Histopathological consequences of hyperzincemia on rat teeth. Experimental study.

The aim of this study was to investigate the histopathological features of dental pulp in acute zinc (Zn) intoxication and to identify possible physiopathological mechanisms of the lesions. Twelve adult male Wistar rats were divided into two groups, the control one and the exposed group. Each animal from the experimental group received a single dose of zinc chloride (ZnCl2) by intraperitoneal injection. Blood samples were collected from exposed animals at 2, 4, and 6 hours after the injection and plasma Zn concentrations were determined by spectrophotometry. After six hours of observation, the animals were sacrificed and two teeth from every rat were removed. Twelve teeth were processed by standard histological technique using Hematoxylin-Eosin (HE) and Szekely trichrome stainings, and the other twelve were subjected to Schliff cutting-grinding technique. The experimental group showed increased plasma zinc concentration (0.46±0.06 mg÷L) after two hours and then slightly decreasing values in the next four hours. Undecalcified teeth did not showed any changing into the dentin or enamel structures, but decalcified teeth revealed numerous deposits into the dental pulp, which consisted of red acellular superposed sediments that could be made up of zinc with some plasma protein, or there could be an unknown compound which precipitated under the influence of zinc cation (Zn2+). We can presume that the dental pulp may be an elective place for zinc accretion and so it must be considered a potential target for this metal.