Purpose: To study possible relationships between Theological parameters of elastomeric impression materials and their dimensional accuracy at different stages during setting within the manufacturers' recommended working time. Methods: Four chemically different impression material-types were tested. Impressions were taken of a master cone at 30-second intervals after mixing and up to 30 seconds beyond the recommended working time. Impression accuracy (Δd) was determined as the dimensional deviation of stone dies from the master cone. The phase angle δ(t) and storage modulus G'(t) were measured and the working time determined according to ISO 4823. Three operators asessed the latest point in time for uncompromised impression taking. Correlation analysis was performed using Spearman's Rho (P= 0.05). Results: For most materials investigated, Δd(t) was constant within the manufacturers' recommended working time whereas δ(t) and G'(t) changed significantly. There was no correlation (P> 0.05) between Δd(t) versus δ(t) and G'(t), respectively. When determined according to ISO 4823, working time was longer than operator-assessed working time for all materials investigated.
|Number of pages||6|
|Journal||American Journal of Dentistry|
|Publication status||Published - 2007 Dec 1|
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