Morphological and biochemical evidence for elastic fibres in the Syrian hamster temporomandibular joint disc

Elastic fibres are considered to be important for the normal biomechanical functions of the TMJ. The objective here was to correlate morphological evidence for the presence of elastic fibres in discal tissues with biochemical evidence for elastin. For light microscopy, the joints were removed en bloc, processed for paraffin embedding, sectioned and stained with resorcin-fuchsin. For biochemical study, a radioimmunoassay for desmosine was used to estimate the amount of elastin in excised articular discs. The histological preparations showed that numerous elastic fibres were present in various areas of the disc and in some of the discal attachments to surrounding bone. Radioimmunoassay also indicated that elastin was present in these tissues. Therefore, the biochemical findings support the morphological in suggesting that elastic fibres are present in the articular disc of the hamster TMJ.     

ADAMTS‐4 and ADAMTS‐5 expression in human temporomandibular joint discs with internal derangement,correlates with degeneration

Temporomandibular joint (TMJ) internal derangement (ID) is one of the most common form of temporomandibular disorders. There is evidence showing the increased expression of matrix metalloproteinases (MMPs) in the cells from degenerated TMJ disc. ADAMTS are a large family of metalloproteases which are responsible for proteoglycans degradation. The present study aimed to evaluate ADAMTS‐4 and ADAMTS‐5 immunohistochemical expression in human TMJ discs from patients affected by ID, and to find out if there is any correlation with the degree of histopathological changes. Eighteen temporomandibular displaced disc specimens and sixteen TMJ disc control were used for the present study. Specimens were immunohistochemically processed and ADAMTS‐4 and ADAMTS‐5 expression were obtained respectively for the anterior (AB), intermediate (IB) and posterior (PB) bands and compared to the histopathological degeneration score (HDS). Immunoreactivity for ADAMTS‐4 and ‐5, was observed in both not degenerated and degenerated human TMJ discs. Both the percentage of ADAMTS‐4 and ‐5 immunostained cells (ES) and the intensity of staining (IS) were significantly greater in affected specimens compared with those in control discs. The ADAMTS‐5 ES and IS of the 3 bands of the disc correlated to the TMJ disc HDS (0.001 < P < 0.05), on the other hand only AB and IB, ADAMTS‐4 immunostaining scores correlated to HDS. According to these findings it can be assumed in that the more histopathological changes in the disc are detected, the higher levels of ADAMTS are produced. This in turn can lead to ECM breakdown and in turn to a more advanced disc displacement.     

改良切口关节盘锚固术治疗颞下颌关节盘不可复性前移位的临床评价

目的: 评价应用改良切口关节盘锚固术治疗颞下颌关节盘不可复性前移位的临床疗效。方法: 选取2014年9月—2016年9月我院颞下颌关节专科就诊的24例（30侧）颞下颌关节紊乱病患者,采用改良切口颞下颌关节盘锚固术进行治疗, 分析术前、术后6个月不同时期患者的疼痛值、开口度的变化及MRI影像学表现,采用SPSS17.0软件包中的t检验评价手术效果。结果: 治疗前平均开口度为（23.63±3.31）mm(17~29 mm),治疗后平均开口度为（38.00±2.30）mm(32~42 mm),治疗后开口度≥35 mm 的患者占 87.5%（21/24）;疼痛直观模拟标尺（visual analogue scale,VAS）值术前为29.76±23.35（0~80）,术后6个月为3.71±7.91（0~50）,术后6个月的开口度及VAS值均与治疗前有显著差异（P<0.05）。MRI影像学评价有效率达96.67%（29/30侧）,所有病例均无并发症发生。结论: 颞下颌关节盘锚固术能有效治疗颞下颌关节盘不可复性前移位,在复位关节盘的前提下,显著改善开口度和缓解疼痛。     

Microscopic changes in the condyle and disc in response to distraction osteogenesis of the minipig mandible.

