Titanium Plasma Research Articles

Removal of HA and TPS implant coatings and fibroblast attachment on exposed surfaces.

The removal of implant coatings may be necessary if rough implant surfaces are exposed subgingivally due to progressive peri-implant bone loss or if they are also supragingivally exposed because of progressive gingival recession, thus facilitating plaque formation and impairing tooth cleaning done at home. The aim of this experimental study was to develop diamond-coated files and rubberized polishers for machine-driven instrumentation of implant cylinders, and present an instrumentation concept for the complete removal of rough titanium plasma spray (TPS) and hydroxylapatite (HA) layers and polishing exposed titanium surfaces. The surface structure and its possible contamination by the instrumentation process was investigated using laser profilometry, scanning electron microscopy, and x-ray fluorescence analysis. The effect of impurities on the growth of human fibroblasts was tested in cell culture. The results show that TPS and HA implant coatings can be removed with the modified implant files. After polishing the exposed titanium surfaces, roughness depths of Rz=4.6 microm (TPS) and Rz=5.7 microm (HA) and, for implant cylinders, 3.4 microm were found. During the instrumentation of implant surfaces, contamination with the material of the instrument must be expected. It was shown that, in principle, growth of human gingival fibroblasts on the instrumented surfaces is possible. The cells were intimately associated with one another and, compared to culture controls, demonstrated good adhesion with strict orientation to the microstructure of the scoring left by instrumentation. The biological consequences and mechanisms of cell adhesion on instrumented surfaces require further investigation.

Dynamic nitrogen and titanium plasma ion implantation/deposition at different bias voltages

Titanium oxynitride films were prepared on AISI 304 stainless steel samples employing dual titanium and nitrogen plasmas in an immersion configuration. The vacuum arc source provided the titanium plasma and the nitrogen plasma was sustained by hot filament glow discharge. A 30 μs implantation duration and 270 μs titanium arc duration were used in our plasma ion implantation and deposition (PIID) process. The impact of the implantation voltages (8 kV, 16 kV and 23 kV) on the film was investigated. The treated samples were characterized using Auger electron spectroscopy (AES) and atomic force microscopy (AFM). Our results reveal that the thickness of the coating is not changed significantly by the applied voltage. However, the surface morphology varies substantially with the implantation voltage. The 8-kV sample shows the highest titanium content and a smooth island-shaped surface whereas the 23-kV sample features peaks with sharper edges.

Single stage surgery combining transmucosal implant placement with guided bone regeneration and bioresorbable materials.

The aim of the present clinical study was to test whether peri-implant bone defects can successfully be filled with bone by applying bioresorbable materials for guided bone regeneration (GBR) procedures in conjunction with implants in the transmucosal healing position. Three women and 7 men ranging in age from 32 to 68 years (median 54.5) needed tooth replacement with dental implants. Eight to 14 weeks following careful tooth extraction, implants of the ITI Dental Implant System were placed at the extraction sites. At this time, all implants presented dehiscence defects of the alveolar bone partly exposing the rough titanium plasma sprayed (TPS) surfaces. GBR procedures were performed using deproteinized bovine bone mineral (Bio-Oss) as a membrane-supporting material and a bioresorbable collagen membrane (Bio-Gide) as a barrier. The membranes and the flaps were adjusted to fit around the necks of the implants, thus leaving the implants extending transmucosally into the oral cavity. Clinical measurements were taken at 6 sites around each implant (mesio-buccal, buccal, disto-buccal, disto-lingual, lingual, mesio-lingual) using a calibrated periodontal probe. These included: i) defect depth measured from the shoulder of the implant to the first bone-to-implant contact, ii) infrabony defect component measured from the bone crest to the first bone-to-implant contact, iii) defect width measured from the crest to the implant body in a direction perpendicular to the long axis of the implant. The Wilcoxon Matched Pairs Signed Rank Test was applied to detect differences over time. At baseline, the mean defect depth per patient amounted to 3.6 mm (Standard Deviation 1.6 mm, range 1.8-6.8 mm). The deepest extensions of the defects were located at the buccal aspects (mean 7.8 mm, SD 1.9 mm). At re-entry, the mean defect had decreased to 2.5 mm (SD 0.6 mm). This difference was statistically significant (P < 0.01). Initially, in 62% of sites the depth ranged from 0-3 mm, in 23% it ranged from 2-4 mm, and in 15% it amounted to more than 6 mm. Six to 7 months later, at re-entry, 95% of sites were 3 mm and less in depth and 5% ranged from 4-6 mm. Defect resolution, as assessed by the amount of coverage of the initially exposed rough implant surface, reached a mean value of 86% (SD 33%). One hundred percent resolution was accomplished at 8 out of 10 implants, 60% at one and 0% at another implant. The tissue at the latter implant showed signs of infection and inflammation during the healing phase. It is concluded that bioresorbable materials in GBR procedures at transmucosal implants can lead to successful bone regeneration into peri-implant defects.

