An investigation of the corrosion behavior of zinc-coated stainless steel orthodontic wires: the effect of physical vapor deposition method.

BACKGROUND: Releasing of metal ions might implicate in allergic reaction as a negative subsequent of the corrosion of Stainless Steel (SS304) orthodontic wires. The aim of this study was to evaluate the corrosion resistance of zinc-coated (Zn-coated) SS orthodontic wires. METHODS: Zinc coating was applied on SS wires by PVD method. Electrochemical impedance spectroscopy (EIS), Potentiodynamic polarization tests and Tafel analysis methods were used to predict the corrosion behavior of Zn-coated and uncoated SS wires in both neutral and acidic environments. RESULTS: The values of Ecorr ,icorr and Rct ,which were the electrochemical corrosion characteristics, reported better corrosion behavior of Zn-coated SS wires against uncoated ones in both artificial saliva and fluoride-containing environments. Experimental results of the Tafel plot analyses were consistent with that of electrochemical impedance spectroscopy analyses for both biological solutions. CONCLUSION: Applying Zn coating on bare SS orthodontic wire by PVD method might increase the corrosion resistance of the underlying stainless-steel substrate.

Preload and Removal Torque of Two Different Prosthetic Screw Coatings-A Laboratory Study.

This study aimed to evaluate the effect of two coating materials, a silicone sealing gel and a polytetrafluoroethylene (PTFE) tape, on the screw preload and removal torque value (RTV) to develop strategies to prevent prosthetic screw loosening. We examined 45 complexes comprising an implant, abutment, and prosthetic screw, of which 15 samples were uncoated, 15 were coated with GapSeal® (Hager & Werken GmbH & Co., Duisburg, Germany), and 15 were coated with PTFE tape (MIARCO®, Valencia, Spain). The screws were tightened to register the preload and then untightened to register the RTV. The preload values showed a statistically significant difference only in the PTFE group, suggesting that this lubricant negatively affects the preload. The RTVs showed statistically significant differences among all groups, with the GapSeal® group and PTFE group showing the highest and lowest values, respectively. It can be concluded that the application of the PTFE tape on the screw significantly reduced the preload and RTV. The silicone sealing gel did not affect the preload but increased the RTV. Therefore, the use of GapSeal® should be considered to prevent prosthetic screw loosening, while the use of PTFE tape should be avoided.

The Importance of Chitosan Coatings in Dentistry.

A Chitosan is a copolymer of N-acetyl-D-glucose amine and D-glucose amine that can be easily produced. It is a polymer that is widely utilized to create nanoparticles (NPs) with specific properties for applications in a wide range of human activities. Chitosan is a substance with excellent prospects due to its antibacterial, anti-inflammatory, antifungal, haemostatic, analgesic, mucoadhesive, and osseointegrative qualities, as well as its superior film-forming capacity. Chitosan nanoparticles (NPs) serve a variety of functions in the pharmaceutical and medical fields, including dentistry. According to recent research, chitosan and its derivatives can be embedded in materials for dental adhesives, barrier membranes, bone replacement, tissue regeneration, and antibacterial agents to improve the management of oral diseases. This narrative review aims to discuss the development of chitosan-containing materials for dental and implant engineering applications, as well as the challenges and future potential. For this purpose, the PubMed database (Medline) was utilised to search for publications published less than 10 years ago. The keywords used were "chitosan coating" and "dentistry". After carefully selecting according to these keywords, 23 articles were studied. The review concluded that chitosan is a biocompatible and bioactive material with many benefits in surgery, restorative dentistry, endodontics, prosthetics, orthodontics, and disinfection. Furthermore, despite the fact that it is a highly significant and promising coating, there is still a demand for various types of coatings. Chitosan is a semi-synthetic polysaccharide that has many medical applications because of its antimicrobial properties. This article aims to review the role of chitosan in dental implantology.

