Orofacial Pain: Molecular Mechanisms, Diagnosis, and Treatment 2021.

The Special Issue "Orofacial Pain: Molecular Mechanisms, Diagnosis, and Treatment 2021" contains 6 articles published by 41 authors from different countries focusing on nucleus accumbens core GABAergic neurons, receptor-interacting serine/threonine-protein kinase 1, pannexin 1-mediated ATP signaling, ultra-low-frequency transcutaneous electrical nerve stimulation, and triamcinolone acetonide. The content covers several pain models, including neuropathic pain caused by peripheral nerve constriction or malpositioned dental implants, tongue cancer, myogenous temporomandibular dysfunction, and oral ulcerative mucositis. In addition, a review paper on trigeminal neuralgia is included.

Effects of exercise therapy on painful temporomandibular disorders.

Temporomandibular disorders (TMD) are common chronic musculoskeletal pain conditions among orofacial pain. Painful TMD condition such as myalgia and arthralgia can be managed by exercise therapy. However, as it is hard to access actual effect of each modality that is included in an exercise therapy programme due to multiple choice of the management modality, their efficacy remains controversial. Therefore, this review focused on the effects of exercise therapy for the management of painful TMD. The aims of this review were to summarise the effects of exercise therapy for major symptoms of painful TMD and to establish a guideline for the management of painful TMD, resulting in higher quality and reliability of dental treatment. In this review, exercise modalities are clearly defined as follows: mobilisation exercise, muscle strengthening exercise (resistance training), coordination exercise and postural exercise. Furthermore, pain intensity and range of movements were focused as outcome parameters in this review. Mobilisation exercise including manual therapy, passive jaw mobilisation with oral appliances and voluntary jaw exercise appeared to be a promising option for painful TMD conditions such as myalgia and arthralgia. This review addressed not only the effects of exercise therapy on various clinical conditions of painful TMD shown in the past, but also an urgent need for consensus among dentists and clinicians in terms of the management of each condition, as well as terminology.

Case report of recurrent temporomandibular joint open lock associated with abrupt reduction of displaced articular disk.

PATIENT: This report describes the case of a 51-year-old male patient who initially presented at age 23 with a habitual intermittent open lock (at >35mm) in the left temporomandibular joint (TMJ). The patient was able to manage this affliction through rapid-repetition jaw opening and closing. Tomography of the joint showed no irregular morphology, but intraoral examination revealed an occlusal interference at the mandibular left third molar during leftwards excursion. For this patient, alteration of lateral guidance using a palatal plate attached to the maxillary left canine precluded this intermittent open lock, but at 22 years of age, the open lock recurred and could not be relieved by the patient, who was unable to assume an occlusal position. Because conservative treatment was ineffective, a pumping manipulation technique was applied to reduce the open lock, after which the patient has maintained good jaw function. MRI taken before and after repositioning indicated that abrupt reduction of a displaced articular disk was the cause of the open lock, and that this articular disk was restored to its proper position during the manipulation. DISCUSSION: Most TMJ open locks occur as anterior dislocation, where the mandibular head becomes trapped anterior to the articular eminences, causing excessive opening and difficulty closing. Our clinical findings from this patient indicate that open lock can occur through abrupt reduction of a displaced articular disk, particularly in patients with chronic internal derangement of the TMJ. CONCLUSION: TMJ open lock can occur following abrupt reduction of a displaced articular disk.

Characterization of patients with disc displacement without reduction unresponsive to nonsurgical treatment: a preliminary study.

PURPOSE: Arthrocentesis and arthroscopic lysis and lavage have been described as effective treatment modalities for temporomandibular joint (TMJ) disc displacement without reduction (DDw/oR). More commonly, nonsurgical intervention is offered as the desired first-line treatment; however, a certain group of DDw/oR patients receiving nonsurgical treatment may remain unresponsive, thereby prolonging suffering and treatment dissatisfaction. The purpose of this study is to characterize these nonresponders by evaluating the characteristic pretreatment findings peculiar to this group. PATIENTS AND METHODS: This retrospective study was based on the review of pretreatment clinical and magnetic resonance imaging (MRI) findings of 52 DDw/oR patients who were treated with stabilization appliance, jaw-stretching exercise, and nonsteroidal anti-inflammatory medication. On the last treatment visit, each patient was classified as either a responder (R) or nonresponder (NR) based on the satisfaction or dissatisfaction with the treatment received, respectively. Pretreatment data were then examined and analyzed by logistic regression to identify which clinical and MRI findings were specifically related to the NR group. RESULTS: Logistic regressions indicated that NR had significantly higher odds ratio for pretreatment pain-free mouth opening of less than 30 mm (odds ratio [OR] = 7.385), "stuck" disc (OR = 4.521), and unchanged disc shape during mouth opening (OR = 4.050). Multiple logistic regression analyses revealed that these factors combined gave the highest likelihood ratio of 15.90 ( P = .001), indicating a strong possibility that these factors are associated with the NR group. CONCLUSIONS: Nonresponders can be characterized by their pretreatment pain-free mouth opening (<30 mm) in combination with MRI confirmation of "stuck" disc and unchanged disc shapes during mouth opening.