Bending properties of additively manufactured commercially pure titanium (CPTi) limited contact dynamic compression plate (LC-DCP) constructs: Effect of surface treatment.

Additive manufacturing of metallic materials, a layer-wise manufacturing method, is currently gaining attention in the biomedical industry because of its capability to fabricate complex geometries including customized parts fitting to patient requirements. However, one of the major challenges hindering the full implementation of additively manufactured parts in safety-critical applications is their poor mechanical performance under cyclic loading. This study investigated both quasi-static bending properties (bending stiffness, bending structural stiffness, and bending strength) and bending fatigue properties of additively manufactured (AM) commercially pure titanium (CPTi) limited contact dynamic compression plate (LC-DCP) constructs based on ASTM International standard for metallic bone plates (ASTM F382). In addition, the effect of post surface treatment methods including single shot-peened (SP), dual shot-peened (DP), and chemically assisted surface enhancement (CASE) on bending fatigue performance was also evaluated. Results indicated that bending stiffness and bending structural stiffness of AM CPTi LC-DCPs are comparable to conventionally manufactured (CM) counterparts; however, the bending strength of AM CPTi LC-DCPs is lower than CM counterparts. While the fatigue strength of as-built AM CPTi LC-DCPs is lower compared to the CM counterparts, AM CPTi LC-DCPs after post surface treatments (SP, DP, and CASE) exhibit statistically comparable fatigue strength to the CM CPTi LC-DCPs.

Some Slippage Issues in High-Pressure Torsion Using Cu and Ti Samples as an Example.

The effect of slippage during High Pressure Torsion (HPT) of technically pure Ti and pure Cu samples was investigated. The "joint torsion of the disk halves" method was used to evaluate the effect of slippage. It was shown that slippage starts already at the early stages of HPT. With a further increase in the number of revolutions n, the slippage effect increases, and no torsional deformation occurs after n = 5. The slippage effect is explained by analyzing the surface friction forces between the sample and the anvil. However, studies via TEM and XRD have shown that the structure of Ti samples after HPT at the investigated conditions is grinded to a nanocrystalline state. A structure is formed in Ti similar to that observed after HPT by other authors. The dislocation density increases with increasing HPT degree from n = 5 to n = 10 revolutions, despite slippage. Consequently, despite slippage at HPT at n ≥ 5, deformation still occurs. The following assumptions are made to explain the accumulated strain in the sample at HPT. It is assumed that the planes of the upper and lower anvil during HPT are at a slight inclination relative to each other. Computer modeling using the Deform 3D software package has shown that this leads to the accumulations of significant strain during HPT.

Johnson-Cook Parameter Identification for Commercially Pure Titanium at Room Temperature under Quasi-Static Strain Rates.

BACKGROUND: To simulate mechanical shocks on an intracranial implant called WIMAGINE®, Clinatec chose a Johnson-Cook model to account for the viscoplastic behavior of grade 2 titanium in a dynamic study using Radioss©. METHODS: Thirty tensile specimens were subjected to tensile tests at room temperature, and the influence of the strain rate (8 × 10-3 and 8 × 10-2 s-1) and sandblasting was analyzed. Relaxations were included in the tests to analyze viscosity phenomena. RESULTS: A whole set of parameters was identified for the elastic and plastic parts. Strain rate influence on stress was negligible at these strain rates. As expected, the sandblasting hardened the material during the tests by decreasing the hardening parameters, while local necking occurred at an earlier strain. CONCLUSIONS: This article provides the parameters of a Johnson-Cook model to simulate the elastoplastic behavior of pure titanium (T40, grade 2) in Finite Element Model (FEM) software.

Sub-nano to nanometer wear and tribocorrosion of titanium oxide-metal surfaces by in situ atomic force microscopy.