An Effective Approach to the Disinfection of Pathogens: Cationic Conjugated Polyelectrolytes and Oligomers.

The synthetic cationic conjugated polyelectrolytes and oligomers have demonstrated great effectiveness and versatility as antimicrobial materials. They have the ability to eliminate or render inactive various pathogens, including viruses like SARS-CoV-2, bacteria, and fungi. These pathogens can be rapidly eradicated when the polyelectrolytes and oligomers are applied as sprays, wipes, or coatings on solid surfaces. Inactivation of the pathogens occurs through two distinct processes: a non-light-activated process similar to Quats, and a more efficient and faster process that is triggered by light. These materials possess fluorescence and photosensitizing properties, enabling prolonged protection when coated on surfaces. The level of fluorescence exhibited by samples applied to nonfluorescent surfaces serves as an indicator of the coating's integrity and viability, making it easily detectable. Importantly, these materials demonstrate low toxicity towards mammalian cells and human skin, allowing for their safe use. While they can serve as durable coatings for pathogen protection, extended exposure to visible or ultraviolet light leads to their photochemical degradation. Our research also suggests that these materials act against pathogens through nonspecific mechanisms, minimizing the likelihood of pathogens developing resistance and rendering the materials ineffective.

Experimental and Numerical Investigation into the Effect of Water Uptake on the Capacitance of an Organic Coating.

Water uptake by organic coating systems used for corrosion prevention on airframes is one of the principal contributors to the loss of barrier properties of the coating. We used equivalent circuit analyses of electrochemical impedance spectroscopy (EIS) data to track changes in coating layer capacitance for a two-layer coating system consisting of an epoxy primer and polyurethane topcoat immersed in NaCl solutions with different concentrations and temperatures. The capacitance curve exhibited two different response regions, consistent with the "two-stage kinetics" mechanisms for water uptake by the polymers. We tested several numerical diffusion models of water sorption and found the most successful to be one that varied the diffusion coefficient as a function of polymer type and immersion time and accounted for physical aging processes in the polymer. We employed the Brasher mixing law along with the water sorption model to estimate the coating capacitance as a function of water uptake. The predicted capacitance of the coating was found to be consistent with the capacitance obtained from the EIS data, which is consistent with theories that water uptake occurs via initial rapid transport followed by a much slower aging process. Thus, both these water uptake processes need to be considered when making EIS measurements to assess the state of a coating system.

Functional Surface Coatings on Orthodontic Appliances: Reviews of Friction Reduction, Antibacterial Properties, and Corrosion Resistance.

Surface coating technology is an important way to improve the properties of orthodontic appliances, allowing for reduced friction, antibacterial properties, and enhanced corrosion resistance. It improves treatment efficiency, reduces side effects, and increases the safety and durability of orthodontic appliances. Existing functional coatings are prepared with suitable additional layers on the surface of the substrate to achieve the abovementioned modifications, and commonly used materials mainly include metal and metallic compound materials, carbon-based materials, polymers, and bioactive materials. In addition to single-use materials, metal-metal or metal-nonmetal materials can be combined. Methods of coating preparation include, but are not limited to, physical vapor deposition (PVD), chemical deposition, sol-gel dip coating, etc., with a variety of different conditions for preparing the coatings. In the reviewed studies, a wide variety of surface coatings were found to be effective. However, the present coating materials have not yet achieved a perfect combination of these three functions, and their safety and durability need further verification. This paper reviews and summarizes the effectiveness, advantages and disadvantages, and clinical perspectives of different coating materials for orthodontic appliances in terms of friction reduction, antibacterial properties, and enhanced corrosion resistance, and discusses more possibilities for follow-up studies as well as for clinical applications in detail.

Effect of Silicon Carbide Coating on Osteoblast Mineralization of Anodized Titanium Surfaces.

