Histological evaluation of changes in the temporomandibular joint after direct and indirect trauma: an experimental study

Abstract – Direct or indirect trauma to the temporomandibular joint (TMJ) may cause several injuries such as fibrous adhesion, ankylosis and fracture. The aim of this study was to examine and compare the histological changes of TMJ and adjacent soft tissue after direct or indirect trauma to TMJ. In this study, a total of 35 healthy young adult guinea pigs were exposed to direct and indirect trauma to their TMJ, and histologic evaluation was done after 24 h, 7, 15 and 45 days. Hemorrhage was the most frequent complication, following that enlargement of the disc, adhesion of the disc to the condyle and fracture of the condyle were seen in both groups. There were regenerative changes in adjacent muscles of the TMJ in indirect trauma group when compared to direct trauma group. Regenerative changes were more obvious on days 15 and 45. As a result, it may be suggested that when a trauma comes to the maxillo-mandibular complex, even TMJ is indirectly affected, TMJ and its adjacent soft tissues should also be examined clinically and followed closely.     

重度磨损患者的临床特点及其对颞下颌关节功能的影响

目的：了解牙列重度磨损患者的临床特点，探讨重度磨损患者的颞下颌关节（temporomandibular joint,TMJ)影像变化特征。方法：对92例（男52例，女40例）关节门诊牙列重度磨损患者的病例资料及其颞下凳关节X线片情况进行统计分析。结果：重度磨损患者中（1）男性多于女性（P＜0．05），30－59岁人群占77．17％。（2）磨牙和颞下颌关节紊乱症（temporomandibular disorders,TMD)发病率之间存在负相关关系（P＜0．05）。（3）各组间颞下颌关节X线改变无显著差异（P＞0．05）。（4）髁状突移位与骨质改变表现呈负相关关系（P＜0．05）。结论：（1）以中年人群为主体的重度磨损与磨牙症、TMD等功能紊乱性疾病的关系并不密切。（2）颞下颌关节X线改变并不规律。     

The role of dental loss and denture status on clinical signs of temporomandibular disorders

Studies concerning the role of denture status on in temporomandibular disorders (TMD) are scarce. The aim of this study was to evaluate the association of tooth loss and denture status with clinical findings of TMD. The data were obtained from 6316 subjects aged ≥30 years from the Finnish Health 2000 Survey. The associations between clinically assessed TMD findings and number of teeth, wearing of removable dentures, need for denture repair and age of the dentures were analysed by means of chi‐square test and logistic regression. Among women after adjusting for age, having fewer teeth or wearing complete dentures associated with restricted maximum interincisal distance and pain on palpation of the temporomandibular joints (TMJ) and masticatory muscles. After adding education level and depression in the model, the associations between TMJ pain and explanatory variables were weakened. Among men, having a higher number of teeth associated with occurence of TMJ crepitation. Subjective need for repair of dentures and having a denture aged ≥5 years associated with pain on palpation in masticatory muscles among women. Among men, both the objective and subjective need for denture repair and having at least one denture aged ≥5 years or been repaired during the past 5 years associated negatively with the presence of TMJ crepitation. It can be concluded that edentulousness, wearing of complete dentures and poor condition of dentures associate with pain‐related TMD findings among women. Psychosocial factors have a modifying effect on these associations.     

Prevalence of tinnitus according to temporomandibular joint disorders and dental pain: The Korean National Population‐based Study

Some studies have reported that temporomandibular joint disorder (TMD) is related to tinnitus. However, there is no study of the relationship and prevalence of dental pain and tinnitus. We evaluated the associations between the prevalence of tinnitus and TMD and dental pain by analysing the Korean national health survey. We analysed totally 11 745 participants. The presence of tinnitus, TMD symptoms and dental pain was surveyed by self‐assessment questionnaires from all the participants. Multivariable regression analysis was applied to acquire odds ratios (OR) and 95% confidence intervals (CI). The prevalence of tinnitus was higher in the subjects with dental pain (21.1%), TMD (22.5%) and both symptoms (31.2%) than subjects without those symptoms (19.6%). After adjusting for all covariates, subjects with TMD had tinnitus 1.6 times more than subjects without TMD. In the subanalysis, age group more than 65 years, women, and obese subjects had tinnitus more than men, age group <65, and non‐obese subjects, respectively. TMD alone and both dental pain and TMD were associated with tinnitus (OR = 1.389 and 95% CI 1.054‐1.832 and 2.206 and 1.637‐2.974, respectively). Subjects with TMD had more tinnitus than subjects without TMD. Moreover, subjects with dental pain in addition to TMD had increased prevalence of tinnitus than TMD alone.     

