JOURNAL OF PROSTHETIC DENTISTRY THE

Vol. 100 No. 1      July - 2008

ISSN: 0022-3913      UBIC: 171

SUMMARY

Statement of problem: Currently, a standard protocol exists to measure the elastic recovery of impression materials from compressive strain; however, no protocol exists for the measurement of elastic recovery from tensile strain. Purpose: The purpose of this study was to compare elastic recovery from tensile strain test with the ISO elastic recovery test for 5 vinyl polysiloxane materials (Aquasil Ultra, Examix, Genie, lmprint 3, and StandOut) and 1 hybrid material (Senn). Material and methods: Specimens (n=5) were fabricated in a brass mold and loaded in tension with a crosshead speed of 300 mm/mm to 50% or 100% strains. Two hours following specimen elongation, the change in length of the specimens was measured. Additional specimens (n=5) were tested in tension until failure at 200 mm/mm. The maximum elongation at failure was recorded. Elastic recovery specimens (n=4) were prepared for each material following ISO standard 4823. The change in dimension of these specimens was measured following a 30% compressive strain. Group means were compared using 1-wayANOVA and Tukey-Kramer HSD test(α=.05). Correlation between different tests was evaluated using Pearson's correlation coefficient. Results: Vinyl polysiloxane materials of varying composition demonstrated significantly different elastic recovery, and the hybrid material demonstrated the least elastic recovery in both tests. All materials exceeded a 100% elongation before failure. Significant linear correlation was found between means of the SO method and those of a 100% tensile strain (r2=0.69, P=.039), but not those of a 50% tensile strain (r2=0.56, P=.086). Conclusions: Elastic recovery from compressive strain can only partially predict elastic recovery from tensile strain, suggesting that elastic recovery from tensile strain is a relevant test. (J Prosthet Dent 2008;1 00:29-33)

| Volver |