The effect of heat- and auto-polymerized denture base polymers on clonogenicity, apoptosis, and necrosis in fibroblasts: denture base polymers induceapoptosis and necrosis

Eluates from poly(methyl methacrylate)-based denture base polymers have rec ently been found to enhance death by apoptosis and necrosis in U-937 human monoblastoid cells. The present study investigated the potential of such po lymers to induce apoptosis and/or necrosis and to alter clonogenicity in L9 29 murine fibroblasts. A fibroblast cell line was chosen because the impair ment of fibroblasts subjacent to denture bases may result in a weaker or mo re permeable mucosa. Two aspects were addressed: the effect of direct conta ct with the denture base polymers and the effect of eluates extracted from the polymers. For this purpose L929 fibroblasts were seeded on disks manufa ctured from three heat-polymerized and four autopolymerized denture base po lymers or in different concentrations of their eluates. The effects were ev aluated by light, fluorescent, confocal and electron microscopy, counting o f colonies, and flow cytometry. Disks and eluates of all polymers enhanced cell death by apoptosis and necrosis in L929 cells and decreased their clon ogenic potential in a dose-dependent manner. Apoptosis was the main form of cell death. In general, the deleterious effects were stronger when cells w ere plated directly on the polymer disks than in the eluates. The autopolym erized polymers, except one, yielded higher percentages of apoptosis and ne crosis than the heat-polymerized polymers. The results of the study indicat ed that poly(methyl methacrylate)-based denture base polymers trigger death -signals in L929 fibroblasts and open doors for possible modulation of the cell/biomaterial interaction.