Induction of mRNA expression of osteogenesis-related genes by guaiacol in human dental pulp cells.

To investigate the stimulating effect of endodontic medications on the mRNA expression of some osteogenesis-related genes associated with reparative dentinogenesis and hard-tissue formation, human dental pulp cells (D824 cells) were treated with calcium hydroxide (Ca (OH)(2)), formocresol, or guaiacol. The effect on growth was determined by growth curves of D824 cells treated for 1-3 days with 0.03-0.3 mM Ca (OH)(2), 0.0007%-0.0014% formocresol, or 0.24-2.43 mM guaiacol. The mitotic activity of individual cells and the mRNA expression of the osteogenesis-related genes for alkaline phosphatase (ALP), type I collagen (COL-1), and bone sialoprotein (BSP) in the cells treated for 24 h with the same concentrations of the medications as described above were determined by colony-forming efficiency and by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis, respectively. Cellular growth and mitotic activity were scarcely affected by Ca (OH)(2), but were significantly reduced by formocresol or guaiacol. The mRNA expression of the osteogenesis-related genes was little affected by Ca (OH)(2) or formocresol, but was significantly enhanced by guaiacol. The results indicate that guaiacol may stimulate the mRNA expression of genes associated with reparative dentinogenesis and hard-tissue formation in human dental pulp cells, suggesting that the novel property of guaiacol provides new insights into the utilization of guaiacol in endodontic therapy.