The objective of this study was to evaluate the influence of the titanium nanotube diameter and the effect of silicon carbide (SiC) coating on the proliferation and mineralization of pre-osteoblasts on titanium nanostructured surfaces. Anodized titanium sheets with nanotube diameters of 50 and 100 nm were used. The following four groups were tested in the study: (1) non-coated 50 nm nanotubes; (2) SiC-coated 50 nm titanium nanotubes; (3) non-coated 100 nm nanotubes and (4) SiC-coated 100 nm nanotubes. The biocompatibility and cytotoxicity of pre-osteoblasts were evaluated using a CellTiter-BlueCell Viability assay after 1, 2, and 3 days. After 3 days, cells attached to the surface were observed by SEM. Pre-osteoblast mineralization was determined using Alizarin-Red staining solution after 21 days of cultivation. Data were analyzed by a Kruskal−Wallis test at a p-value of 0.05. The results evidenced biocompatibility and non-cytotoxicity of both 50 and 100 nm diameter coated and non-coated surfaces after 1, 2 and 3 days. The statistical analysis indicates a statistically significant higher cell growth at 3 days (p < 0.05). SEM images after 3 days demonstrated flattened-shaped cells without any noticeable difference in the phenotypes between different diameters or surface treatments. After 21 days of induced osteogenic differentiation, the statistical analysis indicates significantly higher osteoblast calcification on coated groups of both diameters when compared with non-coated groups (p < 0.05). Based on these results, we can conclude that the titanium nanotube diameter did not play any role on cell viability or mineralization of pre-osteoblasts on SiC-coated or non-coated titanium nanotube sheets. The SiC coating demonstrated biocompatibility and non-cytotoxicity and contributed to an increase in osteoblast mineralization on titanium nanostructured surfaces when compared to non-coated groups.

The Influence of rhBMP-7 Associated with Nanometric Hydroxyapatite Coatings Titanium Implant on the Osseointegration: A Pre-Clinical Study.

Background: Bioceramic nanometer coatings have been regarded as potential substitutes for plasma-sprayed hydroxyapatite coatings, and the association with bone morphogenetic protein (BMP) is an attempt to achieve faster osseointegration to hasten oral rehabilitation. Objective: This study aimed to investigate the effect of recombinant human bone morphogenetic protein-7 (rhBMP-7) on the osseointegration of titanium implants coated with a thin film surface of hydroxyapatite (HA). Methods: Two implants (n = 24) were placed in each white New Zealand rabbits' femur (n = 6). Implants were placed in the right femur after standard instrumentation (A and B) and in the left femur after an over-instrumentation (C and D), preventing bone-implant contact. The distal implants were installed associated with rhBMP-7 (groups B [regular instrumentation] and D [over-instrumentation]) and, also, in the absence of without BMP (control groups A [regular instrumentation] and C [over-instrumentation]). After 4 weeks, the animals were euthanized. The bone blocks containing the implants were embedded in methyl methacrylate and sectioned parallel to the long axis of the implant, which were analyzed by image segmentation. The data were analyzed using a nonparametric statistical method. Results: We observed that Group A had a mean bone formation of 35.6% compared to Group B, which had 48.6% (p > 0.05). Moreover, this group showed 28.3% of connective tissue compared to Group A, with 39.3%. In the over-instrumented groups, rhBMP-7 (Group D) showed an enhanced and significant increase in bone formation when compared with the group without rhBMP-7 (Group C). Conclusion: We concluded that the association of rhBMP-7 to thin nanostructure HA-coated implants promoted greater new bone area than the same implants in the absence of rhBMP-7, mainly in cases of over-instrumented implant sites.

Influence of Titanium Surface Treatments on Viability of Periodontal Fibroblasts Grown in an Osteogenic Culture Medium.

