Search Results (427)

Pure titanium (Ti) and its alloys are the gold standard for dental implants because a stable titanium dioxide passive film provides excellent corrosion resistance in physiological environments. In this study, we aimed to examine electrochemical interactions between Ti and cobalt–chromium–molybdenum alloy (CoCrMo), and between a novel Ti–magnesium composite (BIACOM TiMg) and CoCrMo, when immersed in everyday solutions representing beverage or oral hygiene exposure. Test solutions included Coca-Cola^®, lemon juice, Elmex^® fluoride gel, Listerine^® Cool Mint, and Sensodyne^® fluoride paste. Immersion experiments paired Ti sticks with CoCrMo sticks and, separately, BIACOM TiMg with CoCrMo sticks, with three measurements per configuration. When galvanically coupled with CoCrMo, immersion in Coca-Cola produced galvanic potential differences of ~983 mV for the BIACOM TiMg-CoCrMo couple and 830 mV for the commercially pure grade 4 (CP4) Ti-CoCrMo couple, indicating significant electrochemical instability. Both materials showed significant potential increases in Elmex fluoride gel. Listerine Cool Mint and Sensodyne fluoride exposure produced electrochemical interactions exceeding 200 mV. Significant differences in corrosion stability were observed between CP4 Ti and BIACOM TiMg. These findings indicate that material pairing and electrolyte environment significantly influence galvanic behavior, with the Ti-Mg composite showing greater susceptibility than CP4 Ti, informing dental/biomedical material selection in oral environments. Full article

Background/Objectives: Dental malocclusions are often treated with appliances made of metal alloys. These alloys biodegrade in oral cavity and release toxic metals such as nickel and chromium. This study aimed to assess nickel and chromium content in the saliva of patients with and without fixed metallic orthodontic appliances. Methods: This was a descriptive cross-sectional study aiming to assess nickel and chromium content in saliva. A survey was conducted to record socio-demographic characteristics and clinical signs due to the wearing of fixed metallic orthodontic appliances. A 10 mL saliva sample was used to measure salivary pH and assess nickel and chromium concentrations using atomic emission spectrophotometry. A Student’s t-test compared saliva metal levels in non-wearers and wearers of metal orthodontic appliances. A Chi-square test was used to assess the influence of pH on metal release in patients. Results: A total of 92 participants, divided in two groups; 46 without appliance and 46 wearing appliance were received during the study period. Their mean age was 17.05 ± 6.46 years. Patients’ mean saliva pH was 6.97 ± 0.44. The mean nickel concentration was 4.39 ± 4.01 µg/L in the saliva of non-appliance wearers and 20.41 ± 18.56 µg/L in the saliva of appliance wearers, respectively. The chromium mean concentration was 1.3 ± 1.33 µg/L for non-appliance wearers and 9.38 ± 19.49 µg/L and for appliance wearers. Metal release is influenced by the pH of foods. Conclusions: Metal orthodontic appliances increase the release of nickel and chromium in saliva. It is necessary to monitor the risk of intolerance and optimize treatment duration. Full article