Wear and tribocorrosion of passive oxide film covered metals have been studied at the micro and macroscopic scales. Recent advances in nanotechnology have contributed to breakthroughs in understanding of fundamental friction and wear mechanisms of atomically thin 2D materials at the nanoscale. However, for metals and materials without ultra-flat surfaces, a gap in knowledge exists at or below a few nanometers, which is too small for continuum mechanics theories and experiments including conventional atomic force microscopy (AFM) methods, due to resolution limits arising from surface roughness. Here, we report the near-atomic-scale wear of titanium in air and physiological solution from a single atomic layer to beyond the full oxide thickness using an AFM-based tribology method. Sub-nano to nanometer wear of titanium was revealed with different stages of contact pressure dependent wear regions identified as wear depth increased, featured by a transition from atomic wear (below 2.4 GPa) to elasto-plastic driven wear (above 3.6 GPa) at its oxide thickness (3.8 nm) in air. Higher stress was required to generate a similar wear penetration process in PBS compared to air. Tribocorrosion at this scale was grain orientation and voltage-dependent. Our study opens up a new method to achieve reliable angstrom-level resolution wear quantification to advance the understanding of wear and tribocorrosion of metals at the nanoscale. STATEMENT OF SIGNIFICANCE: Experimental tests of wear for metallic biomaterials at the nanoscale are difficult because engineered metal surfacesare never perfectly atomically flat, limiting the resolution of precise wear measurements to a few nanometers scale or more. To systematically address this problem, we have introduced the AFM 'image-wear-image' tribology method and obtained quantitative stress dependent measurement of the near-atomic-scale wear of titanium surfaces in air and tribocorrosion in physiological solution from a single atomic layer to beyond the full oxide film thickness. This allowedto measure sub-nano scale wear by partial removal of oxide. Nanoscale wear has been found to be grain orientation-dependent above the 'atomic scale' wear region. The nano-tribocorrosion of CP-Ti across scales and voltage effects on oxides in physiological solution was studied. Our study opens up a new method for future studies to advance the understanding of sub-nanoscale and nanoscale wear and tribocorrosion phenomenon as well as oxide growth mechanism of metallic biomaterials.

Characterization of Optimized TiO2 Nanotubes Morphology for Medical Implants: Biological Activity and Corrosion Resistance.

BACKGROUND: Nanostructured surface modifications of Ti-based biomaterials are moving up from a highly-promising to a successfully-implemented approach to developing safe and reliable implants. METHODS: The study's main objective is to help consolidate the knowledge and identify the more suitable experimental strategies related to TiO2 nanotubes-modified surfaces. In this sense, it proposes the thorough investigation of two optimized nanotubes morphologies in terms of their biological activity (cell cytotoxicity, alkaline phosphatase activity, alizarin red mineralization test, and cellular adhesion) and their electrochemical behavior in simulated body fluid (SBF) electrolyte. Layers of small-short and large-long nanotubes were prepared and investigated in their amorphous and crystallized states and compared to non-anodized samples. RESULTS: Results show that much more than the surface area development associated with the nanotubes' growth; it is the heat treatment-induced change from amorphous to crystalline anatase-rutile structures that ensure enhanced biological activity coupled to high corrosion resistance. CONCLUSION: Compared to both non-anodized and amorphous nanotubes layers, the crystallized nano-structures' outstanding bioactivity was related to the remarkable increase in their hydrophilic behavior, while the enhanced electrochemical stability was ascribed to the thickening of the dense rutile barrier layer at the Ti surface beneath the nanotubes.

Fatigue of Narrow Dental Implants: Influence of the Hardening Method.

The use of narrow titanium dental implants (NDI) for small ridges, reduced interdental space, or missing lateral incisors can be a viable option when compared to the conventional wider dental implants. Furthermore, in many cases, standard diameter implant placement may not be possible without grafting procedures, which increases the healing time, cost, and morbidity. The aim of this study was to analyze the mechanical viability of the current narrow implants and how narrow implants can be improved. Different commercially available implants (n = 150) were tested to determine maximum strength, strain to fracture, microhardness, residual stress, and fatigue obtaining the stress-number of cycles to fracture (SN) curve. Fractography was studied by scanning electron microscopy. The results showed that when the titanium was hardened by the addition of 15% of Zr or 12% cold worked, the fatigue limit was higher than the commercially pure grade 4 Ti without hardening treatment. Grade 4 titanium without hardening treatment in narrow dental implants can present fractures by fatigue. These narrow implants are subjected to high mechanical stresses and the mechanical properties of titanium do not meet the minimal requirements, which lead to frequent fractures. New hardening treatments allow for the mechanical limitations of conventional narrow implants to be overcome in dynamic conditions. These hardening treatments allow for the design of narrow dental implants with enhanced fatigue life and long-term behavior.

Effect of different firing atmospheres on debonding strength of dental porcelain fused to commercially pure titanium.

