Contact Angle Measurement of a ROMP Impression Material

Objective: To evaluate the hydrophilic characteristics by measuring contact angles (CA) of a new impression material curable via ring opening metathesis polymerization (ROMP) along with other commercially available polyether or hybrid impression materials curable via acid/imine or addition-cure crosslinking mechanism. Methods: Three low viscosity impression materials including Experimental LB (EXP, Kerr), Impregum Penta Soft LB (IPS, 3M/ESPE) and EXA'lence LB (EXA, GC) were tested. A Drop Shape Analysis System (DSA100, Kruss) equipped with a digital video camera and computer software (DSA100S) was used to obtain and analyze data. The impression materials were mixed and extruded onto a glass slide first. For measurement during cure, a razor blade was used to scrape excess material and create a flat surface (~0.05mm thick). For measurement after cure, another glass slide was placed on top and pressed down until the sample was about 2mm thick. The sample was allowed to fully cure according to the manufacturer suggested setting time. A drop of 4µl distilled water was carefully dispensed and placed onto either the sample during cure or the sample after cure. Contact angle values were obtained at 1sec, 10sec, 30sec and 60sec from time of placing the water droplet. Three measurements on each material were made and the contact angle values were averaged. Results:

*Means with the same letter within the same row are not significantly different (p<0.05, Anova). **Not measurable.

Conclusion: EXP exhibited the lowest contact angle values on samples both during cure and after cure, indicating that EXP is more hydrophilic and has better surface wetability compared to other tested impression materials.