OBJECTIVE:Although catechol-functionalized polymers show promise for improving adhesion in wet environments, these catechol groups also inhibit free-radical polymerization, slowing kinetics, reducing conversion, increasing cytotoxicity, and compromising bonding performance. This study evaluates alternative photoinitiator systems to overcome catechol-induced inhibition in both etch-and-rinse and self-etch adhesives. METHODS:Catechol methacrylamide (CMA) was incorporated into a methacrylate-based adhesive resin (0 to 5 wt%) as a partial replacement for the traditionally employed monomer 2-hydroxyethyl methacrylate (HEMA). The photopolymerization behavior of CMA-modified adhesives were investigated with varying photo-initiating systems, including type II photoinitiator systems camphorquinone (CQ)/ ethyl 4-(dimethylamino)benzoate (EDAB) and CQ/EDAB/diphenyliodonium hexafluorophosphate (DPIHP); type I systems diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) and di-p-tolyl(2,4,6-trimethylbenzoyl) phosphine oxide (TMO). Polymerization kinetics were monitored by real-time spectroscopy, while post-cured resins and bonded interfaces were evaluated by cell viability, micro-tensile bonding strength (μTBS) and interfacial structural analyses. RESULTS:Statistically significant polymerization retardation (one-way ANOVA) was observed when CMA was incorporated at low loadings (1 wt%) in resins with the type II systems CQ/EDAB and CQ/EDAB/DPIHP, whereas type I photoinitiators (TPO, TMO) maintained fast kinetics even at 5 wt% CMA loading. The enhanced kinetics associated with TPO and TMO correlated with improved cell viability. Generally, higher CMA loadings improved bonding strength and durability in both etch-and-rinse and self-etch systems, suggesting enhanced wet adhesion (two-way ANOVA). However, these improvements were not observed in self-etch type II systems, due to the significant polymerization retardation noted above. SIGNIFICANCE:Catechol-induced inhibition is mitigated by optimizing the photoinitiator system, enabling the improvement of dentin bonding without sacrificing polymerization efficiency.
OBJECTIVE:To evaluate whether the novel monomer N-(2-chloro-4,5-dihydroxyphenethyl) methacrylamide (Cl-DMA) provides dual anti-proteolytic and collagen cross-linking effects on demineralized dentin matrices. METHODS:A 10% ethanol/water solution served as the vehicle control, and Cl-DMA solutions were prepared at concentrations of 1, 10, and 100 mM. A 10 mM chlorhexidine acetate (CHX) solution and a 10 mM glutaraldehyde (GA) solution served as positive controls for anti-proteolytic and cross-linking effects, respectively. Inhibitory effects on matrix metalloproteinases (MMP-2, -8, -9) and Clostridium histolyticum collagenase were assessed using enzyme activity kits. In situ zymography with confocal laser scanning microscopy (CLSM) quantified MMP activity at the bonding interface. Demineralized human dentin beams treated with these solutions for 1 h were evaluated for dry mass loss, hydroxyproline release, and swelling ratio. Collagen fibril ultrastructure was observed via FESEM, while Cl-DMA/collagen binding characteristics were analyzed using ATR-FTIR spectroscopy. Molecular docking simulated the binding modes of Cl-DMA and CHX with MMPs. RESULTS:Cl-DMA inhibited protease activity in a generally concentration-dependent manner. While 10 mM Cl-DMA exhibited weaker inhibition of soluble MMPs than CHX, in situ zymography revealed that 10 and 100 mM Cl-DMA significantly inhibited interfacial MMP activity, comparable to CHX. Furthermore, 100 mM Cl-DMA significantly reduced dry mass loss, hydroxyproline release, and swelling ratio. FESEM indicated decreased porosity and increased compactness of the collagen network with higher Cl-DMA concentrations. FTIR confirmed non-covalent hydrogen bond cross-linking without triple-helix disruption. Molecular docking results demonstrated that Cl-DMA could bind to MMP-2, -8, and -9, though with weaker binding affinities than CHX. SIGNIFICANCE:Cl-DMA effectively inhibited protease activity and promoted collagen cross-linking and stabilization. The 100 mM concentration exhibited the greatest overall efficacy under the present experimental conditions, supporting the potential of Cl-DMA as a multifunctional dentin pretreatment agent for reducing enzymatic degradation of demineralized dentin collagen.
