Aim of the study: was to compare the in vitro effect of three different root canal sealers used with gutta-percha, on the fracture resistance of endodontically treated teeth. Materials and Methods: Forty extracted human single-rooted mandibular premolars were used for the study. Teeth were decoronated to a standard root length of 14 mm. MPro rotary files up to master rotary size 25/6% were used for preparing the root canals. Teeth were randomly divided into five groups (n = 8 each) based on the type of root canal sealers used and the obturation was completed using gutta-percha; Group I: AH Plus root canal sealer, Group II: Endoseal MTA sealer, Group III: Bioroot RCS sealer, Group IV: Control-1 (prepared-unfilled) and Group V: Control-2 (unprepared-unfilled). Each specimen was embedded in acrylic mold and subjected to fracture resistance test using a universal testing machine under compressive loading at a rate of 1.0 mm/min until fracture. The force required to fracture each specimen was recorded and the data obtained were statistically analyzed (analysis of variance (ANOVA) and paired-t test) with level of significance set at p ≤ 0.05. Results: The unprepared-unfilled group showed the highest mean fracture resistance followed by AH Plus group, Bioroot RCS group, then the Endoseal MTA group. While the prepared-unfilled group showed the least mean fracture resistance. There was no statistically significant difference between all groups. Conclusion: It could be concluded that Bioroot RCS and Endoseal MTA are able to reinforce the tooth against fracture as good as AH Plus.

Aim of the study: The aim of this study was to compare the adaptation of two calcium silicatebased root canal sealers with a resin-based sealer to root canal walls at the middle and apical levels using scanning electron microscope. Material and methods: Twenty-six single-canalled lower premolars were instrumented and randomly divided into three groups according to the sealer used with gutta-percha (n=8); AH plus, Bioroot RCS, and Endoseal MTA. Two random specimens served as the blank control group to assess the smear layer removal from the dentinal walls. Teeth were sectioned at middle and apical levels and gap width was evaluated using scanning electron microscope. Data were statistically analyzed with significance level set at p ≤ 0.05. Results: At the apical and mid-root levels, the highest mean values were found in Endoseal MTA group followed by Bioroot RCS group while the lowest mean value was found in AH Plus group with statistically significant difference between all groups. Statistically significant differences were found between Endoseal MTA and each of Bioroot RCS and AH Plus groups. No statistically significant difference was found between Bioroot RCS and AH Plus groups. Conclusions: AH Plus and Bioroot RCS showed statistically better results than Endoseal MTA regarding adaptation to the root canal walls.

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Aim of the study: The aim of the present randomized clinical study was to evaluate the effect of OneShape and Protaper Next rotary system on the removal of endotoxins from teeth with asymptomatic necrotic pulp.Materials and Methods: Thirty patients were randomly allocated into two groups (n=15) according to the type of rotary system used in mechanical preparation; either Group OS (OneShape) or Group PN (Protaper Next). Samples were taken before and after mechanical preparation and quantification of endotoxins was done using Human Elisa kit. Statistical analyses were performed using Mann-Whitney U test to compare between the two groups then Wilcoxon signed-rank test was used to study the changes after treatment within each group. The significance level was set at P ≤ 0.05.Results: Group OS, showed a statistically significant reduction in endotoxins levels after treatment (P-value < 0.001, Effect size = 0.880). In Group PN, there was a statistically significant reduction in endotoxins levels after treatment (P-value <0.001, Effect size = 0.931) and Group OS showed statistically significant lower median % reduction in endotoxins level than Group PN. Conclusion:Protaper Next was more effective than the Oneshape in reducing the endotoxins from teeth with asymptomatic necrotic pulp.

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