The gap between dental education and clinical treatment in temporomandibular disorders and orofacial pain

Implementation of research findings in patient care ideally will follow in a continuous cycle, and clinical questions from practitioners should stimulate research. Even in the most optimal situations, there will be a gap between the steady flow of new findings from research and their eventual implementation in clinical practice. In the clinical practice of temporomandibular disorders and orofacial pain (TMD/OFP) simple cases outnumber the more complex cases by far. Therefore, research implications for the general dental practitioner, whose patients are rarely represented in research populations, may differ from what is published and taught. Treatment options like counselling, occlusal treatments (reversible as a rule and irreversible by exception) and physiotherapy can be very successful in the hands of the general dental practitioner. European dental schools should define additional amendments to the recently proposed profile and competencies for the European dentist, in order to focus on the relevant and current knowledge on temporomandibular disorders and orofacial pain. These amendments should address the adequate diagnosis and management of non-complex TMD cases and the need to refer to a TMD/OFP specialist in complex cases. Professional organizations such as the European Academy of Craniomandibular disorders can endorse better TMD/OFP education and training.     

青春期青少年颞下颌关节成熟度与第二恒磨牙牙根发育的相关关系

目的观察12～14岁青少年人群颞下颌关节的影像学表现,探讨关节成熟度与下颌第二恒磨牙发育状况的关系。方法选择12～14岁青少年正畸患者52例为研究对象,于正畸治疗前拍摄全景片和双侧颞下颌关节许勒位片。通过颞下颌关节许勒位片观察并评判颞下颌关节骨质的成熟度,通过全景片观察下颌第二恒磨牙牙根的发育情况。分别对颞下颌关节骨质和下颌第二恒磨牙牙根发育状况进行分级评分,并对二者的相关性进行分析。结果颞下颌关节各部分发育的总体趋势具有一致性,其中关节结节与关节凹骨质成熟度的相关系数为0.709,二者发育的相关性较大。第二恒磨牙发育状况与髁突、关节结节及关节凹骨质成熟度的相关系数分别为0.576、0.064、0.091,第二恒磨牙发育状况与髁突成熟度的关系更为密切。结论青少年的颞下颌关节处于发育成熟期。就影像学表现来说,下颌第二恒磨牙牙根发育状况与髁突发育成熟度有较大的相关性,临床上可以通过下颌第二恒磨牙牙根的发育状况来了解髁突的发育状况。     

Hearing changes after temporomandibular joint arthroscopy: a prospective study

Temporomandibular Joint (TMJ) arthroscopy is considered an effective and safe minimally invasive surgical approach. While the long-term outcomes of arthroscopy tend to be positive and free of secondary effects, patients occasionally complain about their hearing following the treatment. The aim of this prospective study was to investigate possible hearing changes associated with TMJ arthroscopy. Pure-tone audiograms were performed in patients two weeks before TMJ arthroscopy and repeated six weeks after intervention. A total of 15 patients (mean age of 41.73 ± 16.36) were enrolled; 25 TMJ arthroscopies were performed (five unilateral and ten bilateral). Statistically significant differences were found between preoperative and postoperative audiograms in the frequencies 256 Hz (P = 0.011) and 8 kHz (P = 0.058, borderline). For the frequency 256 Hz the difference was favourable, but not superior to 5 dB. For the frequency 8 kHz, in three patients the TMJ arthroscopy resulted in a decrease of 10 dB. However, no clinical hearing changes or complaints were observed in the involved patients. No differences in audiograms between level 1 or 2 arthroscopy were observed. The study reinforces the safety of the TMJ arthroscopy level 1 and 2 with the reported protocol. The authors recommend larger studies to validate the results, specially for frequency 8 kHz.     

Reconstruction of the temporomandibular joint: a comparison between prefabricated and customized alloplastic prosthetic total joint systems

The implantation of an alloplastic total temporomandibular joint (TMJ) prosthesis is an innovative approach for the treatment of end-stage TMJ disorders. Two types of system exist: prefabricated (stock) and customized computer-aided design/computer-aided manufacturing (CAD/CAM) devices. A clinical study was performed to evaluate the effectiveness of these two designs. Twenty-eight patients treated between 2015 and 2017 were included and assigned to two groups: stock prostheses (group 1) and customized CAD/CAM prostheses (group 2). Clinical evaluations were performed at five time-points up to 6 months postoperative. Parameters included maximum interincisal opening, pain, diet, complications, and subjective well-being at the end of follow-up. Differences between pre-surgery and 6-month post-surgery values were highly significant (P < 0.001). No patient required a liquid diet at the end of treatment, and 66% of group 1 patients and 100% of group 2 patients reported improved well-being. Complications were observed in 32% of patients and included temporary paralysis of the facial nerve. In conclusion, clinical outcomes of stock and CAD/CAM prostheses suggested great improvements in mouth opening and reduction of pain as a result of the rehabilitation of TMJ function. Results showed comparable data for the two types of prosthesis design at 6 months postoperative.     

