Clinical factors affecting the outcome of occlusal splint therapy of temporomandibular joint disorders.

The purpose of this study was to test the hypothesis that (1) the presence of a clinical temporomandibular joint-related disorder has effects on short-term changes in temporomandibular joint pain, and that (2) clinical variables of time since pain onset predict treatment outcomes of occlusal splint therapy. The study comprised 76 patients with unilateral temporomandibular joint pain. The clinical disorder subgroup included 47 patients with a clinical pain side-related diagnosis of internal derangement type I (n = 16), internal derangement type III (n = 19), and degenerative joint disease (n = 12). The clinical non-disorder subgroup consisted of 29 patients without a temporomandibular joint disorder. A logistic regression analysis was used to compute the odds ratio for the clinical variables of time since pain onset, adjusted for age, gender, pretreatment pain level, and clinical subgroup. For the temporomandibular joint pain measurements there was no significant 'session'/'clinical subgroup' interaction (P = 0.470). Significant increase in benefit of a successful outcome of 'pain reduction >70%' occurred with a time since pain onset of <or=6 months (15.1 odds ratio) (P = 0.003). The odds ratio that a patient with a time since pain onset of >2 years might belong to the unsuccessful treatment group of 'pain reduction <30%' was strong (6.0) and significant (P = 0.026). Diagnosis of temporomandibular joint disorder proved not to be linked to changes in therapeutic outcome measures of temporomandibular joint pain. Time since pain onset was an important prognostic determinant of successful occlusal splint therapy.