Evaluation of the effect of different chelation agents on the push-out bond strength of calcium silicate-based repair materials

Aim The objective of this study was to investigate how 20% citric acid, 17% EDTA, and 9% HEDP + 2.5% NaOCl solutions employed for dentine tissue treatments in root canals affect the push-out bond strength of the bioceramic root canal repair materials MTA Angelus and Biodentine and the bonding failure within the materials. Material and Method For this study, 15 single-rooted and single-canal permanent human maxillary central teeth were used. The crowns of the teeth were cut away from the enamel cement border with a diamond fissure bur (Microdont, São Paulo-SP, Brazil) and embedded in acrylic blocks (Imicryl SC, Imicryl Dental Materials, Inc, Konya, Turkey). A total of 45 dentin disc samples were prepared from the coronal root region by taking three horizontal sections of 1 mm in thickness using a water-cooled cutting device (Isomet, Buehler, USA). Two standard artificial cavities were created on each side of the canal lumen with a diamond bur that was 1 mm in diameter on each dentin disc. These discs were randomly divided into three different experimental groups to be kept in three different solutions: 17% EDTA (n=15) (Promida, Eskişehir, Turkey), 20% citric acid (n=15) (Promida, Eskişehir, Turkey), and 9% etidronic acid + 2.5% NaOCl (n=15) (Microvem AF, Istanbul, Turkey). Each experimental group was kept in its own solution for 1 min. Afterwards, MTA Angelus (Angelus, Londrina, Brazil) was placed in one of the opened cavities and Biodentine (Septodont, Saint-Maur-des-Fossés, France) was placed in the other, and they were kept in an incubator for 24 hours. The prepared samples were subjected to the push-out bond strength test (Shimadzu Co., Kyoto, Japan). Data were analyzed with IBM SPSS version 23. The bond failures in the materials as a result of the push-out bond test were examined using an SEM device (Quanta FEG 250, FEI Ltd., Oregon, USA), and their percentages were determined for adhesive, cohesive, and mixed types. Result The main effect of the chelating agent was found to be significant on the push-out bond strength (p=0.046). The mean value of the thrust-bond strength was 17.08 MPa in the citric acid group, 13.97 Mpa in the EDTA group, and 11.81 MPa in the HEDP/NaOCl group. The citric acid group showed significantly higher tensile bond strength than the HEDP/NaOCl group (p<0.05). There was no significant difference between the citric acid group and the EDTA group or between the EDTA group and the HEDP/NaOCl group in terms of bond strength. The biomaterial's main effect was discovered to be significant on the push-out bond strength (p=0.005). The average tensile bond strengths of Biodentine and MTA Angelus were 16.75 MPa and 11.81 MPa, respectively. Biodentine showed significantly higher tensile bond strength than MTA Angelus (p<0.05). The interaction between the chelating agent and biomaterial was found to be significant on the push-out bond strength (p=0.021). As a result of the push-out bond strength test, the incidence of mixed-type joint failure was revealed to be almost the same as that of the cohesive-type failure in all samples. Adhesive-type failure rates were significantly lower than in all groups. Conclusion The adhesion of the calcium silicate-based repair materials of the HEDP/NaOCl solution to the dentin was comparable to that of EDTA, and etidronic acid was considered to have the potential to replace conventional EDTA treatment. Further studies are needed on the applications of etidronic acid in the field of endodontics. Keywords: Biodentine, Citric acid, EDTA, Etidronic acid, Failure patterns, MTA, Push-out bond strength.