Background/Objectives: The purpose of this study was to assess the in vitro biocompatibility and corrosion resistance of five titanium alloys that have been recently developed for dental implant applications, whose compositions were designed to align with current approaches in the development of novel biomaterials. Priority was given to limiting the harmfulness associated with specific chemical elements present in common conventional alloys and increasing corrosion resistance to improve the biomaterial–tissue cellular interaction. Methods: For this purpose, five types of titanium alloys with original chemical compositions (Ti1–Ti5) were developed. The electrochemical behavior of the alloys was analyzed by evaluating the corrosion resistance in environments that simulate the oral environment, as well as the cellular behavior, by evaluating the viability, growth, and proliferation of human cells on osteoblasts and gingival fibroblasts. Detailed analysis of the chemical composition by scanning electron microscope (SEM/EDS) methods was used. The corrosion rate of the alloys in artificial saliva was tested using the polarization resistance technique (Tafel). Human osteoblasts (hFOB cell line) and human gingival fibroblasts (hFIB-G cell line) were used to measure biocompatibility in vitro. Results: The Ti5 alloy demonstrated the highest cell viability and the lowest corrosion rate (0.114 μm/year) among all tested compositions, with the Ti3 alloy containing Mo and Zr following closely behind. The Ti2 alloy exhibited reduced biocompatibility because of the inclusion of Ni and Fe in its composition. Conclusions: Taken together, the results of this study provide useful information on the basic characteristics of titanium alloys with original chemical compositions. The titanium alloys were analyzed in comparison with common conventional alloys (Cp–Ti and Ti6Al4V) as well as alloys such as Ti–Zr, Ti–Nb, and Ti–Nb–Zr–Ta, which are considered to be viable alternatives to conventional materials for making dental implants. Full article

Introduction: The success of metal–ceramic restorations depends on the mechanical and adhesive properties of the metal–ceramic interface. With the emergence of additive manufacturing technologies such as selective laser melting (SLM), there is growing interest in comparing these methods with conventional casting. This pilot study aimed to generate hypothesis-forming data on how fabrication method (casting and 3D printing) and alumina sandblasting with two particle sizes (125 μm and 250 μm) influence flexural performance of Co-Cr metal–ceramic systems within the standardized ISO 9693 framework. Materials and Methods: Rectangular Co-Cr alloy specimens were manufactured using two techniques: conventional casting and 3D printing via SLM. Each group was divided based on the sandblasting particle size. After ceramic application in accordance with ISO 9693:2012, samples underwent a three-point bending test using a universal testing machine (Instron 8872) to assess the displacement force required to fracture the ceramic layer. Five specimens were tested per group, and mean values and standard deviations were calculated. Data were statistically analyzed using two-way ANOVA followed by Tukey’s HSD post hoc test (p < 0.05). Results: Cast samples exhibited significantly higher displacement strength than printed ones. Among all groups, the cast samples sandblasted with 250 μm particles (CCT_250) showed the best performance (mean: 12.48 ± 0.91 N), while the 3D-printed group treated with 125 μm particles (CCP_125) showed the lowest strength (mean: 7.24 ± 0.65 N). Larger abrasive particles (250 μm) improved bond strength in both fabrication techniques. Two-way ANOVA revealed significant main effects of manufacturing method (F(1,16) = 13.63, p = 0.002, η² = 0.46) and particle size (F(1,16) = 6.17, p = 0.024, η² = 0.28), with no interaction between factors. Conclusions: Both the manufacturing method and the sandblasting protocol significantly influence the flexural performance of Co-Cr ceramic systems. Conventional casting combined with 250 μm particle sandblasting ensures the highest ceramic adhesion, while SLM-printed substrates may require additional surface treatments to improve bonding efficiency. Complementary surface treatments such as bonding agents or chemical oxidation may enhance the metal–ceramic bond in SLM-fabricated frameworks. Full article

Titanium (Ti) and its alloys are widely used in orthopedic applications, including total hip and knee replacements, bone plates, and dental implants, because of their superior biocompatibility, bioactivity, corrosion resistance, and mechanical robustness. These alloys effectively overcome several limitations of conventional metallic implants, such as 316L stainless steel and Co-Cr alloys, particularly with respect to corrosion, fatigue performance, and biological response. However, dense Ti alloys possess a relatively high elastic modulus, which can cause stress shielding in load-bearing applications. This challenge has motivated significant research toward engineered porous Ti structures that exhibit a reduced and bone-matched modulus while preserving adequate mechanical integrity. This review provides a comprehensive examination of powder metallurgy and additive manufacturing approaches used to fabricate porous Ti and Ti-alloy scaffolds, including additive manufacturing and different powder metallurgy techniques. Processing routes are compared in terms of achievable porosity, pore size distribution, microstructural evolution, mechanical properties, and biological outcomes, with emphasis on the relationship between processing parameters, pore architecture, and functional performance. The reported findings indicate that optimized powder-metallurgy techniques can generate interconnected pores in the 100–500 μm range suitable for osseointegration while maintaining compressive strengths of 50–300 MPa, whereas additive manufacturing enables the precise control of hierarchical architectures but requires careful post-processing to remove adhered powder, stabilize microstructures, and ensure corrosion and wear resistance. In addition, this review integrates fundamental aspects of bone biology and bone implant interaction to contextualize the functional requirements of porous Ti scaffolds. Full article