Background: The integrity of the protective seal provided by the gingiva in direct contact with the implant surface is one of the main factors involved in the prevention of peri-implantitis. Aim: The aim of this study was to assess the viability of periodontal fibroblasts grown in an osteogenic culture medium in contact with titanium surfaces treated either with acid etching alone or with acid etching + anodizing. Materials and Methods: Periodontal fibroblasts grown in an osteogenic culture medium were distributed in a control group, with cells grown in culture bottles, and two experimental groups, with cells grown in contact with titanium disks measuring 6 mm in diameter. The surface of the disks was subjected to acid etching alone (AEG, n = 25) or to acid etching + anodizing (ANG, n = 25), and then evaluated using scanning electron microscopy (SEM). Cell viability was assessed by the [3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium] bromide test on days 1, 2, 3, 7, and 14 of the cell culture. The Mann-Whitney test was used for the statistical analysis (P < 0.05). Results: The SEM assessment revealed that the surface of AEG specimens had micrometric characteristics, whereas the surface of ANG specimens had nanometric characteristics. No significant difference was observed among the groups regarding cell viability at any of the evaluation time points. Conclusion: The titanium surface treatments tested did not affect the viability of periodontal fibroblasts in an osteogenic culture medium.

Evaluation of carbon nanotubes-hydroxyapatite nanocomposites as bioactive implant coats radiated by near infrared laser.

This study aimed to evaluate carbon nanotubes-hydroxyapatite nanocomposites as bioactive titanium implant coats and to assess the effect of near-infrared radiation on these nanocomposites. Carbon nanotubes were acid-functionalized, and hydroxyapatite was prepared by the wet-chemical precipitation method. Both precursors were used to prepare the carbon nanotubes-hydroxyapatite nanocomposites in two concentrations of hydroxyapatite (0.5 and 1 wt.%). The formed nanocomposites were characterized and used to coat silanized titanium discs and cylinders. Half the specimens of each group were radiated by near-infrared laser, then wettability and shear bond strength were tested for all specimens. Bioactivity was tested by monitoring the formation of calcium phosphate compounds after soaking in simulated body fluid. A significant increase in wettability and bond strength was found in the radiated coats compared to the non-radiated ones with the 1% hydroxyapatite group showing the highest values followed by 0.5% hydroxyapatite then the carbon nanotubes group. The two-way ANOVA test showed that both the difference in material and the laser treatment have had a statistically significant contribution to the increase in wettability and bond strength. The radiated groups also contributed to the formation of more calcium phosphate crystals of larger sizes and higher degrees of crystallinity.

Biochemical Modification of Titanium Oral Implants: Evidence from In Vivo Studies.

The discovery of osseointegration of titanium implants revolutionized the dental prosthesis field. Traditionally, implants have a surface that is processed by additive or subtractive techniques, which have positive effects on the osseointegration process by altering the topography. In the last decade, innovative implant surfaces have been developed, on which biologically active molecules have been immobilized with the aim of increasing stimulation at the implant-biological tissue interface, thus favoring the quality of osseointegration. Among these molecules, some are normally present in the human body, and the techniques for the immobilization of these molecules on the implant surface have been called Biochemical Modification of Titanium Surfaces (BMTiS). Different techniques have been described in order to immobilize those biomolecules on titanium implant surfaces. The aim of the present paper is to present evidence, available from in vivo studies, about the effects of biochemical modification of titanium oral implants on osseointegration.

Peptide-mediated surface coatings for the release of wound-healing cytokines.

