title: Effects of changes in vertical occlusal dimension on heart rate fluctuations in guinea pigs.
abstract: BACKGROUND
  We have previously reported that the decrease of the vertical occlusal dimension (VOD) led to heart failure and abnormalities in creatine phosphokinase (CPK) in guinea pigs. In the present study, we investigated the autonomic activity and the origin of the abnormality in CPK under different occlusal conditions.
  
  
  METHODS
  Guinea pigs were separated into the following five groups: untreated control, reduced VOD, slit, restored VOD and increased VOD groups and compared for their electrocardiogram and heart rate fluctuations for two weeks using Fluclet, computer software.
  
  
  RESULTS
  The control group revealed no changes in heart rate fluctuations or posture. The reduced VOD group exhibited a two-phase wave of heart rate fluctuations, with the first peak 0-2 days after teeth grinding, and the second peak starting from 4 days after teeth grinding until sudden death (usually 12th day), accompanied by head drop. The slit and the restored VOD groups exhibited only the first peak. The increased VOD group, with approximately 3 mm-thick acrylic pellets bonded to the posterior teeth, showed no heart rate fluctuations. Body weight loss was most prominent in the reduced VOD group, and became much milder in the order of increased VOD, restored and slit groups. The reduced VOD group exhibited transient elevation of skeletal muscle type of CPK isozyme activity within two days after treatment.
  
  
  CONCLUSIONS
  The present study suggests that the first peak of heart rate fluctuations is caused by pulpal stimulation, and the second peak by excessive contraction (excessive excitation of the motor output system and the autonomic nervous system) of the masticatory muscles. On the other hand, increased VOD did not influence either the motor or the autonomic nervous system.
authors.affiliation: Division of Oral Health in Aging and Fixed Prosthodontics, Department of Oral Health Science, Course for Oral Life Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Taga
authors.forename: Yukio
authors.initials: Y
authors.lastname: Azuma
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Maehara
authors.forename: Shuichi
authors.initials: S
authors.lastname: Nomura
mesh_terms: D000818:Animals; D001259:Ataxia / Q000209:etiology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D015415:Biomarkers; D003402:Creatine Kinase / Q000097:blood; D016757:Death, Sudden, Cardiac; D003782:Dental Pulp / Q000293:injuries* / Q000294:innervation / Q000503:physiopathology; D004562:Electrocardiography; D006168:Guinea Pigs / Q000502:physiology*; D006329:Heart Conduction System / Q000503:physiopathology; D006333:Heart Failure / Q000209:etiology* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D008310:Malocclusion / Q000150:complications* / Q000503:physiopathology; D008410:Masticatory Muscles / Q000294:innervation / Q000503:physiopathology*; D014630:Vagus Nerve / Q000503:physiopathology; D014716:Vertical Dimension; D015431:Weight Loss
chemical_list: D015415:Biomarkers; D003402:Creatine Kinase