Objectives: This in vitro study aimed to evaluate the effects of three framework orientation (FO) positions on an SLM building platform (Horizontal [H], Diagonal-45° [D45°], Diagonal-60° [D60°]) and two designs (with [B] or without [NB] stabilizing bars) on the fitting accuracy of digitally fabricated Co-Cr RPD frameworks. Materials and Methods: A custom RPD framework CAD was performed on a 3D-printed resin-model of an edentulous maxilla with three geometric tooth forms. A Co-Cr alloy was processed via SLM processing into 24 framework specimens, divided into three FO groups (n = 8: H, D45°, D60°) and two subgroups each (n = 4: B, NB). Qualitative/quantitative fit-evaluation was assessed using virtual framework-to-model seating and a custom digital protocol with GOM Inspect software (2018-Hotfix5, Rev.115656). Mean fitting distances were calculated from 220 equidistant points per specimen. Statistical comparisons were performed using ANOVA-on-ranks, Kruskal–Wallis multiple comparisons, and Bonferroni adjustment. Results: FO Sub-Group medians (Q1, Q3: 25% and 75% Quartiles) (mm) were: H/NB 0.150 (0.140, 0.164), H/B: 0.136 (0.121, 0.152), D45°/NB: 0.230 (0.219, 0.241), D45°/B: 0.144 (0.137, 0.154), D60°/NB:0.238 (0.232, 0.247), D60°/B: 0.171 (0.166,0.176). Pairwise comparisons indicated the following statistically significant (p < 0.05) FO Sub-Group differences: H/B-D45°/NB, H/B-D60°/NB, D45°/B-D45°/NB, D45°/B-D60°/NB, H/NB-D45°/NB, H/NB- D60°/NB. Conclusions: Horizontal orientation improved RPD fit accuracy regardless of bar presence. D45° accuracy is enhanced by stabilizing bars, while D60° accuracy is unaffected by bar addition. Full article

Titanium alloys are widely used in dental implants due to their superior biocompatibility and mechanical strength. However, these alloys are prone to corrosion and wear in the oral environment, thereby shortening their clinical lifespan. This study investigates the enhancement of titanium alloy surface properties using magnetic abrasive finishing (MAF) and examines the influence of magnetic needle diameters (0.2–1.5 mm) on surface modification. Titanium alloy samples were processed by MAF and systematically evaluated for surface morphology, grain size, surface hardness, residual stress, electrochemical corrosion behavior, and tribological performance. Results demonstrated that MAF improves surface morphology, significantly refines grain size, and enhances surface hardness and compressive residual stress, thereby optimizing surface properties. The 1.0 mm magnetic needle group demonstrated the best performance, achieving a Vickers hardness of 376.71 ± 12.48 HV and a compressive residual stress of −579.1 ± 8.49 MPa. In addition, this group showed a higher self-corrosion potential (−0.5661 V), a lower corrosion current density (0.0114 μA·cm⁻²), and the lowest wear rate ((4.49 ± 0.42) × 10⁻⁴ mm³/N·m) in artificial saliva, demonstrating superior corrosion and wear resistance. Overall, MAF technology markedly enhances the surface integrity of titanium alloys in artificial saliva through the synergistic effects of grain refinement and stress modulation. These findings provide valuable experimental evidence supporting future efforts to optimize the surface properties of titanium alloy dental implants. Full article

