Investigation of the effect of hydrochloric acid with different concentrations on mineral trioxide aggregate plug and dentin

Abstract

Background: Mineral trioxide aggregate (MTA) becomes a hard mass after setting and making it
difficult to remove and can cause significant problems in the retreatment process. The aim of this
study was to evaluate the effect of different concentrations of hydrochloric acid (HCl) on MTA
dissolution and its effect on dentin.
Materials and Methods: In this in vitro study, 45 single‑root premolars were selected. Artificially
open apex was created in all samples with similar process. The samples were randomly divided into
4 experimental groups of 10, and a control group of 5. Four‑millimeter thick apical plugs of Root
MTA were placed in all samples in an orthograde manner. HCl was used at concentrations of 3.75%,
7.5%, 15%, and 22.5% (w/v) for the experimental groups and normal saline for the control group.
Each sample was exposed to the desired solution for 15 min. Then, MTA retrieval and reaching
the working length were attempted with k‑file # 30. The times of each sample were recorded.
Furthermore, after longitudinal incision of the roots with a disc, the dentin surfaces of canals were
examined with a Dino‑Lite microscope (×50). Results were analyzed by Shapiro–Wilk test and
one‑way analysis of variance tests. The level of significance P value was set at 0.05.
Results: The lowest average time of reaching working length was observed with group 22.5% that
was significantly lower than 15% and 7.5% concentrations (P = 0.005 and P = 0.011). Furthermore,
by examining with ×50 of Dino‑Lite microscope, no difference was observed on the canal walls.
Conclusion: The optimum concentration of HCl was 7.5%. Furthermore, different concentrations
of HCl had no significantly different effect on the dentinal canal wall using Dino‑Lite microscope
with ×50.
Key Words: Dentin, hydrochloric acid, solvents