Objective To investigate whether functionalization of a resin-modified glass ionomer cement (RMGIC) with sodium trimetaphosphate (TMP) and stannous chloride (SnCl₂), individually or in combination, affects its resistance to demineralization, cytocompatibility, and mineralization-related cellular responses. Methods Six experimental RMGIC formulations were prepared: (1) RMGIC; (2) RMGIC + 14% TMP; (3) RMGIC + 400 ppm SnCl₂; (4) RMGIC + 14%TMP + 400 ppm SnCl₂; (5) RMGIC + 800 ppm SnCl₂; and (6) RMGIC + 14%TMP + 800 ppm SnCl₂. The anti-demineralization effect was evaluated using a pH-cycling model by determining final surface hardness (fSH), percentage of surface hardness loss (%SHL), and integrated subsurface hardness loss (ΔKHN). Biological performance was assessed by cell viability, alkaline phosphatase (ALP) activity, and mineralized nodule formation. Results The modified RMGIC formulation showed significantly improved anti-demineralization performance compared with the unmodified RMGIC. Formulations containing both additives exhibited higher final surface hardness and lower surface (%SHL) and subsurface (ΔKHN) mineral loss than the unmodified RMGIC (p < 0.05), whereas formulations containing TMP or SnCl₂ alone showed intermediate effects. None of the modifications adversely affected cell viability, with all formulations maintaining viability above 95%. In addition, the combined incorporation of TMP and SnCl₂ significantly increased ALP activity and mineralized nodule formation compared with the unmodified RMGIC (p ≤ 0.0001), indicating enhanced mineralization-related cellular responses. Clinical significance Incorporation of TMP and SnCl₂ enhanced RMGIC resistance to demineralization while maintaining cytocompatibility and promoting mineralization-associated responses. This functionalization strategy supports the development of multifunctional restorative materials with improved mineral protection and biological activity beyond the properties of conventional glass ionomer cements.
OBJECTIVES:To overcome the intrinsic incompatibility between dense periodontal biofilms and chemodynamic therapy (CDT), we developed a vacancy-engineered MnO₂ nanozyme that integrates redox-state programming, Mg²⁺-enabled endogenous H₂O₂ amplification, and covalently immobilized quorum-sensing inhibition for the local treatment of periodontitis. METHODS:Mg²⁺-coordinated MnO₂ nanoflowers were decorated with Pt nanoparticles and covalently functionalized with BBF. Physicochemical properties, Mn valence states, H₂O₂ and ·OH generation, LuxS/AI-2 signaling, Porphyromonas gingivalis metabolomic changes, antibiofilm activity, and therapeutic efficacy in rat periodontitis were evaluated. RESULTS:Pt decoration increased the Mn²⁺ fraction from 33% to 51%, while Mg²⁺ enhanced SpxB-mediated H₂O₂ production by Streptococcus gordonii. Immobilized BBF reduced AI-2 activity from 67.8% to 22.8% and downregulated luxS, fimA, mfa1, kgp, and rgpA. In dual-species biofilms, MnO₂-Mg/Pt@BBF yielded 68.7% dead cells, an approximately 4-log₁₀ reduction in viable bacteria, and the lowest residual thickness. Metabolomics revealed depletion of G6P, R5P, NADPH, ATP, and α-ketoglutarate in P. gingivalis. In vivo, treatment reduced periodontal bacterial burden by approximately 3 orders of magnitude and decreased the CEJ-ABC distance from 1.44 ± 0.28 mm to 0.56 ± 0.15 mm, accompanied by reduced inflammation and IL-6 expression, improved collagen organization, and elevated Arg-1 levels. SIGNIFICANCE:This locally deliverable platform couples vacancy/valence-tuned catalysis, Mg²⁺-primed endogenous oxidant supply, and surface-immobilized quorum-sensing blockade, offering a composition-guided strategy for controlling polymicrobial periodontal biofilms and limiting infection-associated tissue destruction.
