In-vitro fatigue and fracture testing of temporary materials from different manufacturing processes in implant-supported anterior crowns

Abstract

Abstract Objectives The aim of this study was to investigate the in-vitro fatigue and fracture force of temporary implant-supported anterior crowns with different abutment conicity, with/without a screw-channel, and with different type of fabrication. Materials and Methods 192 implant supported crowns were manufactured (4° or 8° conicity; with/without screw channel) form 6 materials (n = 8; 2x additive, 3x subtractive, 1x cartridge; reference). Crowns were temporary cemented, screw-channels were closed (Teflon, resin composite) and stored in water (37°C; 10 days) before thermal cycling and mechanical loading. Fracture force was determined, and failures were analyzed. Statistics: Kolmogorov-Smirnov, ANOVA; Bonferroni; Kaplan-Meier; Log-Rank; α = 0.05. Results Failure during TCML varied between 0 failures and total failure. Mean survival time was between 1,8 ± 1,6 x105 cycles and 4,8 ± 0 x105 cycles. Highest impact on survival presented type of material (η2 = 0.072, p < .001). Fracture values varied between 265.7 N and 628.6 N. Highest impact on fracture force was found for type of material (η2 = 0.084, p < .001). Conclusion Additively and subtractively manufactured crowns had similar or even higher survival rates and fracture forces. The choice of material is decisive for the survival time and fracture force. The fracture force was higher with smaller conicity. Fatigue testing was only affected by manually inserted screw-channels in cartridge-made crowns. Clinical relevance The highest stability has been shown for crowns with a low abutment conicity, which are manufactured additively and subtractively. In cartridge-fabricated crowns, manually inserted screw channels have negative effects.