Efficacy of a posterior implant support for extra shortened dental arches: a biomechanical model analysis

The purpose of this study was to test the efficacy of utilizing implants underneath distal free-end denture bases to establish a stable occlusal support for extreme shortened dental arches (ESDA). The authors constructed a two-dimensional finite element model of the ESDA where only lower anterior teeth remain. Posterior occlusal support was provided by a fixed partial denture with an osseointegrated implant (IFPD), fixed cantilever partial denture (CFPD), or a removable partial denture with or without an implant underneath (IRPD and RPD). A dentate mandible model was the control. When muscle vectors simulating clenching force were applied, stress levels on the temporal bone surface area under each configuration were compared, to evaluate the efficacy in establishing the occlusal support. The largest stress increase in temporal bone was found in the ESDA situation followed by the RPD. The least amount of stress increase was found with the IFPD followed by IRPD when the implant was placed in the molar region. The stress increase with IRPD was about 20-45% of the amount with RPD. Our results suggest that IFPD provides most favourable and stable occlusal support, however, IRPD with a single posterior implant also provide stable occlusal support with reducing the stress levels in the temporomandibular joint.     

The prevalence of erosive osseous changes of the articular eminence in the temporomandibular joint in patients with mandibular prognathism without internal derangement; MR and helical CT findings

The aim of this study was to assess the prevalence of erosive osseous changes of the articular eminence in the temporomandibular joint without internal derangement. Sixty joints of 30 consecutive patients with mandibular prognathism were evaluated with both MR imaging and helical CT. On MPR images obtained with helical CT, erosive osseous changes of the articular eminence were observed in 18 joints (30%) of 13 patients. None of the joints studied demonstrated an osseous change in the mandibular condyle. MR imaging failed to detect erosive osseous changes of the articular eminence in all of the joints studied. In conclusion, MPR images obtained with helical CT were of value to detect erosive osseous changes of the articular eminence.     

下颌骨延期植骨对兔颞下颌关节影响的扫描电镜观察

目的：观察下颌骨延期植骨后颞下颌关节表面的超微结构变化。方法：通过扫描电镜观察下颌骨延期植骨对兔颞下颌关节的影响,并与同期植骨的家兔关节和相同月龄的正常家兔关节进行比较。结果：下颌骨延期植骨后髁突和关节盘表面的凝胶样物质被破坏,暴露出下面疏松的,排列紊乱的胶原纤维组织。结论：下颌骨延期植骨可导致颞下颌关节退行性改变。     

The prevalence of oral stage dysphagia in adults presenting with temporomandibular disorders: a systematic review and meta-analysis

Objective: Temporomandibular disorders (TMDs) are the most commonly experienced non-dental orofacial pain disorders, with pain and dysfunction potentially resulting in oral stage dysphagia (OD). However, limited research has been conducted on this condition, with potential negative effects on clinical practice. Therefore, the aim of this study was to determine the prevalence of OD in adults presenting with TMDs, diagnosed as per the Research Diagnostic Criteria for Temporomandibular Disorders or the Diagnostic Criteria for Temporomandibular Disorders protocols.

Material and methods: A systematic review of the literature was completed. Nine electronic databases were searched from inception to January 2017, with no date/language restriction applied. Grey literature, conference proceedings, and reference lists were also searched. Studies presenting original data regarding OD prevalence in adults presenting with TMDs were included if they investigated impaired swallowing, mastication, masticatory pain or fatigue, or weight loss. Study eligibility and quality were assessed by two independent reviewers. Methodological quality was assessed using the Down’s and Black tool.

Results and conclusions: This search yielded 20 eligible studies. Swallowing itself was impaired in only 9.3% of patients with TMDs. A range of additional OD signs and symptoms were also commonly reported (e.g. masticatory pain (87.4%) and fatigue (62%)). Study limitations included the small number of studies which were eligible for inclusion. As signs and symptoms of OD are frequently reported by patients with TMDs, psychometrically robust prospective research is warranted to determine current and optimal management of this condition.     

