Search Results (231)

Background/Objectives: This in vitro study evaluated the fracture resistance of computer-aided design and computer-aided manufacturing (CAD-CAM) resin-matrix ceramic crowns cemented with three adhesive resin cements and three novel resin-modified glass ionomer cements. Methods: Ninety crowns representing a maxillary left central incisor were milled from a resin-based nanoceramic hybrid material (Cerasmart, GC) using a chairside CAD-CAM system (Primescan). The typodont preparation included 1.5-mm incisal reduction, 1.5-mm axial reduction, and a 1.0-mm chamfer finish line. Crowns were cemented onto 3D-printed dies of the preparation and assigned to six groups (n = 15 per group) according to cement type: Multilink Automix (ReMu), Panavia V5 (RePa), RelyX Unicem 2 (ReUn), RelyX Luting Plus (GiLu), GC FujiCem Evolve (GiEv), and Meron Plus QM (GiMe). The cemented restorations were subjected to artificial aging with 10,000 thermocycles at 5 to 55 °C with a dwell time of 30 s. Specimens were loaded in compression to fracture. Scanning electron microscopy (SEM) was used to evaluate fracture patterns. Fracture load was analyzed using one-way ANOVA and post hoc Tukey honestly significant difference (HSD) test (p = 0.001). Results: Fracture resistance differed significantly among cement types. Crowns cemented with adhesive resin cements exhibited higher fracture resistance than those cemented with resin-modified glass ionomer cements. The highest fracture resistance was observed for ReUn, followed by RePa and ReMu, whereas GiEv and GiLu showed the lowest values. Conclusions: CAD-CAM hybrid crowns fabricated from a resin composite–ceramic material demonstrated higher fracture resistance when cemented with adhesive resin cements than with the novel resin-modified glass ionomer cements tested. Among the six cements, ReUn produced the highest fracture resistance, whereas GiEv produced the lowest. Full article

Background/Objectives: To compare the effects of different surface treatments on the color and translucency of three types of zirconia ceramics. Methods: Ninety CAD/CAM-milled zirconia disks (10 mm diameter, 1 mm thickness) were fabricated from Cercon HT (3-YTZP), IPS e.max ZirCAD MT (4-YTZP), and Cercon XT (5-YTZP). Baseline CIE Lab* coordinates were measured using a digital spectrophotometer. The disks underwent one of three surface treatments: 50 µm alumina air-particle abrasion (AAA), Zircos-E etching (ZE), or 100 µm glass bead air-particle abrasion (GBA). Post-treatment CIE Lab* measurements were obtained, and color change (ΔE₀₀, CIEDE2000) and translucency change (ΔTP₀₀) were calculated. Results: Regarding color change (ΔE₀₀), 50 µm AAA produced the greatest change, followed by ZE, while GBA caused the smallest change. Surface treatment and its interaction with material type were found to exert a significant effect, whereas material type alone was not significant. Cercon XT showed the highest numerical ΔE₀₀ value among the materials, although the difference was not statistically significant. All ΔE₀₀ values were below the clinical acceptability threshold (<1.8). No significant effects of surface treatment, material type, or their interaction were observed for translucency change (ΔTP₀₀) after surface treatment. Baseline translucency values (TP₀₀) differed significantly, with Cercon XT being the most translucent, followed by ZirCAD MT and Cercon HT, but these differences did not result in significant ΔTP₀₀ changes post treatment. Conclusions: Surface treatments and their interaction with material type significantly affected zirconia color change, with 50 µm alumina air-particle abrasion producing the most pronounced effect. Material type alone did not significantly influence ΔE₀₀, though Cercon XT showed the highest numerical value. Translucency change (ΔTP₀₀) after treatment was unaffected by surface treatment or material–treatment interaction. Full article

