الفهرس 
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Abstract
Objective: The present study aims to evaluate the antibacterial efficiency of 980 nm diode laser agitation and bioceramic root canal sealer (BioRoot RCS) on Enterococcus faecalis biofilm in the infected root canal as well as the efficiency of 980 nm diode laser agitation on BioRoot sealer penetration into the dentinal tubules. Methodology: One hundred and fifteen upper central incisors were cleaned mechanically prepared by protaper system, then divided into two main parts: Part I to evaluate the antibacterial efficiency of 980 nm diode laser agitation and bioceramic root canal sealer (BioRoot RCS) on Enterococcus faecalis biofilm in the infected root canal. Seventy five sample contaminated with E. faecalis biofilm, Five of them were randomly selected as a control group to check the formation of biofilm then the residual seventy samples were divided into equal five groups (n=14) according to the agitation protocol: (Group1) BioRoot sealer without agitation, (Group2) NaOCl agitated by side vented needle (SVN), (group 3) NaOCl agitated by side vented needle + BioRoot RCS, (group 4) NaOCl agitated by 980 nm diode laser, and (group 5) NaOCl agitated by 980 nm diode laser + BioRoot RCS, then the antibacterial efficiency was evaluated by colony forming units, and relative intensity of live/dead bacteria, using Confocal Laser Scanning Microscopy, and, Part II: evaluation the efficiency of 980 nm diode laser agitation on the BioRoot sealer penetration into dentinal tubules. Forty samples were irrigated with 3 ml of 17٪ EDTA, 3 ml of 2.5٪ NaOCl to remove the smear layer, then samples divided into two equal groups according to the agitation method used for smear layer removal (n= 20): Group1(SVN agitation) irrigant were agitated with side vented needle; group 2 (diode agitation) irrigant was agitated with 980 nm diode laser, then all the samples were obturated by using the single cone technique. Finally, these samples were sectioned at 3, 7and 12 mm from the apex by 0.5- mm-thick precision diamond saw before examination by Confocal laser scanning microscopy and stereomicroscope to detect the penetration depth of sealer into dentinal tubules. Data were analyzed by proper statistical analysis with P ≤ 0.05. Results: E. faecalis reduction was significantly better in all the experimental groups than in the control group (p value < 0.001). However, the highest bacterial reduction was achieved with the combined effect of diode laser agitation with the BioRoot RCS. Regarding the BioRoot RCS penetration there were no statistical significant difference between the diode and SVN agitation group at 12 mm, However the BioRoot RCS penetration increased significantly at 3 and 7 mm from the apex in the diode agitation group than the side vented needle one. Conclusion: Although both of diode laser agitation, BioRoot RCS exert antibacterial activity against E. faecalis, their combination is more effective in E. faecalis reduction. Additionally, diode laser agitation supported a better quality of the endodontic filling material with increasing the penetration depth of the sealer into the dentinal tubules at apical, middle and coronal one third.