.06). The results supported the placement of stock prostheses, as evidenced by a low incidence of complications and adverse events, and a long-term improvement in function and reduction in pain in the TMJ. The BS group had significantly fewer prosthetic failures than the CS group.