Three-dimensional positioning analysis of dental implants in printed casts – in vitro study

The purpose of this in vitro study was to evaluate the three-dimensional positioning of dental implants in casts obtained using conventional and digital impressions. A printed typodont with three digital mini-abutment analogues (Neodent, Curitiba, Brazil) and a scan body for mini-abutments (EFF – Dental Components, São Paulo, Brazil) was scanned five times (n=5) with two different scanners (Omnicam, CEREC, Dentsply Sirona and TRIOS 3, 3Shape) Five stone casts were fabricated from conventional impressions of the primary cast and then scanned using a laboratory scanner. Dental implant angulation and displacement were calculated. One cobalt-chrome metal framework was fabricated over the primary cast and seated over each obtained cast, and the misfit was assessed using scanning electron microscopy (SEM) For precision and trueness, data distribution and variance equality were analyzed using the Shapiro-Wilk and Levene’s tests, respectively. Precision was assessed using one-way ANOVA; trueness was assessed using two-way ANOVA. Both analyses were followed by Tukey’s test (α=0.05).The buccal-lingual angle showed no statistically significant differences, and the mesio-distal angle also showed no significant differences between cast types, although worse results were found for the distal implant. Implant displacement showed better results (lower values) for stone casts in all directions (P=.001). The prosthetic interface region showed better outcomes compared to the bevel feature of the scan body in all directions (P=.001). SEM evaluation showed no statistically significant differences in vertical misfit when all implant prosthetic screws were tightened in all groups. Printed casts present greater variability in 3D positioning and misfit of dental implants compared to conventional casts.