PURPOSE: Unilateral mandibular distraction osteogenesis (DO) has been shown to cause gross changes in the mandibular condyle and articular disc. The purpose of this study was to correlate histologic findings with these gross changes in a minipig distraction model. MATERIALS AND METHODS: Semiburied distractors were placed via submandibular incisions in 15 minipigs. Two unoperated animals served as controls. The protocol consisted of 0-day latency and rates of 1, 2, or 4 mm/day for a 12-mm gap. After the minipigs were killed (at 0, 24, or 90 days), ipsilateral and contralateral condyles and discs were harvested, decalcified, prepared for standard paraffin embedding, and evaluated to determine changes in 1) morphology and thickness of the articular cartilage and subchondral bone and 2) morphology of the disc. RESULTS: In control animals, there were no degenerative changes in the articular cartilage and underlying condylar bone; there were no significant differences in the mean articular cartilage thickness. The temporomandibular joint discs were normal. In experimental animals, distracted condyles showed increasing degenerative changes and mean articular cartilage thickness as the DO rate increased. The discs were thinner. These changes were present, but to a lesser degree, in the contralateral condyles. After 90 days, degenerative changes in the condyles and discs were reduced, after remodeling, except in the 4 mm/day DO group. CONCLUSIONS: Histologic changes in the condyles and temporomandibular joint discs in response to mandibular DO correlated with previously reported gross changes. These changes were greater at higher distraction rates and remodeling back to normal occurred in mandibular condyles distracted at 1 mm/day.     

关节盘穿孔对兔颞下颌关节影响的扫描电镜观察

目的研究兔关节盘穿孔后对颞下颌关节（TMJ）髁状突和关节盘表面超微结构的影响。方法12只3～4月龄的新西兰白兔,随机均分为实验组和对照组。以质量分数为50mg/ml的氯胺酮溶液按1ml/kg对实验动物进行肌注麻醉,对照组于无菌条件下先后暴露左右侧关节盘,实验组并以特制的穿刺针于关节盘后外侧部制作直径为2.6mm的穿孔。分别于术后12、24和36周完整取出双侧TMJ,扫描电镜观察关节盘和髁状突的变化。结果扫描电镜下可见关节盘穿孔后关节表面凝胶状物质不完整,关节盘及髁状突表面均出现明显的退行性改变：凝胶样物质掀起、剥脱,胶原纤维疏松、暴露、断裂、排列紊乱。结论关节盘穿孔可以引起TMJ表面退性行改变。     

Biomechanical and biochemical outcomes of porcine temporomandibular joint disc deformation

ObjectiveThe structure–function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs.DesignSurface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥Wilkes Stage 3) and morphologically normal (≤Wilkes Stage 2) TMJ discs.ResultsCompared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface.ConclusionsThe frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering.     

Morphometric investigation of condylar cartilage and disc thickness in the human temporomandibular joint: significance for the definition of ostearthrotic changes

106 human TMJ specimens from 53 individuals (age: 65–85 years) were examined macro- and microscopically and measured for discal and condylar cartilage thickness at five points defined on a mediolateral axis along the middle dense pan of the disc. 27% of the discs showed lateral and laterocentral perforations. In 8% the lateral portion was thinned down to a translucent layer. 62% showed no gross destruction or deviation in shape and thickness. The remaining 3% displayed extensive destruction and their condyles were osteoarthrotic. All discs showed a significant decrease in thickness from their medial towards their lateral portions. The condyles displayed either a smooth articular surface (16%) or an irregular and progressively remodelled surface (81%) with histologically normal fibrocartilage. The condylar cartilage did not show a significant gradient of thickness in amediolateral direction. The results support our previously developed working hypothesis, that the joint is seemingly loaded along its entire articular surface and that a lateral disc perforation in older individuals can be due to a physiological process of wearing rather than to a pathological sequel of functional disorders.     

Surgical induction of TMJ bony ankylosis in growing sheep and the role of injury severity of the glenoid fossa on the development of bony ankylosis

ObjectiveThe purpose of this paper is to summarize our experiences in creating an animal model of TMJ bony ankylosis based on 2 sequential experiments.MethodsTwo sequential experiments were performed with the aim of creating a model of TMJ bony ankylosis. Seven growing sheep were used in the first experiment, in which 1 was served as a control animal. Condylar fracture with disc preservation was performed on the control side. On the contralateral side, condylar fracture, excision of the lateral 2/3 disc and injury to the glenoid fossa were performed to induce bony ankylosis. Three animals were sacrificed respectively at 3 and 6 months after surgery. In the second experiment, 7 growing sheep were used. The only difference of modeling between the 2 experiments was that more serious injury to the glenoid fossa was made in the ankylosis-induced side in experiment 2. Three, 2, and 2 animals were sacrificed respectively at 1, 3, and 6 months postoperatively. The TMJ complexes were examined by computed tomography (CT) and histological evaluation.ResultsIn experiment 1, only fibrous ankylosis was observed in the ankylosis-induced side both at 3 and 6 months postoperatively. In experiment 2, CT and histological evaluation showed that the outcomes of the ankylosis-induced side were fibrous-bony ankylosis, fibrous-bony ankylosis, and bony ankylosis respectively at 1, 3, and 6 months after surgery.ConclusionThrough summarizing the differences of the modeling and the different outcomes in the 2 experiments, we concluded that severe damage to the glenoid fossa played an important role in the development of TMJ bony ankylosis.     

