Prolongation of Working Time with Polyether Retarder

Objective: To evaluate the effect of 3M ESPE Polyether Retarder on the working time of 3M ESPE Polyether impression materials as a function of the ratio retarder : impression material.

Methods: Polyether Retarder #258171, #217930 was mixed together with the investigated impression materials Impregum F, IF #B164283 #C252940, and Impregum Penta Soft, IPS #B224566 #C225369, using a spatula and a mixing block. The change in flowability of the mixture was used as an indicator. It was measured at room temperature using the 2mm slit shark fin device having a weight of 148g±3g (#3292 IADR 1997): A reference without retarder was measured at 45s after start of mix according to ISO 4823:2000. Further measurements were conducted in 15s steps until the height of the shark fin dropped below 90% of the reference. This point was defined as the end of working time. Each measurement was repeated twice.

Results: For comparison of the automix-material IPS and the handmix-material IF a General Linear Model was used (p≤0.5).

Ratio retarder : impression material and corresponding working time obtained from shark fin height.

The retardation of IPS was statistically equal to IF.

The working time of the tested 3M ESPE Polyethers was extended when 3M ESPE Polyether Retarder was added. The extension is controllable by the retarder dosage.

Conclusions: The working time of 3M ESPE Polyethers can be prolonged using 3M ESPE Polyether Retarder. Longer working times may be a clinical advantage especially for cases involving multiple preparations or with time-consuming impression techniques such as functional impressions.