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Int J Clin Exp Pathol 2013;6(12):2697-2702

Original Article
Effects of industrial noise on circumpulpar dentin - a field emission scanning electron
microscopy and energy dispersive spectroscopy analysis

Maria Alzira Cavacas, Vitor Tavares, Maria João Oliveira, Pedro Oliveira, Ana Sezinando, José Martins dos Santos

Center for Interdisciplinary Research Egas Moniz, Health Sciences Institute, Monte de Caparica, Portugal; Department of Anatomy and UMIB of
ICBAS, Abel Salazar Institute for Biomedical Sciences, University of Porto, Porto, Portugal

Received September 10, 2013; Accepted October 21, 2013; Epub November 15, 2013; Published December 1, 2013

Abstract: Chronic exposure to Industrial Noise (IN), rich in Low Frequency Noise (LFN), causes systemic fibrotic transformation and sustained
stress. Dental wear, significantly increased with exposure to LFN, affects the teeth particularly through the circumpulpar dentin. Our goal is to
understand the consequences of IN exposure on the circumpulpar dentin of Wistar rats. 10 Wistar rats were exposed to IN for 4 months,
according to an occupationally simulated time schedule and 10 animals were used as age-matched controls. The first and the second upper
and lower molars of each animal were processed for observation by Field Emission Scanning Electron Microscopy (FESEM) and Energy
Dispersive Spectroscopy (EDS) analysis was performed. In exposed animals FESEM showed a 2.0 to 6.0 µm-dense mineral band between
dentin and the pulp with no regular continuity with the tubules. This structure had a few tubules where the odontoblasts processes could be
observed embedded within the band and collagen fibers were trapped inside. EDS analysis revealed that it was hydroxyapatite similar to
dentin, with a higher carbon content. FESEM results show that the band may be tertiary reparative dentin formed by odontoblast-like cells, but
the increased amount of carbon (EDS) could mean that it is sclerotic dentin. IN should be acknowledge as a strong stimulus, able to cause an
injury to odontoblasts and to the formation of reparative tertiary dentin, in a process that may accelerate the aging of the teeth, either by direct
impact of acoustic pressure pulsations or by increased stress and dental wear. (IJCEP1309029).

Keywords: Industrial noise, low-frequency noise, teeth, circumpulpar dentin, FESEM, EDS

Address correspondence to: Pedro Oliveira, Centro de Investigação Interdisciplinar Egas Moniz, CiiEM, Instituto Superior de Ciências da
saúde Egas Moniz, Quinta da Granja, Monte de Caparica, 2829-511 Caparica, Portugal. Tel: 00351936983136; E-mail: