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PubMed1994

Titanium deposition in regional lymph nodes after insertion of titanium screw implants in maxillofacial region.

The deposition of titanium in regional lymph nodes was studied after insertion of endosseous, plasma-spray-coated titanium screw implants in a total of 19 beagle dogs. Five additional animals with no implants served as the control group. After killing the animals 9 months postoperatively, the regional lymph nodes were carefully excised, and samples were prepared for histologic examination. Other samples were used to identify foreign particles by energy-dispersive x-ray analysis and for measurement of the titanium concentration in the tissue by flameless atomic absorption spectroscopy. Very fine foreign-body particles could be seen in the histologic sections, and they were identified as titanium by energy-dispersive x-ray analysis. The atomic absorption analysis for titanium revealed a significantly higher concentration in the group with implants. The presence of very fine, poorly attached particles on the plasma-sprayed titanium surface suggests that these particles may be mechanically dislodged from the surface on insertion of the implants. This suggests that the fine particles may be transported by phagocytes to the regional lymph nodes, where they could be found without any signs of inflammation or foreign-body reaction.

Animals↗
PubMed2001

Effectiveness of a new perforated 0.15 mm poly-p-dioxanon-foil versus titanium-dynamic mesh in reconstruction of the orbital floor.

Introduction: In recent years a new perforated PDS (poly-p-dioxanon) foil (0.15 mm) has become available and has not yet been proven to be successful in reconstruction of the orbital floor after blow-out-fractures in randomized studies. The main aim of this clinical trial is to compare this new PDS foil with titanium dynamic mesh (0.3 mm) (TD), which is well established in reconstruction of the orbital floor. Patients and Methods: In a prospective multicentre randomized trial, conducted between 1997 and 1998, out of 42 patients with fractures of the orbital floor, 28 patients needing material for reconstruction were randomized to receive either PDS foil or TD. In a comprehensive preoperative and postoperative protocol patients were monitored by the surgeon, radiologist and ophthalmologist with a postoperative follow-up of least 6 months. Results: Maximum defects of the orbital floor were comparable in both groups (PDS group: 13.3 mm, TD group: 13.9 mm). In both groups the surgical procedure was well tolerated, and functional and cosmetic results were evaluated as satisfactory by all patients. Ophthalmological evaluation, performed up to 6 months postoperatively, revealed double vision or vertical strabismus in nine patients (five PDS group, four titanium group). This was not confirmed subjectively in each single patient. Also ex- or enophthalmos, registered in seven patients of the PDS and four of the TD group (mainly +/-1 mm) were not considered as relevant by the patients. Conclusion: The new 0.15 mm perforated PDS foil was comparable to 0.3 mm titanium mesh concerning functional and cosmetic outcome. Obviously, persisting ophthalmometric disorders were compensated very well in both groups. PDS foil is felt to be the preferred material since it is bioresorbable and more convenient to handle. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗
PubMed1999

Comparative in vitro biocompatibility of nickel-titanium, pure nickel, pure titanium, and stainless steel: genotoxicity and atomic absorption evaluation.

The genotoxicity level of nickel-titanium (NiTi) was compared to that of its pure constituents, pure nickel (Ni) and pure titanium (Ti) powders, and also to 316L stainless steel (316L SS) as clinical reference material. In order to do so, a dynamic in vitro semiphysiological extraction was performed with all metals using agitation and ISO requirements. Peripheral blood lymphocytes were then cultured in the presence of all material extracts, and their comparative genotoxicity levels were assessed using electron microscopy-in situ end-labeling (EM-ISEL) coupled to immunogold staining. Cellular chromatin exposition to pure Ni and 316L SS demonstrated a significantly stronger gold binding than exposition to NiTi, pure Ti, or the untreated control. In parallel, graphite furnace atomic absorption spectrophotometry (AAS) was also performed on all extraction media. The release of Ni atoms took the following decreasing distribution for the different resulting semiphysiological solutions: pure Ni, 316L SS, NiTi, Ti, and controls. Ti elements were detected after elution of pure titanium only. Both pure titanium and nickel-titanium specimens obtained a relative in vitro biocompatibility. Therefore, this quantitative in vitro study provides optimistic results for the eventual use of nickel-titanium alloys as surgical implant materials.

Alloys↗
PubMed2003

[SIMS (secondary ion mass spectroscopy) and XPS (x-ray photoelectron spectroscopy) study of titanium implant surfaces coated with anodic titanium-oxide layer].