Properties of titanium oxide biomaterials synthesized by titanium plasma immersion ion implantation and reactive ion oxidation

As an artificial heart valve material, titanium oxide is superior to low temperature isotropic pyrolytic carbon in terms of mechanical properties and biocompatibility. The irregular shape of a heart valve makes conventional fabrication techniques like beam-line ion implantation and ion beam enhanced deposition (IBED) difficult. Plasma immersion ion implantation (PIII) does not suffer from the line-of-sight limitation and is an excellent technique for this purpose. In this work, titanium oxide thin films are synthesized on Ti6Al4V by titanium metal PIII and oxygen PIII. By controlling the deposition/implantation rate of titanium and oxygen plasma density, TiO x films with different compositions and properties can be fabricated. The film properties are evaluated by techniques including atom force microscopy (AFM), X-ray diffraction (XRD), and various mechanical testing methods. AFM results reveal that the TiO x film surface is quite dense without gross voids. The microhardness is enhanced with increasing oxygen partial pressure between the range of 0–3×10 −2 Pa and reaches a maximum value of 17 GPa at an oxygen partial pressure of 3×10 −2 Pa. The wear resistance is also much better than that of Ti6Al4V. In spite of our encouraging results, the TiO x films synthesized in our experiments are still too thin. In order to exploit its full potential as an artificial heart valve material, the films must be thicker. It can be achieved by using a more efficient metal arc source or by increasing the PIII duty cycle.

Micro‐morphometric assessment of titanium plasma‐sprayed coating removal using burs for the treatment of peri‐implant disease

This study evaluated, in vitro, the effectiveness of diamond and carbide burs, and bur sequences to remove the plasma-sprayed titanium coating from IMZ fixture surfaces. Fifteen polishing procedures were tested. They included the use of 12, 16, 30 bladed carbide burs or bevered carbide burs and 30, 15, 8 microns mean-particles-size diamond burs. The treated surfaces were evaluated with profilometer and SEM. Worn burs and titanium debris produced by the grinding were observed with SEM. All procedures produce smoother surfaces than baseline plasma-sprayed surfaces for both Ra and Rz(DIN) parameters (P < 0.001). A roughening effect of the 8 microns mean-grit diamond bur and 30 bladed burs were noted. The single carbide burs produce polished surfaces affected by waviness. Waviness was minimized by sequence or diamond bur use. The carbide bur blades were variously damaged after their use. In contrast, the grit of diamond burs was observed to be clogged by titanium debris whose amount seemed to be inversely related to the diamond mean particle size. Debris produced by diamond burs was granular whereas that produced by carbide bladed burs showed needle or flake morphology. In conclusion, the most effective titanium plasma sprayed removal were obtained by 30 microns and 15 microns mean-particle-size diamond burs, i.e. 30 microns plus 15 microns diamond burs and carbide 12 plus 16 bladed burs used in sequence.