An in vitro investigation was performed to evaluate the bonding characteristics of porcelain fused to metal (PFM)/commercially pure titanium (cp Ti, grade II) in three firing atmospheres of under vacuum and using two noble gases argon (Ar) and helium (He). Three groups of porcelain veneers firing under vacuum, Ar, and He were prepared to evaluate the bonding of porcelain fused to the cold-rolled cp Ti. The bond strength of PFM durability by a three-point bending test, phases, microhardness of cp Ti after firing processes, and fractures were measured and evaluated. Results show the microhardness of cp Ti in group of porcelain firing under He atmosphere was significantly lower than that of the two other groups, which were in vacuum and Ar (P < .05). X-ray diffraction showed the He group produced in relatively small amounts of TiO2 and TiO oxides than other groups but featured relatively high quantity of airhole defects in the porcelain body leading to the lowest bond strength. The Ar group presented the highest bond strength of comparing with the groups under vacuum and using He (P < .05). Although the firing processes in He could efficiently prevent the diffusion of oxygen into Ti, the porcelain-cp Ti bond strength using Ar protective atmosphere presented the advantage to achieve clinical requirement because porcelain firing under He revealed prominent voids and defects within the body of porcelain.

Osteointegrative and microgeometric comparison between micro-blasted and alumina blasting/acid etching on grade II and V titanium alloys (Ti-6Al-4V).

This study evaluated the effect of alumina-blasted/acid-etched (AB/AE) or microabrasive blasting (C3-Microblasted) surface treatment on the osseointegration of commercially-pure Ti (grade II) and Ti-6Al-4V alloy (grade V) implants compared to as-machined surfaces. Surface characterization was performed by scanning electron microscopy and optical interferometry (IFM) to determine roughness parameters (Sa and Sq, n = 3 per group). One-hundred forty-four implants were placed in the radii of 12 beagle dogs, for histological (n = 72, bone-to-implant contact - BIC and bone-area-fraction occupancy -BAFO) and torque to interface failure test at 3 and 6 weeks (n = 72). SEM and IFM revealed a significant increase in surface texture for AB/AE and C3-Microblasted surfaces compared to machined surface, regardless of titanium substrate. Torque-to-interface failure test showed significant increase in values from as-machined to AB/AE and to C3-Microblasted. Considering time in vivo, alloy grade, and surface treatment, the C3-microblasted presented higher mean BIC values relative to AB/AE and machined surfaces for both alloy types. BAFO levels were significantly higher for both textured surfaces groups relative to the machined group at 3 weeks, but differences were not significant between the three surfaces for each alloy type at 6 weeks. Surface treatment resulted in roughness that improved osseointegration in Grade II and V titanium substrates.

The Effect of Potential on Surface Characteristic and Corrosion Resistance of Anodic Oxide Film Formed on Commercial Pure Titanium at the Potentiodynamic-Aging Mode.

Anodic oxidation treatment of commercially pure titanium was carried out at the voltages of 10, 30, 50 V in 0.5 M H2SO4 solution at the potentiodynamic-aging mode so as to obtain the effects of the anodic potential on the surface characteristic and corrosion resistance of the anodic oxide film. The influences of potential on the surface morphology, the roughness, the crystalline behavior, the chemical composition and the corrosion resistance of the anodic oxide films were investigated by using scanning electron microscopy (SEM), atomic force microscope (AFM), Raman spectrum, X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization curves and electrode impedance spectroscopy (EIS). The results show that increasing anodic potential at the potentiodynamic-aging mode can significantly enhance thickness, flatness, crystallization, chemical stability, and corrosion resistance of anodic oxide film.

Effects of polycaprolactone on alendronate drug release from Mg-doped hydroxyapatite coating on titanium.

The scientific objective of this study was to understand the influence of PCL coating on alendronate drug release kinetics in vitro. Our hypothesis was PCL coating would minimize burst release of alendronate from plasma sprayed Mg-doped hydroxyapatite (HA) coated commercially pure titanium (CpTi) samples. In the US alone, over 44 million women and men aged 50 and older are affected by osteoporosis which can lead to replacement and/or revision surgeries. Alendronate is a widely-used drug for treating osteoporosis and would be an ideal drug to be loaded and released from these replacement systems. Initial burst release is a common phenomenon for the most drug loaded devices. To modulate the release kinetics, a biodegradable polymer, polycaprolactone (PCL), coating with slow degradable kinetics was employed. Samples with 2 and 4 wt% PCL showed about 34% and 26% release of alendronate within the first 24 h, respectively, compared to 75% burst release without any PCL coating. With the addition of a PCL coating, a controlled release kinetics of alendronate was achieved from HA coated titanium implants, which can potentially impact millions of patients worldwide having compromised bone due to osteoporosis.

Influence of grade and surface topography of commercially pure titanium on fatigue properties.

The objective was to investigate the influence of grade and surface topography of commercially pure titanium (Cp-Ti) on fatigue properties evaluated via staircase method. Cp-Ti grades 2 and 4 were roughened by shot blasting and acid etching, and compared with machined specimens. Yield force under static loading for Cp-Ti grades 2 and 4 were 672±51 and 1,088±93 N for machined and 724±99 and 1,118±96 N for roughened group. Yield force under cyclic loading for Cp-Ti grades 2 and 4 decreased 27 and 40% compared to static loading. Cp-Ti grade 4 demonstrated significantly greater decrease in yield force after cyclic loading; however surface topography had no effect.

In vitro and in vivo studies of ultrafine-grain Ti as dental implant material processed by ECAP.

The aim of this study was to investigate the surface characterization of ultrafine-grain pure titanium (UFG-Ti) after sandblasting and acid-etching (SLA) and to evaluate its biocompatibility as dental implant material in vitro and in vivo. UFG-Ti was produced by equal channel angular pressing (ECAP) using commercially pure titanium (CP-Ti). Microstructure and yield strength were investigated. The morphology, wettability and roughness of the specimens were analyzed after they were modified by SLA. MC3T3-E1 osteoblasts were seeded onto the specimens to evaluate its biocompatibility in vitro. For the in vivo study, UFG-Ti implants after SLA were embedded into the femurs of New Zealand rabbits. Osseointegration was investigated though micro-CT analysis, histological assessment and pull-out test. The control group was CP-Ti. UFG-Ti with enhanced mechanical properties was produced by four passes of ECAP in BC route at room temperature. After SLA modification, the hierarchical porous structure on its surface exhibited excellent wettability. The adhesion, proliferation and viability of cells cultured on the UFG-Ti were superior to that of CP-Ti. In the in vivo study, favorable osseointegration occurred between the implant and bone in CP and UFG-Ti groups. The combination intensity of UF- Ti with bone was higher according to the pull-out test. This study supports the claim that UFG-Ti has grain refinement with outstanding mechanical properties and, with its excellent biocompatibility, has potential for use as dental implant material.

Effect of metal type and surface treatment on shear bond strength of resin cement (in vitro study).

BACKGROUND: Resin-bonded fixed partial dentures appeared to prevent the excessive preparation of dental tissue. Investigation of surface treatments to improve the bond of resin cements to metals may contribute to the longevity of these restorations. Due to the potential lack of ideal preparation form, the type of alloy and its surface pretreatment may have clinically relevant correlations with the retentive strength of castings to minimally retentive preparations. AIM: The aim of this search is to study the bonding resin cement strength to different types of the metal alloy due to the surface treatment. PURPOSE: Evaluate the effects of two different surface treatments on shear bond strength (SBS) between a palladium-silver alloy (Pb-Ag) and commercially pure titanium (CP Ti) cast alloy with resin luting cements. MATERIALS AND METHODS: A total of 120 cylinders having 5 mm in diameter and 4 mm in height were divided into two different main groups of metal type: 60 cylinders cast from CP Ti Grade I (Tritan - Reintitan - Germany-Dentaurum) as a base metal and 60 cylinders cast from Pb-Ag (Status-Yamakin, Japan) as a noble metal. 30 cylinders from each type were embedded in acrylic resin, and the rest were left without embedded in acrylic resin. All of the cylinders were smoothed with silicon carbide papers and sandblasting with 50-µm aluminum oxide. Specimens of each metal type were divided into two subgroups, which received one of the following luting techniques: (1) Multilink (Ivoclar Vivadent), (2) Multilink (Ivoclar Vivadent) plus metal zirconia primer (MZP). Every two cylinders from the same metal type and surface treatment were bonded to each other. All specimens were stored in distilled water at 37°C for 24 h and then thermal cycled (500 cycles, 5-55°C). After thermal cycling, the specimens were stored in 37°C distilled water for an additional 24 h before being tested in shear strength. Data (MPa) were analyzed using T-s tests to study the significance of various - means among groups and perform a comparison between each two groups of them. RESULTS: The T-s tests indicated significant effect of combination of the sandblasting technique (aluminum oxide particles 50 µm) with the application of primer MZP before using resin cement (P < 0.05) independent of the metal type used. The metal type did not significantly affect SBS for any of the compared surface pretreatments. CONCLUSION: Metal primer application significantly enhanced SBS to base and a noble metal. No significant differences in shear strength were found between alloys.