The nanoscale surface topography and microhardness of additive and subtractive dental polymers were evaluated following exposure to environmental challenges. The study examined two 3D-printed resins (Saremco and Voco) and two milled CAD/CAM blocks (Vita Enamic and Tetric). Specimens were allocated to control or experimental groups and subjected to hydrothermal ageing (thermocycling), in vitro mechanical wear, or a combined protocol involving wear followed by thermal ageing. Surface microtopography was analysed both quantitatively and qualitatively using atomic force microscopy (AFM), while structural stability was assessed through surface microhardness testing. Statistical significance was determined using matrix comparisons (p < 0.05). Milled monolithic blocks demonstrated a dense, uniform baseline topography, whereas 3D-printed resins exhibited structural heterogeneity attributed to their layer-by-layer photocuring process. Saremco maintained polymer network stability under thermal stress (p = 0.1878), while Voco was highly susceptible to hydrothermal swelling and early matrix plasticization (p = 0.0084). The combined protocol of wear and thermal ageing resulted in advanced structural breakdown in all groups (p < 0.001). Industrial subtractive blocks exhibited greater resistance to oral environmental stresses. The ceramic framework of Vita Enamic limited polymer domain collapse, whereas Tetric experienced accelerated inter-layer delamination and embrittlement. The combined protocol of wear followed by thermal ageing resulted in significant and uniform degradation of surface microhardness and topographic roughness in all tested groups. Nevertheless, the additively manufactured resins demonstrated substantial structural integrity and exhibited low volumetric wear rates. Full article

Purpose: This study describes the manufacturing procedure for complete dentures using a milling cutting method with an individual correction of the prosthetic plane. Methods: Complete dentures were fabricated digitally using a hybrid protocol with individual assessment of the prosthetic plane. Results: Subjective and objective studies of evaluation of dentures were used. The sampling of functional impressions with the use of silicone masses of decreasing tension on dentures was used by a patient after the functional formation of their edges with Function type masses. The recording of occlusion on the pre-prepared prosthetic impressions using a silicone recorder was performed. Scanning of dentures and their occlusive relations by means of a laboratory scanner was performed in order to obtain virtual working models. A 3D face photograph of the dentures was taken using the Face Hunter device. Face Hunter offered an individualised adjustment of the prosthetic plane and a unique incorporation of the restoration in a given subject. New restorations in a computer programme were designed. A milling cutting of try-in test dentures was performed in order to make a control in the oral cavity. Control of the test dentures took place at the dentist’s office. The performance of new prosthetic restorations using a milling cutting method in the PMMA target material was evaluated in this study. Conclusions: The Face Hunter device offers an individualised incorporation of dentures in patients’ faces, which considerably improves the aesthetic aspect of the complete dentures. Full article

Background: In the field of minimally invasive restorative dentistry, ultrathin (<0.5 mm thickness) ceramic occlusal veneers are increasing being used as alternatives to full-coverage crowns, particularly for mild occlusal wear and not deep caries. However, only limited research attention has been given to how marked reduction in the thickness of a veneer restoration affects its mechanical performance. The purpose of the present in vitro study was to compare the performance of restorations that comprised a 0.3 mm thick zirconia veneer to the case when a lithium disilicate veneer was used, under quasi-static compressive loading. Methods: Forty extracted human molars, without caries, cracks or fractures and with intact coronal structure, were randomly assigned to two groups: lithium disilicate occlusal veneers (n = 20) and zirconia occlusal veneers (n = 20). The teeth were embedded in acrylic resin up to the cementoenamel junction. Digital scans were used to record the original anatomy and guide restoration design. Standardized occlusal preparations were performed using a 0.3 mm reduction protocol and verified with silicone guides to support a biomimetic, tooth-preserving approach. After preparation, the teeth were rescanned, and restorations were designed and fabricated using CAD/CAM technology. Lithium disilicate restorations were milled from Ivoclar Porcelain System [IPS], esthetic maximized [e.max] computer-aided design [CAD] blocks, whereas zirconia restorations were milled from Prettau 3 zirconia discs. Restorations were adhesively cemented with dual-cure resin cement following material-specific surface treatment protocols. Fracture resistance was tested using a universal testing machine under compressive loading until failure. Results: The fracture loads with lithium disilicate and zirconia occlusal veneers were 481.45 ± 68.23 N and 720.93 ± 95.44 N, respectively. Fracture was catastrophic in lithium disilicate occlusal veneers whereas it was not so when zirconia veneer was used. Conclusion: Quasi-static compressive fracture load when a lithium disilicate veneer was used was significantly lower than when a zirconia veneer was used. Full article

