The Kovacs-customized temporomandibular joint appliance for temporomandibular joint anterior disc displacement: a prospective cohort study of its clinical efficacy and the correlation between pain and functional improvement

Background Anterior disc displacement of the temporomandibular joint is a common cause of orofacial pain and functional limitation. However, rigorous clinical validation of fully digital, standardized protocols that determine therapeutic jaw position in the management of anterior disc displacement of the temporomandibular joint is lacking. Therefore, the aim of this study was to evaluate the clinical efficacy of the Kovacs-customized temporomandibular joint appliance and explore the correlation between pain reduction and functional improvement in patients with anterior disc displacement of the temporomandibular joint. Methods Forty patients with anterior disc displacement of the temporomandibular joint were prospectively enrolled. All participants received a Kovacs-customized temporomandibular joint appliance fabricated via a standardized digital workflow and were assessed over a 6-month period. Primary outcomes included pain intensity measured using a visual analog scale and maximum mouth opening. The relationship between the changes in these two key outcomes was analyzed using Spearman’s correlation coefficient. Joint sounds and disc positions were recorded on magnetic resonance imaging as exploratory observations. Results Kovacs-customized temporomandibular joint appliance treatment resulted in significant clinical improvement. Mean visual analog scale pain scores decreased from 5.30 ± 2.09 at baseline to 1.66 ± 1.42 at 6 months (t = -11.035, P < 0.001). Concurrently, median maximum mouth opening increased from 36.5 mm (interquartile range: 26.25–39.00) to 39.0 mm (interquartile range: 37.25–40.00) (Z = -4.181, P < 0.001). A statistically significant, moderate negative correlation was identified between reduction in pain intensity and increase in maximum mouth opening (ρ = -0.493, P = 0.001), indicating that greater pain relief was associated with greater functional improvement. Clinical improvement was accompanied by resolution of joint clicking in most patients, whereas exploratory magnetic resonance imaging revealed variable changes in disc position. Conclusions The Kovacs-customized temporomandibular joint appliance is an effective conservative treatment for anterior disc displacement of the temporomandibular joint that significantly alleviates pain and improves mandibular function. The demonstrated correlation between symptomatic and functional recovery provides valuable insights into the therapeutic process and underscores the value of this standardized digital protocol. The Kovacs-customized temporomandibular joint appliance represents a promising option within a patient-centered care framework.