Antibacterial activity of glass-ionomer cements, compomers and resin composites: relationship between acidity and material setting phase.

Agar diffusion testing was used with four different media to evaluate the antibacterial activity of six products (one conventional glass-ionomer cement (GIC), two light-activated glass-ionomers, two polyacid-modified resin composites and one resin composite) on Streptoccoccus mutans. Their respective antibacterial activities were also compared during and after setting. The relationship between product acidity and antibacterial activity was evaluated. All the GICs demonstrated antibacterial properties in contrast to the polyacid-modified resin composites and resin composite which did not shown any antibacterial effects. Vitrebond GIC exhibited higher antibacterial action, probably because of a cytotoxic photo-initiator diphenyliodoniumchloride. A direct relationship between material acidity and growth inhibition of S. mutans was observed.