OBJECTIVES:This study aimed to evaluate bio-based, biodegradable polylactic acid (PLA) as a sustainable material for clear aligners by comparing its physicochemical, mechanical, and biological properties with commercial aligner materials (Essix Ace, Essix C+, Zendura FLX, and Zendura). METHODS:PLA and commercial materials, both neat and aged in artificial saliva for up to 14 days, were examined as sheets. Thermal properties were measured using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mechanical and optical properties were evaluated using a universal testing machine (UTM) and UV-visible spectrophotometry. Degradation behavior was assessed via weight and average molar mass changes, and surface morphology via scanning electron microscopy (SEM). Cytotoxicity was tested using human gingival fibroblasts with an MTT assay. RESULTS:PLA showed a glass transition temperature of 55.4 °C, melting temperature of 152.1°C, and degradation onset temperature of 362.9 °C, comparable to commercial aligner materials. Its tensile strength and yield stress were similar to those of commercial materials, indicating adequate strength. However, PLA exhibited lower elongation at break and higher Young's modulus, reflecting higher brittleness and stiffness. Aging caused negligible water absorption, minimal weight loss, and minor thermal property change. Mechanical properties remained stable upon aging. Aged PLA was transparent when wet but became hazy when dry, which occurs reversibly. Extracts from PLA were non-cytotoxic, maintaining 90% cell viability in average. SIGNIFICANCE:PLA demonstrated properties comparable to commercial aligner materials, with the exception of increased stiffness and brittleness. Its stability during aging and favorable biocompatibility supports its potential as a sustainable alternative for clear aligner applications.
OBJECTIVES:This study aimed to develop a myricetin-loaded ZIF-8 (Myr@ZIF-8)-modified universal adhesive with antibacterial, collagen-stabilizing, and matrix metalloproteinase (MMP)-inhibitory properties to improve bonding durability. METHODS:Myr@ZIF-8 nanoparticles were synthesized and characterized. Myr loading efficiency, drug loading, and pH-responsive release were evaluated. Myr@ZIF-8 was incorporated into a universal adhesive at 2.5-10 wt%, and the optimal concentration was selected according to degree of conversion, dentin wettability, and antibiofilm activity. Dentin collagen stability, MMP-mediated gelatinolytic activity, microtensile bond strength (μTBS), interfacial nanoleakage, interfacial mechanical properties, and in vitro cytocompatibility were evaluated. Short-term systemic toxicity was preliminarily assessed by oral gavage of cured adhesive extracts. Molecular docking was performed to investigate potential interactions between myricetin and collagen, MMP-2, and MMP-9. RESULTS:Myr@ZIF-8 exhibited a Myr loading efficiency of 50.72%, drug loading of 50.36%, and pH-responsive release. The adhesive containing 5 wt% Myr@ZIF-8 showed the best overall performance, including enhanced antibiofilm activity, improved collagen stability, and reduced MMP-mediated gelatinolytic activity. Incorporation of 5 wt% Myr@ZIF-8 increased immediate μTBS from 22.79 MPa to 32.07 MPa and aged μTBS after 10,000 thermocycles from 13.91 MPa to 27.99 MPa. Molecular docking predicted potential interactions between myricetin and collagen, MMP-2, and MMP-9. The modified adhesive showed acceptable in vitro cytocompatibility, with no obvious short-term systemic toxicity after oral gavage of cured adhesive extracts. SIGNIFICANCE:These findings demonstrate that Myr@ZIF-8 functions as a multifunctional bioactive nanoplatform and represents a promising strategy for improving bonding durability.
OBJECTIVES:To evaluate the effect of a borosilicate glass coating on the mechanical, surface and chemical properties of multilayer and 4Y-PSZ zirconia, after mechanical fatigue. METHODS:Disc-shaped (13 mm×1.2 mm) sintered specimens were obtained from two types of commercial dental zirconia: structural multilayer (4 / 5Y-PSZ) (ML) and 4Y-PSZ (4Y) (Sagemax Corp.). Specimens (n = 15) were assigned to four surface treatments: control (Ctrl - silane only), airborne-particle abrasion + silane (AL), tribochemical silica coating + silane (SI), and application of borosilicate-based glass + hydrofluoric acid + silane (BG). Surface roughness (Sa) was carried out. After dual-cure resin cement application, specimens underwent mechanical fatigue (1.2 ×106 cycles, 295 N, 4 Hz). Microstructure and phase composition were analyzed using Scanning Electron Microscopy (SEM), Energy dispersive x-ray (EDS) and X-Ray Diffraction (XRD). The biaxial flexural strength (BFS) was evaluated. Data were analyzed using two-way ANOVA and Tukey's test (α=0.05). RESULTS:BFS was significantly affected by the surface treatments (p < 0.0001). BG showed the highest BFS (763.2 A MPa), followed by SI (688.4B), AL (595.3 C), and Ctrl (583.0 C). Surface roughness (Sa, µm) ranged from AL (0.33 A), SI (0.26B), Ctrl (0.08 C), BG (0.05D) in both zirconia. EDS revealed increased Si and Ca in BG; fracture analysis showed more homogeneous crack propagation in BG and intergranular patterns in AL. XRD indicated predominant tetragonal/cubic phases with minor monoclinic content, slightly higher in ML. SIGNIFICANCE:The borosilicate glass coating improved the mechanical strength of both zirconia generations without significantly affecting their physical and surface properties under the conditions of this in vitro study. These findings support its potential as a surface treatment strategy, although further validation is required.
OBJECTIVES:The aim of this study was to investigate the effect of solvents and storage time on the mechanical properties of 3D-printed resin composites for definitive crowns. METHODS:Three 3D-printed definitive crown resin composites: Permanent Crown (Formlab; PCR), VarseoSmile Crown plus (BEGO; VCP) and Crowntec (Saremco print; CT) and one milled resin composites: Grandio Blocs/ Disc (VOCO; Gr) were tested. A three-point bending test was used to measure flexural strength (FS) and flexural modulus (Ef) using a universal testing machine (Zwick/Roell Z020) (n = 10). Martens hardness (HM) and indentation modulus (EIT) were measured using a Martens hardness instrument (Zwick/Roell Z2.5) (n = 18). Properties were evaluated on polished specimens 24 h after fabrication at room temperature in dry condition and then after 1 and 7 days of storage in either distilled water (DW D1/D7) or 75% ethanol/water (75% E/W D1/D7) at 37 °C. Data were analysed using two-way ANOVA and one-way repeated measure ANOVA (α = 0.05). RESULTS:At dry condition, mechanical properties for PCR, VCP, CT and Gr were; for FS 135.6, 120.3, 132.3 and 231.0 MPa, respectively; for Ef 4318, 3963, 4109 and 13500 MPa, respectively; for HM 218.6, 213.6, 219.7 and 858.5 N/mm2, respectively; and for EIT 6.0, 5.7, 5.8 and 22.7 kN/mm², respectively. Findings revealed a differential response to solvent exposure among the tested materials. For 75% E/W D7, there was a significant reduction (≈ 20%) in the FS of all materials (p < 0.001). Storage time in 75% E/W significantly affected the HM of all tested materials: CT (p = 0.002), VCP (p = 0.026), PCR, and Gr (p < 0.001). At 75% E/W D7, HM for PCR, VCP, CT and Gr was 157.1, 178.4, 183.6 and 699.3 N/mm2, respectively; Ef and EIT had a lower reduction. CONCLUSION:This study demonstrated that the mechanical properties of both 3D-printed and milled resin composites for definitive crowns are adversely affected by solvent exposure, particularly in 75% ethanol/water. After seven days of immersion in 75% E/W, all tested materials showed a substantial reduction in flexural strength and Martens hardness. However, the changes in flexural modulus and indentation modulus were less pronounced.
OBJECTIVES:To investigate how different combinations of base monomers, including diurethane dimethacrylate (DUDMA) and bisphenol A-glycidyl methacrylate (Bis-GMA), and diluent monomers, including trimethylolpropane trimethacrylate (TMPTMA) and triethylene glycol dimethacrylate (TEGDMA), as well as their mixing ratios, influence light attenuation behavior, degree of conversion (DC), mechanical properties, and cell viability in dental resins fabricated by layer-wise additive manufacturing. METHODS:Binary systems were formulated at 5:5 and 7:3 wt ratios. Their optical behavior was characterized using Jacob's working curve, while the degree of conversion (DC) was quantified via ATR-FTIR. Mechanical properties and biocompatibility were evaluated using three-point bending tests, Vickers hardness and CCK-8 assays with human gingival fibroblasts, respectively. RESULTS:All formulations exhibited linear working curve behavior. TEGDMA-containing systems showed significantly higher DC and flexural strength, whereas TMPTMA-containing systems demonstrated greater flexural modulus and Vickers hardness. Mixing ratio effects were system-dependent, with no direct correlation between curing behavior, DC, or mechanical properties. All formulations showed no cytotoxicity in human gingival fibroblasts. SIGNIFICANCE:This study provides a comprehensive understanding of how the interplay between base monomers (DUDMA, Bis-GMA) and diluents (TMPTMA, TEGDMA) dictates the performance of 3D-printed unfilled dental resins. By integrating Jacob's working curve analysis with mechanical and biological evaluations, we identified optimal formulations that balance high degree of conversion with clinical-level biocompatibility. These findings offer a precise chemical roadmap for developing next-generation additive manufacturing resins with tailored mechanical properties for restorative dentistry.
OBJECTIVES:To evaluate physicochemical properties, bioactivity and biocompatibility of experimental resin-modified calcium silicate cements (Rm-CSCs) formulated with BPA-free monomers (FUDMA and UDMA), in comparison with a BisGMA-based counterpart and commercial Rm-CSCs (TheraCal LC and BioCal-CAP). METHODS:Experimental FUDMA-, UDMA-, and BisGMA-based Rm-CSCs were synthesized at a 3:5:2 mass ratio (resin matrix: tricalcium silicate: zirconia oxide). Calcium ion release and pH changes were tested over 28 days. Degree of conversion, water sorption, and solubility were assessed. Apatite-forming ability was examined after 28-day immersion in simulated body fluid (SBF) or culture medium. Cytotoxicity was determined using a CCK-8 assay with human dental pulp cells, and initial pulp response was assessed using a vital human tooth model. Data were analyzed using one-way ANOVA or Kruskal-Wallis test followed by Tukey's HSD test (α = 0.05). RESULTS:All materials exhibited alkaline pH and sustained calcium ion release. Degree of conversion of FUDMA-, UDMA- and BisGMA-based formulations were 65.86%, 67.68% and 57.48%, respectively (p > 0.05). Water sorption of FUDMA- (36.22 μg/mm³) and UDMA-based cements (40.80 μg/mm³) were significantly lower than that of BisGMA-based counterpart (91.59 μg/mm³) (p < 0.05). Following SBF immersion, apatite-like calcium phosphate was formed for FUDMA-based version, other materials formed calcium carbonate as the main crystalline phase. Rm-CSCs were all cytocompatible, except TheraCal LC reduced cell viability to 42.60% (p < 0.05). Pulps capped with all Rm-CSCs maintained a well-organized morphology with no necrosis after 2 weeks. SIGNIFICANCE:Within the limitation of this study, the FUDMA-based formulation exhibited favorable physicochemical properties, biocompatibility and bioactivity.
OBJECTIVES:Scale-dependent wetting analyses requires sophisticated generation of drops with adequate, variable drop sizes. Advanced drop shape analysis systems enable the generation of drops from micro- to picoliter range. This study investigates the influence of different drop generation techniques and measurement settings on wetting results on differently modified titanium surfaces. METHODS:Different titanium surfaces, thoroughly characterized by SEM, roughness, and XPS analyses, were included in this study: machined (M), etched (A), grit-blasted (SL), grit-blasted and acid-etched (SLA). To quantify wetting behavior, water drops were generated by three techniques yielding micro, nano and pico drops, respectively. In total, the drop volume varied from 0.3 nL to 1000 nL and the number of droplets added to generate a final drop volume from 1 to 200 drops. RESULTS:With smaller drop volumes, hydrophilicity increased on the A, SL and SLA surface. Furthermore, fewer droplets used to generate the same final volume resulted in increased hydrophilicity. In general, the drop volume has less impact than the droplet number. Additionally, the applied drop dispensing technique influences the contact angle results. SIGNIFICANCE:The study results suggest that multiscale topographies should be evaluated using multiscale wetting approaches. Since wetting analysis results depend on both surface properties and measurement conditions, such as drop application technique and size, careful interpretation of generated data is mandatory.
OBJECTIVE:Stress shielding and bacterial infection are among the main challenges associated with metallic implants. To address these limitations, a Ti-35Nb-4Ag alloy was produced by powder metallurgy, combining a low elastic modulus (67.9 ± 1.1 GPa) with silver incorporated in solid solution to provide antibacterial activity. METHODS:Compression testing was performed to determine the elastic modulus. Roughness, wettability, and surface free energy with its dispersive and polar components were determined. The cytocompatibility study was carried out in accordance with ISO 10993-5, using commercially pure grade 4 titanium as a control. Adhesion and proliferation studies were carried out with human fibroblast cells (hFFS) for 2, 4, 7, and 14 days. Antibacterial studies were performed on three Gram-positive bacterial strains: Streptococcus gordonii, Staphylococcus aureus, and Enterococcus faecalis. The colonies formed (CFU) and the metabolic activity were assessed. RESULTS:The results showed that there were no statistically significant differences in roughness between the different metals tested. However, the Ti-35Nb-4Ag alloy had a lower contact angle (46°) than titanium (62°), and the surface energy was higher for the alloy (58 mJ/m²) than for titanium (41 mJ/m²). The increase in the polar component of the alloy (29 mJ/m2) compared to pure titanium (16 mJ/m2) was noteworthy. The alloy also showed enhanced fibroblast adhesion and proliferation while maintaining excellent cytocompatibility. In addition, the Ti-35Nb-4Ag alloy exhibited significantly lower CFU counts and bacterial metabolic activity than commercially pure titanium. SIGNIFICANCE:The Ti-35Nb-4Ag alloy combines a low elastic modulus, favourable surface properties, good cytocompatibility, and antibacterial activity, making it a promising candidate for hard tissue replacement.
OBJECTIVE:The biological performance of dental liner materials is commonly attributed to mineralizing ion release and presumed bioactivity. However, these materials represent complex chemical systems that may also release organic constituents with potential biological effects. While ion release has been characterized previously, quantitative data on co-released organic constituents and their cytotoxic thresholds in human dental pulp stem cells (hDPSCs) remain limited. This study aimed to identify and quantify organic substances released from six dental liner materials and to assess the cytotoxicity of selected organic and inorganic components in hDPSCs. METHODS:Specimens (n = 4 per material and elution medium) were prepared as standardized discs and incubated for 72 h in methanol or water. Organic substances released from six dental liner materials (an experimental liner/base (EXP), TheraCal LC® (TC), Dycal® (DY), Lime-Lite Enhanced™ (LL), Fuji Lining LC Paste Pak (FL), and Medcem MTA (MC)) were identified and quantified using gas chromatography-mass spectrometry (GC/MS). Based on the analytical findings and previously published ion release data, individual organic compounds and representative inorganic salts were subsequently tested separately in hDPSCs. Cytotoxicity after 24 h exposure was assessed using WST-1 assays, and EC₅₀ values were derived from four-parameter logistic (4PL) nonlinear regression with variable slope. RESULTS:GC/MS detected nine organic substances released into methanol, whereas no organic substances were detected in water eluates. FL showed the highest release of 2-hydroxyethyl methacrylate (HEMA, ≈0.30 mg/mL) and camphorquinone (CQ, ≈0.05 mg/mL). TC released the highest amounts of butylated hydroxytoluene (BHT, ≈0.009 mg/mL) and 4-(dimethylamino) benzoic acid ethyl ester (DMABEE, ≈0.10 mg/mL). In hDPSCs, sodium fluoride (NaF) exhibited the highest cytotoxicity (EC₅₀ ≈0.056 mg/mL), followed by CQ (≈0.068 mg/mL) and triethylene glycol dimethacrylate (TEGDMA, ≈0.475 mg/mL). SIGNIFICANCE:The biological performance of dental liner materials cannot be inferred from ion release alone. The integrated evaluation of organic substance release, inorganic ion elution, and substance-specific cytotoxicity provides a more comprehensive framework for the biological evaluation of so-called "bioactive" liner materials and supports substance-specific hazard characterization under standardized experimental conditions.