Arthroscopic surgery for treatment of anterior displacement of the disc without reduction of the temporomandibular joint

The aim of this study was to investigate the clinical results and efficacy of an arthroscopic approach to correct anterior displacement of the disc without reduction of the temporomandibular joint (TMJ) with limitation of mouth opening. We studied 28 joints with internal derangement in 23 patients, all of whom had had arthroscopic surgery (lavage, lysis of adhesions in the superior compartment, incision parallel to the disc-synovial crease of the upper joint compartment, and pull back of the anteriorly located disc). Objective and subjective data (increase in maximal interincisal opening, magnetic resonance imaging, and visual analogue pain score, VAS) were collected preoperatively and at 7, 30, 60 days, and 6 months or more postoperatively. Maximal interincisal opening improved from a mean (SD) of 20.4 (±4.5) mm preoperative measurement to 38.9 (±3.2) mm by 6 months postoperatively where indicated in previous line. The VAS showed a significant improvement in pain score (p=0.0023). Sixty days postoperatively the positions of the discs in 14 of the TMJs had improved considerably. In 13 of the TMJs the positions had improved slightly. Only 1 of the TMJs had not improved at all. There were no complications in any patient. Our arthroscopic procedure is safe, minimally invasive, and effective for the treatment of patients with displacement of the disc anteriorly without reduction of the TMJ.     

The effect of arthroscopic disc repositioning on facial growth in juvenile patients with unilateral anterior disc displacement

ObjectiveTo investigate the effect of arthroscopic disc repositioning on condylar development and mandibular asymmetry in juvenile patients with unilateral temporomandibular joint (TMJ) anterior disc displacement (ADD).Patients and methodsA retrospective cohort study was conducted on unilateral juvenile anterior disc displacement (UJADD) patients of 10–20 years of age treated in Shanghai Ninth People's Hospital from 2010 to 2017. The primary predictor was TMJ arthroscopic disc repositioning surgery, according to which patients were divided into a surgery group and a control group. Initial and re-examined (with at least 6-month interval) magnetic resonance imaging (MRI) and posteroanterior cephalometric radiographs (PA) were collected. The condylar heights on both sides of the TMJ were measured by MRI and the difference between them was calculated. Menton (Me) deviation was measured based on PA. Changes in condylar height difference and Me deviation were compared between the two groups.ResultsA total of 108 UJADD patients were collected in this study, including 55 patients in the surgery group and 53 patients in the control group. There were no significant differences in age, sex and follow-up time between the two groups. The condylar height difference was (−0.61 ± 2.02) mm in surgery group and (1.68 ± 1.73) mm in control group (P < 0.0001); while the Me deviation was (−1.00 ± 1.15) mm in surgery group and (1.81 ± 1.96) mm in control group (P < 0.0001), indicating that TMJ arthroscopic disc repositioning surgery could significantly improve condylar height difference and Me deviation.ConclusionsUJADD should be treated as early as possible, especially in juvenile patients, in order to improve condylar development and avoid jaw deformities.     

