in vivo biocompatibility of resilon compared with gutta-percha in a pre-clinical model

background: the aim of this study was to investigate in vivo biocompatibility of resilon, compared with gutta-percha, at short and long-term following implantation in a rat subcutaneous implantation model. materials and methods: male wistar rats were implanted subcutaneously with either resilon or gutta-percha or were sham controls. tissues were harvested at 8 days or 60 days after implantation and were evaluated histologically for inflammation and fibrous encapsulation. the severity of histologic injury, scored on a scale of 0-4 and quantitative analysis of the capsule wall thickness were determined for statistical analysis. data were analyzed by student t -test, one-way analysis of variance, kruskal-wallis or mann-whitney’s tests as appropriate. a value of p ≤ 0.05 was considered statistically significant. results: no behavioral changes or visible signs of physical impairment were observed at 8 days or 60 days post-implantation. histopathologic observation of the implanted sites at each timepoint showed that both resilon and gutta-percha implants induced foreign body reaction, showing minimal to mild inflammatory reactions in most cases, which diminished significantly with time. compared with gutta-percha, the capsule wall was thinner ( p > 0.05) after resilon implantation at day 8 and significantly ( p = 0.01) thicker at day 60. in addition, capsule wall thickness showed a trend to increase with time after implantation in the resilon groups ( p > 0.05), opposed to the significant decrease ( p = 0.016) observed after implantation in the gutta-percha groups, suggesting lesser long-term biocompatibility of resilon. conclusion: our findings validate resilon as an in vivo biocompatible material. however, our data suggest that long-term biocompatibility of resilon, despite validated, is inferior to that of guttapercha control. key words: endodontic materials, gutta-percha, rat, resilon, subcutaneous implantation