Regulatory effects of biophysical strain on rat TMJ discs

Recent studies have revealed that dynamic biomechanical forces can exert antiinflammatory and antiproteolytic effects on fibrocartitage. Whether the effects of mechanical strain also involve stimulation of the insulin-like growth factor (IGF) system and, therefore, of growth and repair of fibrocartilage has yet to be determined. The objective of this in vitro study was to determine if continuous biophysical strain regulates the gene expression of IGF1, IGF2, IGF1 receptor (IGF1R), insulin receptor substrate (IRS1), and IGF-binding proteins (IGFBP) 3 and 5 in cells from the fibrocartilaginous disc of the temporomandibular joint (TMJ). Rat TMJ disc cells were subjected to continuous biophysical strain (3% and 20%) for 4 and 24 h. Subsequently, RNA was extracted and real-time PCR was performed using an iCycler iQ detection system to analyze the gene expression of the IGF system. The gene expression of IGF1, IGF2, IGF1R, IRS1, IGFBP3, and IGFBP5 was significantly (p < 0.05) inhibited when cells were subjected to continuous biophysical strain, as compared to control at both time points. High strain induced a stronger inhibition of these molecules as compared to strain of Low magnitude. In conclusion, continuous biophysical strain seems to downregulate the expression of the IGF system and may, therefore, reduce the potential of fibrocartilage for growth and repair.     

Correlation of MRT imaging with real-time axiography of TMJ clicks

There is a series of tools useful for gathering diagnostic information on patients with temporomandibular joint disorders. Tracings of the joint movement (axiography) provide useful information about the motion of the joints. Since the availability of electronic axiographic tracers, the movement of the condyles can be resolved with high resolution both in space and in time. In order to obtain information about the anatomical relation of the joint surfaces and the disc, magnetic resonance tomography imaging (MRI) is routinely carried out. It is common practice to take MR images of the joints with the mouth closed and fully open. In order to correlate the MR images with the axiographic tracings, a series of images can provide much more information. In this study we examined patients with distinct temporomandibular joint (TMJ) clicks. In one case, the click occurs once a day, while in the other case the click happens every time the mouth is opened. In order to obtain information about both motion and anatomical relation of the TMJ at and around the position where the clicks occur, we recorded a series of MRI scans with the mouth gradually opened and before and after joint clicks. Real-time axiographic tracings during the click were taken with an optimized system where the polar moments were reduced as much as possible to follow the movement during the click. These tracings were correlated with the MRI scans to determine the exact internal conditions of the TMJ and the changes during the click. In particular cases, the additional information provided by this procedure can be useful in deciding whether and which therapeutic intervention is advisable.     

复杂修复的咬合设计理念及关键临床步骤

复杂修复由于涉及牙位多、对咬合关系影响大等一直是口腔修复的疑难之一。对这类修复临床问题的解决首先是建立正确的修复理念，文章对修复治疗中如何客观认识咬合与颞下颌关节紊乱病之间的关系进行了梳理，并对复杂修复中如何基于患者口颌系统的功能特点设计个性化咬合的临床步骤进行了阐述。     

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釉质发育不全（amelogenesis imperfecta,AI）是一组影响釉质发育的遗传性疾病,由于釉质形成时造釉器的某些功能障碍,导致釉质在厚度、结构和组织上的改变。临床可分为3型：釉质发育不良型（hypoplastic AI,HPAI）,釉质矿化不良型（hypocalcified AI,HCAI）和釉质未成熟型（hypomaturation AI,HMAI）。AI以牙色改变和釉质缺损为主要表现,严重者可伴有颞下颌关节紊乱病（temporomandibular joint disorders,TMD）等。笔者在临床中遇到1例全口乳牙、恒牙严重AI伴TMD病例,现报道如下。     

Psychometric evaluation of a motor control test battery of the craniofacial region

