Search Results (167)

The polymerization shrinkage stress (SS), degree of conversion (DC), and Vickers hardness (HV) are properties that can affect the performance of resin-based composites (RBCs). This study tested four bulk-fill RBCs used in self-cured mode: Bulk EZ Plus (Zest Dental Solutions), Cention Forte (Ivoclar), Fill-Up! (Coltene), and Stela (SDI Limited), and two light-cured bulk-fill RBCs: Filtek One (Solventum) and SDR flow+ (Dentsply). The test specimens were 6 mm in diameter and 2 mm thick. Axial SS was measured in real time for 4000 s in the self-cured materials and for 1400 s after 10 s of light curing in the light-cured materials (n = 12 for self-cured RBCs; n = 11 for light-cured RBCs). To confirm that the RBCs were adequately polymerized, the DC was assessed using real-time ATR-FTIR spectroscopy, and the HV was measured on the top and bottom surfaces using a 300-gf load for 8 s (n = 5) after 24 h. The SS, DC, and HV differed significantly among the RBCs (p < 0.001). At 1400 s, Cention Forte developed the lowest stress (1.44 MPa), whereas Bulk EZ Plus and Fill-Up! produced the highest stress (3.77 MPa). The self-cured materials continued to develop measurable stress between 1400 s and 4000 s, while the light-cured RBCs had stabilized at 1400 s. Bulk EZ Plus and Stela produced the highest DC values, and Stela had the highest HV. Full article

Background/Objectives: Tooth discoloration can influence the esthetic outcome of restorative treatments. Recently, 3D-printed ceramic-filled hybrid materials have been introduced for dental restorations using digital workflows. The aim of this in vitro study was to evaluate the influence of 3D-printed ceramic-filled hybrid veneers on the final color of discolored teeth using spectrophotometric measurements. Methods: Twenty-five extracted human anterior teeth without caries or restorations were prepared for veneer restorations using standardized reduction protocols. Artificial discoloration was induced by applying light-cured color coatings to the buccal surfaces of the specimens. The prepared teeth were digitally scanned, and veneers with a thickness of 1 mm were designed and fabricated using a 3D printing system and a ceramic-filled hybrid material. Color measurements were performed with a spectrophotometer and recorded in the Commission Internationale de l’Éclairage L*a*b* (CIELAB) color system. Measurements were obtained at four stages: after creation of discoloration, after two weeks of immersion in physiological saline solution, after veneer placement using neutral try-in gel, and after two months of immersion following veneer placement. Color differences were calculated using three color difference formulas (ΔE*ab, ΔE94, and ΔE00). Results: The placement of the 3D-printed veneers produced substantial modifications in the optical characteristics of the discolored substrates, reflected by reduced chroma values and significant color differences between the baseline and veneer stages. After two months of immersion, only minor variations in color coordinates were observed. The calculated color differences between the veneer stage and the post-immersion stage remained low across all evaluated color difference formulas, indicating good short-term color stability of the veneered specimens. Conclusions: Within the limitations of this pilot in vitro study, 3D-printed ceramic-filled hybrid veneers demonstrated the ability to effectively modify the color of discolored substrates while maintaining relatively stable optical properties after two months of immersion. These restorations may represent a promising and cost-effective option for the esthetic management of discolored teeth. Full article

This study investigated the influence of solvent evaporation on the ultimate tensile strength (UTS) and water-related weight changes in contemporary universal dental adhesives. Two two-step universal adhesives (OptiBond eXTRa Universal and G2-BOND Universal) and two one-step universal adhesives (OptiBond Universal and BeautiBond Xtreme) were evaluated. Adhesives were used either under normal storage conditions or after active solvent evaporation by removal of the bottle caps and storage at 37 °C for 2 weeks. Hourglass-shaped specimens were prepared, light-cured, and stored in water at 37 °C for 1 h or 7 days prior to UTS testing (n = 10). Specimen weights were measured before and after water storage. For OptiBond eXTRa Universal, no significant difference in UTS was observed between the original and desiccated groups after 7 days of water storage (p > 0.05). In contrast, G2-Bond Universal exhibited significantly higher UTS values in the desiccated group compared with the original group (p < 0.05). In the original group, the one-step universal adhesives failed to polymerize under the original (non-evaporated) conditions, whereas adequate polymerization was achieved following active solvent evaporation. Weight changes after water storage varied depending on the adhesive composition. These results suggest that residual solvent may influence the polymerization behavior, mechanical performance, and water-related properties of universal dental adhesives, emphasizing the importance of adequate solvent evaporation before light curing. Full article

