Serum cortisol level and disc displacement disorders of the temporomandibular joint

Summary Temporomandibular disorders ( TMD ) are a significant public health problem, affecting approximately 5–12% of the population. Objectives: This retrospective cross‐sectional study investigated the relationship between 8 AM serum cortisol levels (8 ASC ) and disc displacement disorders ( DDD ) of TMD . One hundred and forty patients with DDD were recruited. Among them, 60 patients comprised the case group of disc displacement without reduction with limited opening ( DDWORWLO , age 37·7 ± 17·22), and 80 were ‘other DDD ’ for the control group (age 36·4 ± 13·08). The independent variables included domains of demography, history, malocclusion, comorbid symptoms, comorbid TMD and 8 ASC . Data were analysed with the chi‐square test, logistic regression and receiver operating characteristic ( ROC ) curve. Results of multiple logistic regression showed that 8 ASC was the only factor significantly related to DDWORWLO ( P = 0·006). Receiver operating characteristic analysis of DDWORWLO and 8 ASC indicated an area under the curve of 0·669, standard error of 0·049 and P value of 0·001. The adequate cut‐off point of 8 ASC was 12·45 (μg dL −1 ), with sensitivity of 0·636, and specificity of 0·729. 8 AM serum cortisol level can be used as a clinical clue to differentiate DDWORWLO from other DDD .