Commercially pure titanium (cp-Ti) versus titanium alloy (Ti6Al4V) materials as bone anchored implants - Is one truly better than the other?

Commercially pure titanium (cp-Ti) and titanium alloys (typically Ti6Al4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally, influenced material selection for different clinical applications: predominantly Ti6Al4V in orthopaedics while cp-Ti in dentistry. This paper attempts to address three important questions: (i) To what extent do the surface properties differ when cp-Ti and Ti6Al4V materials are manufactured with the same processing technique?, (ii) Does bone tissue respond differently to the two materials, and (iii) Do bacteria responsible for causing biomaterial-associated infections respond differently to the two materials? It is concluded that: (i) Machined cp-Ti and Ti6Al4V exhibit similar surface morphology, topography, phase composition and chemistry, (ii) Under experimental conditions, cp-Ti and Ti6Al4V demonstrate similar osseointegration and biomechanical anchorage, and (iii) Experiments in vitro fail to disclose differences between cp-Ti and Ti6Al4V to harbour Staphylococcus epidermidis growth. No clinical comparative studies exist which could determine if long-term, clinical differences exist between the two types of bulk materials. It is debatable whether cp-Ti or Ti6Al4V exhibit superiority over the other, and further comparative studies, particularly in a clinical setting, are required.

Effects of Peracetic Acid on the Corrosion Resistance of Commercially Pure Titanium (grade 4)

The aim of this study was to evaluate the corrosion resistance of pure titanium grade 4 (cp-Ti-4), subjected to disinfection with 0.2% and 2% peracetic acid during different immersion periods using anodic potentiodynamic polarization test in acid and neutral artificial saliva. Cylindrical samples of cp-Ti-4 (5 mm x 5 mm) were used to fabricate 24 working electrodes, which were mechanically polished and divided into eight groups (n=3) for disinfection in 2% and 0.2% peracetic acid for 30 and 120 min. After disinfection, anodic polarization was performed in artificial saliva with pH 4.8 and 6.8 to assess the electrochemical behavior of the electrodes. A conventional electrochemical cell, constituting a reference electrode, a platinum counter electrode, and the working electrode (cp-Ti specimens) were used with a scanning rate of 1 mV/s. Three curves were obtained for each working electrode, and corrosion was characterized by using scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS). Data of corrosion potential (Ecorr) and passive current (Ipass) obtained by the polarization curves were analyzed statistically by Student's t-test (a=0.05). The statistical analysis showed no significant differences (p>0.05) between artificial saliva types at different concentrations and periods of disinfection, as well as between control and experimental groups. No surface changes were observed in all groups evaluated. In conclusion, disinfection with 0.2% and 2% peracetic acid concentrations did not cause corrosion in samples manufactured with cp-Ti-4.

Resumo O objetivo deste estudo foi avaliar a resistência à corrosão de titânio puro grau 4 (cp-Ti-4) submetido à desinfecção com ácido peracético a 0,2% e 2% durante diferentes períodos de imersão por meio do teste de polarização potenciodinâmica anódica em saliva artificial ácida e neutra. Amostras cilíndricas de cp-Ti-4 (5 mm x 5 mm) foram usadas para confeccionar 24 eletrodos de trabalho, os quais foram polidos mecanicamente e divididos em oito grupos (n=3) para desinfecção com ácido peracético a 2% e 0,2% por 30 e 120 minutos. Após a desinfecção, foi realizado o teste de a polarização anódica em saliva artificial com pH 4,8 e 6,8 para avaliar o comportamento eletroquímico dos eletrodos. Uma célula electroquímica convencional, composta por eletrodo de referência, contra-eletrodo de platina, e eletrodo de trabalho (amostras de cp-Ti) foi usada com taxa de varredura de 1 mV/s. Foram obtidas três curvas para cada eletrodo de trabalho e a corrosão foi analisada por microscopia eletrônica de varredura (MEV) e espectrometria de energia dispersiva de raios-X (EEDX). Os dados de potencial de corrosão (Ecorr) e corrente passiva (Ipass) obtidos com as curvas de polarização foram analisados estatisticamente pelo teste t de Student (=0,05). A análise estatística não mostrou diferenças significantes (p>0,05) entre os tipos de saliva artificial nas diferentes concentrações e períodos de desinfecção, bem como entre os grupos controle e experimental. Não foram observadas alterações nas superfícies das amostras de todos os grupos avaliados. Conclui-se que a desinfecção com ácido peracético nas concentrações de 0,2% e 2% não provocou corrosão nas amostras confeccionadas com cp-Ti-4.