The demands that must be satisfied by titanium implants applied in medical practice include chemical and physical durability. An anodic oxide protective layer formed on the surface of titanium implants serves for the better attainment of this aim. The composition of the passivizing layer and the changes in its thickness and binding state can be studied by method of material science, e.g. by secondary ion mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS). In this way a possibility arises for the material technological classification of the Ti-TiO2 layer structure and for the observation of the physical and chemical reactions that occur between the implants and the tissues in the organism. The present XPS examinations revealed that the binding state of the titanium forming the surface of the plates involve neither significant quantities of titanium oxide nor impurities. In the SIMS investigation the thickness of the titanium oxide layer was found to be 120-150 nm. Determination of the thickness of the surface, the binding state of the titanium and the exact proportions of the impurities and additives furnishes a possibility for a subsequent comparison with the surface structure of plates removed from the organism. It is important for the assessment of the practical value of the protective layer.

Dental Implants↗
PubMed2006

[Comparison among solis cage, titanium cage, and autogenous iliac crest graft combined with titanium plate in treating prolapse of cervical intervertebral disk].

OBJECTIVE: To compare the clinical effects of treating prolapse of the cervical intervertebral disc by the Solis cage fusion, the titanium cage fusion or the autogenous iliac crest graft combined with the titanium plate fixation. METHODS: Sixty-four patients with prolapse of the cervical intervertebral disc admitted to hospital from February 2002 to May 2005 were retrospectively analyzed. In Group A, 20 patients (15 males and 5 females, aged 38-76 years, 30 intervertebral spaces) were treated with the Solis cage fusion, and the preoperative JOA scores were 9-16, averaged 11.4; in Group B, 21 patients (15 males and 6 females, aged 37-78 years, 23 intervertebral spaces) were treated with the titanium cage fusion, and the preoperative JOA scores were 8-13, averaged 10.1; in Group C, 23 patients (18 males and 5 females, aged 32-76 years, 28 intervertebral spaces) were treated with the autogenous iliac crest graft combined with the titanium plate fixation, and the preoperative JOA scores were 9-14, averaged 10. 6. The comparative analysis was made among the 3 groups in the following aspects: X-ray exposure time, time working on the iliac bone, operation time, hemorrhage amount,complication incidence after operation, cervical vertebral fusion rate, symptom relief rate, and recovery rate of the JOA score. RESULTS: According to the follow-up for 2-15 months averaged 12 months, the time working on the iliac bone was longer in Group C than in Groups A and B (11.5 +/- 2.4 vs. 4.1+/- 1.7 min and 4.2 +/- 1.9 min, P < 0.05); the operation time was longer in Group C than in Groups A and B (98.3 +/- 14.7 min vs. 55. 5 +/- 10.3 min and 56.8 +/- 12.6 min, P < 0.05); and the X-ray exposure time was longer in Group C than in Groups A and B (7.8 +/- 1.8 min vs. 4.3 +/- 1.2 min and 4.2 +/- 1.3 min, P < 0.05). Also, the hemorrhage amount in Group C was much greater than in Groups A and B (145.8 +/- 19.3 ml vs. 65.8 +/- 10.2 ml and 67.2 +/- 12.3 ml, P < 0.05). The postoperative complication rate was lower in Groups A and B than in Group C (P < 0.05). There was a significant difference in the complication rate in the cervical region between Group A (5.0% +/- 1.8%) and Group B (14.3% +/- 2.6%, P < 0.05). The fusion rate in Groups A and B was 100% 3-4 months after operation, and there was no difference when compared with that in Group C. The recovery rates of the JOA scores in the three groups were 81.9% +/- 3.2%, 78.9% +/- 7.3%, and 76.3% +/- 9.4%, respectively, and there was no significant difference among the three groups. CONCLUSION: The Solis cage fusion has a better therapeutic effect in treating prolapse of the cervical intervertebral disc than the titanium cage fusion and the autogenous iliac crest graft combined with the titanium plate fixation. The Solis cage fusion also makes the operation easier, with a more rapid recovery rate and fewer postoperative complications in the patient.

Adult↗
PubMed2006

Titanium(II) and titanium(III) tetrahydroborates. Crystal structures of [Li(Et2O)2][Ti2(BH4)5(PMe2Ph)4], Ti(BH4)3(PMe2Ph)2, and Ti(BH4)3(PEt3)2.