OBJECTIVES:To develop remineralizing dental composites incorporating prepolymerized TMPTMA-HEMA particles charged with CaF₂ (THCaF₂). METHODS:Blends of TMPTMA-HEMA (50/50 wt%), charged with CaF₂ (5, 10, and 15 wt%), were heat-polymerized and crushed to a micrometric scale (THCaF₂). Four dental composites were produced using the same organic matrix (30 wt%) of Bis-GMA/TEGDMA (70/30 wt%). The control composite (C) contained 70 wt% barium borosilicate (BaBSi) fillers, whereas, in CaF5, CaF10, and CaF15, BaBSi fillers were partially replaced by 20 wt% of THCaF₂ particles. The remineralizing potential was evaluated through F⁻ release and the remineralization of caries-like enamel lesions induced by S. mutans biofilm using micro-CT. Physicomechanical properties included degree of conversion (DC%), flexural strength (FS), flexural modulus (FM), water sorption (Wsp), and water solubility (Wsl). Data were analyzed using one-way ANOVA and Tukey's HSD test (α = 0.05). RESULTS:All composites containing THCaF₂ released F⁻ ions, whereas only CaF10 and CaF15 induced enamel remineralization. The DC% did not differ among the dental composites (p > 0.05). C showed the highest FS and FM (p < 0.05), whereas the FS and FM of the other composites did not differ from one another (p > 0.05). The lowest Wsp was observed for C (p < 0.05), followed by CaF5, CaF10, and CaF15, which did not differ statistically from one another (p > 0.05). No statistical difference in Wsl was found among the dental composites (p > 0.05). SIGNIFICANCE:The incorporation of prepolymerized particles charged with CaF₂ (THCaF₂) conferred remineralizing potential to experimental dental composites and represents a promising strategy for developing dental composites capable of preventing enamel demineralization caused by the caries process.
OBJECTIVES:To overcome the limitations of conventional yttria-stabilized zirconia used in dental restorations, including long sintering time, relatively low fracture toughness (especially for high-translucency zirconia, such as 4Y-, 5Y-, and 6Y-PSZ), hydrothermal instability, and limited machinability, this study aims to develop a calcium-stabilized nano-grain zirconia optimized for rapid chairside processing. METHODS:Calcium-stabilized zirconia ceramics were fabricated and subjected to fast sintering with a total sintering time of less than 20 min, and compared with conventionally slow-sintered specimens. Microstructure, phase composition, mechanical properties, optical translucency, machinability, and biocompatibility were systematically characterized. RESULTS:Fast sintering produced a refined nano-grain microstructure with significantly improved flexural strength, fracture toughness, phase stability, and machinability compared with slow sintering. Notably, optical translucency was markedly enhanced under fast sintering conditions, attributable to the effective suppression of CaO-ZrO₂ phase separation during rapid heating. In contrast, slow sintering promoted phase segregation and inferior optical performance. SIGNIFICANCE:These results demonstrate that fast sintering (<20 min) is superior to conventional slow sintering for calcium-stabilized dental zirconia. The developed material combines rapid processing, enhanced mechanical and optical performance, and good biocompatibility, highlighting its strong potential for next-generation chairside zirconia dental restorations.
