Comparative evaluation of the effect of impression materials and trays on the accuracy of angulated implants impressions

BACKGROUND: Vinyl Polyether Siloxane is a newly introduced impression material and studies on that is scarce. Implant insertion in posterior mandible might be angulated due to anatomical considerations. The purpose of this study was to compare the dimensional and angular accuracy of impressions using full-arch versus sectional tray and Vinyl Polysiloxane versus Vinyl Polyether Siloxane in angulated implants. MATERIAL AND METHODS: Four implants were placed in dental areas #19, #21, #28 and #30 of a Kennedy class I mandibular acrylic model with 30° lingual angulation. Twenty sectional and 20 full-arch open trays were made on the primary cast. Impressions were taken using Vinyl Polysiloxane and Vinyl Polyether Siloxane (n=10 in 4 groups); and were poured with type IV dental stone. The coordinate measuring machine was used to measure displacements in the X, Y and Z axes and rotational discrepancies of implants. The data were analyzed using SPSS 22 and two-way ANOVA. RESULTS: Type of tray had no significant effect on the dimensional and angular accuracy of impressions (p >0.05). Type of impression material significantly affected linear displacement (∆r) (P <0.05); but it did not significantly affect the rotational displacement (P >0.05). CONCLUSIONS: Vinyl Polysiloxane yielded more accurate impressions of angulated implants. Key words:Dental implant, impression material, impression tray, vinyl polysiloxane, vinyl polyether silicone, coordinate measuring machine.