Background: Temporary dental crowns are an essential component of fixed prosthodontic treatment, protecting prepared teeth and maintaining occlusal function and aesthetics until delivery of the definitive restoration. Their clinical performance is strongly influenced by their internal microstructure, which directly affects mechanical behavior. Therefore, the aim of this study was to compare the internal porosity and fracture resistance of temporary dental crowns fabricated using conventional and 3D-printing techniques. Materials and Methods: This in vitro study compared the porosity and fracture resistance of three materials for provisional restorations: a bis-acrylic resin (Protemp^TM 4), an autopolymerizing resin (Success CD), and a 3D-printed light-curing resin (V-Print c&b temp). Thirty-six standardized single-unit crowns (n = 12 per group) were fabricated. All specimens were analyzed using high-resolution micro-computed tomography to determine total crown volume, pore volume, and relative porosity. Fracture resistance was evaluated under monotonic compressive loading in a universal testing machine. Data were analyzed using appropriate parametric or non-parametric statistical tests (α = 0.05). Results: The 3D-printed material exhibited the lowest mean porosity (0.0029%), whereas Protemp^TM 4 and Success CD showed substantially higher porosity values. However, Protemp^TM 4 demonstrated the highest mean fracture resistance, followed by the 3D-printed resin and Success CD. No direct correlation between porosity and fracture resistance was observed, indicating that material chemistry and internal bonding play a more decisive role than void content alone. Conclusions: These findings suggest that 3D printing improves structural homogeneity, while bis-acrylic materials provide superior load-bearing capacity, and that each fabrication method offers distinct advantages depending on clinical requirements. Full article

This study comparatively evaluated the influence of processing routes on the optical stability of three dental resin composites: a light-cured direct composite—G-ænial A’CHORD (LCC), a CAD-CAM milled composite—BreCAM.HIPC (MC), and a 3D-printed composite—Saremco Print Crowntec (PC). Specimens were analyzed before (T0) and after hydrothermal aging for 5000 (T1), 10,000 (T2), and 30,000 cycles (T3). Optical stability was assessed through the change in color (ΔE₀₀) and translucency parameter (TP) after aging and immersion in beverages. Surface topography was evaluated using atomic force microscopy (AFM), while Raman spectroscopy was employed to detect aging-induced molecular changes. After aging and staining, all composites exceeded the acceptability threshold for color change. ΔE₀₀ values of 6.8 ± 1.1 (PC), 4.6 ± 0.9 (MC), and 2.1 ± 0.9 (LCC), obtained after initial aging, further increased following prolonged immersion in coffee. After 1 day of immersion in Coca-Cola, MC exhibited the highest ΔE₀₀ values, which slightly exceeded the clinically acceptable threshold. Prolonged immersion (7 days) significantly increased staining for all materials. TP values significantly differed among materials, with the highest values detected for LCC (20.6 ± 3.6) and PC (19.1 ± 1.5) and the lowest values detected for MC (4.9 ± 0.8). Overall, the results demonstrated that ΔE₀₀ was strongly influenced by the processing route and surface topography, whereas changes in translucency parameter (TP) were predominantly governed by the intrinsic properties of the resin composites. Full article

Modern dentistry increasingly relies on light-curing units (LCUs) and lasers in essential clinical procedures such as composite resin polymerization, caries treatment, and periodontal therapy. This review aims to outline the evolution of light-emitting technologies and to assess their potential biological risks, with particular emphasis on effects on the visual system, oral tissues, and microbiome. The development of curing devices is presented chronologically, from the first-generation ultraviolet (UV-A) lamps introduced in the 1970s to current light-emitting diode (LED-LCU) systems and dental lasers (e.g., Er:YAG, Nd:YAG). The progressive increase in light intensity—now exceeding 3000 mW/cm²—has shortened curing times but simultaneously raised safety concerns. Major hazards include the so-called blue-light hazard, where exposure to high-energy visible (HEV) blue light may accelerate macular degeneration, and temperature elevations in the pulp chamber, which may damage the dentin–pulp complex. Laser radiation also exerts significant microbiological effects: Er:YAG and diode lasers demonstrate bactericidal activity against biofilms and oral pathogens (e.g., P. gingivalis), although therapeutic outcomes depend on wavelength, dose, and exposure time. Suboptimal parameters may lead to microbiome disturbances, whereas low-level laser therapy (LLLT; 600–1200 nm) supports tissue regeneration and helps restore microbial balance. The individualization of irradiation parameters, combined with thorough theoretical knowledge, operator expertise, and technical understanding of LCUs and lasers, is essential for maximizing clinical benefits while minimizing health risks and preserving oral microbiome homeostasis. Full article

