Method: With five materials (one alginate, two A-silicone substitutes for alginate, one precision A-silicone system, one polyether) impressions were taken from a master model consisting of a simplified alveolar ridge with stylized teeth (truncated cones) in positions 36, 33, 43 and 46. The teeth had occlusal faces with mean roughness [Rz] ranging from 0,1 µm to 14,2 µm. Prior to pouring with dental stone, one third of the impressions remained untreated (control), the rest was subjected to immersion disinfection with either Impresept (3MESPE) or Silosept (Kettenbach). As a measure of surface quality, mean roughness [Rz] for the top faces of the truncated cones on the stone models was determined by means of a profilometer. Additionally, the models were scanned in a CNC coordinate measuring device, and deviations from master model dimensions were computed for 16 parameters (eight distances [da] and eight diameters [dd] in two levels, four heights [dh]). ANOVA was used for each parameter and material in order to detect significant differences (p<0,05%) between control and disinfection groups (n=7).
Results: Only in 42 out of 240 cases, one of the disinfectants caused statistically significant alterations of a parameter, as compared with the control. No accumulation of significant differences was found with any of the parameters or materials. The most extreme deteriorations for the different types of parameters were: Rz: 1,9 µm; da: 0,06% (15 µm); dd: 0,35% (24 µm); dh: 0,35% (26 µm), which is clinically acceptable.
Conclusions: The proposed method is suited for assessing surface quality and dimensional accuracy on the same stone model after disinfecting the impression. Disinfection of alginate, silicone and polyether impressions is possible without clinically significantly impairing surface quality and dimensional accuracy.