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Introduction: To prevent the ingress of microorganisms and their byproducts into root canal space is the primary goal of obturation. Endodontically treated teeth are weak and more susceptible to fracture than vital teeth. Therefore, to increase the strength of the root canal and increase root fracture resistance by adhesion and mechanically interlocking root canal filling material with radicular dentin is also one of the goal of obturation. Aim: To evaluate and compare the fracture resistance of mandibular premolar canals filled with four different obturation techniques. Materials and Methods: The in vitro study was undertaken at Department of Conservative Dentistry and Endodontics, Krishna Institute of Medical Sciences Deemed To Be University, Karad, Maharshtra, India, from August 2020 to December 2020. Hundred extracted human mandibular premolars with single canals were collected for the study and sectioned horizontally to obtain a standardised length of 14 mm. With the help of 15 K-file (Dentsply) working length was determined and root canals were prepared to an ISO size 45 file at the apex and flared using a # 4 Gates-Glidden drill (Mani, Japan). The teeth were then randomly divided into four experimental groups, Group I-Lateral condensation, Group II-ROEKO GuttaFlow® bioseal, Group IIIGuttacore, Group IV-Thermoplasticised gutta percha (System B) and two control groups, they were Group V-(Negative control), instrumentation was done, but no obturation, Group VI-(Positive control), teeth were neither instrumented nor obturated. All the experimental teeth were filled as per the obturation technique. A universal testing machine was used for evaluating fracture resistance. The results were analysed using the One-way ANOVA test. The significance between the groups was tested with Scheffe's post-hoc test. Results: There were statistically significant difference among six group for mean fracture load (N) with p-value<0.001. furthermore, pair wise comparison of fracture load (N) showed that the mean difference is significant at p-value<0.05. The mean difference between Group IV and V is not significant (p-value=0.935) Conclusion: Under the limitation of this study, it was concluded that the resistance of the root to vertical fracture amongst the experimental group was maximum in Group III (Guttacore) and minimum in Group IV (Thermoplasticised gutta-percha, System B). [ABSTRACT FROM AUTHOR]

Statement of the Problem The efficacy of various decontamination protocols to reverse the effect of blood contamination after acid-etching may depend on the type of adhesive. Objectives To compare the effect of blood contamination and various decontamination protocols on acetone-based and ethanol-based total-etch adhesive systems. Methods Occlusal dentin of 64 human molars was etched and contaminated with fresh human blood. The samples were assigned to two groups as per adhesive used: Prime & Bond NT (acetone-based) and Adper Single Bond 2 (ethanol-based) and then subdivided into eight groups: (1) control, (2) no decontamination, (3) water rinsing, (4) re-etching, (5) sodium hypochlorite, (6) sodium hypochlorite/sodium ascorbate, (7) hydrogen peroxide, and (8) ethanol. Adhesives were applied and specimens were prepared for μTBS after composite buildup. The data were subjected to analysis of variance followed by post hoc Tukey test. Results Blood contamination significantly reduced μTBS of both the adhesives. Re-etching and NaOCl/Asc were effective in restoring μTBS to the level of control for both the adhesives whereas NaOCl was effective only for Prime & Bond NT. Conclusion Both re-etching and NaOCl can be used for regaining μ TBS of blood-contaminated acid-etched dentin. NaOCl/Asc yields better results than NaOCl alone, specifically for ethanol-based adhesive. Clinical Significance Knowing the adverse effects of prolonged acid-etching, other alternatives for decontamination of etched dentin after blood contamination should be considered. NaOCl alone or NaOCl followed by sodium ascorbate may prove to be good alternatives. These choices also may determine the type of adhesive system. [ABSTRACT FROM AUTHOR]