Effect of chemical disinfectant solutions on the stability and accuracy of the dental impression complex

Abstract

Currently available impression materials were not originally formulated to be subjected to disinfection or sterilization, it is conceivable that chemical solutions used in such procedures may adversely affect their critical qualities. The purpose of this study was to evaluate the accuracy and dimensional stability of two dental impressions materials a polyether (Permadine/lmpregum-ESPE) and a poIyvinylsiloxane (Express-3M) retained by their respective adhesives on two different acrylic tray designs (perforated and non perforated). The impression/tray/adhesive complex was immersed for either 30 or 60 min. in disinfectant solutions (Cavicide-ChIorine compound; Coecide XL-2% neutral glutaraldehyde and Cidex Plus-3.5% neutral glutaraldehyde). There were two control groups: distilled water and no immersion treatment. An stainless steel analog similar to ADA specifications No. 19 was used as a test die. A total of 400 impression were made and divided into five groups with all possible combination of impression materials, tray design and soaking times. After each impression was made it was rinsed with tap water for 60 seconds and then immersed in a disinfectant solution for 30 sec. The impression was again rinsed with tap water for 30 seconds and then immersed in 600 ml disinfectant solution either for 30 or 60 min. After soaking, samples were rinsed with tap water and allowed to bench dried for 30 min. before measurements were made. Samples were weighed before and after immersion. Each sample was evaluated for accuracy and stability under a traveling microscope (X100-20) before and 30 min after immersion and 48 hours delay soaking time period. Two long measurements were obtained [D-C(F) and F-H(C)], and three short measurements (A1,A2, A3). Five-way analysis of variance for a factorial design with repeated measurements showed no statistically significant differences (P[greater than]0.001) for lines D-C(F) and F-H(C) between impression materials, tray designs, immersion times and disinfectant solution over time. Also, no combination of the above factors were significant for this lines. For lines Al, A2 and A3 differences among factors were statistically significant (P[greater than]0.001). However, since differences averaged less than 7 microns, result for these lines were no clinical meaningful. Water imbibition from the impression system was no detected. Since these results emphasize the stability and accuracy of the impression system under various conditions, dentist should be urged to strictly follow disinfection/sterilization protocol of this study.