Search Results (568)

Objectives: To systematically evaluate the influence of connector design and pontic span length on the mechanical performance of zirconia fixed dental prostheses (FDPs). Methods: A systematic review was conducted according to PRISMA 2020 guidelines (8). Electronic searches were performed in PubMed, Scopus, Web of Science, and Embase. In vitro and finite element analysis (FEA) studies evaluating zirconia FDPs were included. Results: A total of 11 studies were included. Across all studies, connector regions were consistently identified as the primary site of fracture initiation. Reduced connector dimensions significantly decreased fracture resistance and fatigue life, whereas increased cross-sectional area and optimized geometry improved stress distribution and mechanical performance. Longer pontic spans were associated with increased stress concentration and reduced structural stability. Conclusions: Connector design and pontic span length are critical determinants of the biomechanical behavior of zirconia FDPs. Clinical significance: Optimization of connector dimensions and geometry is essential to improve the longevity and reliability of zirconia FDPs. Full article

The purpose of the present study was to evaluate the effects of zirconia material type, substructure color, cement color, and aging (before and after aging) on the color change of laminate veneers (LVs) prepared from different multilayer translucent zirconia ceramics. LV preparation was performed on a phantom tooth, and the preparation was digitized to produce resin abutments in two shades (light: A1/B1; medium: A2/A3) to simulate different tooth colors. LVs were designed using dental design software and fabricated from three multilayer zirconia ceramics (multilayered super-high-translucent 5Y-TZP zirconia, multilayered high-translucent 4Y-TZP zirconia, and multilayered ultra-translucent 5Y-TZP zirconia), resulting in 12 experimental groups (n = 10). They were then cemented with either clear or white resin cement and subsequently subjected to 10,000 cycles of thermal aging. The color parameters were measured at three time points (before cementation, before aging, and after aging), and the color change values (ΔE₀₀) were calculated. The data were statistically analyzed, and the results were compared with the perceptibility threshold (ΔE₀₀ = 0.8) and the clinical acceptability threshold (ΔE₀₀ = 1.8). Four-way ANOVA revealed an interaction among zirconia material, substructure color, cement shade, and measurement time (p = 0.02). Color change values after cementation (ΔE₀₀-1) across all groups showed a statistically significant difference between the white and clear cement groups. Before aging, the color change values observed in the 4Y-TZP (DD Cube One ML)-medium abutment–white cement (ΔE₀₀-1 = 1 ± 0.2) and 5Y-TZP (Katana UTML)-medium abutment–white cement (ΔE₀₀-1 = 1.6 ± 0.7) groups were above the perceptible threshold value but were clinically acceptable (0.8 < ΔE₀₀ < 1.8). The color change values observed after aging (ΔE₀₀-2) across all experimental groups were clinically unacceptable (ΔE₀₀ > 1.8). The color changeof ultra-translucent zirconia LVs was influenced by zirconia material type, cement shade, substructure color, and aging, with the effect of the zirconia material itself being less pronounced. Aging further reduced color stability, resulting in increased ΔE₀₀ values and clinically unacceptable color differences. Full article

Titanium remains the gold standard in dental implantology; however, its clinical drawbacks, such as hypersensitivity reactions, metallic particle release, and aesthetically compromising discoloration, have driven interest in metal-free alternatives. Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) has emerged as a promising bioceramic candidate, offering favorable aesthetics, mechanical strength, and reduced bacterial plaque affinity. Its pristine surface is nonetheless bioinert, prompting extensive research into surface modification strategies, including sandblasting, acid-etching, femtosecond laser texturing, and bioactive coatings, to enhance osteoconductivity. This comprehensive narrative review synthesizes in vitro evidence on the behavior of key host cell populations—macrophages, mesenchymal stem cells, osteoblasts, fibroblasts, and epithelial cells in response to Y-TZP surface and its modifications, relevant to osseointegration and soft-tissue sealing. A literature search was conducted across PubMed, Scopus, Web of Science, and the Cochrane Library, supplemented by Google Scholar, concluding in March 2026. By integrating findings across multiple cell lineages, this review aims to clarify how engineered zirconia topographies modulate cell-specific pathways, thereby informing the development of next-generation implants optimized for biological integration. Full article

Peri-implantitis, a biofilm-driven inflammatory disease that causes progressive loss of the bone supporting dental implants, is common and difficult to treat: mechanical debridement cannot fully decontaminate the implant surface, and antibiotic adjuncts act non-selectively while promoting resistance. Antimicrobial peptides (AMPs) have emerged as a promising preventive strategy. As cationic, membrane-disrupting molecules they kill a broad spectrum of organisms with a low propensity to select for resistance, and as host-defense peptides they additionally modulate inflammation and promote epithelial and connective-tissue repair. This review examines AMP-functionalized titanium as a prospective strategy against peri-implantitis through a dermatological lens, drawing on the established roles of the cathelicidin LL-37 and the β-defensins in cutaneous and oral wound healing. We argue that the peri-implant transmucosal interface behaves as a healing epithelial barrier, so that a single class of host-defense peptides can address two goals usually pursued separately—suppressing the peri-implant biofilm and reinforcing the soft-tissue seal. Because peri-implant disease initiates at the transmucosal region, we give particular attention to the abutment or transmucosal collar as the primary sealing target, and we consider how the concept extends to zirconia and hybrid components. The evidence assembled here, however, is predominantly preclinical, derived from in vitro and animal studies, and does not yet demonstrate clinical prevention of peri-implantitis in patients. After surveying peri-implant epidemiology, microbiology, AMP biology, surface-engineering strategies, and the in vivo evidence, we appraise the translational barriers—stability, cytotoxicity, cost, regulation, and the absence of human trials—that remain. We conclude that biologically intelligent, multifunctional peptide coatings represent a rational direction for next-generation implant surfaces. Full article

Background and Objectives: Periodontal health represents a condition characterized by homeostasis between the teeth and the surrounding supporting tissues and implies the absence of inflammation, confirmed by the lack of bleeding, epithelial attachment loss, mobility, or periodontal pocket formation. Fixed prosthetic restorations may compromise periodontal health already during the fabrication phase, given that decisions made during their planning and placement affect long-term clinical outcomes. The aim of this manuscript was to provide insight into the interaction between periodontal tissues and fixed prosthetic restorations. Materials and Methods: A narrative literature review was conducted using a structured search of the PubMed/MEDLINE, Scopus, and Google Scholar databases to identify studies addressing periodontal health in relation to fixed dental prostheses. The impacts of tooth preparation, gingival retraction methods, supracrestal tissue attachment, periodontal phenotype, crown emergence profile, and marginal fit of various biomaterials were analyzed. Results: According to the literature data, subgingival margin placement and violation of the supracrestal tissue attachment (biological width) induce chronic inflammation, loss of epithelial attachment, and alveolar bone resorption. Gingival retraction agents, used in chemomechanical retraction procedures, particularly ferric sulfate-based agents, may lead to a transient but significant spike in inflammatory markers and dysbiosis of the subgingival microbiome. Contemporary approaches, such as the biologically oriented preparation technique and the use of CAD/CAM (Computer-Aided Design and Computer-Aided Manufacturing) technology, may improve the precision of marginal fit. Zirconia restorations exhibit significantly better biocompatibility and reduced microbial adhesion compared to metal–ceramic restorations. Conclusions: Biological response of the periodontium to fixed prosthetic restorations depends on the complex interaction between the material, position of the marginal line, and oral hygiene control. Regardless of the material used or the fabrication technique employed, adequate plaque control and regular maintenance remain key factors in preserving periodontal health. 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/Objectives: Metal artifacts from dental implants degrade CBCT image quality and may impair detection of peri-implant bone defects. Zirconia implants produce stronger artifacts than titanium due to its higher atomic number. This study evaluated the impact of a native MAR algorithm (SMARF) on CBCT detection of buccal fenestration and dehiscence of varying sizes adjacent to zirconia versus titanium implants. Methods: In this ex vivo pilot study, two 4 mm × 12 mm implants (one titanium and one zirconia) were implanted in a dry human mandible. Artificial fenestration and dehiscence defects were created at the buccal surface of right and left premolar regions, in three sizes (small 2 mm × 2 mm× 1 mm; medium 2 mm × 4 mm× 1 mm; large 2 mm × 6 mm× 1 mm). Scans were acquired with a Papaya 3D (Genoray) CBCT using a single-tooth FOV (4 cm× 4 cm × 5 cm), 83 kVp, 10 mA, 0.1 mm voxel; each condition was imaged with MAR on and off (six repeats each). Two trained observers scored defect presence on a five-point Likert scale. Sensitivity, specificity, inter- and intraobserver agreement (Cohen’s kappa), and comparisons across conditions were calculated. Results: Interobserver κ = 0.65 (substantial); intraobserver κ = 0.87–1.00 (excellent). For titanium implants, sensitivity and specificity were 100% across all defect types, sizes, and MAR settings. For zirconia implants, fenestration sensitivity with MAR off increased with size (small 50%, medium 75%, large 100%); MAR on raised sensitivity to 100% for all sizes, with a significant improvement for small fenestrations (p = 0.005). Dehiscence sensitivity for zirconia was 100% across sizes and MAR conditions. Specificity for zirconia defects was 83.3% with MAR off and decreased to 66.6% with MAR on (p = 0.07). Conclusions: With the Papaya 3D system used in this pilot study, MAR was unnecessary for defect detection adjacent to titanium implants but affected performance for zirconia implants: MAR increased sensitivity for small fenestrations while reducing specificity (although not statistically significant). Clinicians should weigh the sensitivity–specificity trade off when applying MAR around zirconia implants. Full article

Background: Tooth-supported fixed dental prostheses (FDPs) remain relevant when implant therapy is limited, but their mechanical behavior depends on material selection, connector design, retainer design, prosthesis configuration, and abutment support. This systematic review assessed how these factors affect fracture behavior and stress transmission in tooth-supported FDPs. Materials and Methods: PubMed/MEDLINE, Scopus, Web of Science Core Collection, and Dentistry and Oral Sciences Source were searched for English-language studies published from 1 January 2016 to 15 May 2026. Eligible studies were in vitro mechanical, fatigue, fracture-resistance, or finite element analysis (FEA) studies of tooth-supported FDP designs. Clinical studies were screened during eligibility assessment, but no clinical study met the final inclusion criteria for primary synthesis. In vitro components were appraised with the Quality Assessment Tool for In Vitro Studies (QUIN), and FEA components were appraised with the Risk-of-bias Framework for Dental Finite Element Analysis (ROBFEAD). Findings were synthesized narratively by evidence type and biomechanical theme. Results: Twenty-nine studies were included: 11 in vitro-only studies, 14 FEA-only studies, and four combined experimental and computational studies. No eligible clinical study met the final inclusion criteria. Zirconia-based systems were the most frequent focus. Their behavior depended on connector dimensions, connector shape, framework design, span, retainer configuration, loading direction, abutment selection, periodontal support, and bone support. Larger connector dimensions or greater connector height often improved fracture resistance or reduced modeled stress in zirconia models, but connector area alone did not explain performance across all materials and designs. Conservative FDPs were sensitive to retainer geometry, adhesive-interface behavior, connector design, and abutment support. Conclusions: Current evidence is limited to laboratory and computational studies. Tooth-supported FDP biomechanics should be interpreted as a material, design, and support system, not as a material effect alone. Full article

Multilayer 4Y/5Y-PSZ zirconia materials have been developed to combine strength and translucency in monolithic “all-in-one” dental restorations. This study evaluated the flexural strength of different layers (incisal, transition, and dentin) in four commercially available multilayer zirconia systems using three-point bending tests in accordance with ISO 6872. A total of 360 CAD/CAM-fabricated bar-shaped specimens were prepared from the materials CE (Cercon yo ML, DentsplySirona), KA (Katana YML, Kuraray Noritake), PZ (3D ProZir, Aidite), PE (IPS e.max ZirCAD Prime esthetic), and assigned to layer-specific groups based on their position within the discs. After sintering and standardized surface finishing, specimens were tested under three-point bending conditions. Fracture strength was calculated and statistically analysed. Microstructural and fractographic analyses were performed to assess grain structure and to identify fracture origins. The results demonstrated significant differences in flexural strength both among materials and between layers. In general, dentin layers exhibited the highest strength, reaching mean values up to 1143 MPa, while incisal layers showed significantly lower values, with minima around 572 MPa. Only one material (CE) maintained flexural strength above the ISO threshold of 800 MPa across all layers, qualifying for unrestricted (class 5) clinical use. Other materials showed limitations, particularly in the more translucent incisal regions (KA, PE). One material fell below the ISO threshold (PZ). Weibull moduli revealed differences in reliability, with moduli ranging from 4.7 to 16.5. Fractographic evaluation identified typical fracture patterns such as surface grinding defects and internal porosity, but no abnormal fracture origins. The strength gradient corresponds to microstructural differences, particularly grain size and phase composition, influenced by yttria content. Increased translucency in incisal layers is associated with reduced mechanical performance. These findings emphasize that, despite aesthetic advantages, layer-dependent strength variations must be considered when selecting multilayer zirconia for clinical applications, especially in long-span restorations. Full article

Background/Objectives: Titanium alloy Ti₆Al₄V remains the gold standard in dental implantology due to its excellent mechanical properties, corrosion resistance, and biocompatibility. However, implant-associated infections and insufficient osseointegration continue to represent major clinical challenges, mainly related to bacterial biofilm formation and suboptimal surface–tissue interactions. Biofilm formation refers to the adhesion, accumulation, and growth of microbial communities embedded within a self-produced extracellular polymeric matrix on implant surfaces, which contributes to bacterial persistence and resistance to host defense mechanisms. This review aims to critically evaluate recent advances in multifunctional bioceramic coatings for dental implants, with a particular focus on zirconia (ZrO₂)-based systems and their antibacterial mechanisms. Methods: A structured literature analysis was conducted using major scientific databases including PubMed, Scopus, and Web of Science, focusing mainly on studies published between 2015 and 2025 related to CaP, Ag, and ZrO₂-based coatings for dental implants. The review examines their physicochemical properties, antibacterial strategies, ion release behavior, and biological responses, including osteogenic activity and biofilm inhibition. Particular attention is given to hybrid systems integrating multiple functional phases. Results: CaP coatings exhibit excellent osteoconductivity and promote early osseointegration but show limited intrinsic antibacterial activity. Ag-based coatings provide strong broad-spectrum antimicrobial effects through controlled Ag⁺ ion release, although concerns regarding cytotoxicity and dose-dependent responses remain. ZrO₂ coatings significantly enhance corrosion resistance and surface stability, while their antibacterial performance can be improved through nanostructuring, laser surface modification, and ionic doping. Hybrid Ag–CaP–ZrO₂ coatings demonstrate improved antibacterial activity, enhanced corrosion resistance, and better regulation of ion release kinetics and osteogenic response compared with single-component coating systems. Conclusions: Multifunctional bioceramic coatings represent a promising strategy for improving the performance of dental implants and addressing the dual challenge of infection control and tissue integration. However, challenges remain regarding long-term stability, controlled ion release, and limited clinical validation. Future research should focus on the development of smart, stimuli-responsive coatings and standardized evaluation protocols to facilitate clinical translation. Full article

This study evaluated and compared the mechanical performance of conventionally milled zirconia and two additively manufactured zirconia ceramics fabricated using Lithography-based Ceramic Manufacturing (LCM) technology for potential use in load-bearing dental restorations. A total of 150 zirconia specimens were prepared and allocated into three material groups: milled zirconia and LCM-printed zirconia (LithaCon 3Y 210 and LithaCon 3Y 230), each subdivided into non-aged (control, C) and thermocycled aged (A) conditions (n = 25 per condition). Specimens were standardized using CAD and fabricated by milling or LCM printing. Flexural strength was assessed using a three-point bending test in accordance with ISO 6872:2024, nanoindentation hardness was measured with a Berkovich indenter following ISO 14577-1:2015, and surface roughness was evaluated using optical profilometry per ISO 21920-2:2021. Flexural strength showed no significant differences among groups, while hardness and surface roughness varied significantly. LCM zirconia demonstrated comparable flexural strength to milled zirconia, although milled materials exhibited higher hardness. The 210A group showed the most favorable overall mechanical profile, warranting further investigation of long-term performance. Full article

This study proposes the development of a recycling process for the reintegration of dental zirconia waste into CAD/CAM systems for rapid prototyping, with the objective of demonstrating the feasibility of manufacturing functional products from recycled zirconia obtained from a commercial dental laboratory. The proposed methodology aims to explore a simple and economically viable process, which involves the purification and processing of a heterogeneous zirconia powder, followed by the fabrication of pre-sintered blocks suitable for CAD/CAM applications. The recycled bulk ceramic was characterized and compared with commercial zirconia through density measurements, X-ray diffraction, scanning electron microscopy, Vickers hardness, flexural strength testing, and sintering shrinkage analysis. The results indicated that, although recycled zirconia exhibits lower property values than the commercial reference material, it retains adequate characteristics for specific practical applications. Consequently, to demonstrate industrial feasibility, four components were designed using CAD and machined using CAM from the recycled blocks, simulating a rapid prototyping process. The fabricated components exhibited a smooth and flawless surface, were mechanically robust and solid to the touch, and showed well-defined contours with sharp edges. Dimensional analysis demonstrated high accuracy, with an average percentage error of 0.53% ± 0.14. These findings demonstrate that high-value ceramic waste can be reintegrated into the production chain as functional industrial components through a process that is closely aligned with the real conditions of industrial recycling, while also mitigating environmental contamination from hazardous industrial waste. Full article

Full-arch implant-supported rehabilitations are widely recognized as an effective treatment option for edentulous patients. Nevertheless, clinical decision-making regarding patient selection, surgical planning, prosthetic material choice, and long-term maintenance protocols remains heterogeneous and requires structured evidence-based guidance. A modified Delphi consensus process was conducted involving 29 experts during the Italian Consensus Conference. A systematic literature review covering the period 2015–2024 was performed, and the certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. Consensus was predefined as ≥90% agreement. Seven evidence-based consensus statements were developed addressing: (1) periodontal risk assessment using validated tools; (2) guided bone regeneration outcomes with technique-specific indications; (3) comparative survival of four versus six implants in mandibular full-arch rehabilitations; (4) equivalence of tilted and axial implant configurations; (5) prosthetic material selection, with monolithic zirconia showing high survival; (6) risk-stratified supportive maintenance protocols associated with a reduction in peri-implantitis incidence; and (7) systemic risk stratification, including absolute and relative contraindications, medication-related osteonecrosis of the jaw (MRONJ) risk management, and perioperative antibiotic prophylaxis. Full article

Background/Objectives: Titanium implants remain the gold standard in implant dentistry. However, growing interest in metal-free alternatives has led to increased use of zirconia implants. Despite encouraging short-term outcomes, evidence regarding the medium- to long-term survival of one-piece zirconia implants (O-PZIs) and associated risk factors remains limited. The aim of this retrospective cohort study was to evaluate the survival of O-PZIs over follow-up periods of up to 8 years and to explore variables potentially associated with implant failure. Methods: This retrospective observational cohort study was conducted at a private dental clinic (Madrid, Spain). A total of 307 O-PZIs placed in 196 patients between 2017 and 2021 were analyzed. Implant survival was assessed using Kaplan–Meier analysis, while associations between clinical variables and implant failure were explored using chi-square tests and multivariate Cox regression models (p < 0.05). The mean follow-up period was 61.37 ± 2.25 months. Results: After a mean follow-up of 61.37 ± 2.25 months (range: 39–96 months), 42 failures were recorded, resulting in a cumulative survival rate of 86.32% (CI 95%: 79.28–92.96%). Most failures (64.29%) occurred before prosthetic loading. Kaplan–Meier analysis revealed significantly lower survival for tapered implants (p < 0.001) and among smokers (p < 0.001). Multivariate analysis indicated that only simultaneous guided bone regeneration (GBR) was independently associated with implant failure (Exp(B) = 3.191; 95% CI: 1.299–7.840; p = 0.011). However, this association should be interpreted with caution due to the retrospective design, potential confounding, limited number of events, and lack of adjustment for clustering at the patient level. The discrepancies observed between statistical methods highlight the importance of time-to-event analyses in implant research. Conclusions: Within the limitations of this study, O-PZIs demonstrated acceptable medium- to long-term survival. Simultaneous GBR may be associated with increased risk of failure. However, these findings should be considered exploratory. Further prospective studies are required to confirm these results and to better define risk factors in ceramic implant therapy. Full article

This study investigated the effect of post-silanization processing on the surface chemistry and dispersion stability of 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) nanoparticles intended for the reinforcement of dental photopolymer resins. The nanoparticles were silanized using 3-Methacryloxypropyltrimethoxysilane and subjected to different post-treatment protocols, including control, drying, and centrifugation. Particle morphology was examined using field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Dispersion behavior was analyzed by dynamic light scattering (DLS) and zeta potential measurements, performed in triplicate (n = 3), while surface chemical modifications were evaluated using Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Post-silanization processing significantly influenced nanoparticle surface chemistry and dispersion stability. Centrifugation promoted the formation of Si–O–Zr and Si–O–Si linkages, reduced loosely adsorbed silane species, decreased particle agglomeration, and increased zeta potential magnitude, resulting in a more uniform hydrodynamic size distribution compared to the dried group (Z-average ≈ 814 nm, PDI ≈ 0.44). These findings suggest that post-silanization centrifugation acts as an interfacial selection mechanism that distinguishes covalently grafted silane from weakly adsorbed species. Within the limitations of this in vitro study, further investigations under varied conditions are required to confirm broader applicability. Full article