title: Industrial noise and tooth wear - experimental study.
abstract: Tooth wear is a complex multifactorial process that involves the loss of hard dental tissue. Parafunctional habits have been mentioned as a self-destructive process caused by stress, which results in hyperactivity of masticatory muscles. Stress manifests itself through teeth grinding, leading to progressive teeth wear. The effects of continuous exposure to industrial noise, a "stressor" agent, cannot be ignored and its effects on the teeth must be evaluated.
  
  
  OBJECTIVE
  The aim of this study was to ascertain the effects of industrial noise on dental wear over time, by identifying and quantifying crown area loss.
  
  
  METHODS
  39 Wistar rats were used. Thirty rats were divided in 3 experimental groups of 10 animals each. Animals were exposed to industrial noise, rich in LFN components, for 1, 4 and 7 months, with an average weekly exposure of 40 hours (8h/day, 5 days/week with the weekends in silence). The remaining 9 animals were kept in silence. The areas of the three main cusps of the molars were measured under light microscopy.
  
  
  METHODS
  A two-way ANOVA model was applied at significance level of 5%.
  
  
  RESULTS
  The average area of the molar cusps was significantly different between exposed and non-exposed animals. The most remarkable differences occurred between month 1 and 4. The total crown loss from month 1 to month 7 was 17.3% in the control group, and 46.5% in the exposed group, and the differences between these variations were significant (p<0.001).
  
  
  CONCLUSIONS
  Our data suggest that industrial noise is an important factor in the pathogenesis of tooth wear.
authors: 1. Anatomy Department, Center for Interdisciplinary Research Egas Moniz, Health Sciences Institute, Monte de Caparica, Portugal;
authors: Maria Alzira
authors: MA
authors: Cavacas
authors: 1. Anatomy Department, Center for Interdisciplinary Research Egas Moniz, Health Sciences Institute, Monte de Caparica, Portugal;
authors: Vitor
authors: V
authors: Tavares
authors: 2. Pathology Department, Hospital Santa Maria, Lisboa, Portugal;
authors: Gonçalo
authors: G
authors: Borrecho
authors: 3. Anatomy Department, Abel Salazar Biomedical Health Institute, Porto, Portugal;
authors: Maria João
authors: MJ
authors: Oliveira
authors: 1. Anatomy Department, Center for Interdisciplinary Research Egas Moniz, Health Sciences Institute, Monte de Caparica, Portugal;
authors: Pedro
authors: P
authors: Oliveira
authors: 4. Statistics Department, Center for Interdisciplinary Research Egas Moniz, Health Sciences Institute, Monte de Caparica, Portugal.
authors: José
authors: J
authors: Brito
authors: 3. Anatomy Department, Abel Salazar Biomedical Health Institute, Porto, Portugal;
authors: Artur
authors: A
authors: Águas
authors: 1. Anatomy Department, Center for Interdisciplinary Research Egas Moniz, Health Sciences Institute, Monte de Caparica, Portugal;
authors: José Martins
authors: JM
authors: Dos Santos
mesh_terms: D000818:Animals; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000503:physiopathology*; D009622:Noise / Q000009:adverse effects*; D051381:Rats; D057085:Tooth Wear / Q000503:physiopathology*
keywords: bruxism.; industrial noise; low frequency noise; parafunctional habits; stress; tooth wear