Supporting the wound healing process by sending the appropriate cytokine signals can shorten healing time and overcome chronic inflammation syndromes. Even though adhesion peptides consisting of Arg-Gly-Asp (RGD) are commonly used to enhance cell-surface interactions, peptide-mediated cytokine delivery has not been widely exploited so far. Cytokines interact with high affinity with their cognitive receptors but also with sulfated glycosaminoglycans (GAGs), both of which form a base for incorporation of cytokines into functional biomaterials. Here, we report on a mussel-derived surface coating as a prospective cytokine delivery system using covalently bound heparin mimetics, receptor-derived chemokine-binding peptides, and heparin-binding peptides (HBP). The latter enabled non-covalent immobilization of heparin on the surface followed by chemokine binding and release, whereas the former allowed direct non-covalent chemokine immobilization. The peptide displayed excellent binding to custom-made polystyrene 96-well plates, enabling convenient testing of several compounds. Released chemokine successfully induced migration in Jurkat cells, especially for the non-covalent heparin immobilization approach using HBPs as evaluated in a transwell assay. In comparison, heparin-mimetic coatings, comprised of sulfated peptides and GAG derivatives, proved less efficient with respect to amount of immobilized chemokine and migratory response. Thus, our study provides a roadmap for further rational optimization and translation into clinics.

Intramedullary implants coated with cubic boron nitride enhance bone fracture healing in a rat model.

BACKGROUND: Boron nitride is a biocompatible and an osteo-inductive material for orthopedic applications. The aim of this study was to evaluate the effects of two different allotrope boron nitride coated implants, cubic boron nitride and hexagonal boron nitride, on fracture healing. METHODS: In this experimental study, a total of 24 rats were divided into three groups. Group A was the control group with Kirschner wire without coating, while the wires were coated dominantly by cubic boron nitride in Group B and hexagonal boron nitride in Group C. Then a mid-third femoral fracture was created. The fracture healing was examined in terms of new bone formation with micro-CT analysis and histopathological examination, quantitative measurement of bone turnover metabolites and scintigraphic examination of osteoblastic activity on 28th day post fracture. RESULTS: Micro-CT measurement results revealed a statistically significant increase in bone volume/tissue volume ratio and bone surface values in group B compared to group A. Cortex diameter and osteoblast counts were statistically higher in group B compared to group A. Inflammatory response was increased in group C compared to groups A and B. Biochemical test results showed significantly increased alkaline phosphatase levels and decreased osteocalcin levels in group B compared to group A. The increase in serum phosphorus and decrease in serum calcium levels was statistically significant in group C compared to Group A. CONCLUSION: Both types of boron nitride coating had superior fracture healing features compared to control group. Therefore, c-BN coating can accelerate the fracture healing and could lead to shorten of union time.

Manganese dioxide coating reduces bacterial adhesion and infection in silicon implants in animal model.

PURPOSE: To propose a new coating to silicone implants using Manganese dioxide. We present bacterial adhesion and proliferation when implants are challenged with Escherichia coli. METHODS: Coated and control silicon implants were placed in two independent subcutaneous pouches in the dorsum of Wistar rats. After skin closure, 0.5 ml of E. coli solution was injected in each incision. The animals were euthanized at 7 and 28 days. Extracted material was cultured and analyzed by confocal microscopy. RESULTS: At 1 week, uncoated implants had a 17-fold higher infection rate (p < 0.001). Coated samples showed a mean bacterial count of 28,700 CFU/ml, while the control ones 503,000 CFU/ml, with a significant mean difference of 474,300 CFU/ml (95% CI 165,900-782,600). At 4 weeks, the mean bacterial growth in coated group was 7600; while in control one was 53,890. The mean difference between groups was 46,200 (95% CI 21,100-71,400). Confocal microscopy presented the percentage of implant's surface with attached bacteria: at 7 days, coated implants had 6.85% and controls 10.9% and the difference was not significant (p =0.32). At 4 weeks, the coated group showed 0.98% of the surface with attached bacteria, while control group showed 7.64%, which resulted in a significant 11-fold difference (p = 0.004). CONCLUSIONS: Manganese dioxide coating inhibits bacterial proliferation and adhesion in subcutaneous silicon implants in an animal model. These findings can be useful to improve development of biomaterials.

Bioactive characteristics of an implant surface coated with a pH buffering agent: an in vitro study.

