The agony that accompanies the incidence and symptoms of temporomandibular disorders (TMDs) is an important concern in the oral and maxillofacial region. The objective of this study was to explore the clinical findings after centric relation occlusal splint (CROS) treatment and intra-articular injection treatment with liquid phase concentrated growth factors (LPCGFs) in patients with disc displacement without reduction (DDWOR). The group under investigation of this retrospective cohort study included patients with DDWOR who received treatment from April 2014 until March 2016. The predictor variable was the therapeutic method. The outcome variables included joint crepitus sound, visual analog scale (VAS) of temporomandibular joint (TMJ) arthralgia, TMD-associated headache, myofascial pain with referral, deviation of the mandible during opening (DoM), and maximal interincisal opening (MIO). At the stage of CROS treatment, evaluation of all variables adopted the individual as the unit; at the stage after LPCGF injection, the evaluation of joint sound adopted the joint as the unit, whereas the other variables adopted the individual as the unit. Among the 29 patients, 6 (20.68%) were males and 23 (79.31%) were females. Distribution by age ranged from 15 to 84 years (mean age 39.55 +/- 15.49 years). After CROS treatment, except for the joint crepitus sound, which failed to achieve significant improvement (P >0.05), other symptoms, such as DOM, TMD-associated headache, myofascial pain with referral, TMJ arthralgia, and MIO, all achieved statistically significant improvements (P < 0.05). After 2mL of LPCGF was injected once after CROS treatment, 26 joint crepitus sound symptoms were relieved (P < 0.001) after an average of 48.5 +/- 64.1 days. CROS alone can alleviate TMD clinical symptoms, except for the joint crepitus sound. Approximately 72.2% of joint crepitus sounds could be improved within 48 days, on average, once 2 mL of LPCGF was injected. Comparisons were still required in the future, with the effects of other therapeutic methods.