Titanium alloys are widely used in orthopedic and dental implants, yet their limited bioactivity and bacterial resistance remain critical challenges. This study aimed to enhance the surface performance of a Ti-13Zr-13Nb alloy through the formation of a porous oxide layer and the application of a bioactive, drug-loaded coating. Porous oxide layers composed of Ti, Zr, and Nb oxides with fluoride incorporation were fabricated using a novel anodizing process. The fluoride-assisted electrochemical mechanism controlling oxide growth was elucidated through SEM and EDS analyses. The anodized surface exhibited reduced microhardness, beneficial for minimizing stress-shielding effects. Subsequently, chitosan–tetracycline composite coatings were produced via EPD and compared with dip-coating method. Characterization by ATR-FTIR, optical microscopy, SEM, and UV-VIS spectroscopy confirmed the formation of uniform, adherent, and moderately porous coatings with sustained drug release when produced by EPD, while dip-coated layers were less homogeneous and released the drug faster. Microhardness testing revealed improved mechanical integrity of EPD coatings. The developed chitosan–tetracycline–oxide layer system provides tunable nano/microgram-scale drug release and enhanced surface functionality, offering promising perspectives for acute and medium-term regenerative and antibacterial biomedical applications. Full article

Objective: The Ti6Al4V titanium alloy is widely used for dental implants because of its excellent mechanical properties, corrosion resistance, and biocompatibility. However, its bioinert surface limits both osseointegration and resistance to bacterial colonization. Methods: To address these challenges, this study develops a composite coating based on calcium phosphate (CaP) and silver (Ag), reinforced with zirconium oxide (ZrO₂). The coating was deposited on Ti6Al4V using an immersion technique to improve the surface properties of the alloy. Electrochemical analyses (OCP, EIS, and potentiodynamic polarization) were performed in simulated physiological conditions to evaluate the corrosion behavior, while SEM/EDS was used to characterize the surface morphology and composition. Results: The Ag- and Zr-containing CaP coatings significantly improved the corrosion resistance of Ti6Al4V compared with uncoated and CaP-coated samples. Conclusions: This approach provides a promising strategy to enhance the electrochemical stability and long-term durability of titanium dental implants, thereby contributing to their reliable performance in the oral environment. Full article

Microbial colonization is a major factor contributing to peri-implantitis, and creating durable glassy surfaces with antimicrobial agents such as silver and copper may reduce microbial accumulation on dental abutments. This study aimed to develop antimicrobial thin-film glassy surfaces on Ti6Al4V alloy and to evaluate their surface and mechanical properties, antimicrobial effectiveness, and biocompatibility before and after thermal aging. A sol–gel-derived glassy matrix (G) was synthesized, and two antimicrobial coatings were prepared by incorporating ionic Ag (GAg) or a combination of Ag/Cu (GAgCu). Ti6Al4V specimens; these were either left uncoated or dip-coated with G, GAg, or GAgCu and cured at 450 °C. Half of the specimens underwent thermal aging between 5 °C and 55 °C for 3000 cycles. Surface roughness, contact angle, hardness, adhesion strength, scratch resistance, cytotoxicity (Agar diffusion and MTT assay on L929 fibroblasts), and microbial adhesion were evaluated using Streptococcus sanguinis, Porphyromonas gingivalis, and Candida albicans as representative oral microorganisms. Both coatings exhibited low surface roughness, hydrophilic surfaces, improved hardness, and significantly reduced microbial adhesion for all tested species. GAg showed superior mechanical properties, whereas GAgCu demonstrated a relatively stronger antimicrobial effect. Cytotoxicity tests indicated that all coatings were biocompatible at levels suitable for oral use. Overall, these coatings demonstrated strong adhesion, durability, and antimicrobial activity, suggesting their suitability for dental abutments made of Ti6Al4V. Full article