PURPOSE: The purpose of this study was to evaluate the effectiveness of conventional sandblasted, large-grit, acid-etched (SLA) surface coated with a pH buffering solution based on surface wettability, blood protein adhesion, osteoblast affinity, and platelet adhesion and activation. METHODS: Titanium discs and implants with conventional SLA surface (SA), SLA surface in an aqueous calcium chloride solution (CA), and SLA surface with a pH buffering agent (SOI) were prepared. The wetting velocity was measured by the number of threads wetted by blood over an interval of time. Serum albumin adsorption was tested using the bicinchoninic acid assay and by measuring fluorescence intensity. Osteoblast activity assays (osteoblast adhesion, proliferation, differentiation, mineralization, and migration) were also performed, and platelet adhesion and activation assays were conducted. RESULTS: In both the wetting velocity test and the serum albumin adsorption assay, the SOI surface displayed a significantly higher wetting velocity than the SA surface (P=0.000 and P=0.000, respectively). In the osteoblast adhesion, proliferation, differentiation, and mineralization tests, the mean values for SOI were all higher than those for SA and CA. On the osteoblast migration, platelet adhesion, and activation tests, SOI also showed significantly higher values than SA (P=0.040, P=0.000, and P=0.000, respectively). CONCLUSIONS: SOI exhibited higher hydrophilicity and affinity for proteins, cells, and platelets than SA. Within the limits of this study, it may be concluded that coating an implant with a pH buffering agent can induce the attachment of platelets, proteins, and cells to the implant surface. Further studies should be conducted to directly compare SOI with other conventional surfaces with regard to its safety and effectiveness in clinical settings.

Influence of zirconia-coated bioactive glass on gingival fibroblast behavior

Abstract The objective of this study was the development of a bioactive glass coating on zirconia (Zr) to modulate the gingival fibroblast phenotype. For this purpose, Biosilicate® (BS) particles in a water/isopropyl alcohol (1:1) vehicle (6 mg/mL) were applied to zirconia discs followed by thermal treatment at 1100 °C for 20 min. The surface topography (SEM), chemical composition (EDX), surface roughness (Ra; confocal microscopy), surface free energy (goniometry), and color alteration (UV-vis spectrophotometry) were assessed (n=6). Thereafter, L929 fibroblasts were seeded onto Zr and Zr+BS discs, and cell proliferation (Alamar Blue; n=6), morphology (SEM; n=2), migration (wound healing; n=4), and collagen synthesis (Sirius Red; n=6) were evaluated up to 7 days. Data were analyzed by ANOVA/Tukey tests (a=5%). A homogeneous coating consisting of Si, Na, O, and Ca was detected on the Zr surface after thermal treatment with BS, which led to a significant increase in surface roughness and free energy (p<0.05). No change in color parameters was observed (p>0.05). Cells seeded on the Zr+BS surface featured increased proliferation, collagen expression, and migration capability in comparison with those cultured on plain Zr (p<0.05). SEM images revealed that cell spreading occurred faster in the presence of BS. Therefore, it was concluded that thermal treatment of the Zr surface with BS led to the deposition of a bioactive coating, which induced gingival fibroblast spread, proliferation, migration, and collagen expression in vitro.

