Introduction. Occlusal splints are oral appliances that have been designed to relieve the temporomandibular symptoms. However, the thickness of occlusal splints in order to have optimal efficacy is still controversial. Methods. An electronic search in Medline, Scopus, and Web of Science databases was conducted, using the following keywords up to 2025: (“occlusal splint” OR “stabilization splint” OR “bite splint”) AND (“vertical dimension” OR “thickness” OR “occlusal height”) AND (“temporomandibular disorder” OR “TMD” OR “disc displacement” OR “myofascial pain”). All titles and abstracts were screened. Studies comparing different thicknesses of occlusal splints were included. Results. Eight studies met the inclusion criteria, of which five were randomized controlled trials, one a retrospective study, and two finite element analyses. Mixed quality of the studies was found. Based on current evidence, although limited, the following results could be deduced: Occlusal splints with moderate thickness, 3 mm, are recommended for cases that involve both muscular and joint components, particularly when masticatory muscle pain is the primary complaint. Occlusal splints with minimal thickness, 2 mm, may be appropriate in internal derangements in the early stage, though evidence is low. Thicker splints, ≥4 mm, are for DDwoR and cases with crepitus. Occlusal splints of ≤2 mm and >6 mm were associated with symptoms such as reduced functional outcomes or comfort. Conclusion. In most cases, occlusal splints with thicknesses of 3–5 mm seem to be optimal for most TMD cases; however, personalized treatment based on the respective diagnosis is recommended. The decision on splint thickness should be based on evidence according to the severity of the diagnosis, but also patient-centered, to achieve comfort, compliance of the patient, and oral structure preservation. Further high-quality RCTs are needed to gain evidence-based guidelines and to achieve consistent results.

Introduction: Disc displacement with reduction (DDwR) and myalgia are among the most common temporomandibular disorders, frequently affecting young adults. While conservative therapy is considered the first-line approach, the evidence on long-term outcomes is still limited. Case Presentation: A 22-year-old female had a 7-month history of left-sided TMJ clicking, deviation to the left during opening, and 2 months of bilateral masticatory pain, which was worsened by mastication. During clinical examination, reproducible left TMJ clicking and tenderness of the masseter and temporal muscles were observed. Based on DC/TMD Axis 1, DDwR with myalgia diagnosis was made. Intervention and Results: A full maxillary stabilization splint was constructed and delivered together with patient education, dietary adjustments, and guided mandibular exercises. At baseline, pain intensity was VAS 6/10 with a maximum unassisted mouth opening of 41 mm and reproducible joint clicking. After 2 weeks, the patient reported a decrease in pain, VAS 2/10, mouth opening was 44 mm, and joint sounds were absent. After 1 year, the patient was asymptomatic (VAS 0/10) with stable function, preserved mouth opening, and completion of daily activities without limitations. Clinical Relevance and Conclusions: This case shows that multi-directional non-invasive therapy can result in complete and long-term remission of DDwR with myalgia. It emphasizes the need for careful diagnosis, through standardized instruments such as DC/TMD, and the need for personalized treatment to ensure durable clinical success.