Dental Materials最新文献

Objectives: This study evaluated the long-term clinical performance and survival of CAD-CAM-fabricated partial ceramic crowns (PCCs) luted with either self-adhesive resin cement, or conventional luting composite combined with a universal adhesive, applied without or with selective enamel etching.

Methods: A 12 year follow-up of a randomized split-mouth clinical trial initially including 48 patients was conducted. PCCs were luted with three different randomized luting protocols (all material: Solventum): RXU (RelyX Unicem), SBU-E (RelyX Ultimate/Scotchbond Universal, no selective enamel etching), SBU+E (RelyX Ultimate/Scotchbond Universal, with selective enamel etching). Clinical performance was assessed using FDI criteria at baseline and after 12 years. Survival rates were calculated using Kaplan-Meier analysis, and statistical differences between groups and over time were tested using Chi-square and log-rank tests (α=0.05).

Results: After a median observation period of 12.2 years, 16 patients (38 restorations) were available for clinical evaluation. By including information from files of patients that were not available for clinical evaluation, the Kaplan-Meier survival analysis included 35 patients (87 restorations). The survival rates significantly differed between the groups: RXU (36.4 %), SBU-E (60.7 %), and SBU+E (80.8 %). RXU demonstrated significantly lower survival compared to both SBU-E (p = 0.034) and SBU+E (p = 0.001), while no significant difference was observed between SBU-E and SBU+E (p = 0.141). Clinical performance evaluated according to FDI criteria remained acceptable for all groups and criteria at 12 years, with mostly minor aging-related changes observed, e.g. in terms of a significant increase in marginal staining (p ≤ 0.002) for all groups and a significant deterioration in marginal adaptation for RXU (p = 0.009) and SBU-E (p = 0.003) over time. PCCs placed with a universal adhesive and conventional luting composite combination showed a significantly higher survival compared to PCCs placed with self-adhesive resin cement. Selective enamel etching by tendency improved the performance of the conventional luting composite.

Significance: The study highlights the importance of adhesive protocols in achieving long-term survival and clinical success for PCCs, particularly emphasizing the benefits of universal adhesives without or with selective enamel etching combined with luting composites.

Objective: Implantoplasty is sometimes performed to eliminate the contaminated titanium surface of peri-implantitis affected implants. Bone regeneration treatments are performed in conjuction with implantoplasty. The aim of this study was to evaluate if produced titanium debris alter the bone-regeneration potential and if dexamethasone-doped polymeric nanoparticles, combined with calcium phosphate, may help to overcome this situation.

Methods: Four critical bone defects were performed on six New Zealand-bred rabbit skulls. In each of the four bone defects, the following biomaterials were placed: 1) unfilled (control), 2) calcium phosphate granules (CaP), 3) titanium debris (Tid) and CaP, 4) dexamethasone-doped polymeric nanoparticles (DexNPs) doped onto CaP and Tid. After six weeks, animals were euthanized and the bone architecture was evaluated radiographically with micro computed tomography through BoneJ pluging and ImageJ script, and histologically after Von Kossa staining.

Results: Bone defects filled with CaP plus Tid showed lower defect closure than those filled with CaP. The presence of DexNPs restored the defect closure values, being similar to those of the CaP group. Bone filling area and bone area fraction attained the highest values in the presence of DexNPs. Aligned new bone islands were formed and grew up around the CaP granules, infiltrating its porous structure. In the CaP+Tid group a lower bone ingrowth was formed. When applying DexNPs, bone bridging processes were located surrounding the CaP biomaterial.

Significance: The presence of Tid reduces the bone healing and DexNPs doped on CaP produced an increase in the osteogenic potential, improving the bone defect closure.

Objective: The purpose of this study was to evaluate the adhesion potential of two universal resin cements compared to a gold standard adhesive system, considering application mode and storage time, using a novel method for interfacial fracture toughness (iFT).

Methods: iFT was measured using the Chevron-Notched Beam (CNB) method with a novel modified split-CNB sandwich specimen design. One hundred human third molars were sectioned into enamel-dentin rods, adhesively conditioned, notched, and cut apart in the dentin area. Specimens were bonded using the universal luting resin in self-adhesive mode or with their corresponding adhesive system/primer (RelyX Universal and Scotchbond Universal Plus, Solventum; GCem One and Adhesive Enhancing Primer, GC Corp.). A gold standard adhesive (OptiBond FL, Kerr) in combination with a flowable resin composite as luting material (x-tra base Universal, VOCO) served as a control. The influence of storage time (24 h vs. 180 days), application mode (adhesive vs. self-adhesive), and the material itself on the iFT measured as fracture toughness in mode I (K_Ic) according to ASTM C1421-10 was evaluated. Scanning electron microscopy (SEM) was employed to analyze interfacial characteristics and failure modes.

