Tissue Response to a Heat Resistant Silicate-Based and an Epoxy Resin-Based Endodontic Sealer Implanted in Rat Tibias

Introduction: The effect of high temperatures on the properties of endodontic sealers during warm compaction of gutta-percha may be a matter of concern. This study aimed to evaluate the effect of heat on the biocompatibility and bioactivity of EndoSequence BC Sealer HiFlow (ESHF; Brasseler, Savannah, GA, USA) and AH Plus (AHPS; Dentsply, De Trey, Konstanz, Germany) when implanted into the bone tissue of rat tibias. Methods: Medical-grade silicone tubes containing freshly prepared ESHF or AHPS were heated to 100 °C and then cooled down to 65 °C before being implanted in the tibias of 24 Wistar rats. The outer walls of the tubes served as controls. After 10, 30 and 90 days, the animals were euthanized and the implants and their surrounding tissues were dissected, fixed in formalin, and processed for microscopic evaluation. Results: After 10 days postoperatively, a severe inflammatory reaction without reactionary bone formation was observed in contact with ESHF and AHPS. The severity of the reaction had decreased at the 30-day observation period for both sealers but only ESHF samples showed new bone formation adjacent to the sealer. After 90 days, no inflammatory cells were found in contact with ESHF, while a thin fibrous tissue capsule and complete bone reparation of the surrounding areas were observed in contact with the material. For AH Plus, a fibrous connective tissue containing scarce remaining inflammatory cells could be observed in most of the samples, however, in the absence of new bone formation. No significant differences (p > 0.05) between ESHF and AHPS were found at the 10-day observation period. At the 30 and 90-day, significant differences (p < 0.05) between both materials were observed. The reaction to the controls showed significant differences with ESHF and AHPS for all experimental periods. Significant differences (p < 0.05) for the total effect of time were also found between both sealers (p < 0.05). Conclusions: At the end of the experiment, heated ESHF reacted as a biocompatible/bioactive material and stimulated continued development of new healthy bone. Although AHPS was tolerated well by the surrounding tissues, the sealer did not promote new reparative bone formation.