Porcelain-fused-to-metal (PFM) crowns continue to serve as a cornerstone of restorative dentistry owing to their strength, affordability, and esthetics. However, late-onset complications such as oral burning and lichenoid reactions have been observed in long-serving PFMs, suggesting complex host–material interactions that extend beyond simple mechanical wear. This Perspective introduces the Nallan–Nickel Effect, a theoretical model proposing that a host- and environment-dependent threshold of bioavailable nickel ions (Ni²⁺), once exceeded, may trigger a neuro-immune cascade culminating in a burning phenotype. Within this framework, slow corrosion at exposed PFM interfaces releases Ni²⁺ into saliva and crevicular fluid, facilitating epithelial uptake and activation of innate immune sensors such as TLR4 and NLRP3. The resulting cytokine milieu (IL-1β, IL-6, TNF-α) drives NF-κB, mediated inflammation and T-cell activation, while neurogenic mediators—including nerve growth factor (NGF), substance P, and CGRP—sensitize TRPV1/TRPA1 nociceptors, establishing feedback loops of persistent burning and neurogenic inflammation. Modifying factors such as low salivary flow, acidic oral pH, mixed-metal galvanic coupling, and parafunctional stress can lower this threshold, whereas replacement with high-noble or all-ceramic materials may restore tolerance. The model generates testable predictions: elevated local free Ni²⁺ levels and increased expression of TLR4 and TRPV1 in symptomatic mucosa, along with clinical improvement following substitution of nickel-containing restorations. Conceptually, the Nallan–Nickel Effect reframes PFM-associated burning and lichenoid lesions as threshold-governed, neuro-immune phenomena rather than nonspecific irritations. By integrating corrosion chemistry, mucosal immunology, and sensory neurobiology, this hypothesis offers a coherent, testable framework for future translational research and patient-centered management of PFM-related complications. Full article

Background/Objectives: This retrospective study aimed to evaluate the five-year clinical performance of removable partial dentures (RPDs) made of chromium–cobalt–molybdenum alloy, comparing two different post-casting cooling methods: slow furnace cooling (LRF) and room temperature air cooling (RATA). The investigation aimed to determine whether LRF treatment could reduce the incidence of technical complications, such as fractures and clasp deformations, particularly on RPD with thin clasps for aesthetic reasons. Methods: In total, 22 RPDs were examined, 11 of which were treated with LRF (test group) and 11 with RATA (control group). The prostheses in the LRF group had clasps intentionally reduced by 2/3 tenths of a millimeter compared to those in the RATA group. All the prostheses were made and evaluated by the same operator, who analyzed the presence of changes, fractures, or clasp widening after five years. Statistical analysis was performed using Fisher’s exact test with a significance level of p < 0.05. Results: Clinical data showed a lower complication rate in the LRF group compared to the RATA group in all parameters evaluated: prosthesis modification (9.1% vs. 18.2%), clasp fractures (9.1% vs. 36.4%), and enlarged clasps (54.4% vs. 72.7%). However, the statistical comparison between the two groups did not show significant differences, p-value ˃ 0.05 for all parameters. Conclusions: Despite the lack of statistical significance, likely due to the limited size of the cambium and the confounding variable of clasp thickness, clinical trends indicate a potential superiority of the LRF method in the parameters examined, such as modification prosthesis, fractured clasp, and enlarged clasp. The reduction in complication rates in the LRF group suggests that the superior mechanical properties conferred by this treatment may compensate for the potential structural weakening caused by clasp thickness. Future studies with a larger sample size and a prospective design will be needed to validate these results and confirm LRF as the preferred protocol for the production of aesthetic RPD. Full article

