title: Influence of the menstrual cycle on the pressure pain threshold of masticatory muscles in patients with masticatory myofascial pain.
abstract: OBJECTIVE
  The aim of this study was to investigate the influence of the menstrual cycle and oral contraceptive (OC) intake on the pressure pain threshold (PPT) of masticatory muscles in patients with masticatory myofascial pain (MFP).
  
  
  METHODS
  The sample was composed of 36 women, divided into 4 groups, according to the presence of MFP and the intake of OC (15 patients had MFP [7 taking OC] and 21 were pain-free controls [8 taking OC]). The algometer-based PPT of masseter and temporalis, and the record of subjective pain by visual analog scale (VAS) were determined during 2 consecutives menstrual cycles at 4 phases (menstrual, follicular, periovulatory, and luteal). A 3-way ANOVA for repeated measurements, Kruskal-Wallis, Friedman, and Dunn tests, with a 5% significant level analyzed the data.
  
  
  RESULTS
  PPT was significantly lower in MFP patients when compared with controls throughout the experiment (P < .001). The menstrual phases did not influence PPT (P > .05), while the intake of OC seems to raise PPT levels for the left temporalis (P = .01) and right masseter (P = .04). VAS was, in general, higher at the menstrual phase
  
  
  CONCLUSIONS
  Different phases of the menstrual cycle have no influence on PPT values, regardless of the presence of a previous condition, as masticatory myofascial pain, while the intake of OC is associated with decreased levels of reported pain.
authors.affiliation: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo Bauru, São Paulo, Brazil. valebolola@hotmail.com
authors.forename: Valeria
authors.initials: V
authors.lastname: Vignolo
authors.forename: Gabriela Modesti
authors.initials: GM
authors.lastname: Vedolin
authors.forename: Carlos Dos Reis Pereira
authors.initials: Cdos R
authors.lastname: de Araujo
authors.forename: Paulo César
authors.initials: PC
authors.lastname: Rodrigues Conti
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D003276:Contraceptives, Oral / Q000494:pharmacology; D005157:Facial Pain / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008410:Masticatory Muscles / Q000503:physiopathology*; D008597:Menstrual Cycle / Q000502:physiology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D018709:Statistics, Nonparametric; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000503:physiopathology*
chemical_list: D003276:Contraceptives, Oral