Assessment of Pain Sensitivity in Patients with Deep Bite and Sex- and Age-Matched Controls

Aims: To compare pain sensitivity between deep bite patients and a sex- and age-matched control group with normal occlusion. Methods: Pain sensitivity was assessed by injections of the excitatory amino acid glutamate into the masseter and brachioradialis muscles. Intensity of glutamate-evoked pain was scored by the subjects ( n = 60) on a 0 to 10 cm visual analog scale. Subjects drew the perceived pain area on a face and arm chart and described the quality of pain on the McGill Pain Questionnaire. Thresholds for cold detection, cold pain, cold tolerance, warmth detection, heat pain, and heat tolerance were assessed on the masseter and brachioradialis muscles. Pressure pain threshold and pain tolerance threshold were determined on the temporomandibular joint, masseter, anterior temporalis, and brachioradialis muscles. The differences between groups, age, and gender were tested by two-way ANOVA, and the significant differences were then tested for the effect of the presence of temporomandibular disorder (TMD) by linear regression. Results: Glutamate-evoked pain intensity was significantly different between groups with no gender differences. Quality of pain did not vary between groups, but significant gender-related differences were observed. Significant differences in thermal sensitivity between groups and gender were found, whereas mechanical sensitivity did not vary between groups but between genders. None of the significant differences were due to the effect of TMD. Conclusion: These data provide further evidence of gender-related differences in somatosensory sensitivity and for the first time indicate that subjects with deep bite may be more sensitive to glutamate-evoked pain and thermal stimuli. Keywords: deep bite, occlusion, orofacial pain, quantitative -sensory testing, trigeminal physiology