Dimensional stability of impression materials at different temperature: comparative study.

Objective: The aims of this study are to determine the influence of temperature on linear dimensional change of vinylpolisiloxane and polyether and indicate the best dimensional stability material. Method: The evaluation of linear dimensional change was made according to UNI EN ISO 4823. Specimens of vinylpolisiloxane Hydrorise Maxi Monophase (Zhermack, Badia Polesine, Italy) and polyether Impregum Penta (3M Espe, Dental Products, St. Paul, MN) were realized using test blocks NIOM 380 ml: four specimens of both materials were realized at temperature of 23°C and stored at 23°C; four specimens of both materials realized at temperature of 35°C and stored at 23°C. For each specimen were made four measurements: results allowed the calculation of the dimensional change percentage. The dimensional changes were recorded at 24, 72 hours and 5 days using comparator millesimal Mitutoyo and microscope Olympus SZX9. The results were subjected to statistical analysis. Result: Vinylpolisiloxane at temperature of specimens realization of 23°C showed the following average dimensional change percentage: -0.066 ± 0.011 after 24 hours, -0.105 ± 0.038 after 72 hours, -0.117 ± 0.024 after 5 days; at temperature of specimens realization of 35°C: -0,272 ± 0,013 after 24 hours, -0,292 ± 0,010 after 72 hours, -0,304 ± 0,032 after 5 days. Polyether at temperature of specimens realization of 23°C showed the following results: -0.171 ± 0.054 after 24 hours; -0.276 ± 0.072 after 72 hours; -0.311 ± 0.081 after 5 days; at temperature of specimens realization of 35°C: -0,395 ± 0,008 after 24 hours; -0,459 ± 0,032 after 72 hours; -0,525 ± 0,021 after 5 days. All the results showed statistically significant differences (p <0.05). Conclusion: The temperature during the impression making affects significantly on linear dimensional change of impression materials: increase in temperature results in increase in contraction of impression material. Vinylpolisiloxane demonstrates better dimensional stability compared to polyether.