Resumo O objetivo deste estudo foi o desenvolvimento de um recobrimento de vidro bioativo sobre a zircônia (Zr) para modular o fenótipo de fibroblastos gengivais. Para este propósito, partículas de Biosilicato® (6 mg/mL) em um veículo a base de água/álcool isopropílico (1:1) foram aplicadas sobre discos de zircônia seguido por tratamento térmico a 1100 °C por 20 min. A topografia de superfície (MEV), composição química (EDX), rugosidade de supefície (Ra; microscopia confocal), energia livre de superfície (goniômetro) e alteração de cor (Espectrofotometria UV-vis) foram avaliadas (n=6). A seguir, fibroblastos L929 foram semeados sobre discos de Zr e BS+Zr e a proliferação (Alamar Blue; n=6), morfologia (MEV; n=2), migração celular (wound healing; n=4) e a síntese de colágeno (Sirius Red; n=6) foram avaliados até 7 dias. Os dados foram analisados pelos testes ANOVA/Tukey (a=5%). Um recobrimento homogêneo consistindo de Si, Na, O e Ca foi detectado na superfície da Zr após o tratamento térmico com BS, o qual promoveu um aumento significante na rugosidade e energia livre de superfície (p<0,05). Nenhuma mudança nos parâmetros de cor foi observada (p>0,05). Células semeadas na superfície de Zr+BS apresentaram maior proliferação, expressão de colágeno e capacidade de migração em comparação com aquelas cultivadas sobre a superfície de Zr (p<0,05). Imagens de MEV revelaram que o espalhamento celular ocorreu mais rápido na presença de BS. Assim, conclui-se que o tratamento térmico da superfície da Zr com BS levou a deposição de um recobrimento bioativo, o qual induziu in vitro o espalhamento, proliferação e migração de fibroblastos gengivais e expressão de colágeno.

Safety and efficacy of a novel, gradually anodized dental implant surface: A study in Yucatan mini pigs.

BACKGROUND: A newly developed dental implant system combining advancements in surface chemistry, topography, nanostructure, color, and surface energy aims to address biological challenges and expand clinical applications. PURPOSE: To assess the short- and long-term safety and efficacy of a novel, gradually anodized dental implant surface/anodized abutment. MATERIALS AND METHODS: Twenty-four Yucatan mini pigs (20-24 months old) received two dental implants in each jaw quadrant. Each site was randomized to receive either a commercially available anodized implant/machined abutment or a gradually anodized implant/anodized abutment with a protective layer. Animals were euthanized at 3, 6, and 13 weeks. Microcomputed tomography and histological analyses were performed. RESULTS: No significant histological differences in inflammation scores, epithelium length, bone-to-implant contact, or bone density were observed between groups for any healing time. Mucosal height was significantly higher at 3 weeks for controls (Δ = 0.2 mm); no differences were observed at 6 and 13 weeks. No significant differences in radiographic bone volume, bone-to-implant contact, trabecular thickness, and crestal bone levels were observed, irrespective of healing time. Trabecular spacing was borderline significant at 3 weeks in favor of the test implant sites; no differences were observed at 6 weeks. No significant differences were observed between experimental groups at 13 weeks. CONCLUSIONS: The new implant system yielded results comparable to a commercially available predicate device.

Bioactive characteristics of an implant surface coated with a pH buffering agent: an in vitro study

PURPOSE: The purpose of this study was to evaluate the effectiveness of conventional sandblasted, large-grit, acid-etched (SLA) surface coated with a pH buffering solution based on surface wettability, blood protein adhesion, osteoblast affinity, and platelet adhesion and activation.METHODS: Titanium discs and implants with conventional SLA surface (SA), SLA surface in an aqueous calcium chloride solution (CA), and SLA surface with a pH buffering agent (SOI) were prepared. The wetting velocity was measured by the number of threads wetted by blood over an interval of time. Serum albumin adsorption was tested using the bicinchoninic acid assay and by measuring fluorescence intensity. Osteoblast activity assays (osteoblast adhesion, proliferation, differentiation, mineralization, and migration) were also performed, and platelet adhesion and activation assays were conducted.RESULTS: In both the wetting velocity test and the serum albumin adsorption assay, the SOI surface displayed a significantly higher wetting velocity than the SA surface (P=0.000 and P=0.000, respectively). In the osteoblast adhesion, proliferation, differentiation, and mineralization tests, the mean values for SOI were all higher than those for SA and CA. On the osteoblast migration, platelet adhesion, and activation tests, SOI also showed significantly higher values than SA (P=0.040, P=0.000, and P=0.000, respectively).CONCLUSIONS: SOI exhibited higher hydrophilicity and affinity for proteins, cells, and platelets than SA. Within the limits of this study, it may be concluded that coating an implant with a pH buffering agent can induce the attachment of platelets, proteins, and cells to the implant surface. Further studies should be conducted to directly compare SOI with other conventional surfaces with regard to its safety and effectiveness in clinical settings.

