Prevalence of articular disc displacement among Thai TMD patients: a retrospective study on the association with demographic and clinical characteristics.

BACKGROUND

Disc displacement (DD) is among the most prevalent intra-articular temporomandibular disorders. Identifying associated factors can support early diagnosis and management. The objective of this study was to evaluate the relationship between disc conditions and patient demographics and clinical characteristics.

METHODS

This retrospective study analyzed 770 patient records collected from 2021 to 2025 using data extracted from the hospital's digital system. Variables included demographic information, behavioral habits, occlusal characteristics, clinical findings, and temporomandibular joint (TMJ) diagnoses. Statistical analyses were performed using descriptive statistics, chi-square tests, independent t-tests, one-way analysis of variance, and binary logistic regression, with significance set at p < 0.05.

RESULTS

DD was diagnosed with 420 patients (54.5%). DD patients were significantly younger (mean 39.0 years, p < 0.001), predominantly in the 21-40 age group (p = 0.002), and more often female (72.0%, p < 0.001). Behavioral habits such as resting the chin on the hand (p < 0.001) and previous orthodontic treatment (p = 0.010) were more prevalent in the DD group. Occlusal characteristics, including overjet, overbite, midline deviation, and occlusal scheme, showed no significant association with DD. However, DD patients exhibited reduced posterior and total static articulation (p < 0.05), as well as decreased working contacts and increased non-working contacts during the right excursion. The distribution of TMJ clicking and disc diagnoses was comparable between the left and right sides. More advanced subtypes of DD were linked to younger age, female sex, reduced mouth opening capacity, and greater mandibular deviation.

CONCLUSIONS

DD was associated with demographic and behavioral factors, particularly younger age, female sex, and certain oral habits. Functional occlusal contacts were also found to be associated with an increased likelihood of DD. Comprehensive assessment is essential for diagnosis and management.