The incidence of disc displacement may be an indication for temporomandibular disorder (TMD). Disc displacement of the temporomandibular joint (TMJ) is an intracapsular biomechanical disorder, in which the articular disc is mostly displaced to the anterior relative to the condylar head [1]. TMD can be influenced by various factors, including oral parafunction, such as clenching and bruxism, psychological distress, and comorbid systemic conditions [2]. One of the strong causative factors of TMD with disc displacement is macrotrauma, such as traffic accidents, falls, and assaults [3]. Any traumatic incident to the TMJ may modify the preexisting relationship of the TMJ and related structures, causing multiple problems, such as joint effusion, dislocation, disc displacement, and jaw movement limitation [3,4]. Acute retrodiscitis, which is an inflammatory state of the retrodiscal tissue of the TMJ, is one of the possible symptoms after macrotrauma and is often followed by disc displacement [5]. Acute retrodiscitis is commonly accompanied by swelling in the TMJ area, which can induce malocclusion of the ipsilateral teeth and severe pain during chewing. Overall, symptoms linked to macrotrauma-induced TMD are characterized by acute inflammation, pain, and displacement of the adjacent structures.

TMD symptoms after macrotrauma are likely to progress rapidly. Due to the rapid development of TMD symptoms after macrotrauma, early assessment and management to stabilize the TMJ structure are critical to prevent further aggravation, including joint degeneration or ankylosis of the TMJ [6]. Several diagnostic methods, such as magnetic resonance imaging (MRI), have been indicated to specifically assess the current state of the patient [7]. Simultaneously, innovative treatment tools have also been developed to provide optimal treatment plans for each patient. Possible treatment options include medication, intra-articular injection, occlusal stabilizing with stabilization splint, and manual manipulation; in other words, conservative therapy is still efficient for the acute pathological state of the TMJ [7]. These are targeted at effectively alleviating acute inflammation and pain and stabilizing associated TMJ structures to their physiological position. This analysis highlights a case, in which various methods were employed to diagnose and manage disc displacement linked to retrodiscitis after macrotrauma.

A 60-year-old male visited the Department of Oral Medicine at Kyung Hee University Dental Hospital with a major complaint of right facial pain with a burning sensation. His symptoms began five days prior to the visit, after he got hit on the right side of his face. He experienced severe pain and headache during mastication and mouth opening, complaining of pain with a visual analog scale (VAS=0-10) rating of 8. Radiological examination of his TMJ revealed an increased volume of the intra-articular space and anterior location of the right TMJ compared with the left side (Fig. 1). At the Department of Oral and Maxillofacial Radiology, Kyung Hee University Dental Hospital, panoramic radiography with exposure settings (70 kVp, 12 mA, exposure time 13.6 seconds) was conducted, and a protocol for occlusion examination in a closed-mouth state was employed. During clinical assessments of the oral cavity and face, his both molars were shown to be in noncontact, and severe pain occurred when attempting to make the teeth on the right side occlude (Fig. 2). A mouth-opening limitation was also observed, with a maximum unassisted opening of 19 mm and a maximum assisted opening of 21 mm. During mouth opening, the patient complained of pain in the right TMJ and masseter. Palpation influenced pain in the right masseter, right anterior temporal muscle, and right TMJ capsular area, in which swelling and burning sensation were observed. After the examinations, we made a tentative diagnosis of acute disc displacement without reduction with retrodiscitis of the right TMJ combined with local myalgia. The diagnosis of disc displacement and local myalgia was performed following the guidelines of diagnostic criteria for DC/TMD [1].

During the first visit, we manually twisted the right TMJ to relocate the disc. However, since swelling of the TMJ and masseter muscle stiffness provoked severe pain, TMJ injection with a mixture of 2% lidocaine and dexamethasone was performed. For muscle relaxation, botulinum toxin was injected into both masseter muscles, and 25 units were injected into each side. Baclofen (10 mg, thrice daily), aceclofenac (100 mg, twice daily), and prednisolone (5 mg, once a day) were prescribed for five days to control pain and inflammation. Blood tests carried out on the same day indicated normal findings except for the erythrocyte sedimentation rate (ESR). ESR was 95 mm/hour, which is more than six times over normal ranges, indicating an acute inflammatory state according to the Department of Diagnostic Laboratory Medicine at Kyung Hee University Medical Center. In traditional ESR criteria, ESR ≤15 mm/hr is deemed normal in males <50 years old [8]. Two days after the first visit, his pain was mildly reduced from VAS 8 to 5, but the headache and malocclusion persisted. The maximum assisted opening amount was 25 mm with pain. To alleviate pain and muscle stiffness, a mixture of 2% lidocaine and dexamethasone was administered to the right TMJ, temporal muscle, and sternocleidomastoid muscle. The same medication was prescribed for five days, and the patient was recommended to take these after the preexisting prescribed medication.