Closed lock (MRI fixed disc): a comparison of arthrocentesis and arthroscopy

Twenty-six patients with a sudden-onset of persistent limited mouth opening and with MRI signs of articular discs fixed to the glenoid fossa were studied. After unsuccessful non-surgical treatment, arthroscopy with sodium hyaluronate infusion was performed in 16 joints. Follow-up ranged from 24 to 60 months (mean: 30.3 months). All patients were clinically assessed preoperatively, and at 1, 3, 6, 9, 12, 18 and 24 months postoperatively. The clinical variables analysed were: joint pain using a visual analogue scale (VAS) (1-15), joint noises (clicking, crepitus or none), history of locking, duration of the symptoms, maximal interincisal opening (MIO), maximal protrusive movement (MP) and maximal contra-lateral movement (ML). MRI images were obtained preoperatively to analyse the morphological and dynamic characteristics of the temporomandibular joint. Eight of the patients who refused to undergo arthroscopy were treated with arthrocentesis. These patients were studied following the same criteria as stated above. Mean age of the group was 24.3 years (16-35 years). 20 patients were female and 6 male. The preop-MRI examination revealed a normal disc position in 16 joints and an anteriorly displaced disc in 10 cases. All of the discs were fixed to the glenoid fossa preventing an anterior translation of the condylar head. After non-surgical treatment only two patients improved while all the other patients showed a severe decrease in the MIO (mean 23.3 +/- 2.2 mm), LM (3.8 +/- 1.4) and a high pain level (9.7 scale). Sixteen patients underwent arthroscopy. A significant reduction in pain was noted after arthroscopy. Furthermore, a significant increase in MMO and LM was demonstrated postoperatively. Arthroscopic findings included the presence of adherences and synovitis. Eight patients who refused arthroscopy were treated with TMJ arthrocentesis. All such patients improved their symptoms postoperatively. In conclusion both TMJ arthroscopy and arthrocentesis give good results upon treating patients with anchored disc phenomenon (ADP).     

Changes in the condyle and disc in response to distraction osteogenesis of the minipig mandible.

PURPOSE: Distraction osteogenesis (DO) is a commonly used technique for mandibular lengthening, but changes in the temporomandibular joint have not been well documented. The purpose of this study was to evaluate the effect of DO, at varying rates, on the mandibular condyle and articular disc. MATERIALS AND METHODS: Semiburied distractors were placed via submandibular incisions in 15 minipigs. Two unoperated animals served as controls. The protocol consisted of 0 day latency and rates of 1, 2, or 4 mm/d for a 12-mm gap. After the animals were killed (0, 24, or 90 days), ipsilateral and contralateral condyles and discs were harvested and evaluated to determine changes in 1) condylar form and size, 2) condylar surface, and 3) the articular disc. RESULTS: Articular surfaces of the condyles in control animals were smooth, with no irregularities or erosions. In animals undergoing distraction, ipsilateral condyles showed increasing changes in morphology and AP dimension, and surface contour irregularities as the DO rate increased. These changes were present, but to a lesser degree, in the contralateral condyles. Articular discs of both ipsilateral and contralateral sides showed variable thinning at the medial aspect at end DO. After 90 days, changes in the condyles and discs were reduced by remodeling except in the 4 mm/d DO groups. CONCLUSIONS: Results of this preliminary study indicate that gross changes occur in condyles and discs after unilateral mandibular DO. These changes are more severe at faster distraction rates (4 mm/d) and tend to resolve during neutral fixation when a rate of 1 mm/d is used.     

Surgical repair of defects in the rabbit temporomandibular joint disc: a comparison of various techniques

A study was designed to evaluate the effects of different types of repair (suture vs. graft), donor graft tissues (dermis vs. fascia), and methods of graft fixation (sutured vs. laser-assisted) on excisional defects of the rabbit TMJ disc made anterior to the retrodiscal tissue. Groups created to compare the different variables were assessed at 30 and 90 days postoperatively by macroscopic and histologic methods, microangiography, and mechanical strength testing. Without repair, all excisional defects of the disc failed to heal. Suturing of the reapproximated margins did not appear to promote healing or provide much strength beyond the properties of the suture material. Dermal grafts, fixed by suturing, induced healing by becoming incorporated into the disc, restoring discal continuity, and approximating normal disc strength. The use of laser-assisted tissue welding for dermal graft fixation was found to be inadequate and was subsequently abandoned. Fascial grafts could be fixed into position by both suture and laser-assistance, but consistently failed to exhibit successful transplantation and promote healing at the disc site.     