The molecular structures of the titanium(III) borohydride complexes Ti(BH4)3(PEt3)2 and Ti(BH4)3(PMe2Ph)2 have been determined. If the BH4 groups are considered to occupy one coordination site, both complexes adopt distorted trigonal bipyramidal structures with the phosphines in the axial sites; the P-Ti-P angles deviate significantly from linearity and are near 156 degrees. In both compounds, two of the three BH4 groups are bidentate and one is tridentate. The deduced structures differ from the one previously described for the PMe3 analogue Ti(BH4)3(PMe3)2, in which two of the tetrahydroborate groups were thought to be bound to the metal in an unusual "side-on" (eta(2)-B,H) fashion. Because the PMe3, PEt3, and PMe2Ph complexes have nearly identical IR spectra, they most likely have similar structures. The current evidence strongly suggests that the earlier crystal structure of Ti(BH4)3(PMe3)2 was incorrectly interpreted and that these complexes all adopt structures in which two of the BH4 groups are bidentate and one is tridentate. The synthesis of the titanium(III) complex Ti(BH4)3(PMe2Ph)2 affords small amounts of a second product: the titanium(II) complex [Li(Et2O)2][Ti2(BH4)5(PMe2Ph)4]. The [Ti2(BH4)5(PMe2Ph)4]- anion consists of two Ti(eta(2)-BH4)2(PMe2Ph)2 centers linked by a bridging eta(2),eta(2)-BH4 group that forms a Ti...(mu-B)...Ti angle of 169.9(3) degrees. Unlike the distorted trigonal bipyramidal geometries seen for the titanium(III) complexes, the metal centers in this titanium(II) species each adopt nearly ideal tbp geometries with P-Ti-P angles of 172-176 degrees. All three BH4 groups around each Ti atom are bidentate. One of the BH4 groups on each Ti center bridges between Ti and an ether-coordinated Li cation, again in an eta(2),eta(2) fashion. The relationships between the electronic structures and the molecular structures of all these titanium complexes are briefly discussed.

Journal Article↗
PubMed2006

Relations between structure, acidity, and activity of WOx/TiO2: influence of the initial state of the support, titanium oxyhydroxide, or titanium oxide.

Two series of WO(x)/TiO(2) catalysts, containing W surface densities up to 4.4 W atoms/nm(2), were prepared by pore volume impregnation of two different supports, titanium oxyhydroxide (amorphous) or titanium oxide (crystallized, 100% anatase). The influence of W surface density and the nature of the support on the surface structure, development of the acidity, and catalytic performances were examined. The texture and structure of the catalysts were investigated by Brunauer-Emmett-Teller measurements, X-ray diffraction (XRD), and Raman and infrared spectroscopy. The catalytic activity was tested for 2-propanol dehydration and n-hexane isomerization. For catalysts obtained by impregnation of titanium oxide, XRD and Raman results showed that W was present as a surface phase. Infrared spectra indicated an increase in the degree of polymerization of W species with increasing W surface density. CO and lutidine adsorption, followed by infrared spectroscopy, showed an increase in the strength and abundance of Brønsted acid sites (measured after lutidine desorption at 573 K) with the W surface density above a threshold of 1.3 W atoms/nm(2). The development of Brønsted acidity correlated with the evolution of the infrared bands attributed to polymerized W species. A direct relationship was observed between the concentration of Brønsted acid sites and the catalytic activity for 2-propanol dehydration. Catalytic activity, for n-hexane isomerization, appears to be associated with the presence of highly condensed W species. The catalysts synthesized by impregnation of titanium oxyhydroxide exhibited a comparable behavior. Hence, for a given W surface density, the W surface structure, concentration of Brønsted acid sites, and catalytic performances were similar. Thus, no significant effect of the initial form of the support (titanium oxyhydroxide versus titanium oxide; 100% anatase) was evidenced.

Journal Article↗
PubMed2000

Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride

Many reactive metals are difficult to prepare in pure form without complicated and expensive procedures. Although titanium has many desirable properties (it is light, strong and corrosion-resistant), its use has been restricted because of its high processing cost. In the current pyrometallurgical process--the Kroll process--the titanium minerals rutile and ilmenite are carbochlorinated to remove oxygen, iron and other impurities, producing a TiCl4 vapour. This is then reduced to titanium metal by magnesium metal; the by-product MgCl2 is removed by vacuum distillation. The prediction that this process would be replaced by an electrochemical route has not been fulfilled; attempts involving the electro-deposition of titanium from ionic solutions have been hampered by difficulties in eliminating the redox cycling of multivalent titanium ions and in handling very reactive dendritic products. Here we report an electrochemical method for the direct reduction of solid TiO2, in which the oxygen is ionized, dissolved in a molten salt and discharged at the anode, leaving pure titanium at the cathode. The simplicity and rapidity of this process compared to conventional routes should result in reduced production costs and the approach should be applicable to a wide range of metal oxides.