Background: There are certain disadvantages to using CAD/CAM technologies. Marginal and internal accuracy of fit is valued as one of the most important criteria for the clinical quality and success of all-ceramic crowns. The assessment of the marginal fit of lithium disilicate and zirconia CAD/CAM crowns before and after ceramic layering is crucial. Methods: One ideally prepared model tooth was duplicated into 64 plaster models. A standardized wax pattern for a monolithic crown and a coping were produced and used to mill 16 lithium disilicate monolithic crowns and 16 cores using a soft milling process. 16 zirconia crowns and 16 cores were also fabricated. A factorial design with (material) (lithium disilicate [E] or zirconia [Z]); (design) (monolithic, [M] or (core) [C]); and (finish) (as-produced [P] or veneered/glazed [G]) was used to create the following groups: ZMP, ZMG, ZCP, ZCG, EMP, EMG, ECP, and ECG (n = 8). The milled restorations were treated accordingly using ZirLiner, IPS e.max Ceram, and IPS e.max Glaze. The restorations were cemented to their dies, embedded in epoxy resin, and sectioned into two planes with a diamond saw. Vertical and horizontal marginal fit at the finishing line was measured in a standardized way at four locations (mesial, distal, facial, and lingual). Results: There were no differences, p > 0.05, between all Z groups; however, they had significantly wider horizontal gaps, p < 0.05, (116 ± 5 µm) than E groups (64 ± 13 µm). Among lithium disilicate groups, the glazed monolithic (EMG) and veneered/glazed coping (ECG) subgroups showed significantly smaller horizontal gaps (approximately 50 ± 6 µm). Statistical analysis was performed using two-way ANOVA with a significance level set at α = 0.05. Conclusions: Veneering techniques did not affect zirconia. Lithium disilicate had a better marginal fit than zirconia, but this was influenced by veneering techniques. Lithium disilicate veneering and/or glazing significantly improved the marginal fit. Full article

To investigate the effect of print orientation (0°, 45°, and 90°) and artificial aging on flexural strength and fatigue resistance of 3D-printed denture bases compared to CAD/CAM milled controls, we fabricated 320 maxillary complete dentures, divided into 8 groups based on the fabrication method: horizontal, oblique, and vertical printing, alongside milled controls. Half of the specimens in each group were pre-conditioned via thermocycling and 240,000 cycles of chewing simulation. All specimens underwent static flexural strength testing and cyclic fatigue testing, followed by SEM fractography. The CAD/CAM milled bases demonstrated the highest mechanical durability, with non-aged specimens peaking at 149.43 ± 5.35 MPa. The horizontally 3D-printed non-aged specimens yielded the highest flexural strength (101.14 ± 4.80 MPa), while vertically printed aged specimens recorded the lowest (70.35 ± 8.18 MPa). Artificial aging degraded flexural strength uniformly across all orientations. Conversely, cyclic loading disproportionately devastated the older people’s vertical group, resulting in a 70% fracture rate. Fractography corroborated these findings, revealing severe interlaminar delamination in vertical builds, contrasting with cohesive, trans-layer fractures in horizontal prints. In conclusion, Horizontal orientation provided improved structural durability; however, CAD/CAM milled dentures remain superior and are recommended for long-term clinical applications. Full article

