Abstract
The objective of this review was to collect information on available additive manufacturing technologies used for the fabrication of either single crowns or fixed-dental prosthesis (FDP) with a focus on the chemistry, surface characteristics and interaction between frameworks and veneering ceramics. Original scientific papers in MEDLINE (PubMed), Embase, Scopus databases, published between 01 January 1996 and 30 June 2020 were included in this review. The following MeSH terms, search terms and their combinations were used: ‘in vitro’, ‘crowns’, ‘denture, partial, fixed’, ‘dentistry’, ‘fixed dental prosthesis’, ‘FDP’, ‘bridges’, ‘additive manufacturing’, ‘alloys’, ‘surface roughness’, ‘adhesion’. Two reviewers performed screening and analysed the data. Only the studies that reported on chemistry, surface characteristics and ceramic adhesion for FDPs were included. The selection process resulted in the final sample of 91 journal articles. In total, 16 articles were identified related to chemistry of alloys used in additive manufacturing: 1 on surface characteristics, and 9 on adhesion of veneering ceramics to alloys. In addition, review articles, books, patents and manufacturers` information were retrieved. Accordingly, it was noted that current additive technologies use mainly Co-Cr or titanium alloys but the production of the starting material presently lacks sufficient standardization and regulations. For these alloys, rougher surface microstructure (3.2 ± 0.4 µm) than for cast alloys (2.3 ± 0.6 µm) was reported which may have clinical implications in implant dentistry. There is some evidence that surface roughness contributes to increased bond strength of veneering ceramic to metal frameworks ranging between 24 ± 10 and 54 ± 14 MPa but the detailed underlying metal-ceramic adhesion mechanism remains to be elucidated.