Effect of storage period on the accuracy of elastomeric impressions

Abstract

Aims:To investigate the effect of the storage period on the accuracy of recently developed elastomeric materials.Methods:Simultaneous impressions of a steel die were taken using a polyether (I: Impregum Soft Heavy and Light body, 3M ESPE) and vinyl polysiloxane (P: Perfectim Blue Velvet and Flexi-Velvet, J.Morita). The trays were loaded with the heavy-bodied impression materials while the light-bodied impression materials were simultaneously spread on the steel die. The impressions were poured after 2 hours, 24 hours, and 7 days. Impressions were stored at approximately 55% relative humidity and room temperature. Ten replicas were produced for each experimental condition (n=60). Accuracy of the stone dies was assessed with a depth-measuring microscope. The difference in height between the surface of the stone die and a standard metallic ring was recorded in micrometers at four demarcated points, by two independent examiners. Dxata were submitted to two-way ANOVA and Tukey test (α = 0.05).Results:Significant differences were found among the groups. Smaller discrepancies were observed when pouring was performed up to 24 hours (I-2h= 65.0 ± 15.68 μm; I-24h= 81.6 ± 11.13 μm) for the polyether, and up to 7 days for the vinyl polysiloxane (P-2h= 79.1 ± 13.82 μm; P-24h= 96.8 ± 6.02 μm; P-7d= 81.4 ± 4.3 μm). Significant dimensional discrepancies, however, were observed when polyether was stored for 7 days (I-7d= 295.3 ± 17.4 μm).Conclusion:Storage may significantly affect the dimensional accuracy of impressions and, thus, a maximum period and storage condition should be specified for the recently developed materials.

Variables Affecting the Accuracy of Implant Master Casts: An In Vitro Pilot Study

“…In the study at hand, no significant effect of impression storage for 24 h was noticed although delayed pouring caused an increased variation in master cast accuracy. This limited effect of impression storage seems to be consistent with a study conducted by Franco and coworkers where only minor changes were found when pouring of the impressions was performed within 24 h [21]. Similar findings were reported for polyvinylsiloxane duplicating materials even after several weeks of storage [22].…”

Evaluation of Dimensional Accuracy of Three Combinations of Polyvinyl Siloxane Impression Material: An In Vitro Study

“…All the impressions were poured after 1 hour of setting. According to Franco et al 11 delay in pouring will allow the material to recover elastically and release of by-products may influence the accuracy.…”

Precisión dimensional de una silicona de condensación: comparación del tiempo de almacenamiento y el método de medición

“…La réplica precisa de las preparaciones en el diente y la posición del mismo en el arco dental requieren de mate-riales de impresión con alta estabilidad dimensional, ya que el vaciado de escayola inmediato no es posible cuando existe gran demanda de trabajos de restauraciones indirectas. En el caso de los elastómeros, la estabilidad dimensional depende directamente de su recuperación elástica, de la contracción, de la evaporación de componentes volátiles 18,19 y de la contracción térmica de los mismos 19 . La estabilidad dimensional de los materiales de impresión puede verse afectada también por los productos y las técnicas de desinfección, así como por el tiempo de almacenamiento de estos, si no se siguen adecuadamente las instrucciones del fabricante 8,20 .…”