Beyond the bite: canine guidance and psychological factors in TMDs

OBJECTIVES: To evaluate the association between canine guidance, psychological factors, and temporomandibular disorders (TMDs) by comparing patients with painful TMDs, patients with non-painful TMDs, and healthy individuals. The study examined right, left, and bilateral canine guidance and the relationship between psychological status and diagnostic group within the current biopsychosocial framework of TMDs.

MATERIALS AND METHODS: A cross-sectional study was conducted on 152 participants recruited at the Orofacial Pain Unit and the School of Dentistry of the University of Siena between November 2025 and June 2026. Participants were divided into three groups: 58 patients with painful TMDs, 40 with non-painful TMDs, and 54 healthy individuals. TMD diagnoses were established according to the RDC/TMD criteria. Canine guidance was assessed bilaterally during mandibular lateral movements by two calibrated operators blinded to TMD diagnosis. Psychological status was evaluated using the Hamilton Anxiety Rating Scale (HAM-A) and Hamilton Depression Rating Scale (HAM-D), and participants were classified according to the presence or absence of the corresponding psychological traits. Between- group differences were analyzed using chi-square tests, with statistical significance set at p <0.05.

RESULTS: Mean age was similar across the three groups, whereas females were more prevalent in the painful TMD group. Inter-operator agreement for occlusal assessment was high (97–100%). No statistically significant association was found between diagnostic group and canine guidance. Left canine guidance was present in 36.2% of patients with painful TMDs, 40.0% of patients with non-painful TMDs, and 50.0% of healthy individuals (p = 0.320). Similarly, no significant differences were observed for right canine guidance (34.5%, 47.5%, and 46.3%; p = 0.325) or bilateral canine guidance (44.8%, 57.5%, and 59.3%; p = 0.256). In contrast, psychological factors were significantly associated with diagnostic group. Depressive traits were more frequent in patients with painful TMDs (p <0.001; Cramer’s V = 0.341), with significant differences compared with both non-painful TMD patients and healthy individuals.
Anxiety was also associated with diagnostic group (p = 0.001; Cramer’s V = 0.297), with higher values in patients with painful TMDs and a significant difference between painful and non-painful TMD groups.

CONCLUSIONS: The presence or absence of canine guidance does not appear to distinguish patients with painful or non-painful TMDs from healthy individuals. In contrast, anxiety and depression show a stronger association with TMDs, particularly painful forms. These findings support a biopsychosocial interpretation of TMDs and further question the etiological relevance traditionally attributed to specific occlusal schemes. However, the cross-sectional design does not allow causal relationships to be established.

CLINICAL SIGNIFICANCE: Creating or restoring canine guidance through occlusal, orthodontic, or prosthodontic procedures does not appear justified as a strategy to prevent or treat TMDs on the basis of the present findings. Clinical assessment should focus on pain, functional limitations, oral behaviors, and the patient’s psychological context, favoring conservative and symptom-oriented management. In the absence of pain or functional impairment, non-painful findings should not automatically constitute an indication for treatment.

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