Ten days after the first visit, he complained of severe pain throughout the day, particularly during mouth opening. Due to the lingering pain and swelling in the right area, we performed MRI for precise evaluation of the TMJ and to make a stabilization splint. We also administered nortriptyline (10 mg once a day) for additional pain control. After obtaining consent, we made an impression of the maxillary teeth and delivered a stabilization splint the next day. Thirteen days after the first visit, MRI images revealed a slight posterior displacement of the right TMJ, with disc degeneration and joint effusion (Fig. 3). His symptoms were also alleviated, with pain reduced to VAS 3, and a maximum assisted opening of 30 mm was achieved. We prescribed the same medication, including nortriptyline, and injection into the right TMJ. Twenty days after the first visit, his pain declined to VAS 1, and occlusion of his right teeth was observed (Fig. 4). The same medication was administered for 10 days, followed by the injection. He stopped visiting our clinic after that day, but during a telephone interview 40 days after the first visit, he explained that he could achieve a comfortable occlusion with no residual pain. This case research was approved by the Institutional Review Board of the Kyung Hee University Dental Hospital (IRB no. KH-DT22031). Informed consent was obtained from the patient.

Herein, we present a patient with disc displacement, retrodiscitis, and malocclusion after macrotrauma. MRI was employed for an adequate analysis of the TMJ and adjacent soft tissues. To control acute pain and inflammation, treatment methods, including medication, manual manipulation, intra-articular injection, botulinum toxin injection, and stabilization splinting were conducted. After 40 days of treatment, his symptoms markedly improved, and no pain persisted.

Macrotrauma is one of the main causative factors of TMD. After macrotrauma, an immediate and accurate diagnosis is crucial to manage the acute pathological state of the TMJ and to achieve pretraumatic function [9]. MRI is a reliable diagnostic procedure to analyze the soft tissue of the TMJ, including the disc and retrodiscal tissue, and its findings correspond with clinical findings [10]. After macrotrauma, an increased signal intensity of the capsule and extended retrodiscal tissue with joint effusion is typically observed on MRI images [11]. These findings are intimately linked to severe pain, suggesting inflammation and an increase in vascularity in the retrodiscal tissue. With an accurate diagnosis, pain control is also necessary to ensure patient compliance with treatment, considering that severe pain is frequently accompanied by macrotrauma. Conservative treatments, such as medication and physical therapy, are generally chosen as the first option [12]. Herein, we prescribed nortriptyline for pain control. As the patient demonstrated inflammation of retrodiscal tissue and headache, which were not alleviated by anti-inflammatory drugs, it was suspected that a neurological factor induced the pain. Since tricyclic antidepressants are among the first-line medications favorable for neuropathic pain [13,14], we chose nortriptyline; his pain was effectively lowered.

As revealed in the MRI findings, traumatic damage has a greater influence on mobile tissues, such as the capsule and retrodiscal tissue, rather than on the disc itself, which can explain the high incidence rate of disc displacement and retrodiscitis after traumatic events [11]. This results in the acute dislocation of TMJ structures, especially discs, which may result in a limited mouth opening. These abruptly changed relationships can be normalized by mechanical relocation, such as manual manipulation and stabilizing with a stabilization splint, considering the adequate mobility of TMJ tissues due to the TMJ condition not being fully adapted to the current location [6,15]. Clinically, manual manipulation can efficiently resolve the limitation of mouth opening and associated TMJ pain by lowering the disc to its physiological position. However, there are some contentious studies concerning the outcomes of manual manipulation; the presence of joint inflammation, such as joint effusion, has been reported to promote disc recapture failure [16-18]. The stabilization splint can alleviate pain by relieving muscle tension while reducing the physical load on the TMJ and can be employed to stabilize the physiological structure of the TMJ. An anteriorly displaced articular disc can be recaptured by an oral appliance, unless the disc is extremely anteriorly positioned or the disc morphology is greatly altered [19]. Therefore, it would be conceivable to combine manual manipulation with stabilization splint therapy rather than performing it alone. If patients indicate acute pain or no response to conservative treatments, less invasive treatments, such as intra-articular injection, can be further applied, even at the first visit. Intra-articular corticosteroid injections can efficiently alleviate pain and improve mouth opening. Furthermore, proper administration of intra-articular injections can directly remove inflammatory agents in the synovium, which helps improve the acute inflammatory state after trauma [20].

Overall, macrotrauma is one of the key contributing factors to TMD. In patients who experienced macrotrauma, it is essential to comprehend the current state of the patient and make a diagnosis as precise as possible. Among the diagnostic methods, MRI is often suggested for further analysis of the joint tissue. In many cases after trauma, acute inflammation and severe pain are often present; thus, pain control with anti-inflammatory treatments should be considered to increase patient cooperation and to promote the proper application of subsequent treatments. If a structural dislocation is found, mechanical relocation can prevent prolonged pain and permanent dislocation. However, since the aspects of traumatic events are varied and atypical, it is difficult to precisely predict their traumatic impact on TMJ structures. Thus, the goal is to make the diagnosis as precisely as possible. Only after the current state of the patient is specifically assessed could the following treatments be planned optimally for each patient. Clinicians must consider all possible diagnoses and treatments to optimally manage patients.

No potential conflict of interest relevant to this article was reported.

This work was supported by the National Research Foundation of Korea (NRF) grant founded by the Korean government (MSIT) (No. NRF-2020R1F1A1070072).

The authors extend their special thanks to Jung-Pyo Hong of the Department of Orofacial Pain and Oral Medicine, Kyung Hee University Dental Hospital.

Conceptualization: YHL. Data curation: YHL, TSK. Formal analysis: YHL, TSK. Funding acquisition: YHL. Methodology: YHL. Project administration: YHL. Visualization: YHL, TSK. Writing original draft: YHL, TSK. Writing review & editing: YHL, TSK.