Implant-Supported Fixed Prostheses (ISFPs) have become a common option for the rehabilitation of fully edentulous arches and have traditionally incorporated metallic substructures with ceramic or acrylic veneering. The rapid expansion of CAD/CAM technologies has introduced not only a range of polymer-based materials as alternatives to conventional metallic frameworks but also the possibility of the fabrication of monolithic rehabilitations. However, the evidence regarding the mechanical behavior of monolithic polymer-based full-arch rehabilitations remains limited. This study aimed to evaluate and compare the mechanical performance of monolithic polymer-based complete prostheses under static loading using Digital Image Correlation (DIC). A total of 12 specimens (3 per group) simulating an FP3 maxillary full-arch ISFP supported by four implants were milled from four materials: poly(ether ether ketone) (G1-PEEK), poly(ether ketone ketone) (G2-PEKK), poly(methyl methacrylate) (G3-PMMA), and fiber-reinforced composite (G4-FRC). All specimens were subjected to static loading up to 200 N at the incisors region, corresponding to the anterior unsupported span, and at the occlusal surface of the molars, corresponding to the most distal portion of the cantilever, using a universal testing machine. Full-field vertical displacement and strain distributions (principal tensile, compressive, and von Mises) were acquired through a stereo DIC system and analyzed using a Linear Mixed-Effects Model with Tukey’s HSD post hoc comparisons (α = 0.05). All prostheses withstood the applied load without macroscopic failure. G3-PMMA exhibited the highest vertical displacement, exceeding 1000 µm in the anterior span and 1500 µm in the cantilever region, along with the greatest strain concentrations, particularly at the interproximal embrasures distal to the terminal abutment. G1-PEEK provided the lowest displacement in the anterior span. G4-FRC presented displacements similar to G1-PEEK and G2-PEKK at the distal cantilever, but the lowest tensile strains and the most homogeneous strain dissipation in both loading at the anterior unsupported span and distal cantilever. This indicated that the biomechanical performance of full-arch ISFPs is highly influenced by the polymer used. PEEK, PEKK, and FRC appear as promising alternatives to PMMA for monolithic full-arch rehabilitations. Full article

This study presents a simulation-assisted engineering framework intended to support comparative machining parameter selection for quartz sintered materials. The approach integrates CAD/CAM-based analysis, an illustrative Design of Experiments (DOE) framework, and preliminary experimental validation to improve process planning and machining quality. The analysis focuses on key technological parameters, including cutting speed (vc), feed rate (f), and depth of cut (ap), evaluated across cutting, milling, and finishing stages. The results indicate that feed rate is the dominant parameter influencing process stability, surface quality, and edge integrity. A practical transition region of approximately 1200 mm/min was identified, above which increased vibration, defect formation, and surface degradation occur. The complementary DOE analysis confirms the relative importance of process parameters and reveals interaction effects, particularly between feed rate and depth of cut, which significantly influence defect formation under high-load conditions. Preliminary industrial observations provide trend-oriented support for the simulation-predicted process behavior. Based on the integrated analysis, a preliminary technological operating region was identified (vc = 1080–1320 m/min, f = 800–1200 mm/min, ap = 0.5–1.0 mm), suggesting a practical compromise between machining efficiency and surface integrity. The proposed methodology provides preliminary engineering support for comparative process planning and defect-reduction-oriented parameter selection in the machining of brittle materials. The novelty of this work lies in the integration of CAD/CAM simulation, DOE-based interaction analysis, and experimental validation for supporting the identification of a practical technological operating region for machining brittle materials. The presented results should therefore be interpreted as engineering-oriented comparative process-planning guidelines rather than statistically generalized machining laws. The presented study should be interpreted as an exploratory simulation-assisted engineering investigation intended to support comparative process planning rather than as a fully experimentally validated machining model. Full article

Background-Objectives: Edentulism remains a major global health problem, and implant-supported overdentures (ISODs) are widely used to restore oral function and improve quality of life in edentulous patients. Among the available attachment systems, bar configurations play an important role in determining biomechanical behaviour, retention, stability, and maintenance requirements. This scoping review aimed to map and evaluate the influence of key bar attachment parameters—such as cross-sectional geometry, material, splinting configuration, and distal extension—on the clinical performance of overdenture therapy. Methods: The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) framework. A comprehensive search was conducted in PubMed, Scopus, and the Cochrane Library. Eligible studies included clinical investigations, in vitro mechanical studies, and finite element analyses addressing bar-retained implant-supported overdentures. Extracted data included bar configuration characteristics, implant distribution, and reported outcomes such as retention forces, stress distribution, prosthetic complications, and patient-reported measures. Results: The available evidence indicated a recurring balance between increased retention and higher peri-implant stress, particularly in association with Hader bar designs. Material selection also appeared to influence performance. CAD/CAM-milled titanium bars demonstrated favourable mechanical durability, whereas alternative materials such as PEEK and zirconia were associated with improved stress distribution and potential biological advantages, although concerns regarding long-term durability remain. Differences related to arch type were also observed, with splinted bars supported by four implants generally favoured in the maxilla, while two-implant bar overdentures appear to provide satisfactory outcomes in the mandible. Conclusions: Bar selection should be individualised according to anatomical conditions, biomechanical demands, and patient-specific factors. Longer-term clinical studies and more standardised testing protocols are still required, particularly for newer materials and digitally fabricated bar systems, to support more consistent evidence-based decision-making. Full article

