Effect of an oily calcium hydroxide suspension (Osteoinductal) on human periodontal fibroblasts. An in vitro study.

The efficacy of an oily calcium hydroxide suspension (Osteoinductal) as an adjunct to periodontal regenerative therapy has been demonstrated in recent clinical and histological studies. However, little is known about the molecular mechanisms in vitro, particularly, about the effect of oily calcium hydroxide paste on periodontal ligament (PDL) cells. Therefore the aim of the present study was to analyze the mitogenic response of cultured PDL cells to Osteoinductal in comparison to calcium hydroxide and enamel matrix derivative (EMD) in vitro. Human periodontal ligament cells were derived from a third molar extracted for orthodontic reasons and incubated in the presence of Osteoinductal, calcium hydroxide, EMD, phosphate-buffered saline plus 10% glycerol (PBS) or standard culture medium for 15 and 60 minutes. The mitogenic response of the PDL cells was determined by Western Blot with antibodies specific for extracellular signal-related kinase (ERK)1/2 as well as the activated, tyrosine-phosphorylated form of ERK1/2 (p-ERK). Relative phosphorylation of ERK1/2 was normalized to total ERK1/2 levels by densitometry. Cell proliferation was measured after 1, 3 and 8 days using a Neubauer haemocytometer to determine the total cell number. Results demonstrated that the mitogenic response to Osteoinductal, calcium hydroxide and enamel matrix derivative was associated with the activation of ERK1/2 and was more pronounced as compared to PBS and standard culture medium treated cells. Although Osteoinductal and calcium hydroxide activated mitosis and caused phosphorylation of ERK1/2 in PDL cells, its effects were less pronounced as compared to EMD. Furthermore EMD exhibited the highest proliferative response in comparison to Osteoinductal, calcium hydroxide and the negative control after one, three and eight days. In conclusion, our data indicate that Osteoinductal enhances the mitogenic response of human PDL cells by activation of ERK1/2 and increases cell proliferation, however, it is inferior in comparison to EMD.