Digital analysis of fabrication accuracy and fit in additively and subtractively manufactured implant-supported fixed complete dentures

Objectives: To digitally evaluate the trueness and fit of additively and subtractively manufactured fixed complete dentures in materials intended for definitive use. Methods: An edentulous maxillary model with implants at the left first molar, left canine, right canine, and right first molar site was digitized and a fixed complete denture was designed. This design was used to fabricate fixed dentures in an additively manufactured resin for definitive use (AM), a high-impact polymer composite (SM-CR), and a strength gradient zirconia (SM-ZR) (n = 10). Each fixed denture was digitized and the surface (overall, occlusal, except occlusal, and abutments), linear, and interimplant distance deviations were analyzed. The fit was assessed with the triple-scan protocol. Data were analyzed with Welch analysis of variance and Games-Howell tests (alpha = 0.05). Results: SM-ZR led to lower overall deviations than AM, which had the highest occlusal and the lowest abutments deviations (P <= 0.007). SM-ZR had the lowest occlusal and SM-CR had the highest except occlusal deviations (P <= 0.002). AM mostly had higher linear and SM-CR mostly had higher interimplant distance deviations (P <= 0.043). AM led to the highest marginal gap at the left canine site, while SM-CR had the highest and SM-ZR had the lowest gaps at the right canine site (P <= 0.022). Conclusions: SM-ZR dentures mostly had trueness and marginal fit similar to or better than the other groups. Tested fixed complete dentures were mostly smaller than the design file in terms of interimplant distances.