Effects of Disinfection on Orthodontic Plaster Models

Background and aims: The purpose of this study was to evaluate the effects of disinfection and different brands of alginate impression material on the accuracy of orthodontic stone models. Materials and methods: Six different alginate impression materials and four different disinfectants were included in the study. A total of 168 impressions were taken and divided into 24 groups. Fifty-six impressions taken with extended pour-type alginates were kept in sealed plastic bags for four days and then poured. One hundred and twelve impressions were poured immediately after the disinfection process. A 3-D laser scanner was used for dimensional measurements on the vestibule surface area, while the mesial–distal width of the right upper molar was measured with screen caliper software. Results: This study showed that the contraction of models varied significantly depending on the alginate material and disinfectant. Evaluation of the upper first molar showed that molar contraction varied between 1.2 and 3.2% in dimension. According to molar data, the best accuracy was obtained from Blueprint-Zeta, while the worst was obtained from the Hydrogum Ext Pour–NaOCl alginate– disinfectant combination. Two-way ANOVA of data from the vestibule surface area showed significant results for all pairwise comparisons of alginate and disinfectant materials and their interactions. According to the results of the two-way ANOVA, the best accuracy was obtained from Hydrogum and Blueprint alginates with Unident disinfectant. The worst accuracy was obtained from Hydrogum Ext Pour alginate with Zeta disinfectant. Conclusions: The dimensions of stone models produced from disinfectant-treated alginate impression materials demonstrate various degrees of contraction.