Antimicrobial activity and biocompatibility of the mixture of mineral trioxide aggregate and nitric oxide-releasing compound

Abstract

Background/purpose: Antimicrobial activity and biocompatibility of root canal sealer are related to the success of endodontic treatments. This study investigated the efficacy of mixture of mineral trioxide aggregate (MTA) and a NO-releasing compound for the antimicrobial activity, biocompatibility, and physical properties.

Materials and methods: MTA was mixed with diethylenetriamine-NO (MTA-NO), and the extracts from MTA and the MTA-NO mixture before and after setting was obtained were investigated the antimicrobial activity against Enterococcus faecalis and Porphyromonas endodontalis. After setting MTA and MTA-NO, pulp cell was incubated in the presence of MTA and MTA-NO disk using Transwell® cell culture insert, and the proliferation assay and mineralization-stimulated factors of the cells were analyzed by MTT assay and real-time RT-PCR, respectively. The physical properties of MTA and the MTA-NO mixture, such as surface hardness and flowability was also analyzed.

Results: The MTA-NO mixture showed stronger antimicrobial activity against E. faecalis and P. endodontalis than that by MTA. Both MTA and MTA-NO mixture increase the ratio of cell proliferation and induced the expression of alkaline phosphatase, collagen type I, osteocalcin, and osteopontin. Moreover, the induction of gene expression by MTA-NO mixture was higher than that by MTA alone. No significant difference was observed for surface hardness and flowability between MTA and MTA-NO mixture.

Conclusion: The addition of a NO-releasing compound to the endodontic treatment using MTA root canal sealer might reduce the risk of bacterial infection and help to regenerate the dental pulp tissue.

Keywords: Antimicrobial activity; Biocompatibility; MTA; NO-Releasing compound; Physical property.

Figure 1

Antimicrobial activity of the extracts from MTA and MTA-NO mixture before and after setting. E. faecalis (A and B) and P. endodontalis (C and D) were cultured with the extracts from MTA and MTA-NO before and after setting in a 96-well microtiter plate. Bacterial growth was measured by a spectrophotometer at 660 nm of wavelength after cultivating for 36 h. The experiments were performed three times in triplicate, and the data are represented as mean and STDEV. Asterix (∗) indicates statistically significant difference compared with the control group (P < 0.05).

Figure 2

Cell proliferation. Pulp cells were incubated in the presence or the absence of MTA and MTA-NO disk using Transwell® culture insert for 24 h and 48 h. the cell image were taken by a phase contrast microscope.

Figure 3

Cell proliferation assay. Pulp cells were incubated in the presence or the absence of MTA and MTA-NO disk using Transwell® culture insert for 24 h and 48 h. After removing the media, MTT solution was added in the well containing cell, and the cells were incubated for 4 h. The optical density was measured by a microplate reader. The experiments were performed three times in duplicate, and the data are represented as mean and STDEV. Asterix (∗) indicates statistically significant difference compared with the control group (P < 0.05).

Figure 4

Induction of the expression of mineralization-related genes by MTA and MTA-NO mixture. Human pulp cells were cultured in the presence or absence of MTA and MTA-NO disk using Transwell® culture insert for 24 h. After extracting total RNA from the cultured cells, the expression of ALP (A), Bone sialoprotein (B), Col I (C), OC (D), OPN (E), and Runx2 (F) was analyzed by real-time RT-PCR. The experiments were performed three times in duplicate, and the data are represented as median and interquartile range. Asterisk (∗) indicates statistically significant differences compared with untreated cells (P < 0.05), and sharp (#) indicates statistically significant differences between MTA and MTA-NO treated cells (P < 0.05).