Does the ovarian cycle influence the pressure-pain threshold of the masticatory muscles in symptom-free women?

Aims: To test the hypothesis that the ovarian cycle influences the pressure -pain threshold of the masticatory muscles. Methods: Eighteen healthy women with a regular menstrual cycle (28 +/- 2 days), ranging in age from 18 to 35 years, participated in the study. For each subject, pressure-pain thresh olds (PPTs) of the masseter and temporalis muscles were assessed at 4 muscu lar sites by means of an electronic algometer. Measurements were taken at 4 separate sessions across the menstrual cycle corresponding to the followin g phases: menstrual, follicular, periovulatory, and luteal. Menstrual cycle phases were determined by a pelvic ultrasonographic screening. The study w as carried out in a single-blind design, and the initial session was random ly determined for each individual. Data collected were analyzed by repeated -measures analysis of variance. Results: The findings suggest that the PPTs of several masticatory muscles (2 of 4) are influenced by the ovarian cycl e, but to a minor extent (P < 0.05), and the influence is of limited clinic al relevance. Conclusion: In healthy subjects, there is a link between mech anical sensitivity of the masticatory muscles and fluctuation of the ovaria n hormones. The relationship between PPTs of the masticatory muscles and th e ovarian cycle should be also investigated in patients with temporomandibu lar disorders and/or orofacial pain conditions.