title: Patients with myogenic temporomandibular disorders have reduced oxygen extraction in the masseter muscle.
abstract: OBJECTIVE
  The objective of the present study is to investigate if changes in the oxygen saturation of masseter muscle during a chewing task can differentiate patients with myogenic temporomandibular disorders (TMD) from healthy subjects and if these differences are related to the gravity of the disorder and to the orofacial myofunctional status.
  
  
  METHODS
  Twelve women with moderate TMD (TMD group; 37 ± 16 years) and ten healthy control women (CTRL group 24 ± 5 years) participated. Validated protocols were used to evaluate the severity of TMD and the orofacial myofunctional status. Oxygen saturation in the masseter muscle was measured using near-infrared spectroscopy (NIRS) during unilateral chewing of a silicon device. Data were compared using Student's t test, Mann-Whitney test, and Spearman's rank correlation coefficient.
  
  
  RESULTS
  The women of the TMD group showed higher total score of severity of symptoms of TMD, lower total score of the orofacial myofunctional status, and lower oxygen extraction capacity during mastication than healthy control subjects (p < 0.01). Moreover, percentage O2extraction was significantly related to the severity of signs/symptoms of TMD and of orofacial myofunctional disorders (p < 0.01).
  
  
  CONCLUSIONS
  Women with TMD had a lower muscle oxygen extraction capacity than healthy subjects: the higher the signs and symptoms' severity, the lower the O2extraction. NIRS proposes as an important instrumental method to assess the metabolic alterations in the muscles of patients with TMD.
  
  
  CONCLUSIONS
  The findings could be useful to complement clinical assessments, favoring the diagnosis and providing extra data for planning the rehabilitation of TMD patients, especially those with associated myofunctional orofacial disorders.
authors.affiliation: Department of Biomedical Sciences for Health, Functional Anatomy Research Center (FARC), Università degli Studi di Milano, via Luigi Mangiagalli 31, 20133, Milan, Italy.
authors.forename: Claudia Lúcia Pimenta
authors.initials: CLP
authors.lastname: Ferreira
authors.affiliation: Department of Biomedical Sciences for Health, Functional Anatomy Research Center (FARC), Università degli Studi di Milano, via Luigi Mangiagalli 31, 20133, Milan, Italy.|Institute of Bioimaging and Molecular Physiology, National Research Council, Segrate, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bellistri
authors.affiliation: , Parma, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Montagna
authors.affiliation: Department of Ophthalmology, Otorhinolaryngology, and Head and Neck Surgery, School of Medicine, Ribeirão Preto, Craniofacial Research Support Centre, University of São Paulo, São Paulo, Brazil.
authors.forename: Claudia Maria
authors.initials: CM
authors.lastname: de Felício
authors.affiliation: Department of Biomedical Sciences for Health, Functional Anatomy Research Center (FARC), Università degli Studi di Milano, via Luigi Mangiagalli 31, 20133, Milan, Italy. chiarella.sforza@unimi.it.|Institute of Bioimaging and Molecular Physiology, National Research Council, Segrate, Italy. chiarella.sforza@unimi.it.
authors.forename: Chiarella
authors.initials: C
authors.lastname: Sforza
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008406:Masseter Muscle / Q000378:metabolism* / Q000503:physiopathology*; D010100:Oxygen / Q000378:metabolism*; D012720:Severity of Illness Index; D019265:Spectroscopy, Near-Infrared; D013705:Temporomandibular Joint Disorders / Q000378:metabolism* / Q000503:physiopathology*
chemical_list: D010100:Oxygen
keywords: Chewing; Masseter muscle; Muscle fatigue; Near-infrared spectroscopy; Orofacial myofunctional evaluation; Temporomandibular disorders