Journal of Esthetic and Restorative Dentistry最新文献

Objective: This study aimed to evaluate the effects of resin coatings on bond strength using immediate and delayed cementation protocols.

Materials and methods: One hundred twenty dentin specimens were assigned to four groups: Noncoated, TK-100B (a novel single-bottle adhesive), Hybrid Coat II, and Clearfil SE bond 2. The specimens of the latter three groups were resin coated with their respective materials. Each group was subdivided into immediate and delayed cementation after 1-week provisionalization with a polycarboxylate cement. All specimens were luted with resin cement and subjected to shear bond testing. Data were analyzed by two-way analysis of variance and Tukey's post hoc test (α = 0.05).

Results: TK-100B and Clearfil SE Bond 2 produced significantly higher bond strengths than the non-coated group for both cementation schedules. Delayed cementation reduced the bond strengths of Hybrid Coat II and Clearfil SE Bond 2 (p < 0.05), whereas the non-coated group and TK-100B showed no time-related changes. Most failures in the resin-coated groups occurred at the resin-cement interface.

Conclusions: Bonding strength was enhanced with TK-100B and Clearfil SE Bond 2. A 1-week delay weakened Hybrid Coat II and Clearfil SE Bond 2 but had no effect on non-coated dentin or TK-100B, confirming material-specific effects.

Clinical significance: Both the novel single-bottle adhesive TK-100B and the established Clearfil SE Bond 2 yield high bond strengths when used as resin coatings in both immediate and 1-week delayed cementation.

Objective: This study evaluated the probability of survival, failure modes, and fatigue-induced wear progression, as well as assessed damage tolerance under simulated mastication in two resin matrix ceramics (polymer-infiltrated ceramic networks (PICN) and resin nanoceramic (RNC)).

Methodology: Specimens underwent step-stress accelerated life testing (SSALT) (n = 21), mouth-motion simulation (n = 12), followed by wear analysis and flexural strength testing. Probability of survival and flexural strength were analyzed using Weibull statistical modeling. Damage mechanisms were characterized by optical microscopy, scanning electron microscopy (SEM), and high-resolution 3D quantitative analysis of wear depth and volumetric loss after mouth motion simulation. Two-way ANOVA was used, followed by Tukey Post Hoc with a significance level of 5% (α = 0.05).

Results: At 600 N, PICN exhibited significantly lower probability of survival (6%) compared to RNC (60%). SEM images showed delamination and radial cracking for both groups, being more frequent in PICN. Both materials demonstrated progressively significant increases in volumetric wear with the increase in the number of cycles and showed 0.014 mm³ for PICN and 0.016 mm³ for RNC after 100,000. Flexural strength was higher for RNC (303 MPa) than for PICN (189 MPa). Also, it decreased after 1,000 cycles for PICN, while for RNC it decreased only after 100,000 cycles, and it was always higher than for PICN. SEM images showed that fracture originated at wear craters.

Conclusions: RNC exhibited superior probability of survival, particularly under more demanding conditions compared to PICN. Both materials showed a progressive increase in surface wear as the number of cycles increased. The flexural strength of RNC remained consistently higher over time. Regarding failure mechanisms, both materials experienced delamination and crack formation; however, radial cracks were more frequently observed in PICN, indicating a higher susceptibility to structural failure under fatigue conditions.

Clinical significance: Selection of restorative materials must balance mechanical performance and long-term durability under functional loading. Resin nanoceramic appears to be a more reliable option than polymer-infiltrated ceramic networks for restorations in high-stress areas, such as posterior teeth or patients with parafunctional habits.

The cover image is based on the article The Multilayer Flowable Injection Technique for Highly Esthetic Restorations by Yolanda M. Liaropoulou et al., https://doi.org/10.1111/jerd.13500.

Objectives: To evaluate nanozeolite (NZ)-modified 3D-printed hybrid ceramics at 0.25%, 0.5%, and 1% versus milled hybrid resin-ceramics, focusing on fracture toughness, surface roughness, microhardness, degree of conversion (DC), water sorption, and color stability.

Materials and methods: NZ was incorporated into 3D-printed ceramic-filled resin (VarseoSmile Crown Plus, VA) and tested alongside unmodified VA (control) and milled CAD-CAM ceramic (Vita Enamic, VE). Bars (18 × 3.6 × 1.8 mm) were prepared for fracture toughness, and discs (10 × 2 mm) for roughness, microhardness, water sorption, and color/translucency. Fracture toughness was measured by the single-edge notched beam (SENB) method, roughness and microhardness by profilometer and Vickers test, and DC by FTIR. Water sorption/solubility was gravimetrically measured, and ΔE00 and translucency parameter (TP) by spectrophotometry. Tests were conducted before and after thermocycling (1000 cycles, 5°C-55°C). Data were analyzed using ANOVA, Kruskal-Wallis, t-tests, and Wilcoxon signed-rank tests (p < 0.05).

Results: VE exhibited the highest fracture toughness and microhardness, which decreased after thermocycling (p < 0.001). NZ-0.25% improved toughness versus VA both before and after aging (p = 0.04), while NZ-0.5% and 1% slightly reduced toughness but increased microhardness and decreased roughness after aging (p < 0.01). All NZ groups showed higher DC than control (p < 0.001). Thermocycling reduced toughness in VE and VA, but not NZ-VA. Water sorption and solubility were significantly lower in all NZ groups (p < 0.0001). ΔE00 remained < 1.8 for all groups after thermocycling, with 0.25% NZ-VA showing the most color stability and 1% NZ-VA showing minimal TP changes (p < 0.05).

Conclusion: Milled hybrid ceramic (VE) outperformed printed hybrid ceramic (VA). Nanozeolite improved VA, with 0.25% providing the best balance of fracture toughness and microhardness, while preserving color and aging stability. Higher concentrations (0.5%-1%) mainly enhanced surface characteristics but added little to bulk properties and translucency.

Clinical significance: Nanozeolite integration at 0.25% enhances strength, durability, and color stability in 3D-printed hybrid ceramics, improving their reliability for dental restorations. Higher loadings enhance surface properties but may modestly reduce bulk toughness and translucency, relevant for clinical decision-making.