Accuracy of Regular- and Fast-Setting Vinylpolysiloxane Impressions Using Customized Trays

Objectives: Fast-setting impression materials can save prosthetic treatment time. Customized single-use plastic trays gain importance. This laboratory study compared dimensional accuracy for vinylpolysiloxane (VPS) impressions differing in curing time and taken with metal or plastic trays.
Methods: The metal reference model simulated a partially edentulous situation of an upper jaw with 6 teeth prepared to serve as a crown abutments. The model comprised 5 precision balls (d = 3.175mm) distributed over the dental arch. A digital data set was generated. From the reference model one-time two-phase VPS impressions (Aquasil Ultra+heavy/XLV; Dentsply Sirona) in a regular- (AR) and fast- (AF) setting variant (n=40 each) were taken. For each half of the impressions customized border-lock metal trays or plastic trays were used. Resulting gypsum models (esthetic-base gold; Dentona) were digitized (D2000; 3Shape) and compared with the reference data set. Concerning global accuracy, distance and angle deviations between precision ball centers and virtual reference points attached to the abutment teeth were computed. Local accuracy on a single tooth level was described by trueness and precision after individual alignment. Analysis of variance was used to estimate effects of impression and tray materials (SPSS Ver. 28; IBM).
Results: In all cases, dimensions of the plaster casts were too small. Global accuracy was favorable, even for long distances mean absolute distance changes were < 100 μm. While absolute distance deviations were smaller (p < 0.001) for plastic trays, metal trays provided a better accuracy in the vertical dimension (p < 0.001). Regarding trueness and precision, all tray and impression material combinations yielded mean values < 10 μm.
Conclusions: The observed accuracy parameters were promising for all combinations of impression materials and trays. Plastic trays and fast-setting VPS material can be a viable alternative in prosthetic management.