Titanium alloys are widely used in dental implants due to their excellent mechanical properties. However, their inertness and poor antibacterial activity cause interfacial loosening and failure, shortening service life. This study integrates surface microtexturing with coating technologies, employing modified light-curing composite resins to boost the bioactivity of medical titanium alloys via surface modification. The results reveal that surface microtexturing enlarges the coating-substrate contact area by 42.5% compared with rough surfaces, concurrently diminishing stress per unit area, and the coating on microtextured Ti-6Al-4V (TC4) surfaces achieves adhesion with a damaged area of only 0.5%, thereby notably enhancing adhesion between the coating and TC4 matrix. In comparison, with rough surfaces (surface roughness of 0.658 μm), smooth TC4 planes (surface roughness of 0.014 μm) show a significantly reduced bacterial colony count (from 130 ± 6 to 42 ± 3) with an antibacterial rate of 67.7%, as the water contact angle on TC4 surfaces increases with decreasing roughness (reaching 80.95° on the smoothest surface), making bacterial adhesion more challenging and reducing colonization. The composite resin coating based on a mixture of titanium-doped hydroxyapatite and titanium dioxide (Ti-HA/TiO₂) further improves the antibacterial rate to 74.6% through a photocatalytic synergistic effect and endows TC4 with excellent remineralization capacity—mineralization deposits appear on the coated surface after 3 days of immersion in artificial saliva, while no obvious deposits are found on uncoated rough and smooth surfaces even after 7 days—thereby enhancing its bioactivity effectively. This study on the modification of Ti-based implant surfaces will enrich the field by introducing new technologies and methodologies. These advancements provide a theoretical basis for improvement of the remineralization capacity and antibacterial properties of Ti-based dental implants, thereby promoting broader biomedical applications. Full article

Dual-cure composite cements are an important element of modern dental prosthetics, enabling a stable and long-lasting bond between prosthetic restorations and tooth tissues. Thanks to the combined mechanism of chemical- and light-curing polymerization, they are characterized by high clinical versatility. Despite their wide application, the impact of storage/pre-conditioning temperature on the mechanical properties of dual-cure composite cements remains unclear. The study evaluated the shear bond strength (SBS) of the bond between four dual cements—Bifix Hybrid Abutment (VOCO GmbH, Cuxhaven, Germany), MaxCem Elite (Kerr Corporation, Orange, CA, USA), EnaCem HF (Micerium, Avegno, Italy), and Multilink Automix (Ivoclar Vivadent, Schaan, Lichtenstein)—and dentin depending on their storage temperature (25 °C or 50 °C) and curing method. The tests were carried out on extracted human permanent teeth. The cements were divided into two temperature groups—stored for 7 days at 25 °C or stored for 7 days at 50 °C—and then each of these two temperature groups was divided into two groups—light- and chemically cured (dual-cured, LC) and chemically cured only (CC). Dual-cured cements showed higher shear bond strength at 25 °C. Storage at 50 °C lowered the SBS values, especially for the purely chemically bound cements. LC Bifix Hybrid Abutment achieved the highest SBS at 25 °C, but at 50 °C its properties deteriorated. EnaCem HF showed higher strength at a lower temperature; MaxCem Elite was stable at both temperatures, whereas Multilink Automix showed lower SBS at 50 °C. The study showed that the chemical composition of cements, especially the presence of a benzoyl peroxide (BPO) initiating system, can play a key role in their SBS when bonded to teeth tissue and stability at different storage temperatures. MaxCem Elite showed the best resistance to temperature changes—it achieved the highest temperature stability in both temperature groups. Full article

