Morphological study of the pulp of Wistar rats molars under experimental occlusal interference

Abstract

Pulpal morphological alterations in mandibular molars of rats, resulting from an experimental external stimulus (occlusal interference), were studied using light microscopy. We placed amalgam restorations in supraocclusion in the right superior first molars of 10 Wistar rats divided into three groups, which were sacrificed by transcardiac perfusion with 10% formalin, after 10, 20 and 30 days. The evaluation of the right (experimental side) and left (control side) inferior molars was made after decalcification of the bony specimens with EDTA solution associated with microwaves, followed by routine histologic technique and staining with HE and Mallory’s Trichrome. On the control side, an intense reaction characterized by an atypical positioning of the odontoblasts was observed, followed by the appearance of pulp stones and, subsequently, by an apparent and uniform accommodation of the tissue in the whole pulp, with moderate incidence of collagenous fibers. On the experimental side, the alterations were similar, but they apparently increased with time, specially after 30 days, when the histologic image was similar to that of the control side after 10 days. We can conclude that the occlusal interference induces alterations in the pulpal connective tissue both on the experimental side and on the control side, and they are proportional to the direction of the mandibular movements.