Effect of impression technique and material on accuracy of implant impressions

Dental implant treatment becomes one of the most predictable and successful dental rehabilitation therapies. After successful osseointegration, impression making is one of the most important and critical steps in implant prothesis fabrication for long term successful use. An accurate impression and stone casts are extremely important because inaccuracy in any of these can lead to mechanical and /or biological complications which ultimately result in failure of implant restoration. An in vitro study was carried out to evaluate linear dimensional accuracy of implant impressions by using different silicone impression materials and different impression techniques. Four implants (Arrow Mytis Implant System, Brainbase Co. Ltd., Tokyo, Japan) were parallelly placed in the edentulous mandible model using the surgical guide at canines and first molar areas. Fixture-level impressions were made by using addition silicone (Perfit, Huge, Rizhao, China) or condensation silicone (Silect Set, Muller-Omicron GmbH&Co.KG, Germany) with putty-light body wash one-step procedure, with closed tray or open tray technique and poured with dental stone (Silky Rock, Type IV stone, U.S.A). Three hours after removal of impression from the stone cast, four measurements (AB, BC, CD, AD) were taken between implants by using digital slide caliper (Hummer, Thailand) with accuracy of +0.03mm. Data was analyzed by using one-way ANOVA. There was no statistically significant difference in deviation of linear dimension between the impression materials and techniques. It is concluded that both addition and condensation silicones may ensure acceptable accuracy with either closed tray or open tray technique for implant impressions.