Temporomandibular disorders (TMD) are common in clinical practice, with an incidence of 5%–12% (De Kanter et al., 1993). They can cause pain, restricted mouth opening, joint noises and other symptoms that may affect the patient's quality of life. Anterior disc displacement (ADD) is a common type of TMD that accounts for 77%–94% (Dias et al., 2016) of TMDs, and is a risk factor for osteoarthritis (Lamot et al., 2013). At present, the treatment of TMD includes conservative treatment such as patient education, mandibular manipulation, medication, exercise, and occlusal splint, as well as open surgery, which includes arthroscopic surgery, disc repositioning, discectomy, eminectomy, condylar shave and total joint replacement. Disc repositioning surgery is used for patients who do not respond to conservative treatment and in whom the disc shape and condylar bone status are salvageable. After being first proposed by Annandale in 1887, disc repositioning was continuously modified by Wolford (Mehra et al., 2013) and Yang et al. (Yang et al., 2012). Short-term and long-term magnetic resonance imaging (MRI) follow-up showed that the disc position was stable after the surgery (Mehra and Wolford, 2001; Yang et al., 2012; He et al., 2018; Gonçalves et al., 2015) and that the patients' pain and mouth opening were improved (Abramowicz and Dolwick, 2010; Liu et al., 2019a, Liu et al., 2019b; Liu et al., 2019a, Liu et al., 2019b; Loureiro Sato and Tralli, 2020Loureiro Sato et al., 2020; Zhu et al., 2012). However, there have not been any studies comparing the common conservative treatment stabilization splints (SS) with open disc repositioning.

In this paper, we compared the clinical outcomes between SS and disc repositioning by open surgery (DROS) in the treatment of ADDwoR. We hypothesized that DROS would yield better results than SS by both subjective and objective evaluations.