This study investigates the mechanical properties of titanium (Titanflex®) and cobalt-chromium (Co-Cr) alloys for potential use in removable denture bases. Titanium alloys have gained attention due to their biocompatibility and regulatory concerns surrounding Co-Cr, which has been classified as a carcinogenic, mutagenic, and toxic to reproduction (CMR) substance under EU MDR (2017/745). Using selective laser melting (SLM), test specimens of Titanflex® and Co-Cr alloys were 3D-printed at different angles (0°, 45°, 90°) and compared to conventionally cast Co-Cr samples. Tensile testing was conducted to assess modulus of elasticity (E), proof stress (Rp_0.2), ultimate tensile strength (Rm), elongation parameters (Ag, Agt, At), and maximum load (Fm). Results showed that Titanflex® printed at 45° (Ti45) exhibited the highest Rp_0.2, Rm, and Fm, indicating superior strength and plastic resistance. Ti0 displayed the greatest elongation properties, highlighting titanium’s ductility. Co-Cr alloys demonstrated higher stiffness but lower ductility. Printing orientation significantly influenced mechanical properties, particularly in 3D-printed samples. Overall, Ti45 presented a balanced profile of strength and flexibility, making it a promising candidate for denture bases, while Co-Cr remains a rigid alternative with established clinical use. Future research should explore long-term performance under functional and biological conditions to guide clinical application. Full article

The aim of this laboratory study was to evaluate the fitting accuracy of complete-arch implant-supported fixed dental prostheses (ISFDPs) and the occurrence of possible constraint forces after ISFDP fixation using the All-on-four treatment concept. A titanium model was fabricated with support posts for implants in positions 15, 12, 22, and 25. The forces acting on these posts were assessed using strain gauge half bridges. Implants (BEGO Semados^® SCX Implantat 4.1 mm × 10 mm, BEGO Implant Systems, Bremen, Germany) were fixated on top of the support posts. Based on conventional impressions and intraoral scans, two 12-unit monolithic ISFDPs made from cobalt–chromium alloy (CoCr) and zirconia (ZrO₂) were fabricated, jointed with titanium adhesive abutments (PS TiB NH, BEGO), and successively attached to the model. Constraint forces caused by ISFDP fixation were measured for each implant without external force. After testing four ISFDPs with different materials and impression techniques, four new implants were fixated (n = 10 model situations). A standard linear mixed model was used to assess horizontal and vertical constraint forces. The horizontal constraint forces acting on the implants were oriented in the oral direction, indicating that the ISFDPs were too small. The highest constraint forces were measured on implant 22 in the horizontal and vertical directions. Within the limitations of the present laboratory study, the fitting accuracy of complete-arch CoCr and ZrO₂ ISFDPs based on the All-on-four concept was sufficient for clinical use. Restorations made using conventional impressions had better fitting accuracy and reliability than those made using intraoral scans. Full article

Metal additive manufacturing (AM) techniques, particularly laser powder bed fusion, are being increasingly recognized not as brand-new technologies, but as emerging technologies with their recent advancements—such as the development of optimized alloys, seamless digital workflow integration, and applications in patient-specific prostheses. With the rise in patient-specific approaches in dentistry, clinicians are seeking customized devices that precisely match individual anatomical and functional needs. AM offers various advantages, such as the fabrication of complex geometries directly from digital designs, enhanced clinical precision, reduced material waste, and simplified manufacturing workflow, and hence can uniquely address these demands. Recent advancements in AM techniques have led to the development of titanium and cobalt–chromium alloys with improved mechanical properties, corrosion resistance, and biological compatibility. These alloys show great potential for clinical applications. Additionally, AM enables precise control over the microstructures and surface topographies of these alloys during fabrication, facilitating their optimized integration with biological tissues. This mini review summarizes recent advancements in metal AM technologies relevant to personalized dentistry, highlights key material developments, discusses current clinical applications, and identifies key challenges such as high cost, materials limitations, and regulatory hurdles, and highlights future opportunities including multi-materials AM, smart implants, and AI-driven optimization for fully integrated, digitally driven personalized dental care. Full article