The purpose of this study was to compare mineral trioxide aggregate (MTA; Dentsply, Tulsa Dental, Tulsa, OK, USA), which is widely used as root-end filling material, with DiaRoot BioAggregate (DB; Innovative BioCaramix Inc, Vancouver, BC, Canada), newly developed product, by using MG63 osteoblast-like cells. MTA, DB, and Intermediate Restorative Material (IRM; Dentsply Caulk, Milford, DE, USA) were used for root-end filling material while tissue culture plastic was used for control group. Each material was mixed and, the mixtures were left to set for 24 hours. MG63 cells were seeded to each group and then they were cultured for attachment for 4 hours. Following the attachment of cells to the root-end filling material, early cellular response was observed. After another 12 hours'culture, the level of attachment between cells and material was observed and in order to identify the effect of each material to bone formation, transforming growth factor beta1 (TGFβ1) and osteocalin (OC) were estimated by using enzyme-linked immunosorbent assay (ELISA), and the amount of alkaline phosphatase (ALP) was also measured. The data were analyzed using one-way ANOVA. As a result, only at OC and the number of cells which were attached to materials, there was no statistical difference between MTA and DB. At other items, there was statistically significant difference in all groups. Although DB has not shown exactly the same cellular response like that of MTA, the number of attached cells shows that biocompatibility of the material and OC indicates bone formation rate. Therefore, if DB is used for root end filling material, it is expected to lead to similar results to MTA.

The purpose of this study is to monitor the secretion of matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) produced by human osteosarcoma cell line (MG63) stimulated with Prevotella nigrescens lipopolysaccharides (LPS), and to compare the level of secretion before and after the treatment of calcium hydroxide on P. nigrescens LPS.

LPS was extracted and purified from anaerobically cultured P. nigrescens. MG63 cells were stimulated by the LPS (0, 1, 10 µg/ml) or LPS (10 µg/ml) pretreated with 12.5 mg/ml of Ca(OH)₂ for 3 days.

Total RNA was isolated from the cell, and real-time quantitative polymerase chain reaction (PCR) was performed for quantification of MMP-1 and TIMP-1.

The results were as follows.

1. MMP-1 mRNA expression at 48 hr was highly increased by stimulation with P. nigrescens LPS. The increase was dose-dependent.

2. When stimulated with 1 µg/ml of LPS, TIMP-1 mRNA expression was highly increased at 24 hr and 48 hr. However, TIMP-1 expression was suppressed at higher concentration (10 µg/ml).

3. When P. nigrescens LPS was pretreated with Ca(OH)₂, MMP-1 and TIMP-1 gene expression was downregulated.

The results of this study suggest that transcriptional regulation of MMP-1 and TIMP-1 by P. nigrescens LPS could be one of the important mechanisms in bone resorption of periapical inflammation. The result of calcium hydroxide on MMP-1 and TIMP-1 gene expression suppression shows that calcium hydroxide detoxified bacterial LPS and thus should be used the medication of choice for intracanal dressings in root canal infected with black-pigmented bacteria.