Evaluation of the effects of traditional irrigation solutions and different uses of etidronic acid on the bond strength of bioceramic and resin-based sealers

Success in root canal treatment is associated with biomechanical shaping and a hermetic root canal filling. While many irrigation solutions are used in clinics for irrigation of root canals, many alternative root canal filling materials are available for hermetic root canal filling. The aim of this study was to evaluate the effect of EDTA and HEDP solutions used during irrigation of root canals on the bond strength of epoxy resin based AH Plus sealer and calcium silicate based EndoSequence BC Sealer HiFlow. In the study, 152 lower premolar human teeth were used. Root lengths of 16 mm were separated from the enamel-cementum boundary. The root canals were shaped using the ProTaper Next Ni-Ti rotary file system. Then, the sample teeth were divided into 4 main groups according to the final irrigation protocol to be used, with 38 teeth in each group: Group 1: NaOCl, EDTA ; Group 2: NaOCl, HEDP (distilled water) ; Group 3: HEDP (NaOCl) ; Group 4: NaOCl. After irrigation of all main groups was completed by applying the appropriate procedure for that group, 2 teeth from each main group were separated for examination of the smear layer by scanning electron microscopy (SEM). The remaining 36 teeth in each main group were divided into 2 subgroups (n=18) to be filled by using AH Plus sealer and BC Sealer HiFlow and warm vertical root canal filling method: Group 1a: NaOCl, EDTA + AH Plus; Group 1b: NaOCl, EDTA + BC Sealer HiFlow ; Group 2a: NaOCl, HEDP (Distilled water) + AH Plus ; Group 2b: NaOCl, HEDP (Distilled water) + BC Sealer HiFlow ; Group 3a: HEDP (NaOCl) + AH Plus ; Group 3b: HEDP (NaOCl) + BC Sealer HiFlow ; Group 4a: NaOCl + AH Plus ; Group 4b: NaOCl + BC Sealer HiFlow. After the root canal filling procedures were completed, the teeth were kept at 37 0C in 100% humid environment for 1 week. Then, three horizontal sections of 1 mm (± 0.1 mm) thickness were obtained from each specimen from the apical centre and coronal side. The specimens were placed in the Instron, a universal testing machine, and the thrust force was applied at a constant speed of 1mm/min until failure occurred at the junction between the root canal filling and dentin. The failure forces were recorded in Newtons (N) using Nexygen data analysis software and the bond strength was calculated by converting to megapascals (MPa). Then, the dentin discs with push out measurements were examined under stereomicroscope and the failure types were evaluated. Statistically significant differences were observed between all groups in terms of push-out averages (p=0,0001). The push-out averages of NaOCl, EDTA group were statistically significantly higher than NaOCl, HEDP; HEDP (NaOCl) and NaOCl groups (p=0,0001). The push-out averages of NaOCl group were statistically significantly lower than NaOCl, HEDP and HEDP (NaOCl) groups (p=0,0001). No statistically significant difference was observed between the push out averages of AH Plus Sealer and BC Sealer HiFlow groups (p=0,883). A statistically significant difference was observed between the push out averages of the coronal, middle and apical regions (p=0,0001) and the push out averages of the apical region were statistically significantly higher than the coronal and middle regions (p=0,0001). The push out averages of the middle region were also statistically significantly higher than the coronal region (p=0,0001). Push-out measurements of the discs were examined under stereomicroscope and failure types were evaluated. Cohesive failure was found to be high in NaOCl, EDTA, NaOCl, HEDP and HEDP (NaOCl) groups and mix failure was found to be high in NaOCl group. Keywords: Bond strength, Sodium Hypochlorite, EDTA, HEDP, warm vertical compaction, EndoSequence BC Sealer HiFlow, AH Plus