title: Mandibular movement during sleep bruxism associated with current tooth attrition.
abstract: METHODS
  Observation of attrition patterns suggests that mandibular movement in sleep bruxism (SB) may be associated with current tooth attrition. The aim of this study was to confirm this phenomenon by investigating mandibular movement and masseter muscle activity. The subject was a healthy 21-year-old Japanese male. We recorded biological signals including mandibular movement and masseter electromyograms (EMGs) with a polysomnograph. Based on the EMG using Okura's criteria, SB events were classified into clenching, grinding and mixed types according to mandibular movement criteria. The close-open mandibular movement cycles (CO-cycles) during grinding and mixed type events were selected based on mandibular movement trajectories.
  
  
  CONCLUSIONS
  Fifty-eight CO-cycles were selected in seven grinding and three mixed types. We found that SB mandibular movements associated with current tooth attrition. Excessive lateral movements (ELM) beyond the canine edge-to-edge position were observed in the closing (10.3%) and opening (13.8%) phases of the CO-cycle. Total masseter muscle activity was significantly higher during voluntary grinding (VGR) than during CO-cycle including ELM (working side: P=0.036, balancing side: P=0.025). However, in the middle and late parts of the opening phase, working side masseter muscle activity was significantly higher during CO-cycle including ELM than during VGR (P=0.012). In the early part of the closing phase, balancing side masseter muscle activity was significantly higher during CO-cycle including ELM than during VGR (P=0.017).
  
  
  CONCLUSIONS
  These findings suggest that excessive forceful grinding during ongoing SB events may have caused canine attrition in this patient.
authors.affiliation: Department of Stomatognathic Function and Occlusal Reconstruction, Subdivision of Clinical Dentistry, Division of Oral Science, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Tokushima, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Okura
authors.affiliation: Department of Stomatognathic Function and Occlusal Reconstruction, Subdivision of Clinical Dentistry, Division of Oral Science, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Tokushima, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Shigemoto
authors.affiliation: Department of Stomatognathic Function and Occlusal Reconstruction, Subdivision of Clinical Dentistry, Division of Oral Science, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Tokushima, Japan; Faculté de Médecine Dentaire, Université de Montréal, CP 6128, succ. Centre-ville, Montréal, Québec H3 C 3J7, Canada.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Department of Oral Treatment and Clinical Education, Tokushima University Hospital, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Tokushima, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Noguchi
authors.affiliation: Department of Stomatognathic Function and Occlusal Reconstruction, Subdivision of Clinical Dentistry, Division of Oral Science, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Tokushima, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Omoto
authors.affiliation: Department of Oral Treatment and Clinical Education, Tokushima University Hospital, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Tokushima, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Abe
authors.affiliation: Department of Stomatognathic Function and Occlusal Reconstruction, Subdivision of Clinical Dentistry, Division of Oral Science, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Tokushima, Japan. Electronic address: matsuka@tokushima-u.ac.jp.
authors.forename: Yoshizo
authors.initials: Y
authors.lastname: Matsuka
mesh_terms: D004576:Electromyography; D006801:Humans; D008297:Male; D008334:Mandible / Q000503:physiopathology*; D008406:Masseter Muscle / Q000503:physiopathology; D009068:Movement; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*; D020186:Sleep Bruxism / Q000150:complications* / Q000503:physiopathology*; D019217:Tooth Attrition / Q000209:etiology*; D055815:Young Adult
keywords: Canine attrition; Mandibular movement; Masseter muscle activity; Sleep bruxism; Tooth grinding