Characteristics of multi-layer coating formed on commercially pure titanium for biomedical applications.

An innovative multi-layer coating comprising a bioactive compound layer (consisting of hydroxyapatite and calcium titanate) with an underlying titanium oxide layer (in the form of anatase and rutile) has been developed on Grade 4 quality commercially pure titanium via a single step micro-arc oxidation process. Deposition of a multi-layer coating on titanium enhanced the bioactivity, while providing antibacterial characteristics as compared its untreated state. Furthermore, introduction of silver (4.6wt.%) into the multi-layer coating during micro-arc oxidation process imposed superior antibacterial efficiency without sacrificing the bioactivity.

On the importance of crystallographic texture in the biocompatibility of titanium based substrate.

The role of grain size and crystallographic orientation on the biocompatibility of commercially pure titanium was investigated. Samples, with significant differences in crystallographic texture and average grain size (from 0.4 to 40 µm) were produced by equal channel angular pressing (ECAP) and post deformation annealing. X-ray diffraction and electron back scattered diffraction (EBSD) were used to evaluate differences in texture and microstructural characteristics. The titanium oxide film present on the surface of the samples was analyzed to determine the oxidation state of titanium and the chemical bonds between oxygen and titanium using X-ray photoelectron spectroscopy (XPS). Biocompatibility experiments were conducted using MC3T3 preosteoblast cells. Cell attachment was found to be texture-sensitive, where the number of attached cells was higher on the samples with higher number of (0002) planes exposed to the surface, regardless of the grain size. A relationship was also found between the titanium oxide species formed on the surface and the crystallographic texture underneath. The surface texture consisting of more densely packed basal planes promote the formation of Ti-OH on the surface, which in turn, enhances the cell-substrate interactions. These surface characteristics are deemed responsible for the observed difference in cell attachment behaviour of surfaces with different textures. Finally, it is inferred that texture, rather than the grain size, plays the major role in controlling the surface biocompatibility of biomedical devices fabricated from pure metallic titanium.

Assessment of anodized titanium implants bioactivity.

OBJECTIVES: This study was conducted to create nanostructured surface titanium implants by anodic oxidation process aiming to bring out bioactivity and to assess the resultant bioactivity both in vitro and in vivo. MATERIALS AND METHODS: An economic protocol was used to apply anodic spark discharge and create surface nanoporosities on grade II commercially pure titanium (cpTi). The in vitro investigation included morphology, surface chemical analysis, roughness and crystalline structure of titanium oxide (TiO2) film prepared. Assessment of the bioactivity was carried out by immersing the specimens in simulate body fluid (SBF) and investigating the surface-deposited layer. The in vivo investigation was conducted by surgically placing the anodized implants into rabbits tibia for different healing periods. Then biomechanical evaluation was performed to verify the effect of treatments on the interface resistance to shear force. Routine histological analysis was performed to evaluate the bone tissue reactions to anodized implants. RESULTS: Anodization of titanium implants produced morphological changes, raised the percentage of oxygen in the TiO2 layer, increased surface area and roughness of implants remarkably, and modified the crystallinity of the film. The in vitro assessments of bioactivity showed that a layer of calcium phosphate was precipitated on the titanium surfaces 7 days after soaking into SBF. The implant-bone interface resistance to shear force was enhanced at 2-week healing period. This was confirmed by histological findings. CONCLUSION: Nanostructured surface titanium implants could be prepared by anodic oxidation with resultant accelerated bioactivity that may be recommended for early loading.