Results: Statistical analysis (Kruskal-Wallis H test with Bonferroni-Holm correction) revealed significant differences in iFT between the groups. Specimens stored for 180 days exhibited lower iFT compared to those stored for 24 h. The adhesive application significantly enhanced iFT relative to the self-adhesive mode. GCem One with Adhesive Enhancing Primer (24 h) exhibited the highest interfacial fracture toughness among all investigated groups. SEM analysis indicated a predominance of adhesive failures at the dentin-resin interface, particularly within the self-adhesive groups.

Conclusions: The application mode and material significantly influence interfacial fracture toughness. The adhesive-assisted application enhances bond stability, while the self-adhesive approach exhibits lower long-term adhesion.

Clinical significance: The use of universal resin cements along with their adhesive system/primer significantly enhances adhesion between the tooth and the restoration, leading to improved long-term clinical success. For restorations without microretention, universal resin cements must be used in combination with their adhesive system/primer.

Objectives: To evaluate the effect of aging on the color and whiteness of single- and group- shade resin composites in restorations with different cavity configurations and dental shades.

Methods: Class I and V cavities (length of 8.0 mm, depth of 2.0 mm and width of 2.5 mm) were prepared in artificial acrylic mandibular right molars with different shades (A1, A2, A3, A3.5, and A4). Three single- (OMNI- Omnichroma, UNI- Vittra APS Unique, CHA- Charisma Diamond ONE) and two group-shade (FIL- Filtek Universal Restorative, HAR- Harmonize) resin composites were evaluated. The ISO 4892-2 was used to perform the accelerated artificial aging (AAA). Spectral reflectance measurements were obtained and CIELAB color coordinates were calculated (CIE D65 standard illuminant and 2º CIE1931 Standard Observer) at baseline and after AAA. CIEDE2000 color differences (ΔE₀₀), %∆L₀₀,%∆C₀₀,%∆H₀₀and whiteness variations (ΔWI_D) were calculated. Generalized linear models (GLM) were used for the comparison between combined groups (shade, aging, and cavity configuration) for each outcome individually and all possible associations between groups (α = 0.001). The corresponding perceptibility (PT₀₀ = 0.8 and WPT = 0.7) and acceptability (AT₀₀ =1.8 and WAT = 2.6) thresholds were used for the analysis of the results.

Results: In general, the color stability of single- and group-shade composites after aging was better for Class V restorations, presenting lower ΔE₀₀ and ΔWI_D values. For Class I restorations, group shade composites (FIL and HAR) exhibited lower ΔE₀₀ and ΔWI_D values; FIL generally showed the lowest ΔE₀₀ and ΔWI_D values for both Class I and Class V restorations. These values were below the AT₀₀ and WAT values for Class V restorations, but above the AT₀₀ and WAT values for Class I restorations.

Clinical significance: The influence of cavity configuration on color and whiteness stability indicates that restoration geometry should be considered when predicting long-term shade matching and esthetic durability of single- and group-shade composites."

Objectives: To evaluate the effects of post-curing light wavelength and intensity on the surface morphology, flexural strength, degree of conversion (DC), and cytotoxicity of 3D-printed denture base polymers.

Methods: A custom-built post-curing device with adjustable light wavelength and intensity was used to treat 3D-printed specimens. Nine groups were created by combining three wavelengths (365, 385, 405 nm) with three intensities (200, 800, 2000 W/m²). Flexural strength and modulus were assessed via three-point bending tests, DC was measured using FTIR, surface morphology was analyzed by SEM, and cytotoxicity was evaluated in L929 fibroblasts using extract-based CCK-8, LDH release, and Calcein-AM/PI staining assays. Data were statistically analyzed using two-way ANOVA and Tukey's post hoc test.

Results: No discernible differences in surface morphology were observed among the groups. Cytotoxicity was significantly influenced only by light intensity (p < 0.05), yet all groups exhibited acceptable biocompatibility. Light intensity and its interaction with wavelength had significant effects on flexural strength and DC (p < 0.05), while wavelength alone showed no significant effect (p > 0.05). The highest flexural strength (147.2 ± 11.2 MPa) and DC (∼85 %) were obtained at 2000 W/m² with wavelengths of 405 nm and 385 nm, respectively.

Significance: Considering the clinical application of 3D-printed denture base polymers, light intensity was the primary factor influencing post-curing performance and interacted with wavelength. At specific wavelengths, moderate increases in light intensity could improve flexural strength, DC, and biocompatibility, suggesting that optimizing light parameters could enhance clinical reliability.

