Effect of Mixing and Impression Techniques Using Vinyl Polysiloxane (VPS) on the Accuracy of Fixed Partial Dentures

Abstract

Two critical factors that influence the accuracy of an impression include the proper manipulation of the impression materials and the technique used to make the impression. The purpose of this study was to clinically evaluate the effect of different mixing techniques on the accuracy of vinyl polysiloxane (VPS) impressions by assessing metal framework fit of fixed partial restorations. The study included 92 consecutive patients diagnosed with partial edentulism and treated with fixed partial denture restorations. The mixing technique was one of the two following mixing methods: hand mixing technique (45 patients), with the putty material mixed according to the manufacturer’s instructions; or mechanical mixing technique (47 patients), with the putty material mixed by a Pentamix device. Under both mixing methods, vinyl polysiloxane was used as the impression material. Two impression techniques were randomly used by the operators (One/Two-stage putty –wash impression techniques). The accuracy of the metal framework restorations was tested clinically and radiologically, resulting in significant statistical difference (p = 0.04) between different mixing techniques. The mechanical mixing produced more accurate restorations (metal framework misfit only in 14.9% of patients vs. hand mixing 31.1%). Regarding the impression techniques, the two-stage impression technique was found to be significantly more accurate (p = 0.04), resulting in 14.6% ill-fitted metal frameworks vs. 31.8%, in the one-stage technique. It can be concluded that mechanical mixing yields more accurate impressions leading to more accurate restorations, especially when combined with two-stage impression technique.

A Methodological Approach for Motor Selection in Dental Impression Material Dispensers Using Experimental and Image Analysis Techniques

“…Fitting with an exponential function was conducted, employing the exponential model as outlined in Equation (14).…”

“…Keck et al validated its enhanced efficacy in preventing contamination and in reducing voids [12]. Di Felice et al reported that mechanical mixing results in fewer voids than manual methods [13], whereas Zelikman et al highlighted the merits of mechanical mixing for producing more precise dental replicas [14]. Lepe et al assessed the influence of various mixing techniques on the contact angle, absorption, and mass reduction of impression materials [15].…”