Effect of denture cleansers on metal ion release and surface roughness of denture base materials

Chemical disinfectants are usually associated with mechanical methods to remove stains and reduce biofilm formation. This study evaluated the effect of disinfectants on release of metal ions and surface roughness of commercially pure titanium, metal alloys, and heat-polymerized acrylic resin, simulating 180 immersion trials. Disk-shaped specimens were fabricated with commercially pure titanium (Tritan), nickel-chromium-molybdenum-titanium (Vi-Star), nickel-chromium (Fit Cast-SB Plus), and nickel-chromium-beryllium (Fit Cast-V) alloys. Each cast disk was invested in the flasks, incorporating the metal disk to the heat-polymerized acrylic resin. The specimens (n=5) were immersed in these solutions: sodium hypochlorite 0.05%, Periogard, Cepacol, Corega Tabs, Medical Interporous, and Polident. Deionized water was used as a control. The quantitative analysis of metal ion release was performed using inductively coupled plasma mass spectrometry (ELAN DRC II). A surface analyzer (Surftest SJ-201P) was used to measure the surface roughness (µm). Data were recorded before and after the immersions and evaluated by two-way ANOVA and Tukey's test (α=0.05). The nickel release proved most significant with the Vi-Star and Fit Cast-V alloys after immersion in Medical Interporous. There was a significant difference in surface roughness of the resin (p=0.011) after immersion. Cepacol caused significantly higher resin roughness. The immersion products had no influence on metal roughness (p=0.388). It could be concluded that the tested alloys can be considered safe for removable denture fabrication, but disinfectant solutions as Cepacol and Medical Interporous tablet for daily denture immersion should be used with caution because it caused greater resin surface roughness and greater ion release, respectively.

Desinfetantes químicos são normalmente associados a métodos mecânicos para remover manchas e reduzir a formação do biofilme. Este estudo avaliou o efeito de desinfetantes na liberação de íons metálicos e na rugosidade superficial do titânio comercialmente puro, ligas metálicas e resina acrílica termopolimerizável, simulando 180 ensaios de imersões. Espécimes em formato de discos foram confeccionados com titânio comercialmente puro (Tritan), liga de níquel-cromo-molibdênio-titânio (Vi-Star), liga de níquel-cromo (Fit Cast-SB Plus) e liga de níquel-cromo-berílio (Fit Cast-V). Os espécimes (n=5) foram imersos nestas soluções: hipoclorito de sódio a 0,05%, Periogard, Cepacol, Corega Tabs, Medical Interporous e Polident. Como controle, foi utilizada a água deionizada. A análise quantitativa de liberação de íons metálicos foi realizada por meio de espectrometria de massa com plasma indutivamente acoplado (ELAN DRC II). O rugosímetro (Surftest SJ-201P) foi utilizado para medir a rugosidade superficial (µm). Os dados foram registrados antes e depois das imersões e avaliados por ANOVA com dois fatores e teste de Tukey (α=0,05). A liberação de níquel provou ser mais expressiva nas ligas Vi-Star e Fit Cast-V após a imersão em Medical Interporous. Houve diferença significante na rugosidade superficial da resina (p=0,011) após a imersão. O Cepacol causou maior rugosidade superficial de forma significativa. Os produtos de imersão não influenciaram nos resultados da rugosidade do metal (p=0,388). Pode-se concluir que as ligas metálicas testadas podem ser consideradas seguras para a fabricação de próteses removíveis, mas as soluções desinfetantes como o Cepacol e a pastilha Medical Interporous para a imersão diária da prótese devem ser utilizados com cautela, pois causaram maior rugosidade superficial da resina e maior liberação de íons, respectivamente.

Biocompatibilidade do titânio e a superfície Vulcano® / Titanium biocompatibility and Vulcano® surface

Apesar do titânio apresentar excelente biocompatibilidade, mediante tratamentos da superfície dos implantes dentários é possível acelerar os mecanismos envolvidos nas interações entre as células e o implante para obter melhor osseointegração. No presente trabalho faz-se a análise dos parâmetros que modificaram as reações das células com o titânio, apresenta-se a influência da incorporação de Ca e P na superfície dos implantes dentários, descreve-se os processos de tratamento eletroquímicos da superfície dos metais e são apresentados resultados de estudos da superfície Vulcano® obtida por anodização

Commercial pure titanium has an excelent biocompatibility, but after the dental implant surface treatment is possible to improve the osteointegration mechanism. Interactions between dental implants and cells mainly depend on surface characteristics of implants, including surface topography, charges, components and chemical states. It is generally accepted that rough, textured and porous surfaces could stimulate cell attachment, differentiation and the formation of extracellular matrix. The purpose of this work was to analyze the influence of dental implant surface characteristics on cell adhesion and spread. It was analyzed the influence of Ca and P deposition on the implant surface, described the electrochemical surface treatment method for surface modification and showed studies results of Vulcano surface