Effectiveness of chlorine dioxide in disinfection on two soft denture liners

Statement of problem. Soft tissue denture liners frequently require replace ment that necessitates complete removal from the denture base. A high speed lathe located in a "clean laboratory" is often used to facilitate removal of these materials, but it is unclear whether routine disinfection procedur es reduce bacterial contamination sufficiently to prevent contamination of the laboratory. Purpose. The first phase of this study evaluated the effectiveness of 3-min ute chlorine dioxide spray and immersion disinfection procedures on 2 dentu re liners (Coe Soft and Coe Comfort) and stainless steel specimens used as controls. The second phase evaluated the effectiveness of spray disinfectio n at time intervals of 1, 3, and 10 minutes. Material and methods. Specimens made of soft denture liners attached to acr ylic resin bases (10 per group) were contaminated with Escherichia coli, St aphylococcus aureus, and Candida albicans. Colony-forming units were counte d after different disinfection techniques were applied. Kruskal-Wallis 1-wa y analysis of variance on ranks and all all pairwise multiple comparison pr ocedures (Dunn's method) were used to test for significant differences amon g test groups at the P < .05 level of significance. Results. Chlorine dioxide was effective against nonporous stainless steel s pecimens but was inadequate for denture liners at the recommended 3-minute time of disinfection. The immersion technique was more effective than the s pray technique, but the difference was not significant. Increasing the time of disinfection did not significantly reduce the numbers of microorganisms . Conclusion. Coe Soft and Coe Comfort denture liners should be removed befor e entering the laboratory. These materials contain sufficient viable bacter ia after routine disinfection procedures to cause contamination of the ''cl ean laboratory."