Effect of different radiotherapy doses applied before and after root canal treatment on the fracture resistance of the teeth: An in vitro study

Effect of Different Radiotherapy Doses Applied Before and After Root Canal Treatment on the Fracture Resistance of the Teeth: an in vitro study This in-vitro study aimed to investigate the effect of radiotherapy (RT) dose applied before and after root canal treatment (RCT) on the fracture resistance of maxillary anterior teeth filled with AH Plus (AHP) and AH Plus Bioceramic (AHPB) root canal sealers. One hundred and ten extracted human maxillary incisor teeth were randomly divided into 5 basic groups equally (n = 22) according to the RT application time and dose: control (non-irradiated), 60 Gy before RCT, 60 Gy after RCT, 70 Gy before RCT, 70 Gy after RCT. These groups were then divided into 2 subgroups according to the root canal filling paste: AHP and AHPB. After endodontic access cavity preparation of the teeth, the root canals were prepared upto X4 with ProTaper Next files. The teeth were obturated with AHP and AHPB sealers using lateral condensation method. All these endodontic procedures were performed before irradiation procedure for the pre-RCT groups and after irradiation procedure for the post-RCT groups. The roots of the teeth were embedded in cold acrylic molds. The Universal Testing Device was used for fracture test. The force required to break the teeth was recorded in Newtons (N). t-test and ANOVA test were used for statistical analyzes. Statistical significance level was determined as p<0,05. After RT application at a dose of 70 Gy, the group filled with AHPB showed statistically significantly lower fracture strength than the group filled with AHP (p<0,05). The group that was filled with AHPB after RT application at a dose of 70 Gy caused a statistically significant lower fracture resistance than the group that was filled with AHPB before 70 Gy RT (p<0,001) and the non-irradiated and filled with AHPB group (p<0,001). There was no statistically significant difference between all other pairwise comparisons (p>0,05). It was observed that RT dose, application period and root canal filling paste had an effect on the fracture strength of the teeth.