Comparison and Evaluation of Linear Dimensional Accuracy of Three Elastomeric Impression Materials at Different Time Intervals Using Vision Inspection System: An Study.

Background: Making an impression represents a crucial step in fabrication of a prosthesis. Elastomers are the most commonly used materials for precise and accurate recording and reproduction of tooth morphology and surrounding soft tissue.

Aims And Objective: The aim of this study was to compare and evaluate the linear dimensional accuracy of three elastomeric impression materials: addition silicone, condensation silicone, and polyether at different time intervals up to 15 days using a vision inspection system.

Materials And Methods: Dimensional accuracy of impression materials was measured at certain designated time periods using stainless steel die. The impressions of die were made using one representative material of each type of elastomeric impression material. The die along with the impression material in the mold was held using a clamp and put in a water bath maintained at mouth temperature. The linear dimensional changes taking place in each material with time were measured using the vision inspection system.

Results: On comparison with master die impression at 30min, 1h, and 1½ h time interval, a significant decreased mean dimension of condensation silicone was observed, whereas addition silicone and polyether showed statistically nonsignificant difference. At 2, 3, 4, and 12h time span, a significant difference in mean dimension of addition and condensation silicone was noted, whereas polyether showed a nonsignificant difference. At 24h, 1 week, and 15 days duration, on comparison with the master die, a significant reduction in mean dimension of condensation silicone was discovered, whereas addition silicone and polyether showed nonsignificant difference.

Conclusion: Polyether showed significantly lesser dimensional changes among all three materials, though the differences were small enough to be considered clinically acceptable.