Evaluation of the effects of retro-cavity preconditioning with or without ethylenediaminetetraacetic acid on root surface pH and dislodgement resistance of NeoMTA2 and MTA Flow retro-fills; an ex vivo investigation

Abstract Background The aim of this study was to investigate the effects of retro-cavity preconditioning with or without 17% ethylenediaminetetraacetic acid (EDTA) solution on root surface pH as well as dislodgement resistance of NeoMTA2 and MTA Flow retro-fills. Methods Forty-eight single-rooted human incisors were selected. After completion of endodontic treatment, root-end resections were done and retro-cavities prepared. The samples were randomly divided into two groups of A and B (n = 24 each). In group A, retro-cavities were pre-conditioned with 2.5% NaOCl, followed by 17% EDTA solution, whereas in group B, pre-conditioning was done using 2.5% NaOCl before final irrigation with normal saline. Samples in each group were randomly subdivided into two subgroups of 1 and 2. Retro-fillings in A1 and B1 subgroups were done with MTA Flow and in A2 and B2 subgroups with NeoMTA2. Root surface pH was measured in each sample at three different stages; before preparation of retro-cavities (pH0), after retro-cavity pre-conditioning (pH1), and three days after retro-filling (pH2). Subsequently, pushout bond strength (PBS) of the retro-filling materials was measured by a universal testing machine and their failure modes visualized under 64x magnification. Results Preconditioning with EDTA caused a significant increase in PBS for both materials (p < 0.001). There was no significant difference between average bond strength of MTA Flow and Neo MTA2 (p = 0.271). There was an increase in average pH2 compared to pH1 and pH0 in all groups (p < 0.001). Use of EDTA resulted in a significant increase in average pH2 in MTA Flow compared to Neo MTA2 (p = 0.027). Groups preconditioned with EDTA more frequently indicated a cohesive failure mode. Conclusion Use of EDTA significantly increased pushout bond strength of retro-fill materials to dentin. However, it did not prevent ultimate alkalinity of retro-filled cavities.