Purpose: To investigate the bending moment of implants restored with a directly screwed single-unit fixed dental prosthesis (FDP) compared to implants restored with an FDP polymerized to a titanium base before and after thermomechanical aging. Materials and Methods: A total of 240 implants (120 with and 120 without a titanium base) were restored with FDPs manufactured from conventionally sintered 3Y-TZP, 5Y-TZP, 4Y-TZP, and CoCrMo, as well as high-speed sintered 4Y-TZP. Half the specimens per subgroup were aged using chewing simulation combined with thermocycling (1,200,000 cycles at 50 N; 6,000 cycles at 5° to 55°). Initial and aged fracture load were measured. The bending moment was calculated and subjected to statistical analysis (Kolmogorov-Smirnov test, one-way ANOVA followed by post hoc Scheffé, t, and chi-square tests; P < .05). Failure types were analyzed. Results: Implants without a titanium base showed higher bending moments for all initially tested zirconia groups compared to implants with a titanium base. The highest initial values were observed for 4Y-TZP FDPs regardless of implant type. High-speed sintered FDPs demonstrated higher initial bending moments compared to conventionally sintered FDPs. Artificial aging led to a decrease of the bending moment in most subgroups. After aging, no differences were found within the restoration materials, sintering protocols, or implant types. Implant deformation occurred mainly with directly screwed FDPs, whereas FDP mobility was predominantly observed among implants with a titanium base. FDP fractures were mainly observed for 5Y-TZP. Conclusions: Both implant types exhibited similar values after aging. Thus, implants without a titanium base seem to show equally sufficient stability for clinical applications with all tested materials.

Purpose: To investigate the discoloration and surface properties of four CAD/CAM composite resins following storage in various food solutions and exposure to cigarette smoke. Materials and Methods: A total of 74 specimens (N = 370) were prepared for five materials: Brilliant Crios (BC), Cerasmart (GC), Lava Ultimate (LU), Shofu Block HC (SH), and Sonic Fill 2 (SO). Discoloration (ΔE) was investigated with a spectrophotometer. Measurements were taken before immersion in storage media (carrot juice, curry, cigarette smoke, red wine, energy drink, and distilled water), after 2 weeks of immersion, and after manual polishing of the specimens following immersion. The average surface roughness (Ra) was measured with a profilometer. Qualitative surface observation was performed with scanning electron microscopy (SEM). Data were analyzed using Kolmogorov-Smirnov test, Mann-Whitney U test, and one-way ANOVA with Tukey post hoc test. Results: The highest influence on ΔE after immersion was observed for storage medium (η_P² = 0.878, P < .001), followed by the interaction between storage medium and material (η_P ² = 0.770, P < .001) and material (η_P ² = 0.306, P < .001). For ΔE after polishing, the highest influence was indicated by the interaction between material and medium (η_P ² = 0.554, P < .001), followed by medium (η_P² = 0.244, P < .001) and material (η_P² = 0.196, P < .001). Immersion in carrot juice led to the highest color change (ΔE: 8.0 to 10.4), whereas the lowest values were recorded in distilled water (ΔE: 2.0 to 2.4). Carrot juice and the energy drink caused the highest Ra values (0.120 μm to 0.355 μm). SEM pictures indicated a loss of the organic matrix after manual polishing. Conclusion: The different materials reacted dissimilarly to the various storage media in terms of discoloration. Surface roughness increased after immersion or polishing. Neither discoloration nor surface roughness could be reset to default by manual polishing.

Aufgrund der stetigen Weiterentwicklung von polymerbasierten Werkstoffen ergibt sich heutzutage ein breites Anwendungsspektrum im dentalen Bereich. Die Materialeigenschaften von 3-D-druckbaren Harzen und Kompositen müssen jedoch noch verbessert werden, damit sie als definitiver Zahnersatz eingesetzt werden können. Für die Verbesserung der Oberflächeneigenschaften polymerbasierter Werkstoffe kommen verschiedene Verfahren zur Anwendung. Palabras clave: additive Fertigung, 3-D-Druck, Oberflächenbehandlung, Politur, Versiegelungslack