Scanning electron microscopical analysis of laser-treated titanium implant surfaces—a comparative study

Design and surface qualities of titanium implants are of vital importance for long-term stability following implantation. Four different implant surfaces treated individually were analyzed with special attention focused on laser surface treatment. Surfaces with machine roughness, titanium spray coating, treated by aluminum oxide and treated by laser were examined individually. Evaluation of the surface was carried out by electron microscope examination and mechanical profilometry. The EDS analysis determined the degree of contamination of the implant surface. Electron microscope examination showed that the titanium plasma spray as well as the laser-treated implants have optimum surface qualities: a secondary and tertiary structure with micro-roughness of 10 mm and roughness ranging from 0.5 to 4 mm. The least contamination was found for machine rough surfaces as well as those treated by laser. The other implants showed contamination corresponding to the method of surface treatment. In summary the optimal surface structure with the least contamination was found for the laser-treated titanium surface. Similar surface purity was found for the machine rough surfaces. An optimal structure was also achieved by the titanium plasma spray method, however, at the cost of surface purity.

Abrasive waterjet peening: a new method of surface preparation for metal orthopedic implants.

Abrasive waterjet (AWJ) peening is a new mechanical surface treatment process envisioned for use on metal orthopedic implants. The process utilizes an abrasive waterjet to simultaneously texture and work harden the surface of a metal substrate through controlled hydrodynamic erosion. In this study, a titanium alloy (Ti6Al4V) was subjected to AWJ peening over a range of parametric conditions. The textured surfaces were quantified in terms of the apparent interdigitation volume (V(i)), the effective stress concentration factor (K(t)) posed by the surface topography, and the magnitude of residual stress (sigma(r) ). Topographical features of the prepared surfaces were determined using contact profilometry, and X-ray diffraction was used in evaluating the in-plane residual stress. It was found that a large range in V(i) (9.4-43.8 microm(3)/microm(2)) and K(t) (1.3-2.7) are available through selection of the AWJ peening process parameters. Furthermore, a compressive residual stress (-409 +/- sigma(r) +/- -33) was found to result within the surface of the Ti6Al4V substrates regardless of treatment conditions. When compared to a titanium plasma spray coating used for cementless fixation, the AWJ peened Ti6Al4V exhibited a surface topography with significantly lower effective stress concentration and higher compressive residual stress. Based on results from this study, AWJ peening may serve as a new method of surface treatment for metal orthopedic implants, which supports the development of stable primary fixation and simultaneously enhances the component fatigue strength.

A comparison of the electron component within laser-ablated titanium plumes formed by UV and visible lasers

A Langmuir probe was used as a diagnostic of the temporally evolving electron number densities within a low-temperature laser-ablated titanium plasma expanding in vacuum. Measurements were made following ablation by a KrF excimer laser (248 nm, τ=30 ns) and a frequency-doubled Nd:YAG laser (532 nm, τ=7.5 ns) for laser power densities between 85 MW cm-2 and 1130 MW cm-2 on target. Electron number density data were obtained from the saturation electron current region of the probe (I/V) characteristic. Peak electron number densities in the range 1.5×1010 cm-3 to 1.5×1013 cm-3 were measured, at a distance of 5 cm along the target normal, for the laser power range investigated. Above ablation threshold the temporally integrated electron flux increased linearly with incident power density for both ablation wavelengths. The ablation thresholds, in terms of peak power density within the laser spot on the target, were found to be 85±20 MW cm-2 for KrF ablation and 300±50 MW cm-2for 2ω YAG ablation.

An investigation of neutral and ion number densities within laser-produced titanium plasmas in vacuum and ambient environments

Optical absorption spectroscopy in combination with laser-induced fluorescence imaging is applied to determine spatially and temporally resolved number densities within laser-produced titanium plasmas, expanding into vacuum and low-pressure nitrogen. Contour mapping of species number density and subsequent volumetric integration to yield the total number of absorbing species in the plume are demonstrated for Ti I expanding into vacuum. The results obtained indicate that for an incident KrF energy density of ∼4 J cm-2 the total plume content is >1017 Ti neutrals and ions. The ground-state neutral and ground-state ion yields are both observed to increase linearly with laser fluence above thresholds of ∼2.2 J cm-2 and ∼3.7 J cm-2, respectively. Reduction in absorption linewidths and spatial widening of the corresponding LIF images, observed for plume expansion in the presence of low-pressure ambient gases, reflects the reduction in species velocities and randomisation of the velocity distributions of plume species with increasing ambient pressure.