Relationship between temporomandibular joint dynamics and mouthguards: feasibility of a test method

Abstract – A test system was developed establishing the feasibility of collecting biomechanical data as they relate to the use of mouthguards. Previous experimental studies have examined the physical and mechanical properties of mouthguard materials. This information has been used as a guide for establishing material standards and specifications for the fabrication of mouthguards, but it lacks the key biomechanical parameters required for a thorough mouthguard evaluation. The current study was designed to assess whether the impact force, condylar deflection, and strain superior to the temporomandibular joint region could be measured. A drop test was conducted on a cadaveric specimen to simulate loading at the chin point. To measure the force of impact, an accelerometer was attached to an impactor of known mass. High‐speed biplanar (1000 frames per second) radiographs were used to determine condylar displacement. Radio‐opaque markers were inserted into the bone at predetermined locations. Total displacement of these markers was determined in reference to anatomical landmarks. Strain gauges were attached to the mandible and skull to monitor the effects of the condyle impacting the base of the skull. Based on the data collected, forces were calculated by determining the product of the time‐based acceleration and known mass. A measurable change in force between the mouthguards and the control (no mouthguard) was demonstrated. The average condylar displacement was successfully measured and indicated as an increase in total deflection for impacts conducted with mouthguards. Quantifiable strain was measured in the region above the mandibular fossa with and without the insertion of a mouthguard at all impact conditions. However, it was determined that additional gauges would provide critical data. Key biomechanical parameters for chin‐point impacts were determined in the current study. The technique demonstrated that both displacement within the mandibular fossa and loading of the condyles occur during the impact event. Although the current study established a technique that can be used to examine the relationship between mouthguards and jaw‐joint injuries, the role, if any, mouthguards play in the reduction of injuries cannot be established until a thorough analysis is completed.     

Counselling and self‐management therapies for temporomandibular disorders: a systematic review

The aim of this review was to investigate the effectiveness of counselling and other self‐management‐based therapies on muscle and temporomandibular joint (TMJ) pain relief and increasing the functional abilities of patients with temporomandibular disorders (TMD). A systematic literature review was conducted by three independent reviewers and included articles published up to 2012. PubMed and Cochrane Library electronic databases were used in addition to hand‐searching to assess clinical outcomes for counselling and self‐management approaches for TMD treatment. The review yielded 581 records that were narrowed down to 7. All included studies were classified as blind‐randomized controlled clinical trials. The selected articles analysed revealed that counselling was able to improve tenderness upon masticatory muscle palpation and maximum mouth opening with and without pain in patients with TMD, with similar results to those of interocclusal appliances approaches. Thus, counselling‐ and self‐management‐based therapies could be considered a conservative low‐cost and beneficial treatment alternative for treating TMD to potentially improve psychological domains and remove harmful behaviours for the control of the signs and symptoms of TMD.     

The incidence of osteoarthritic change on computed tomography of Korean temporomandibular disorder patients diagnosed by RDC/TMD; a retrospective study

Objective Osteoarthritis (OA) of the temporomandibular joint (TMJ) is generally thought to be an age-related disease like those of other joints. This study aims to investigate the incidence of computed tomographic (CT) OA changes in Korean temporomandibular disorder (TMD) patients diagnosed by the Research Diagnostic Criteria for TMD (RDC/TMD). Materials and methods The clinical records and radiographs of 1038 TMD patients (297 men and 741 women with mean age 31.1?±?17.4 and 34.0?±?16.2, respectively) diagnosed based on RDC/TMD Axis I in 2010 were reviewed. Results The incidence rate of OA changes in TMD patients is estimated to 27.3%, and higher in women than in men (15.5% in men and 32.0% in women) by 2.3 odds (p?p?Conclusions These results imply that the OA changes in young Korean TMD patients are as common as in the old and have no correlation with clinical pain and noise. Considered with high prevalence of TMDs known in the young population, the overall/absolute OA changes in the TMJ can be even higher in the young than in the old population, not like in other joints.     

Body posture during sleep and disc displacement in the temporomandibular joint: a pilot study

Many possible factors associated with internal derangement of the temporomandibular joint (TMJ) have been discussed, but the causal factors remain unproven. The present study aimed to investigate habitual body posture during sleep (HBP) of patients with anterior disc displacement (ADD) in the TMJ. The sample comprised 87 patients (12 males, 75 females) aged 13-68 years (mean 25 years) and diagnosed by magnetic resonance imaging as having unilateral or bilateral ADD in the TMJ. The HBPs were classified into five categories: supine, prone, right lateral, left lateral, and no-dominant positions. Of the 50 patients with the unilateral ADD, 33 (66%) had the ipsilateral HBP to the affected joint while none (0%) had the contralateral HBP. This contrast showed that the HBP was a possible contributing factor to the ADD. It was suggested that HBP allows the ipsilateral condyle to displace posteriorly and this posterior position causes relative ADD.