Introduction: Cytotoxicity testing is critical in assessing the biocompatibility of dental materials with regard to the pulp, however, conventional methods such as the extract test (ISO 10993-5) do not reflect the protective effects of dentin in the dentin-pulp complex. Traditional dentin barrier testing techniques (ISO 7405) address this problem, but face challenges due to their complex and expensive production and the difficult and error-prone handling. Therefore, the aim of this study was to develop a novel, user-friendly and easily accessible dentin barrier culture system (DBCS) to improve cytotoxicity testing of dental materials.

Method: The DBCS was designed and manufactured using stereolithography 3D printing. The components were assembled with dentin discs to create a barrier between an upper and lower compartment (pulp side/restoration side). Dentin discs were pretreated (EDTA or citric acid) and primary human pulp cells (HPC) or mouse fibroblasts (L-929) were cultured in the upper chamber, while a self-adhesive composite (Vertise Flow, Kerr; Scafati, Italy) was applied to the opposite side of the disc after 48 h. Scanning electron microscopy (SEM) was used to visualize dentin structure and cell attachment. Analyses included assessment of cell metabolism (MTT test), membrane integrity (LDH assay), and performing live/dead staining. To validate the model, various dentin disc parameters were evaluated, including species origin (human or bovine), location relative to the pulp (proximal or distal), thickness, and the effects of autoclaving. Statistical evaluation was performed using the Kruskal-Wallis or the Mann-Whitney test (P ≤ 0.05).

Results: Both HPC and L-929 formed confluent cell layers in the DBCS setup. Pretreatment of dentin discs with EDTA or citric acid reliably removed the smear layer, with the latter having a positive effect on cell viability (P ≤ 0.03). The self-adhesive composite had a similar effect on the viability of both cell types, and SEM revealed apoptotic cell morphology. Dentin provided a protection only at a thickness of greater than 400 µm. There were no significant differences in cellular responses to the material depending on dentin origin or autoclaving (P > 0.9999).

Conclusion: This 3D-printable culture system offers a readily available, user-friendly dentin barrier model for evaluating the cytotoxicity of dental materials and can be easily reproduced by anyone with access to a standard 3D printer.

Objectives: To evaluate effects of additively manufactured microstructures, airborne-particle abrasion (APA), and thermocycling on zirconia-resin shear bond strength (SBS).

Methods: Zirconia discs (N = 280) with microarchitectures of varying protrusion coverage (30 %, 50 %, 70 %) and height (50 μm, 100 μm), along with a non-textured control, were fabricated using Advanced Customized Jetting (ACJ). Specimens were assigned to groups based on APA treatment and thermocycling (15,000 cycles, 5-55 °C). Surface topography was evaluated through contour maps and roughness parameters. After bonding specimens to resin columns (Clearfil AP-X) using light-cured resin cement (Clearfil SA Luting), SBS was tested and analyzed using stepwise linear regression. Failure modes were classified via stereomicroscopy and analyzed using chi-square tests.

Results: Microstructured groups exhibited significantly higher SBS than controls (P < 0.001), with height (β=0.769) and APA (β=0.268) as key predictors (adjusted R²=0.660). The 50 % proportion/100 µm height/APA group achieved the highest SBS (6.78 ± 0.82 MPa pre-aging; 6.25 ± 0.83 MPa post-aging) and a low adhesive failure rate. Thermocycling increased adhesive failures (P < 0.001) without affecting SBS (P = 0.954).

Significance: Additively manufactured microstructures, particularly those with 50 % proportion, 100 µm height and APA treatment, significantly enhance zirconia-resin bond strength and durability, offering a promising strategy for improving clinical retention of zirconia restorations.

Objective: To optimize build angles to improve the accuracy of 3D-printed resin crowns using a quadratic regression model.

Methods: Resin crown specimens (n = 6) were fabricated using a digital light processing (DLP) printer at four build angles (0°, 30°, 60°, 90°) and two layer thicknesses (50 μm, 100 μm). The dimensional accuracy was quantified by 3D scanning and calculating root mean square error (RMSE). A quadratic regression model was developed and trained on experimental data to establish predictive relationships between build angle and dimensional accuracy. The optimal build angle was further verified.

Results: Mid-range angles (37° for 50 μm layers, 45° for 100 μm layers) yielded the lowest RMSE values, indicating optimal trueness. Extreme angles (0° and 90°) demonstrated statistically significant deviations, probably due to anisotropic shrinkage stress (0°) and gravitational effect (90°). The quadratic model effectively captured the nonlinear relationship between build angle and geometric accuracy (p < 0.0001).