Background/Objectives: Light-curing dental resin composites remain limited by high polymerization shrinkage, inadequate wear resistance, and elevated water sorption. The combined influence of filler shape, size, and loading level on mechanical performance and hydrolytic stability remains insufficiently understood. This study aimed to systematically investigate the effects of filler morphology and particle size distribution on the key properties of dental composites. Methods: Spherical silica (SiO₂) nanoparticles (D50 = 0.50 μm) were synthesized via the Stöber method, while irregular aluminosilicate glass was used in coarse (D50 = 3.71 μm) and fine (D50 = 1.98 μm) fractions. Three composite groups were formulated: Group 1 (72 wt.% filler with 0–30% SiO₂), Group 2 (maximum filler loading 76–80 wt.% with 10–30% SiO₂), and Group 3 (74.5 wt.% filler with varying coarse/fine glass ratios). Flexural strength, flexural modulus, Vickers microhardness, depth of cure, water sorption, and solubility were evaluated according to ISO 4049:2019. Results: Incorporation of spherical SiO₂ nanoparticles significantly reduced composite viscosity, enabling maximum filler loading to increase from 72 to 80 wt.%. All composites exceeded ISO requirements for flexural strength (80.54–118.11 MPa), depth of cure (3.01–5.65 mm), water sorption (14.61–22.87 μg/mm³), and solubility (1.20–5.90 μg/mm³). The highest flexural strength (118.11 ± 10.54 MPa) and modulus (9.26 ± 1.12 GPa) were achieved at 78 wt.% filler loading. Bimodal glass systems (50/50 ratio) demonstrated optimal mechanical properties, while higher fine fractions reduced strength. Conclusions: Spherical SiO₂ nanoparticles effectively reduce viscosity and enable higher filler loading. The optimal balance between filler loading, particle shape, and size distribution should be tailored to clinical requirements, with high-strength formulations suited for posterior restorations and bimodal formulations for universal applications. Full article

Objectives: The aim of this study was to present and describe a digital workflow integrating Digital Smile Design (DSD) with computer-aided design/computer-aided manufacturing (CAD/CAM) and additive manufacturing technologies for the fabrication of dental preparation guides, focusing on workflow feasibility, design reproducibility, and clinical handling. Materials and Methods: A digital workflow was implemented using intraoral scanning and Exocad DentalCAD 3.1 Elefsina software to design dental preparation guides based on digitally planned restorations. Preparation margins, insertion paths, and minimal material thickness were defined virtually. The guides were fabricated using both subtractive (PMMA milling) and additive (stereolithographic-based 3D printing) manufacturing techniques. Post-processing included chemical cleaning, support removal, additional light curing, and manual finishing. The evaluation was qualitative and descriptive, based on visual inspection, workflow performance, and guide adaptation to printed models. Results: The proposed digital workflow was associated with consistent fabrication of preparation guides and predictable transfer of the virtual design to the manufactured guides. Digital planning facilitated clear visualization of preparation margins and insertion axes, supporting controlled and minimally invasive tooth preparation. The workflow demonstrated good reproducibility and efficient communication between clinician and dental technician. No quantitative measurements or statistical analyses were performed. Conclusions: Within the limitations of this qualitative feasibility study, the integration of DSD with CAD/CAM and 3D printing technologies represents a viable digital approach for designing and fabricating dental preparation guides. The workflow shows potential for improving predictability and communication in restorative dentistry. Full article

As a commonly used dental restorative material, light-cured composite resin exhibits mechanical properties that closely match those of natural tooth structure. In the process of biting, the filling material falls off severely due to fretting between the filling material and the fixed interface of the teeth, which shortens the life of the filling material. This study aimed to investigate the mechanisms and contributing factors of this phenomenon. In particular, this study investigated the friction and wear mechanisms at the tangential fretting interface between light-cured composite resin and the tooth substrate under varying fretting amplitudes, normal loads, and lubrication conditions. In artificial saliva, the friction coefficient increased with the fretting amplitude and decreased with the increase in the normal load. The result showed that when the fretting amplitude was large or the normal load was small, the fretting was always in the complete slip regime. When the fretting amplitude was small or the normal load was large, the fretting changed from the complete slip zone to the partial slip regime. The minimum friction coefficient in milk was 0.117, and the maximum friction coefficient in artificial saliva was 0.567. Coke and milk have little effect on the fixation of filling materials. Abrasive wear was the predominant mechanism, with small amplitudes or high loads leading to adhesive wear. The composite resin exhibited the least wear in cola and milk, while soda water and artificial saliva caused significantly greater damage. Full article

