Evaluation of the fabrication trueness and internal fit of additively manufactured two-piece zirconia abutments with different build orientations compared to subtractively manufactured abutments.

Objective: To evaluate the effect of build orientation on the fabrication trueness and fit of additively manufactured 2-piece zirconia abutments when compared with those manufactured subtractively in 3 mol% and 4 mol% yttria-stabilized zirconia (3Y-TZP and 4Y-TZP).
Methods: A titanium-base (Ti-base) abutment was digitized with a scan body and an industrial scanner to design a 2-piece zirconia abutment with a 50 µm cement gap. This design was used to manufacture zirconia abutments additively in different orientations (0-degree, AM-0; 15-degree, AM-15; 30-degree, AM-30; 45-degree, AM-45; 180-degree, AM-180) and subtractively from 3Y-TZP and 4Y-TZP (SM-3 and SM-4) (n=5). An intraoral scanner was used to digitize all abutments, when they were seated on the Ti-base, and only the Ti-base. Abutments' trueness (overall, external, intaglio, and marginal) was analyzed with the root mean square (RMS) method, and their fit was assessed with the triple-scan protocol. Data were analyzed with 1-way analysis of variance and Tamhane's T2 tests (α = 0.05).
Results: SM-3 abutments had the lowest overall and external RMS (P ≤ 0.023). SM-3 and SM-4 abutments mostly had lower intaglio and AM-0 abutments mostly had lower gingival RMS (P ≤ 0.013). Except for AM-0 and SM-3 (P ≥ 0.930), SM-4 abutments had the lowest average gaps (P ≤ 0.041).
Conclusions: SM-3 abutments mostly had higher fabrication trueness, while AM-0 abutments had trueness similar to or higher than the other additively manufactured abutments. AM-0, SM-3, and SM-4 abutments had similar fit with average gaps lower than 50 µm.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)