The osteogenic effect of mineral trioxide aggregate and modified-mineral trioxide aggregate on normal human osteoblast cells

Thesis (MSD) -- Boston University Goldman School of Dental Medicine, 2006 (Endodontics).Includes bibliography: leaves 89-96.Mineral Trioxide Aggregate (MTA), a relatively new material, has been widely used for root-end fillings, Pulp capping, perforation repairs and other endodontic procedures. Many studies have reported the biocompatibiIity of MTA in vitro and in vivo. Previous studies have shown that MTA provides a biologically active substrate for bone cells, stimulates interleukin production, and that osteoblasts have a favorable response to MTA as compared with IRM and amalgam (Koh et al. 1998; Zhu et al., 2000). In this in vitro study a modification was made to conventional MTA (modified MTA), with the addition of Silicon (Si). The effects of MTA and modified-MTA, on cell attachment efficiency, cell proliferation rate, alkaline phosphatase activity and osteocalcin expression were compared. Human osteoblast-like cells derived from healthy alveolar bone explants were used and grown to second passage in order to perform these experiments. Human osteoblast-like cells were grown and cultured in 24 well plates, in the presence of MTA, modified-MTA and control (plastic culture dish, PCD). Cells were cultured in Dulbecco’s Modified Eagle Medium (DMEM) supplemented with F-12 nutrient mixture, fetal bovine serum (FBS), Penicillin G (5000 U/ml)/streptomycin sulphate (5000 [mu]g/ml), and 250 [mu]g/ml Amphotericin B. Cells were cultured for periods of 12 and 20 days. MTA and modified-MTA were mixed according to manufacturer’s instructions and made into 15.5 mm in diameter, 1.5 mm thickness discs and allowed to set for a period of 24 hours at 37[degrees]C, 5%CO[2], and 1OO% humidity. Before the 12th and 2Oth day, differentiation medium containing vitamin D3 was added to the cell cultures, a period of 48 hours before the day the experiment was conducted. Observation of pH was made throughout the duration of the culture. Cell attachment and proliferation rate were determined by measuring the optical density of crystal violet dye in fixed culture cells. Alkaline phosphatase activity was determined by measuring the optical density of released p-Nitrophenol from a fixed cellular layer. Osteocalcin expression was determined by measuring I[125]-labeled antibody in extracted culture media. All data was normalized on per 10[4]or 10[5] cells basis. One-way analysis of variance (ANOVA) and a two sample t-test assuming equal or non-equal variance were used for statistical analysis on the data. The mean pH of the culture medium cultured in the presence of MTA, modified-MTA, and control decreased over 18 days of culture with a slight increase around 20 days. There was no significant difference between osteoblast cells grown in the presence of MTA, modified-MTA, and control regarding cell attachment efficiency at 16 hours. At 12 and 20 days, attachment and proliferation rate was significantly higher with the MTA and modified-MTA groups, bu there was no significant difference between them. At 12 and 20 days, the control group of osteoblast cells had higher ALP activity than the MTA and modified-MTA group. At 20 days, MTA and modified-MTA expressed higher amounts of osteocalcin than the control group. Based on the results of this in vitro study, MTA and modified-MTA are both capable of stimulating osteogenic effects in normal human osteoblast cultures. This study demonstrated the role of silicon in stimulating osteogenesis of normal human osteoblast cells. Further studies need to be conducted in order to evaluate better modifications of conventional MTA in order to evaluate the favorable response from human osteoblast cells in contact with the material