Investigation of the influence of ion etching parameters on the structure of nitrided case in hot working steel

The paper discusses the influence of the ion etching process on the nitrided case structure created with the use of the gas nitriding method in hot working steel. The nitrided case structure is of key importance for the final effect of duplex treatment, consisting of the nitriding process and subsequent deposition of a hard coating, because it significantly determines the adhesion of PVD coating. It was found out that during the initial stage of the coating deposition, i.e. during ion etching, decomposition of the Ë and Ë+γ′- ‘white’ compound layer can occur, which results in backward diffusion of nitrogen and destruction of the created nitrided case. The critical temperature for the decomposition process is 500°C, although in some conditions, it can start even at 350°C. The purpose of the investigation described in the paper was to examine changes in the nitrided case structure (in the hot working steel ISO 35CrMoV5) caused by the etching process executed in different experimental conditions (1: different pressures: 2×10−5 mbar, 1×10−3 mbar, 1×10−2 mbar; 2: different working atmospheres: titanium plasma and mixed titanium–argon plasma; 3: two types of substrate polarization: Ubias=900 V/d.c., and pulsed Ubias=900 V, f=5 kHz, Δ=90%. The experiments were carried out in the vacuum arc deposition equipment MZ383 manufactured by Metaplas Ionon (Germany). Prepared samples were examined, before and after ion etching, in the microscopic metallographic investigation using the optical microscope Neophot32 and in the investigation of the phase composition using the X-ray diffractometer Philips PW1830. The influence of the ion etching process conditions on the nitrided layers structure and on the intensity of compound zone decomposition was characterized on the basis of results obtained from experimental investigations.

Microdamage adjacent to endosseous implants

Intense remodeling occurs in lamellar bone adjacent to osseointegrated endosseous implants. The purpose of this study was to compare microdamage accumulation subsequent to ex vivo fatigue loading of bone that surrounds an endosseous implant, (a) immediately after placement (nonadapted bone) and (b) following a 12 week healing period after placement (adapted bone). We hypothesize that there is less microdamage in the more compliant adapted bone than in the older nonadapted bone. Nonthreaded titanium plasma sprayed (TPS)-coated endosseous implants were placed into dog midfemoral diaphyses and allowed to heal for 12 weeks. Block sections of bone, each containing one implant, were cut anteroposteriorly, resulting in an implant containing lateral cortex, and a medial cortex that was used for testing the nonadapted specimens. Control specimens (n = 14 each for adapted and nonadapted) were loaded at 0 N. Experimental specimens (n = 13, adapted; n = 14, nonadapted) were loaded at 100 N in cantilever bending for 150,000 cycles at 2 Hz, at 37°C on a Bionix 858 testing machine. Specimens were bulk stained with basic fuchsin and 120–140 μm sections were obtained. Crack numerical density (Cr.Dn = Cr.N/B.Ar, #/mm 2), crack surface density (Cr.S.Dn = Tt.Cr.Le/B.Ar, mm/mm 2), and percent damage area (Dm.Ar = Cr.Ar × 100/B.Ar, mm 2/mm 2) were measured at ×250. Statistically significant differences ( p < 0.0001) were seen for Cr.Dn, Cr.S.Dn, and Dm.Ar on the compressed cortices suggesting that adapted bone near the implant accumulated significantly less microdamage than nonadapted bone. Also, the adapted nonloaded control specimens had approximately 20-fold less damage than the respective nonadapted specimens. This study suggests that the compliant adapted bone adjacent to endosseous implants is relatively resistant to fatigue loads. The high success rates of endosseous implants may be due to the presence of a rapidly remodeling region that maintains tissue compliance and limits microdamage initiation.

