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The aim of this study was to make a comparison between the cyclic fatigue (CF) resistance of F360, twisted files (TF), FlexMaster (FM) and RaCE instruments with 4% taper. A total of 40 instruments were evaluated 8 mm from the tip. A stainless steel block with a simulated canal of 1.5 mm diameter, and a 60° angle of curvature was tested using CF testing. One-way ANOVA and posthoc Tukey's test (P 0.05). F360 instruments with a double S cross-section had the highest CF resistance among the group. The TF led the NiTi rotary files to be more resistant to fatigue than the FM and RaCE instruments.

Aim: The aim of this study was to compare the fracture resistance of teeth filled with AH Plus and MTA Fillapex root canal sealers by using different root canal obturation techniques. Materials and Methods: One hundred and twenty pieces of single-rooted-and-canalled mandibular premolar teeth were selected. After the crowns were removed from the cemento-enamel junction, they were divided into 10 groups (n = 12). All the root canals except for the Group 1 were shaped until F4 file with ProTaper Nickel- Titanyum (Ni-Ti) rotary system. Group 1: was not instrumented. Group 2: the root canals were shaped but not filled. Group 3: roots were filled with cold lateral condensation technique (CLC) by using AH Plus. Group 4: roots were filled with CLC by using MTA Fillapex. Group 5: roots were filled with single cone technique by using AH Plus. Group 6: roots were filled with single cone technique by using MTA Fillapex. Group 7: roots were filled with AH Plus by using vertical compaction method with continuous heat. Group 8: roots were filled with MTA Fillapex by using vertical compaction method with continuous heat. Group 9: roots were filled with AH Plus by using thermoplastic core carrier method. Group 10: roots were filled with MTA Fillapex by using thermoplastic core carrier method. Before embedding the samples in acrylic resin after standing in an oven at 37°C for 2 weeks for the hardening of the root canal sealers the 5 mm apical portion of the roots were immersed in wax in order to imitate the surrounding tissues. Polyvinyl siloxane impression material was used for the samples which were embedded in acrylic resin in a way that the coronal 8 mm remained outside in order to imitate the periodontal ligament. Lateral force was applied to the samples with 1 mm/min speed in the Universal Tester. The maximum force values (F-max) which cause fractures in the examples were determined and the results were subjected to statistical evaluation by using one-way Anova and Tukey HSD tests with the significance set at (P

The aim of this study was to make a comparison between the cyclic fatigue (CF) resistance of F360, twisted files (TF), FlexMaster (FM) and RaCE instruments with 4% taper. A total of 40 instruments were evaluated 8 mm from the tip. A stainless steel block with a simulated canal of 1.5 mm diameter, and a 60° angle of curvature was tested using CF testing. One-way ANOVA and posthoc Tukey's test (P0.05) were used. The F 360 files showed the highest CF resistance while the TF files had greater CF resistance than the FM and RaCE (P0.05). There was no significant difference between the FM and RaCE (P0.05). F360 instruments with a double S cross-section had the highest CF resistance among the group. The TF led the NiTi rotary files to be more resistant to fatigue than the FM and RaCE instruments.

The aim of this study was to compare the fracture resistance of teeth filled with AH Plus and MTA Fillapex root canal sealers by using different root canal obturation techniques.One hundred and twenty pieces of single-rooted-and-canalled mandibular premolar teeth were selected. After the crowns were removed from the cemento-enamel junction, they were divided into 10 groups (n = 12). All the root canals except for the Group 1 were shaped until F4 file with ProTaper Nickel- Titanyum (Ni-Ti) rotary system. Group 1: was not instrumented. Group 2: the root canals were shaped but not filled. Group 3: roots were filled with cold lateral condensation technique (CLC) by using AH Plus. Group 4: roots were filled with CLC by using MTA Fillapex. Group 5: roots were filled with single cone technique by using AH Plus. Group 6: roots were filled with single cone technique by using MTA Fillapex. Group 7: roots were filled with AH Plus by using vertical compaction method with continuous heat. Group 8: roots were filled with MTA Fillapex by using vertical compaction method with continuous heat. Group 9: roots were filled with AH Plus by using thermoplastic core carrier method. Group 10: roots were filled with MTA Fillapex by using thermoplastic core carrier method. Before embedding the samples in acrylic resin after standing in an oven at 37°C for 2 weeks for the hardening of the root canal sealers the 5 mm apical portion of the roots were immersed in wax in order to imitate the surrounding tissues. Polyvinyl siloxane impression material was used for the samples which were embedded in acrylic resin in a way that the coronal 8 mm remained outside in order to imitate the periodontal ligament. Lateral force was applied to the samples with 1 mm/min speed in the Universal Tester. The maximum force values (F-max) which cause fractures in the examples were determined and the results were subjected to statistical evaluation by using one-way Anova and Tukey HSD tests with the significance set at (P 0.05).The control group showed the maximum fracture resistance (P 0.05). Thermafil group showed higher fracture resistance than single cone technique, cold lateral condensation technique, and system B (P 0.05).It was concluded that shaping and widening of the root canals reduced the fracture resistance of teeth while Thermafil increased the resistance of roots against fracture.