The Effect of Silver Nano-Irrigant and Erbium Chromium: YSGG Laser on the Smear Layer Removal and Microhardness of Root Canal Dentine "In Vitro Study"

Background: Root canal treatment involves irrigation protocols that affected both smear layer removal and microhardness of root canal dentine. Aim: Evaluate and compare the effect of using Silver Nanoparticles irrigant (AgNP), Erbium Chromium: YSGG Laser (Er;Cr: YSGG) and their combination on the removal of smear layer and microhardness of root canal dentine compared to 5.25% NaOCl and 17% EDTA. Materials and methods: Forty dentin samples from mandibular single canaled premolars were selected, where twenty samples were allocated for each assessment. For microhardness, a baseline score was gained before irrigation using Vickers microhardness tester. Samples for each assessment were randomly allocated in 4 groups (n=5): Group 1 (5.25% NaOCl + 17% EDTA), Group 2 (Er;Cr: YSGG), Group 3 (AgNP) and Group 4 (Er;Cr: YSGG + AgNP). Smear layer removal samples were examined under Environmental Scanning Electron Microscope (ESEM) at magnification 1000X to obtain a total average score out of 5 for each sample. Similarly, microhardness samples were assessed for after irrigation scores to obtain a percent change in microhardness. Results: Group 4 showed statistically significant the highest score in the amount of smear layer left behind after irrigation than 3 and 2. Groups 1 and 4 reported statistically significant less percent decrease in microhardness than groups 2 and 3. Conclusion: Neither AgNP and Er;Cr: YSGG per se nor their combination was effective in removing smear layer. AgNP and Er;Cr: YSGG per se have decreased the microhardness of root canal dentine while their combination was similar to 5.25% NaOCl and 17%EDTA.