A 5-year comparison of hydroxyapatite-coated titanium plasma–sprayed and titanium plasma–sprayed cylinder dental implants

Objective. A preliminary report from this study showed that hydroxyapatite-coated (HA) titanium plasma–sprayed (TPS) cylinder implants had fewer failures than TPS cylinder implants before prosthetic loading. The purpose of this article is to report the long-term success associated with the 2 systems. In addition, local and systemic factors that may influence the success or failure of the implants were analyzed. Study Design. Each of 65 subjects was randomized to either HA-coated TPS or TPS cylinder implants. Loss of an implant was considered a failure. Failures were analyzed in terms of the coating of the implant, age and gender of the patient, location and length of the implant, opposing dentition, and smoking status. Data were statistically analyzed through use of chi-quare tests. Results. Of 351 implants that were placed, 13 were lost before prosthetic loading and 17 were lost after prosthetic loading. The overall success rate was 92.8%. Three hundred thirty-eight implants were prosthetically loaded. The implant success rate after prosthetic loading was 95.3%. There was an overall nonsignificant higher failure rate for the TPS implants (8.0%). Patient age and patient gender were nonsignificant variables. Ten-mm implants had a significantly higher failure rate (17.4%; chi-square, 1.00; P = .39). Before prosthetic loading, more implants failed in the posterior mandible; after prosthetic loading, more implants failed in the anterior maxilla (chi-square, 8.97; P = .03). More implants failed when they were opposed by natural dentition or hybrids (chi-square, 7.36; P = .007). Smoking history was a significant factor (chi-square, 5.2; P = .002). Conclusions. Statistically, there is little difference between the 2 systems. Local and systemic factors appear to play a greater role in implant failure than does the surface of the implant. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:649-52)

High voltage sheath behavior in a drifting plasma

We describe a simple experiment in which a high voltage substrate is immersed in a streaming, vacuum-arc-produced, titanium plasma. We show that high substrate voltages that are orders of magnitude greater than the electron temperature can be sustained, effectively on a direct current basis, by a well-rounded substrate (no sharp points or edges) immersed in the plasma stream, for the case of a plasma with density not too low (greater than about 109 cm−3) and with drift velocity that is equal to or greater than the sheath propagation speed, typically of order the ion acoustic speed. This result is significant not only from a basic plasma physics perspective, but also for the technology of carrying out plasma immersion surface processing.

Fast ICCD imaging of KrF excimer laser induced titanium plasma plumes for silicon metallization

Pulsed laser deposition (PLD) is applied to grow titanium thin films on silicon substrates for wafer metallization. Dynamics of plasma during the thin film deposition is investigated by fast intensified charge coupled detector (ICCD) time integrated photography. Plasma images at different gate delays after laser irradiation are taken to study plasma size, distribution, expansion and interaction with the substrates. Plume flying and expansion speeds in the directions normal and parallel to target surface are calculated. Fast ICCD imaging shows that the plasma starts to fly and expand at speeds as high as 10 6 cm/s and reduces gradually to zero with gate delay. The dependence of plume size and speeds on laser fluence, gate delay, target-to-substrate distance and chamber pressure is analyzed to optimize processing parameters for the thin film deposition.

Influence of various structure treatments on histological fixation of titanium implants

In this study, three types of titanium test pieces were manufactured with different surfaces and implanted into dog femoral condyles, and tissue response was assessed histologically and radiographically for 24 weeks thereafter. The study confirmed that thickening of lamellar bone could be observed around titanium plasma spray-coated titanium alloy implants 24 weeks after implantation, whereas thick fibrous tissue surrounded by corticalized bone formed around those made of smooth-sided titanium alloy. With an implant made of an artificial osteochondral composite material, thickening of ingrown trabeculae could be observed as early as 4 weeks, and abundant bone growth into the titanium fiber mesh continued to increased with time. This bone ingrowth resulted in the complete integration of this composite device implant and the host bone. Our findings suggest that cell response to the various implants is quite different, even though the implants were made of the same kind of material. The implants with the open-pore structure has great significance in the ideal fixation between the implants and the viable bone.

