To evaluate and compare the effect of disinfectants on dimensional stability and surface quality of two commercially available zinc oxide-eugenol impression paste materials -an in vitro study

Background and Objectives: Contaminated impressions can cross infect gypsum casts that are poured against them. Prosthodontic treatment procedure may begin with the making of the dental impression which forms the first link in the microbial contamination during dental care. The disinfectant must be effective antimicrobial agent, yet cause no adverse effect to the dimensional accuracy and surface features of the impression material and the resultant gypsum cast. Method: 80 impressions of die constructed according to ADA specification No. 19 were made with special tray fabricated with two types of commercially available zinc oxide-eugenol impression paste materials and disinfected by 2% gluteraldehyde, 1:213 iodophor, 0.2% chlorhexidine gluconate and distilled water for five minutes followed by rinsing in a tap water and dried then kept in the water bath at 370C, simulating the mouth temperature under the weight of 1 kilogram simulating operators finger pressure. Dimensions of the resultant casts made of type IV die stone poured after disinfection of impressions were measured using stereomicroscope.Surface quality of resultant casts was assessed by visual examination under stereomicroscope and grading of casts surfaces were done according to specific scoring system. Conclusion: 1:213 Iodophor causes least dimensional and surface quality changes in impressions made from Denzomix and DPI zinc oxide-eugenol impression paste materials where as Chlorhexidine disinfectant causes more dimensional and surface quality changes. So it may be advisable to consider 1: 213 Iodophor as a selected disinfectant for disinfecting Denzomix and DPI zinc oxide-eugenol impression paste impression materials for 5 minutes.