Der dentale 3-D-Druck deckt mittlerweile ein breites Indikationsspektrum ab. Die additive Fertigung von Langzeitprovisorien bietet heutzutage zunehmend eine Alternative zur konventionellen Fertigung. Dieser Beitrag gibt einen Überblick der bisherigen Forschungsergebnisse über 3-D-gedruckte Restaurationen, den Postprocessing-Prozess sowie Befestigungsstrategien. Palabras clave: additive Fertigung, 3-D-Druck, harzbasierte Restauration, Postprocessing, Befestigung

Purpose: To investigate the impact of high-speed sintering on the accuracy (trueness and reproducibility) and fit of 4Y-TZP full-coverage single-unit fixed dental prostheses (FDPs) and three-unit FDPs. Materials and methods: Single-unit FDPs, conventional three-unit FDPs, and cantilever three-unit FDPs (N = 108; n = 12 per subgroup) were fabricated from: (1) high-speed sintered (1,580°C, about 20 minutes) multi-layer 4Y-TZP (Zolid RS, Amann Girrbach; ZMLH group), as well as two conventionally sintered (1,450°C, about 10 hours) materials: (2) multi-layer 4Y-TZP (Zolid Gen-X, Amann Girrbach; ZMLC group) and (3) monochrome 4Y-TZP (Ceramill Zolid HT+ PS, Amann Girrbach; ZMOC group). All specimens were scanned. Trueness, reproducibility, and fit were measured with 3D analysis software. For data analysis, Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests were performed (α = .05). Results: Three-unit FDPs made from ZMLH presented a deterioration of accuracy in comparison to ZMLC (P ≤ .001 to .008). The influence of highspeed sintering on marginal and general fit was not clinically relevant (P = .154 to .877). Conclusion: High-speed sintering influenced the accuracy of 4Y-TZP full-coverage single-unit and three-unit FDPs. However, no clinically relevant impact on fit was observed.

Purpose: To investigate the influence of different cleaning methods for additively manufactured fixed dental prostheses (FDPs) for long-term temporary use on the degree of conversion (DC), surface roughness, Martens parameters, and biaxial flexural strength. Materials and methods: A total of 180 specimens per material (3Delta Etemp, DeltaMed; Freeprint Temp, Detax; Temp PRINT, GC Europe; Temp C&B and C&B MFH, NextDent; N = 180) were additively manufactured (D20 II, Rapid Shape) and subsequently cleaned by different methods: by rinsing for 5 minutes in acetone (Höfer Chemie; 99.5%); butyl glycol (Algin Chemie; 100%); ethanol (Otto Fischar; 96%); isopropanol (SAV LP; 100%); Yellow Magic 7 (Bradley Systems; 100%); or by applying centrifugal force for 4 minutes (n = 30 per subgroup). After postpolymerization (Otoflash G171, NK-Optik), the DC was measured using Raman spectroscopy, and the surface roughness, as well as the Martens parameters, were recorded. Biaxial flexural strength was investigated after artificial aging (thermocycling for 10,000 cycles). Data were statistically analyzed (Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests, and Pearson correlation coefficient). Results: The highest DC was recorded after the use of butyl glycol or isopropyl (P < .001 to P = .047). The highest surface roughness was measured after the use of butyl glycol (P < .001 to P = .024). The use of centrifugal force or Yellow Magic resulted in the highest Martens parameter values (P < .001 to P = .036) and the highest biaxial flexural strength (P < .001 to P = .013), while acetone and butyl glycol led to the lowest values. Conclusion: The use of centrifugal force and Yellow Magic resulted in the highest Martens parameter values and the highest biaxial flexural strength. Concerning Yellow Magic, no negative effect on the mechanical properties was observed. The 3Delta Etemp material especially was prone to degradation after chemical cleaning.

Im 3-D-Druck können heutzutage Modelle, Hilfsstrukturen, provisorischer und definitiver Zahnersatz und Rekonstruktionen im Kopf-Halsbereich gefertigt werden. Um reproduzierbare und vergleichbare Ergebnisse zu erhalten, ist eine Norm für die additive Fertigung dentaler Werkstoffe notwendig. Palabras clave: 3-D-Druck, Polymere, Prüfmethoden