UNLABELLEDOBJECTIVE To investigate the in vitro antimicrobial activity of nano-hydroxyapatite/polyamide 66 composites (nHA-PA66) as a pulp capping agent.

METHODSThe micro-organisims used in this study included Streptococcous mutans (S. mutans), Lactobacillus casei (L. casei) and Actinomyces viscosus (A. viscosus), three standard bacterial strains predominant in deep carious lesions. Agar diffusion test was used to determine the diameter of bacterial inhibition zones of nHA-PA66 compared with hydroxyapatite paste, calcium hydroxide paste and nHA-PA66 mixed with iodoform paste.

RESULTSIt showed that the polymerized films and fresh paste of nHA-PA66 had no antimicrobial activity to S. mutans and very little to L. casei and A. viscosus. The antimicrobial activity of nHA-PA66 mixed with iodoform paste obviously increased, but no significant difference compared with calcium hydroxide paste. There, was no antimicrobial activity of hydroxyapatite paste to the three test bacterial strains.

CONCLUSIONThese findings suggest nHA-PA66 used as pulp capping agent alone almost has no antimicrobial effect to the three test bacteria, but the antimicrobial activity can be increased by combining with iodoform.