Fracture load of 3D-printed fixed dental prostheses compared with milled and conventionally fabricated ones: the impact of resin material, build direction, post-curing, and artificial aging—an in vitro study

• Published in: Clinical oral investigations Vol. 24; no. 2; pp. 701 - 710
• Main Authors: Reymus, Marcel, Fabritius, Rosalie, Keßler, Andreas, Hickel, Reinhard, Edelhoff, Daniel, Stawarczyk, Bogna
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-02-2020; Springer Nature B.V
• Subjects: Aging; Aluminum; Dental Materials; Dental Prosthesis; Dental prosthetics; Dental Restoration Failure; Dental restorative materials; Dental Stress Analysis; Dentistry; Kruskal-Wallis test; Load; Materials Testing; Medicine; Original Article; Printing, Three-Dimensional; Prostheses; Artificial aging; Fracture load; Post-curing; Build direction; 3D printing
• ISSN: 1432-6981; 1436-3771
• DOI: 10.1007/s00784-019-02952-7

Objective
To investigate the impact of 3D print material, build direction, post-curing, and artificial aging on fracture load of fixed dental prostheses (FDPs).
Materials and methods
Three-unit FDPs were 3D-printed using experimental resin (EXP), NextDent C&B (CB), Freeprint temp (FT), and 3Delta temp (DT). In the first part, the impacts of build direction and artificial aging were tested. FDPs were manufactured with their long-axis positioned either occlusal, buccal, or distal to the printer’s platform. Fracture load was measured after artificial aging (H
2
O: 21 days, 37 °C). In the second part, the impact of post-curing was tested. FDPs were post-cured using Labolight DUO, Otoflash G171, and LC-3DPrint Box. While the positive control group was milled from TelioCAD (TC), the negative control group was fabricated from a conventional interim material Luxatemp (LT). The measured initial fracture loads were compared with those after artificial aging. Each subgroup contained 15 specimens. Data were analyzed using Kolmogorov-Smirnov test, one-way ANOVA followed by Scheffé post hoc test,
t
test, Kruskal-Wallis test, and Mann-Whitney
U
test (
p
 < 0.05). The univariate ANOVA with partial eta squared (
η
P
2
) was used to analyze the impact of test parameters on fracture load.
Results
Specimens manufactured with their long-axis positioned distal to the printer’s platform showed higher fracture load than occlusal ones (
p
 = 0.049). The highest values were observed for CB, followed by DT (
p
 < 0.001). EXP showed the lowest values, followed by FT (
p
 < 0.001). After artificial aging, a decrease of fracture load for EXP (
p
 < 0.001) and DT (
p
 < 0.001) was observed. The highest impact on values was exerted by interactions between 3D print material and post-curing unit (
η
P
2
 = 0.233,
p
 < 0.001), followed by the 3D print material (
η
P
2
 = 0.219,
p
 < 0.001) and curing device (
η
P
2
 = 0.108,
p
 < 0.001).
Conclusions
Build direction, post-curing, artificial aging, and material have an impact on the mechanical stability of printed FDPs.
Clinical relevance
The correct post-curing strategy is mandatory to ensure mechanical stability of 3D-printed FDPs. Additively manufactured FDPs are more prone to artificial aging than conventionally fabricated ones.