The primary objective of this study was to determine the structural and known‐group validity as well as the inter‐rater reliability of a test battery to evaluate the motor control of the craniofacial region. Seventy volunteers without TMD and 25 subjects with TMD (Axes I) per the DC/TMD were asked to execute a test battery consisting of eight tests. The tests were video‐taped in the same sequence in a standardised manner. Two experienced physical therapists participated in this study as blinded assessors. We used exploratory factor analysis to identify the underlying component structure of the eight tests. Internal consistency (Cronbach's α), inter‐rater reliability (intra‐class correlation coefficient) and construct validity (ie, hypothesis testing‐known‐group validity) (receiver operating curves) were also explored for the test battery. The structural validity showed the presence of one factor underlying the construct of the test battery. The internal consistency was excellent (0.90) as well as the inter‐rater reliability. All values of reliability were close to 0.9 or above indicating very high inter‐rater reliability. The area under the curve (AUC) was 0.93 for rater 1 and 0.94 for rater two, respectively, indicating excellent discrimination between subjects with TMD and healthy controls. The results of the present study support the psychometric properties of test battery to measure motor control of the craniofacial region when evaluated through videotaping. This test battery could be used to differentiate between healthy subjects and subjects with musculoskeletal impairments in the cervical and oro‐facial regions. In addition, this test battery could be used to assess the effectiveness of management strategies in the craniofacial region.     

Outcomes of physical therapy in patients with temporomandibular disorder: a retrospective review

Temporomandibular disorder (TMD) encompasses a spectrum of disorders that are associated with pain in the temporomandibular joint (TMJ) and surrounding musculature. Current research shows that conservative physical therapy is beneficial in the management of the disorder. This study further explores if physical therapy is an effective approach to treating patients with TMJ disorders. Our objectives were to determine the effect of conservative physical therapy interventions on pain, maximal mouth opening, and TMJ disability index for patients with TMD. Medical records from 2013-2018 were retrospectively reviewed to identify patients and obtain demographic, baseline, and short-term outcomes of maximal mouth opening (MMO), pain, and temporomandibular disability index (TDI). A total of 100 patients were included. Significant changes were noted in MMO, pain rating, and TDI from initial evaluation to discharge from physical therapy. Sex, age, and weight did not affect the outcomes. There was also no correlation between the number of visits attended and change in MMO. Patients treated conservatively did show improvements in short term outcomes (MMO, pain rating, and TDI). These changes were statistically significant, indicating that conservative therapy may be a beneficial treatment option for patients with TMJ dysfunction. Future studies assessing the long-term outcomes of TMJ patients treated conservatively would determine if this treatment is beneficial in the long-term. In addition, researching the effectiveness of specific interventions for TMJ patients, and if certain TMJ disorders are more responsive to conservative care than others would be valuable in providing information on the effectiveness of conservative treatment in this patient population.     

Temporomandibular Disorders in Burning Mouth Syndrome Patients: An Observational Study

BACKGROUND: Burning Mouth Syndrome (BMS) is a chronic disease characterized by absence of any lesions and burning of the oral mucosa associated to a sensation of dry mouth and/or taste alterations. The purpose of our study is to estimate signs and symptoms of Temporomandibular Disorders (TMD) in patients with BMS and to investigate for the existence of an association between BMS and TMD.MATERIALS AND METHODS: Forty-four BMS patients were enrolled; BMS subtype was established according to the classification of Lamey. After a gnathological evaluation, according to the protocol of the European Academy of Craniomandibular Disorders, patients were classified by RDC/TMD criteria. The data were compared and analyzed using a chi-square test to describe the existence of an association between BMS and TMD.RESULTS: 65.9% the BMS patients showed disorders classified as primary signs and symptoms of TMD according to RDC / TMD criteria, and 72.7% showed parafunctional habits. The chi-square test revealed a statistically significant association (p = 0.035) between BMS and TMD.CONCLUSION: The data suggest that there is a possible relationship not yet well understood between BMS and TMD, may be for neurophatic alterations assumed for BMS that could be also engaged in TMD pathogenesis.     

Blindness associated with platelet-rich plasma temporomandibular joint injections

This case report highlights an ocular complication associated with platelet-rich plasma temporomandibular joint injections. This pioneering treatment can risk irreversible visual loss. This case highlights the importance of an experienced technique, in depth understanding of facial anatomy, and promptly recognising and referring the patient to a specialist to manage the complication should it arise.