改良耳屏切口颞下颌关节盘复位固定术手术入路介绍及效果评价

目的: 介绍一种改良耳屏切口颞下颌关节盘复位固定术术式并初步评价其临床效果。方法: 选取符合条件的颞下颌关节盘不可复性前移位患者6例（7侧关节）,依据Wilkes-Bronstein分期,纳入IV~V期患者,采用改良耳屏切口行颞下颌关节盘复位固定术。结果: 术中术区视野显露充分,术后MRI显示全部7侧关节盘复位良好,面神经功能保存良好。结论: 经改良耳屏切口行颞下颌关节盘复位固定术,术中暴露关节区充分,术后短期疗效可靠,且具有切口美观,手术创伤小,面神经受损程度轻等优点。可作为颞下颌关节手术的入路之一。     

Apoptosis in displaced temporomandibular joint disc with and without reduction: an immunohistochemical study

J Oral Pathol Med (2011) 40 : 103–110 Internal derangement (ID) of the temporomandibular joint (TMJ) is due to an abnormal relationship of the articular disc to the mandibular condyle, glenoid fossa and articular eminence. The two most common types of internal derangement are anterior disc displacement with (ADDwR) and without reduction (ADDwoR). Disc displacement is associated with degenerative tissue changes. The histological features of discs from patients with TMJ ID reflect a general remodelling caused by abnormal loading. A correlation has been demonstrated between TMJ ID and apoptosis. Few investigations have addressed the role of apoptosis or caspase activity in TMJ ID. The apoptosis activation process was studied in different areas of discs from 18 patients with ID (both ADDwR and ADDwoR) and four cadavers (controls), with emphasis on the expression of caspase 3, whose activation makes the death process irreversible. The results showed a greater proportion of caspase 3‐positive cells in ADDwR and ADDwoR than in control discs. Immunopositivity also varied between disc areas; in particular, in ADDwoR sections labelled cells were significantly more numerous (P < 0.01) in the posterior disc attachment than in the anterior and intermediate bands. In addition, a significantly greater proportion of labelled cells was seen in the anterior (+) and intermediate (++) band of ADDwR compared with ADDwoR discs both bands (P < 0.05). These data suggest the importance of programmed cell death in the progression of TMJ ID.     

Effects of soft tissue injury to the temporomandibular joint: report of 8 cases

Our aim was to describe the effects of soft tissue injury to the temporomandibular joint (TMJ), to analyse possible reasons for it, and to evaluate the results of treatment. Eight patients (12 joints) who developed disorders of the TMJ after trauma to the mandible without fracture of the condyle were treated in our department from 2009 to 2010. Magnetic resonance imaging (MRI) and computed tomography (CT) were used to check the condition of the joint. Five patients had their joints explored to relieve pain and improve mouth opening. MRI showed all 12 joints had displaced discs. CT showed that the surface of the condylar bone was “intact” immediately after injury but destroyed later in 8 joints. Exploration showed fibrous ankylosis in 5, osteoarthritis with intra-articular adhesions in 2, and internal derangement in 1. Four were treated by costochondral graft (CCG) with 7 symptomatic joints. The disc was repositioned in 1 case with 1 affected joint. The mean maximal incision opening at follow-up were significantly better than the one before treatment (mean 34 compared with 23 mm, p = 0.02). Pain in the TMJ was relieved by operation in all patients so treated. The other 3 patients (4 joints) had no treatment because their symptoms were minor and mouth opening was not restricted. Soft tissue injuries of the TMJ can potentially lead to internal derangement, osteoarthrosis, and possibly fibrous ankylosis, which should be considered during follow-up. Displacement of the disc and damage to the condylar cartilage seem to be the causes of these complications. Surgical management is effective in the short term.     

颞颌关节关节盘再造的研究

目的：用组织工程方法进行颞颌关节关节盘的再造。方法：用Ⅱ型胶原酶消化法收集兔耳廓软骨细胞，将细胞按5×10^7／ml的终浓度接种于纤维蛋白原中，固化成为膜片状后，将负载软骨细胞的纤维蛋白植入裸鼠背部皮下组织中，2个月后取材，通过大体标本观察、组织学观察颞颌关节关节盘的构建情况。结果：植入术后2个月，在裸鼠背部形成了膜片状的组织，为亮白色，具有一定的弹性和韧性；组织学检查见新形成的组织由软骨构成，纤维蛋白己完全吸收。结论：纤维蛋白负载软骨细胞，可以有效进行颞颌关节关节盘的再造。     

Suprafoveal condylar arthroplasty in unilateral disc displacement without reduction – A retrospective study

