Subcutaneous Reaction of Rat Tissues to Nanosilver Coated Gutta-Percha

Introduction: Gutta-percha (GP), is a neutral and non-toxic material. The aim of this animal study was to compare the biocompatibility of nanosilver coated GP (NS-GP) with conventional GP in subcutaneous tissues in a rat model. Methods and Materials: Conventional GP and NS-GP were subcutaneously implanted in the backs of 20 male Wistar rats (n=10). A control animal was assigned for each trial period. Ten animals were sacrificed after 7 and 30 days and light microscopic evaluation of tissue reaction to NS-GP (n=20) and conventional GP (n=20) was accomplished. The Mann-Whitney U, Wilcoxon Signed Ranks, Fisher Exact, and McNemar tests were used for statistical analysis of the data. Results: After 7 days, inflammation was moderate and mild for NS-GP and conventional GP, respectively (P<0.001). After 30 days, no inflammation was discernible in conventional GP. However, mild inflammation was reported for NS-GP (P<0.001). Regarding inflammatory cell type, there was a significant difference between two experimental groups at both times (P<0.001). Conclusion: Inflammation decreased over time in both groups. Fibrous connective tissue, a representative of healing and control of inflammatory process, surrounded both test materials. NS-GP was biocompatible and might be a reasonable endodontic obturation material.Keywords: Gutta-Percha; Inflammation; Nanosilver Coated Gutta-Percha; Subcutaneous Connective Tissue

Evaluation of push-out bond strength of AH26 sealer using MTAD and combination of NaOCl and EDTA as final irrigation

Background: During endodontic procedures, the smear layer is formed as a result of mechanical instrumentation of the canal. Combination of ethylenediamine tetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) is widely used for removal of the smear layer. Application of Mixture of tetracycline, acid, and detergent (MTAD) as final irrigant subsequent to initial irrigation of 1.35% NaOCl has been proposed to increase clinical efficiency, biocompatibility and prolonged intra-canal antibacterial activity. Considering the importance of adhesion of endodontic sealers to the dentin walls of a prepared root canal, the present study evaluated push-out bond strength of AH26 sealer using final irrigation of MTAD and EDTA + NaOCl. Materials and Methods: Sixty five single-rooted teeth were prepared endodontically with the same chemomechanical technique and were randomly divided into three groups based on their final irrigation regimen: 17% EDTA + 5.25% NaOCl group (n = 30), MTAD group (n = 30) and control group (n = 5). Obturation of the canals was performed with gutta-percha and AH26 sealer. All teeth were sectioned in order that two specimens of 1 mm thickness were obtained from the coronal and the middle one third of each root resulting in 60 specimens for each experimental group and 10 specimens for control group. For push-out test, universal-testing machine was used to exert a constant compressive apico-coronal load at a speed of 0.5 mm/min. Minimum amount of compressive load caused dislodgement was measured and converted into megapascal (MPa) scale. One-way analysis of variance and the post hoc Tukey test were used for statistical analysis of the data (α = 0.05). Results: In MTAD group, mean micro-push-out bond strength of AH26 sealer to dentin walls was obtained 2.23 MPa compared to 2.0 MPa for EDTA + NaOCl group. The mean bond strength of AH26 sealer to dentin walls was significantly greater using MTAD compared with combination of EDTA and NaOCl or saline. Conclusion: MTAD final rinse significantly increased micro-push-out bond strength of AH26 sealer to canal dentin walls compared with EDTA + NaOCl