OBJECTIVETo investigate the effect of alloy leaching liquor of four different types of base metal alloy on the expression of prostaglandin E(2) (PGE(2)) and cyclo-oxygenase-2(COX-2) by human gingival fibroblast(HGF) in vitro.

METHODSNi-Cr, Co-Cr, pure Ti and Au ceramic alloys were incubated in Dulbecco's modified Eagle's medium (DMEM) to prepare alloy leaching liquor, and then added in HGF medium. DMEM was prepared as negative control. Aliquots were taken from exposed media after 1, 6, 12, 24 h. Assays for PGE(2) were carried out by enzyme-linked immunosorbent assay (ELISA).

RESULTSIn 6, 12, 24 h, the expression of PGE(2) in Ni-Cr and Co-Cr alloy groups (Ni-Cr: 45.568 ± 0.926, 60.538 ± 0.988, 73.754 ± 0.507; Co-Cr: 40.496 ± 0.693, 53.216 ± 0.327, 65.470 ± 1.086) were significantly higher than those in other experimental groups (Ti: 31.564 ± 0.719, 31.998 ± 0.856, 32.066 ± 0.513; Au alloy: 31.540 ± 0.821, 31.136 ± 0.518, 31.340 ± 0.443) and control group (31.122 ± 0.642, 31.230 ± 0.634, 30.980 ± 0.746) (P < 0.05). No significant difference were found in the expression of PGE(2) among pure Ti, Au alloy groups and the control group (P > 0.05). Immunofluorescence showed dark and uniform COX-2 stain in Ni-Cr and Co-Cr alloy groups, while in pure Ti group, Au alloy group, and negative control group shallow and uneven distribution of COX-2 stain were observed.

CONCLUSIONSOur findings suggested that pure Ti and Au alloy did not cause elevated PGE(2) and COX-2 release from HGF. However, Ni-Cr and Co-Cr alloy caused increase in PGE(2) and COX-2 levels.