The aim of this study was to evaluate the efficacy of suprafoveal condylar arthroplasty (SFCA) in the management of patients with unilateral temporomandibular joint (TMJ) disc displacement without reduction (DDWoR). A retrospective study comprising patients who underwent unilateral SFCA for clinically and radiologically confirmed unilateral DDWoR from 2008 to 2020 was conducted. Patients older than 18 years at the time of diagnosis with a minimum of 6 months of unsuccessful non-surgical and minimally invasive management (including diet and life style modification, physiotherapy, appliance therapy, pharmacotherapy, arthrocentesis and arthroscopic lysis and lavage) before undergoing surgery with a minimum of 1 year follow-up post-surgery were included in the study. Patients with other articular and extra-articular causes of restricted mouth opening, prior history of mandibular surgery and/or trauma, growth abnormalities, systemic, metabolic, infective, neoplastic conditions affecting TMJ, including gross occlusal disharmony, untreated existing para-functional habits and bilateral DDWoR, were excluded from the study. Patients were assessed in terms pain on a visual analog scale (VAS), interincisal mouth opening (MO) and subjective assessment of mandibular range of movements including deviation of mouth opening, protrusion and ability for contralateral laterotrusion. 23 patients (10 males and 13 female) were included in the study, with a mean age of 35.09 years and mean follow up period of 37.7 months (range = 12–58; SD = 15.3). The mean pain scores on the VAS reduced from 6.35 preoperatively to 1.13 postoperatively and were found to be statistically significant (p < 0.0001). The improvement of the mean pre-operative mouth opening of 21.83 mm to a mean post-operative mouth opening of 42.09 mm was also found to be statistically significant (p < 0.0001). The subjective improvement in protrusive (p = 0.0003), laterotrusive (p = 0.0005) and opening movements (p = 0.0001) after 1 year were also found to be statistically significant. No patient developed any significant changes in occlusion post-operatively. Four of 23 (17.3%) patients developed transient neuromotor deficit of the temporal branch of the facial nerve. Within the limitations of the study, it seems that SFCA (without addressing the disc) might be an alternative to less invasive treatment approaches, if the latter turned out not to be successful.     

Temporomandibular joint morphology and disc position in skeletal class III patients

INTRODUCTION: The purpose of this study was to investigate the relationship between temporomandibular joint (TMJ) morphology, including discal tissue and clinical symptoms in class III dentofacial deformity patients. MATERIAL AND METHODS: Forty-four patients were examined with lateral, frontal and axial cephalograms. They were divided into two groups, consisting of a class III symmetry and a class III asymmetry group. By using magnetic resonance imaging the 88 joints could be classified into four types on the basis of disc position and shape: anteriorly displaced disc, anterior type, fully-covered type and posterior type. Furthermore, TMJ morphology was measured tomographically in the sagittal plane. RESULTS: Anteriorly displaced discs in the asymmetry group (56.8%) occurred significantly more frequently than in the symmetry group (18.2%; p <0.05). TMJ symptoms (clicking, crepitus, closed lock, pain) were seen in 17/44 joints (38.6%) of the symmetry and 24/44 joints (54.5%) of the asymmetry group, for a total of 41/88 joints (46.6%). There were no differences in joint space ratio and condyle ratio. However, the fossa ratio on the deviation side was significantly higher than on the nondeviation side in the asymmetry group (p<0.05). CONCLUSION: The incidence of internal derangement in asymmetrical class III patients is higher than in symmetrical mandibular prognathism, and this difference is associated with a difference in TMJ morphology of both sides.     

Total alloplastic temporomandibular joint reconstruction using Biomet stock prostheses: the University of Florida experience

The purpose of this study was to report the subjective and objective outcomes of temporomandibular joint (TMJ) replacement with Biomet stock prostheses at a single institution in Florida. In this retrospective study, patients who underwent TMJ replacement using a Biomet stock prosthesis from 2005 to 2012 were analyzed. Subjective (pain, diet) and objective (maximal incisal opening) information was obtained. In addition, a quality of life measure was obtained pre- and postoperatively. Significance was set at <0.01. Thirty-six patients (26 bilateral, 6 left, and 4 right) who underwent TMJ replacement using a Biomet stock prosthesis were eligible for the study. Maximal incisal opening improved from 26.1 mm preoperatively to a mean of 34.4 mm postoperatively. The pain score decreased from 7.9 preoperatively to a mean of 3.8 postoperatively. Diet restriction decreased from 6.8 preoperatively to a mean of 3.5 postoperatively. Quality of life improved from a median of 4 preoperatively to a postoperative median of 2. Four implants were removed/replaced because of heterotopic bone formation, infection, and/or loose hardware. Follow-up ranged from 6 to 83 months. Overall, TMJ reconstruction using the Biomet stock joint is effective and safe in this patient population.