Basic properties of an alginate impression material supplemented with chlorhexidine. I. Disinfectant effects on oral microbes.

To examine the disinfectant effects on oral microbes of an alginate impression material supplemented with 1% chlorhexidine as the aseptic ingredient (Coe Hydrophilic Gel, CHG), several cell suspensions of oral microbes (3 Gram-positives, 2 Gram-negatives and 1 yeast) were exposed to the surface of cast CHG or that of a control impression material for 5 or 30 min. They were then transferred to the surfaces of agar plates. Colony formation was estimated after culture for several incubation periods. No growth of bacteria on the plates was observed when the suspensions had been exposed to CHG even for 5 min, whereas for the control material, all the bacteria formed colonies. The yeast showed colony formation irrespective of the kind of impression material and the duration of exposure. Thus, it appears that use of an impression material supplemented with 1% chlorhexidine such as CHG may protect clinical staff and dental technicians from possible bacterial infections associated with the impression procedures.