Objective: To evaluate the linear dimensional change and detail reproduction of a new impression material curable via a ring opening metathesis polymerization (ROMP) mechanism along with other commercially available polyether and vinylpolysiloxane impression materials curable via acid/imine and addition-cure crosslinking mechanisms. Methods: Four high viscosity impression materials: experimental material HB (EXP, Kerr), a polyether material Impregum Penta Soft HB (IPS, 3M/ESPE), a vinylpolysiloxane material Take 1 HB (T1, Kerr) and a hybrid polyether/silicone material SENN HB (SEN, GC) were tested. A stainless steel block for detail reproduction and linear dimensional stability (Sabri Dental Enterprises) was used. Three samples each were prepared and were stored in an environmentally controlled room at 23°C and 40% humidity prior to test. Samples were measured according to ISO Standard No. 4823, by using a Titan Zoomatic Measuring Microscope (Model TM-II). Results: All tested materials shrunk slightly at 1h and 24h by comparing to the distance between two v-shaped grooves on the test block. EXP showed the lowest shrinkage and IPS showed the highest shrinkage. There were no significant differences between T1 and SEN. All of the materials passed the detail reproduction test, accurately reproducing the 75 micron line. The results were listed in the following table.
* Means with the same letter are not statistically different at p<0.05
Conclusion: EXP exhibits the lowest linear dimentional change among the tested materials apparently due to the ROMP curing mechanism. It also meets the detail reproduction requirements for dental impression materials.