Dimensional Change of Two Addition Silicones

Objectives: To evaluate the effect of disinfection and sterilization, in the dimension stability of Imprint 4 Penta Putty (3M ESPETM) and analysis of the respective casts. Materials and Methods: 90 silicon samples were prepared with a metal matrix, according to the standard ISO 4823:2000 for the elastomeric impression materials. The samples' viability was confirmed by the presence of 75micra line and 9 groups were formed. Groups 1, 2 and 3 correspond to the Control at different times (0h, 24h, 1week); groups 4, 5 and 6 were submitted to 10 minutes immersion in sodium hypochlorite at 5.25% and measured at different times (0h, Tm, 24h, 1week); and groups 7, 8 and 9 were submitted to autoclaving at 134 °C for 40 minutes and they were also measured at different times. After the last measurement, the samples were passed to plaster type IV and it was confirmed the reproducibility of the 75micra line and it was also measured the dimensional stability. The measurements were made with a Michelson interferometer. Results: Following the silicone samples' dimensional change analyses, it was found that there weren't statistically significant changes over time (p> 0.05) in the Control and Hypochlorite groups. In the Autoclaving groups, it was concluded that except for the values obtained in Tm and 24h, all other values presented significant changes (p 0.05). For the casts, none of the groups presented significant statistically changes over time (p> 0.05). Conclusion: Both for silicones as for casts, the biggest changes were presented in the Autoclaving groups. The silicone samples must be passed to plaster after 24h printing. The changes found in silicones were bigger than those found in the plaster, which shows the highest capacity of the latter to maintain the initial reference values of the matrix. Keywords: dimensional changes, PVS, disinfection, sterilization, Michelson interferometer