Significance: Mid-range build angles balance structural integrity and dimensional accuracy, mitigating distortion mechanisms while preserving print efficiency. The proposed data-driven method enables evidence-based parameter selection, offering a potential approach to enhance precision in DLP-fabricated dental restorations.

Objective: To evaluate the clinical performance of a universal adhesive (Futurabond U, Voco) when applied using different bonding techniques in non-carious cervical lesions (NCCLs) after 7.5 years.

Material and methods: In two clinical centers, two hundred restorations (n = 50 per group) were randomly placed in 50 participants with at least four NCCLs, using four adhesive strategies: self-etch only (SEE); selective enamel etching + self-etch (SET); etch-and-rinse with dry dentin (ERDry); and etch-and-rinse with wet dentin (ERWet). Restorations were evaluated at baseline and after 6 months, 1, 3, 5 and 7.5 years using the FDI and USPHS criteria for material fracture and retention (primary outcome), along with marginal staining, marginal adaptation, post-operative sensitivity, and caries at restoration margins (secondary outcomes). The survival rates of the different groups were calculated by the Kaplan-Meier analysis and log-rank test. For secondary outcomes, differences between groups were assessed using Kruskal Wallis and Mann-Whitney test (α = 0.05).

Results: After 7.5 years, with a recall rate of 84 %, a total of 135 restorations were analyzed (SEE 33, SET 34, ERDry 34, and ERWet 34). Thirty-two restorations loss retention (SEE 9, SET 8, ERDry 8, and ERWet 7). Retention rates (95 % confidence interval) were 72.7 % (55.8-84.9) for SEE, 76.5 % (60.0-87.6) for SET and ERDry, and 79.4 % (63.2-89.6) for ERWet (p > 0.05). Sixteen restorations (SEE 7, SET 5, ERDry 2, and ERWet 2) showed minor marginal staining, and twenty-eight restorations (SEE 12, SET 5, ERDry 5, ERWet 6) presented minimal marginal adaptation defects (p > 0.05). One restored tooth (ERWet) showed caries at the restoration margin (p > 0.05).

Conclusion: The clinical performance of a universal adhesive in NCCL restorations was satisfactory after 7.5 years, regardless of the bonding technique.

Trial registration number: NCT03244124.

Objective: Camphorquinone (CQ) is a photo-initiator popularly-included in the dentin bonding agent (DBA) and composite resin for tooth decay restoration. CQ application during operative procedures may affect the viability and inflammation of dental pulp. Cytochrome P450 (CYP), NAD(P)H quinone oxidoreductase (NQO) 1 and NQO2, glutathione S-transferase (GST), and glutathione peroxidase (GPx) are crucial enzymes for metabolism of chemicals with quinone structure. The expression and involvement of various enzymes in CQ metabolism and toxicity were investigated.

Methods: Human dental pulp cells (HDPCs) were treated by four DBAs or CQ with/without inhibitors (α-naphthoflavone [CYP inhibitor], dicoumarol & ES936 [NQO1 inhibitors] or quercetin or melatonin [NQO2 inhibitors], ethacrynic acid [GST-P inhibitor], a26 [GPx4 inhibitor], cefoxitin [GPx1 inhibitor]) for 24 h. Enzyme-linked immunosorbent assay was used for 8-isoprostane, and PGE₂ analysis in culture medium. MTT assay was used for cell viability estimation. Real-time PCR and immunofluorescent staining were used for mRNA/protein expression analysis.

Results: We found that in various concentrations, four clinically-used DBAs induced 8-isoprostane and PGE₂ production in HDPCs. CQ stimulated CYP1A1, CYP1A2, NQO1, NQO2, GST-P, GPx1 and GPx4 mRNA and protein expression, and some of the stimulation can be attenuated by U0126 (a MEK/ERK inhibitor). The α-naphthoflavone, ES936, ethacrynic acid, melatonin and a26 showed little effect on the CQ-induced cytotoxicity to HDPCs. Most inhibitors (α-naphthoflavone, dicoumarol, ES936, quercetin, melatonin, a26) except ethacrynic acid and cefoxitin showed preventive effect on CQ-induced PGE₂ and 8-isoprostane production, but to a different extent.

Significance: DBAs and CQ may affect the inflammatory responses and tissue viability of dental pulp during clinical dental practice. Expression of CYPs, NQO1/NQO2, GST-P and GPx in HDPCs affects the metabolism of CQ, cell viability, 8-isoprostane and PGE₂ of HDPCs. Results are important for the clinical success of operative restoration to decrease pulp inflammation and necrosis by modulation of these metabolic enzymes.