Background/Objectives: The purpose of this in vitro study is to evaluate the effect varying palatal vault depths have on the accuracy of complete maxillary denture bases fabricated using additive manufacturing technology. Methods: One hundred complete maxillary denture bases were manufactured on two different digital light processing (DLP) dental 3D printers at five different palatal depths. After manufacturing, the denture bases were post-cured, scanned, and then analyzed in metrology software. Statistically significant differences were determined using two-way ANOVA tests for normally distributed data and the Kruskal–Wallis test for non-normally distributed data. Color deviation maps were used to give clinical relevance to the results. Results: Significant differences were found for both printers among some groups for the different palatal depths. In relation to the negative mean deviation, the data revealed that the NextDent printers were the least accurate (0.047 ± 0.004) in the group with the deepest palate. The positive mean deviation revealed the most deviation (0.077 ± 0.009) in the group with the deepest palate, which was also mirrored in the Asiga printer (0.050 ± 0.002). The color deviation maps revealed areas of positive and negative average deviation in all groups. The effect of the printer model (p = 0.007) and palatal depth (p = 0.04) on negative average deviation was significant. The effect of the interaction of printer and palatal depth was also significant (p = 0.001). Conclusion: Deeper palatal vaults are associated with higher deviation in DLP 3D-printed complete maxillary denture bases manufactured through additive manufacturing. Full article

Dental composites are widely used in restorative dentistry; however, their long-term clinical performance is strongly influenced by mechanical and tribological behavior under oral conditions. Understanding the relationship between material structure, surface characteristics, and functional properties is therefore essential. This preliminary methodological study evaluated the mechanical, tribological, and wetting properties of three light-cured dental composites—Enamel Plus HRi, Amaris, and Estelite Asteria—commonly used in clinical practice. The materials were characterized in terms of surface morphology, hardness, Young’s modulus, coefficient of friction, and wear resistance under controlled laboratory conditions. Instrumental indentation and tribological tests were performed, and results were expressed as mean values with standard deviations calculated from multiple measurements. The results demonstrated that filler composition and surface topography affected material performance. Estelite Asteria exhibited the highest hardness (HIT > 300 MPa), while Enamel Plus HRi showed the highest Young’s modulus (EIT ≈ 14.5 GPa). Materials with more complex surface morphology retained lubricating artificial saliva more effectively, resulting in lower friction coefficients (minimum µ = 0.85), although this did not reduce wear. The highest wear was observed for Estelite Asteria, with a wear scar approximately 62% greater than that of Enamel Plus HRi. These preliminary findings provide a methodological basis for further investigations under more clinically relevant conditions. Full article

The aim of the study was to evaluate the effect of the oxygen-inhibited layer on the bond strength of dental adhesives. The protocol was registered in PROSPERO. PRISMA 2020 guidelines were followed. The focused structured question using Population (P), Intervention (I), Comparison (C), and Outcome (O) was: “What is the effect of oxygen inhibited layer on bonding strength of dental adhesives?” The literature was screened via PubMed, Google Scholar, Scopus, and Web of Science. The last search was carried out in September 2024 with an English language restriction. Two reviewers independently performed screening and evaluation of articles. A total of 71 articles were retrieved from databases, in which only 35 articles were selected for full-text analyses. After implementing the exclusion criteria, eight studies were evaluated and included in the review. The results showed that the presence of an oxygen-inhibited layer led to an increased bond strength when light-cured composite resin was used, but there was a decrease in bond strength and an increased bond failure rate when chemically cured composite was used upon dental adhesive application. Meta-analysis could not be performed due to heterogeneity in the studies. The presence of an oxygen-inhibited layer is beneficial in improving the interfacial bond strength when used with light-cured composite resin (when light curing was performed in accordance with the manufacturer’s instructions). Full article

Advances in additive manufacturing have accelerated the development of 3D-printed dental resin composites. These materials contain a higher proportion of organic matrix and less filler than light-cured representatives, which may affect their behavior in the oral environment. This study aimed to evaluate the biological and chemical properties of 3D-printed dental resin composites before and after artificial aging, and to compare them with the light-cured representative. Specimens from a light-cured composite (Omnichroma—OMCR) and two 3D-printed composites (GT Temp PRINT—GTPR; SprintRay CROWN—SPRY) were subjected to aging treatments: unaged (T0) or thermocycled for 5000 (T1) and 10,000 cycles (T2). Biological evaluation was performed using MTT assay and Live/Dead cell fluorescence microscopy using human gingival fibroblasts, whereas Raman spectroscopy analysed materials’ structural changes. Materials exhibited good biocompatibility (>70% cell viability), with OMCR displaying greater variability. OMCR was more susceptible to chemical degradation under thermal stresses than both 3D-printed materials. Tested 3D-printed composites can provide comparable or even superior biological and chemical properties compared to light-cured representative, likely due to optimized resin formulations and post-curing protocols that improve polymer network organization and reduce residual monomer release. These findings support the potential of tested 3D-printed composites for manufacturing dental restorations. Full article