ObjectivesThe aim of this study was to use four sets of success criteria to evaluate the outcomes of arthrocentesis treatment with hyaluronic acid injection in patients with internal derangement (ID) of the temporomandibular joint (TMJ).Materials and MethodsThe study included 40 patients diagnosed with unilateral Wilkes stage III TMJ dysfunction. Clinical parameters, including maximum mouth opening (MMO) and pain during function, were evaluated preoperatively, 6 months, and 1 year after TMJ arthrocentesis. Outcomes were assessed and compared using four sets of success criteria from the following: the American Association of Oral and Maxillofacial Surgeons (AAOMS; MMO ≥35 mm and visual analogue scale [VAS] score ≤3), Murakami et al.'s criteria (MMO >38 mm and VAS score <2), Emshoff and Rudisch criteria (MMO ≥35 mm and >50% pain reduction), and patient self-reports (self-evaluation of treatment as successful or unsuccessful).ResultsSignificant improvements in MMO and pain reduction during function were observed between the preoperative period and 6 months and 1 year postoperatively (P<0.01). The success rates of treatment determined using AAOMS (52.5%), Emshoff and Rudisch criteria (57.5%), and self-reported patient criteria (40.0%) were similar. Application of the Murakami et al. criteria reported the lowest success rate (12.5%).ConclusionThe AAOMS and Emshoff and Rudisch criteria are consistent with patient expectations and can be used to assess treatment efficacy.