Low frequency noise effects on the periodontium of the Wistar rat - A light microscopy study

Long-term low-frequency noise (LFN) (≤500Hz, infrasound included) exposure is known to cause extracellular matrix proliferation with fibrosis, in the absence of inflammatory signs. The aim of this work was to study the morphological alterations to the periodontium of Wistar rats exposed to LFN. 10 rats were exposed to LFN for 2184 consecutive hours and another 10 were kept in silence. The mandibles were removed, kept in 10% buffered formalin, sectioned sagitally, stained with haematoxylin-eosin (HE) and Masson's trichromic solution (TCM) and observed with light microscopy (LM). The results revealed a disappearance of the cementum, irregular erosion of surface alveolar bone, and signs of bone necrosis, with detached bone particles. The periodontal ligament was disorganized and had deficient anchorage of the fibers. These findings may be due to a direct effect of noise and vibration impinging on the structures, to stress, to vascular alterations or to a combination of these factors. They may also explain the alterations in alveolar bone, reported by other authors.