Evaluation of the effect of different root canal obturation techniques using two root canal sealers on the fracture resistance of endodontically treated roots

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