Accuracy of computerized and conventional impression-making procedures for multiple straight and tilted dental...

To compare the accuracy of implant impressions using computer-aided impression-making technology and a conventional approach in a standardized setting in vitro, and to verify the effect of implant angulation (40 to 45 degrees) on the accuracy of digital and conventional impression-making procedures.

Four different edentulous mandibular reference models (RMs) were manufactured. Two straight (RM1); four straight (RM2); two straight and two tilted (RM3); and six straight (RM4) dental implants were placed, simulating four different clinical scenarios. The computer-aided impressions (n = 5 for each RM) were made using an intraoral scanner (IOS) (True Definition, 3M ESPE). Polyether (n = 5 for each RM) and vinyl polysiloxane (n = 5 for each RM) impression materials were utilized for the conventional approach. The collected data were analyzed in terms of trueness. The statistical analysis was performed using one-way analysis of variance (ANOVA).

The overall differences of interimplant distance, identified in mean values, were statistically significant among the different impression-making groups in RM1, RM3, and RM4. The data analyses of overall interimplant angle deviations yielded statistically significant differences in all four RMs. However, the deviations obtained with both impression-making approaches did not exceed an interimplant distance threshold of 100 µm, and an interimplant angle of 0.5 degrees, which seems to be clinically acceptable.

Within the limits of this in vitro study, the accuracy of the computer-aided and conventional impression-making approaches for straight and tilted dental implants was comparable, and might be clinically considered for full-arch, multiple-implant restorations. However, further clinical studies are required to verify the feasibility of different IOSs (with and without scanning powder application), different implant systems, and multiple implant configurations.