Background/Objectives: The growing adoption of digital technologies in prosthodontics has led to the widespread use of computer-aided design and computer-aided manufacturing (CAD/CAM) and three-dimensional (3D) printing for dental prostheses. However, differences in mechanical performance, particularly flexural strength and fracture resistance, remain a concern. Objective: To systematically evaluate and compare the flexural strength and fracture resistance of milled CAD/CAM and 3D-printed dental prostheses. Methods: A systematic review and meta-analysis were conducted following PRISMA 2020 guidelines. A comprehensive search was performed across multiple databases, including PubMed, Scopus, Web of Science, and Cochrane Library. In vitro studies comparing milled and 3D-printed prosthetic materials were included. Data extraction and risk of bias assessment were performed independently by multiple reviewers. A random-effects meta-analysis using standardized mean differences (SMD) was conducted. Results: Five studies were included in the meta-analysis for flexural strength. Milled CAD/CAM materials demonstrated significantly higher flexural strength compared to 3D-printed resins (SMD = 3.70; 95% CI: 0.80–6.59; p = 0.012), with substantial heterogeneity (I² = 93.3%). Fracture resistance results were inconsistent and influenced by individual studies, with sensitivity analyses showing variability in pooled estimates. Overall, the risk of bias was considered low, although some concerns were identified in randomization and blinding. Conclusions: CAD/CAM-milled materials exhibit superior flexural strength, while fracture resistance outcomes remain variable. Although 3D-printed materials may be clinically acceptable, further standardized studies are required to confirm their mechanical reliability. Full article

This study focuses on streamlining the manufacturing process for milling dental prosthetic components from biopolymer materials in order to achieve the best possible surface roughness. Various combinations of cutting parameters were systematically tested in experiments, and their impact on the final surface roughness of the material was analyzed. The study provides a comprehensive view of how variations in cutting speed, feed per tooth and cutting depth affect the final surface quality. The results show that the appropriate configuration of cutting parameters can significantly improve surface roughness, reducing the need for additional finishing and increasing production efficiency. The findings provide valuable information for the manufacture of polymer-based dental prosthetic components, support process optimization, and contribute to the development of accurate and reproducible computer-aided design and computer-aided manufacturing (CAD/CAM) manufacturing procedures. A full factorial design of experiments (DoE) approach was applied to evaluate the influence of cutting speed, feed per tooth, and cutting depth on the resulting surface roughness. The results confirmed that feed per tooth represented the most influential machining parameter affecting the resulting Ra values. The optimized cutting conditions resulted in the lowest surface roughness and improved process stability compared to manufacturer-recommended machining conditions. Full article