Integrated barrier/plug fill schemes for high aspect ratio Gb DRAM contact metallization

New contact fill integration schemes were developed for high aspect ratio Gb DRAM contact metallization. Integration schemes for both tungsten-plug contacts and aluminum-plug contacts were studied. For tungsten-plug contacts, various types of titanium liners and titanium nitride barriers were investigated and evaluated. These included collimated PVD (physical vapor deposition) titanium, ion metal plasma (IMP) titanium, and CVD (chemical vapor deposition) titanium liners; plasma enhanced CVD (PECVD) titanium nitride and plasma enhanced MOCVD (ECVD) titanium nitride barriers. The electrical results of 0.3 μm, 5:1 aspect ratio (AR) contact structures processed with a TiCl 4-based CVD titanium liner and plasma enhanced CVD titanium nitride barrier show the lowest and the most tightly distributed contact parametrics. This is attributed to the conformal nature of the CVD process. In addition, the high titanium-deposition temperature, which leads to a simultaneous titanium silicide formation during the CVD titanium deposition process, may also have attribution to the low contact resistance and diode leakage obtained. In the case of aluminum-plug contacts, two different types of titanium nitride barriers (ECVD titanium nitride vs. silane-treated MOCVD titanium nitride) were evaluated and both showed comparable contact parametrics.

Spectroscopic studies of three osseointegrated implants

Objectives: The purpose of this study was to investigate the surface characteristics of titanium implants. Methods: The chemical state of the surfaces of three types of osseointegrated titanium implant, Brånemark (Nobelpharma, Göteborg, Sweden), IMZ (Friatec, Mannheim, Germany) and ITI-Bonefit (Straumann, Waldenburg, Switzerland), were analysed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). Results: The outermost layers of the implants investigated were speculated to be TiO 2. In the Brånemark implants pure titanium was found under the TiO 2 layer. By contrast, in the IMZ and ITI-Bonefit implants which are titanium plasma spray coated, oxygen atoms were observed at considerable depths by AES, and the material under the TiO 2 layer showed a chemical shift by XPS. Furthermore, shifted peaks were not of pure titanium or of titanium oxide. Conclusion: The three titanium implants investigated were found to have different surface characteristics when examined by spectroscopy. As these implants show similar osseointegration it is suggested that they may be found to interact differently with vital bone.

Observations of the plasma dynamics of a vacuum spark from its soft x-ray emission

Experimental observations of the plasma dynamics in a vacuum spark are presented which permit measurements of the electron density and temperature during a large part of the compression phase of the pinch. The vacuum spark is generated by a low-impedance pulse forming line with a maximum current in excess of 100 kA. The discharge is operated in the hybrid mode in a titanium plasma. A laser focused onto the cathode provides the preionizing source. Soft x-ray emission from the current sheath is observed with an x-ray framing camera well before maximum compression. These observations are compared with holographic interferograms, both showing the formation of an axisymmetric rhombic boundary to the plasma sheath. The temperature and density of both the sheath and the internal plasma are observed until the formation of hot spots at the time of maximum compression. The temperature evolution of the hot spots is presented, showing a repeatable behavior that depends on the axial position.

OSSEOINTEGRATED TITANIUM PLASMA COATED IMPLANTS IN RECONSTRUCTION OF EDENTULOUS MANDIBLE

Fifteen patients underwent surgical insertion of titanium plasma sprayed screws in the mandible ridge over the symphysis region. In 3 patients, along with the screws in the symphysis region, hollow basket implant type 'H', one each in the mandible first/second molar region were inserted. Implants were fixed only in those patients who had retention and stability problems of mandibular artificial denture. Indication, technique and biocompatibility of titanium implants and tissue supported over denture have been discussed.

Deposition of titanium carbide films from mixed carbon and titanium plasma streams

Dual source metal plasma immersion ion implantation and deposition was used to deposit TixCy films over a wide range of Ti:C composition. This technique is well adapted for this purpose and allows one to tailor the microstructure and properties of the films. We investigated the variation of the composition, bonding states, and structure as functions of the deposition conditions. Excess carbon and contamination oxygen are incorporated in the TiC lattice interstitially and substitutionally, respectively. The wear mechanism of a stoichiometric TiC film was investigated and compared to that of a diamondlike carbon film. TiC fails by wear and microcrack propagation.