Midterm Results of Cementless Total Knee Arthroplasty: A Retrospective Case Series.

BACKGROUND: There is an ongoing debate about whether to use cementless or cemented fixation for Total Knee Arthroplasty (TKA). OBJECTIVE: The study aimed to assess midterm survivorship of the Vanguard cementless system, and to demonstrate the utility of the Bone Hardness Test (BHT) for the selection of cementless fixation TKA. METHODS: From September 2009 through November 2014, 123 total knee arthroplasties were completed, with cementless Vanguard Cruciate Retaining TKA in 110 knees (102 patients) and cemented Vanguard in 13 cases (12 patients). Implant fixation was based on intraoperative assessment of posterior cruciate ligament stability, bone quality, and BHT. All patients with a cementless Vanguard implant were eligible for this retrospective study. Preoperative and postoperative Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index were obtained. Standardized standing anteroposterior and lateral radiographs were taken. RESULTS: Three patients (4 TKAs) were lost to follow-up. The mean follow-up time was 5.5 ± 1.4 years. All scores significantly improved postoperatively. No radiographic failures were observed. Five-year implant survival, with revision of any component for any reason as an endpoint, was 97.2% (95% confidence interval, 91.7 - 99.1%). Five-year survival with revision for aseptic loosening was 100%. Only one knee required revision due to an isolated unrelated bearing exchange, and two additional knees required secondary resurfacing of the patella for retropatellar pain. CONCLUSION: Good midterm results were obtained with the cementless Vanguard Cruciate Retaining TKA for the treatment of osteoarthritis. The Bone Hardness Test appears to be an effective way to determine the selection of cementless TKA.

Micropatterned Silica Films with Nanohydroxyapatite for Y-TZP Implants.

This investigation aimed at developing micropatterned silica thin films (MSTFs) containing nanohydroxyapatite (nano-HA) microaggregates that were not completely covered by silica so that they could directly interact with the surrounding cells. The objectives were 1) to evaluate the effect of the presence of 2 films (MSTF with or without nano-HA addition) on the characteristic strength (σ0) and Weibull modulus ( m) of a yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and 2) to evaluate the effect of these 2 films, as applied onto the Y-TZP surface, on the morphology, orientation, and proliferation of MG63 cells. Sol-gel process and soft lithography were used to apply the MSTF onto the Y-TZP specimens. Three experimental groups were produced: Y-TZP, Y-TZP + MSTF, and Y-TZP + MSTF + sprayed nano-HA. All surfaces were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy and tested for 4-point flexural strength ( n = 30) in water at 37 °C. Weibull analysis was used to determine m and σ0 (maximum likelihood method). In vitro biological behavior was performed with human osteoblast-like cells (MG63). Y-TZP was successfully coated with MSFT and MSFT + nano-HA. Scanning electron microscopy micrographs indicated that the microaggregates of nano-HA were not entirely covered by the silica. There was no statistically significant difference among the experimental groups for σ0 and m. In the groups containing the films, the cells were elongated and aligned along the lines. The MSFT + nano-HA group showed significantly higher cell metabolic activity than that obtained for the Y-TZP group at day 7. This investigation was successful in producing an MSTF containing nano-HA microaggregates that remained exposed to the environment. The developed films did not jeopardize the structural reliability of a commercial Y-TZP, as confirmed by the Weibull statistics. The MG63 cells seeded over the films became elongated and aligned along the films' micropatterned lines. Y-TZP specimens coated with MSTF and nano-HA showed a higher cell metabolic activity and proliferation after 7 d of culture when compared with uncoated Y-TZP.