Background: Elderly patients often experience difficulty adapting to occlusal reconstruction. Therefore, accurate bite registration is mandatory to ensure precise transfer of the established maxillomandibular relationship to the definitive prosthesis. However, conventional bite registration methods may compromise reproducibility because of deformation of registration materials and instability of mucosa-supported record bases. Methods: A 65-year-old woman with the primary complaints of unstable occlusion and difficulty in mastication underwent occlusal reconstruction. After occlusal stabilization using provisional crowns, bridges, and removable partial dentures, definitive impressions were made with and without the provisional restorations. The casts were scanned, and the digital datasets were superimposed to reproduce the established occlusal morphology of the provisional restorations. This occlusal morphology was used to design a tooth-supported computer-aided design–computer-aided manufacturing (CAD–CAM)-fabricated milled provisional restoration. Following intraoral verification of occlusal stability, the milled provisional restoration served as a mounting guide for the working casts on an articulator. Definitive crowns, bridges, and removable partial dentures were then fabricated. Results: Following comprehensive prosthodontic rehabilitation with definitive prostheses, occlusal stability and masticatory function improved, and the patient was satisfied with the functional outcomes of treatment. Conclusions: A tooth-supported CAD–CAM-fabricated milled provisional restoration used as a bite registration device enables potentially more consistent transfer of the maxillomandibular relationship while avoiding mucosal displacement and material deformation. This technique, which integrates digital and conventional workflows, may provide a new option for addressing adaptation challenges in occlusal reconstruction. Full article

Background/Objectives: Wettability is a key surface property of denture base resins and is related to denture retention through interfacial cohesive–adhesive forces; conversely, compromised material wettability facilitates bacterial adhesion and colonization. Although three-dimensional (3D) printing has become an increasingly popular method for fabricating dentures, there is insufficient evidence regarding the wettability of 3D-printed denture base resins. This study aims to evaluate the wettability of 3D-printed, heat-polymerized, and milled denture base resins by comparing their contact angles. Methods: A search was conducted in MEDLINE, Scopus, and Web of Science, while grey literature was also assessed. The risk of bias was evaluated using the Quality Assessment Tool for In Vitro Studies (QUIN). Meta-analyses were conducted using inverse variance and the random effects model. Results: A total of nine and seven studies were included in the quantitative synthesis comparing 3D-printed denture base resins with heat-polymerized and milled resins, respectively. A statistically significant difference of −6.50 degrees was observed in favor of 3D-printed denture base resins compared to heat-polymerized ones (95% CI: −12.11 to −0.90, I² = 99%), while the comparison between 3D-printed and milled resins showed a non-statistically significant mean difference (MD: 0.87, 95% CI: −5.08 to 6.82, I² = 98%). Conclusions: The available in vitro evidence indicates that 3D-printed denture base resins tend to exhibit improved surface wettability compared with heat-polymerized resins and perform similarly to milled resins. However, given the extremely high heterogeneity, these findings should be interpreted with caution, as clinical performance depends on the complex interplay between surface characteristics and microbial adhesion rather than solely on wettability. Full article

Background: Digital fabrication techniques such as CAD/CAM milling and 3D printing are widely used for provisional dental restorations. However, differences in mechanical performance remain controversial. Objective: To compare the hardness and flexural strength of CAD/CAM-milled resins versus 3D-printed resins used in restorative dentistry. Methods: A systematic review and meta-analysis were conducted following PRISMA 2020 guidelines and registered in PROSPERO (CRD420251045547). Electronic searches were performed in PubMed, Scopus, Web of Science, Embase, and LILACS. In vitro studies comparing CAD/CAM-milled and 3D-printed resins in terms of hardness and/or flexural strength were included. A random-effects inverse-variance model was applied using standardized mean difference (SMD) with 95% confidence intervals (CI). Risk of bias was assessed using the RoB-Iv tool. Results: Four studies (n = 124 specimens) were included in the hardness meta-analysis. CAD/CAM-milled resins showed significantly higher hardness (SMD = 2.92; 95% CI: 0.34–5.49; p = 0.026), although heterogeneity was high (I² = 94.9%). Funnel plot asymmetry suggested possible small-study effects. For flexural strength, three studies (n = 40 specimens) were analyzed, demonstrating a significant effect favoring milled resins (SMD = 1.28; 95% CI: 0.42–2.14; p = 0.0036) with low-to-moderate heterogeneity (I² = 27.8%). Sensitivity analyses confirmed robustness for both outcomes. Overall methodological quality was acceptable, with no high risk of bias identified in strength studies. Conclusions: CAD/CAM-milled resins tend to demonstrate higher hardness and flexural strength compared with 3D-printed resins. However, the substantial heterogeneity observed, particularly for hardness, and the potential influence of methodological variability, warrant cautious interpretation of these findings. Full article