Biological Compatibility of the Endodontic Paste Prepared with Tetracycline, Thiamphenicol and Zinc Oxide Implanted on the Subcutaneous Tissue of Rats

An important requirement for endodontic paste with antibiotics placed in direct contact with living tissues is biocompatibility. The aim of this study was to evaluate the paste biocompatibility prepared with zinc oxide (1.25mg), tetracycline (8mg) and thiamphenicol (26.67mg). The paste and its components were implanted separately through polyethylene sterile tubes of 10mm in length and 1.3mm in diameter, in the subcutaneous tissue of rats with the experiment control at intervals of 3, 7, 15 and 30 days. Each day 6 rats were used, being 3 of them with implant of the substances in four sites placed on the back of the animals and 3 sham animals where it was implanted the polyethylene empty tubes. The experimental animals were anesthetized in an intra-peritoneal way with ketamina and xilazina (0.75ml / g body weight). After the experimental periods, the animals were anesthetized with the same anesthetic overdose. It was held an excision biopsy of the implant area with 10 mm to the security limit included in paraffin following a plan of random histological cut and uniformly isotropic or oriented cuts according to stereological principles, getting a statistical estimative of the relative amount of inflammatory cells or not on the test system, getting as a result the paste biocompatibility, being the zinc oxide the most toxic element for the cell quality found.