Journal Article↗
PubMed2002

[Histological observation of the interface of oral epithelium and titanium implant with titanium dioxide on the surface]

OBJECTIVE: To investigate the healing process at the interface between oral epithelium and a titanium implant with titanium dioxide on the surface and whether a good epithelial barrier could be formed. METHODS: Titanium implants with titanium dioxide on the surface were placed in the mandibular alveolar area of Beagle dogs after their premolars had been removed three months previous. On the 15th day, second month and loading second month after implantation specimens were taken and examined after HE staining as well as by transmission electron microscopy. RESULTS: Fifteen days after implantation the epithelial collar was formed, junctional epithelium actively regenerated and attachment to the matrix on the surface of the implant occurred by hemidesmosomes. Two months after implantation junctional epithelium was increasing, showing three to four layers consistent with each other. Junctional epithelium appeared to be generated when stimulated by inflammation and shaped into epithelium rete pegs after loading for two months. CONCLUSION: Oral junctional epithelium can attach very well to titanium implants with titanium dioxide on the surface which also provides a biological barrier.

Journal Article↗
PubMed1997

Hydroxyapatite-coating on titanium arc sprayed titanium implants.

We developed a new titanium spray technique using an inert gas shielded arc spray (titanium arc spray). Hydroxyapatite (HA)-coating can be applied to the implant without any surface pore obstruction after the rough surface is made by this technique. Scanning electron microscopy (SEM) of various porous implant surfaces after HA-coating revealed that the bead and fiber metal-coated implants had either a pore obstruction or an uneven HA-coating. On the other hand, the titanium arc sprayed implant demonstrated an even HA-coating all the way to the bottom of the surface pore. In the first set of animal experiments (Exp. 1), the interfacial shear strength to bone of four kinds of cylindrical Ti-6A1-4V (Ti) implants were compared using a canine transcortical push-out model 4 and 12 weeks after implantation. The implant surfaces were roughened by titanium arc spray (group A-C) and sand blasting (group D) to four different degrees (roughness average, Ra = group A: 56.1, B: 44.9, C: 28.3, D: 3.7 microns). The interfacial shear strength increased in a surface roughness-dependent manner at both time periods. However, the roughest implants (group A) showed some failed regions in the sprayed layers after pushout test. In the second set of animal experiments (Exp. 2), four kinds of Ti implants; HA-coated smooth Ti (sHA) with Ra of 3.4 microns, bead-coated Ti (Beads), titanium arc sprayed Ti (Ti-spray) with Ra of 38.1 microns and HA-coated Ti-spray (HA + Ti-spray) with Ra of 28.3 microns were compared using the same model as that in Exp. 1. The interfacial shear strength of HA + Ti-spray was significantly greater than that of sHA and Beads at both time periods, and that of Ti-spray at 4 weeks. Although a histological examination revealed that HA-coating enhanced bone ingrowth, sHA showed the lowest shear strength at both time periods. SEM after pushout test showed that sHA consistently demonstrated some regional failure at the HA-implant substrate interface. HA + Ti-spray had many failed regions either at the HA-bone interface or within the bone tissue rather than at the HA-implant substrate interface. These results suggested that the HA-coated smooth surfaced implants had a mechanical weakness at the HA-substrate interface. Therefore, HA should be coated on the rough surfaced implants to avoid a detachment of the HA-coating layer from the substrate and thus obtain a mechanical anchoring strength to bone. HA-coating on this new type of surface morphology may thus lead to a solution to the problems of conventional HA-coated and porous-coated implants.

Alloys↗
PubMed1982

Comparison of the elastic properties of nickel-titanium and beta titanium arch wires.

The elastic strength, stiffness, and range of two titanium alloys are compared as a function of wire configuration. From the four beta titanium and eight nickel-titanium sizes available, all arch wire permutations were evaluated both in bending and in torsion. Results show that the stiffnesses of the two alloy compositions overlap substantially, except for those wires with the lowest and the highest stiffnesses--that is, the 0.016 and 0.018 inch nickel-titanium and the 0.017 by 0.025 and 0.019 by 0.025 inch beta titanium arch wires, respectively. To conclude, both "variable-cross-section" and "variable-modulus" orthodontics are illustrated within the context of an equivalent wire stiffness chart which includes conventional stainless steel arch wires.

Dental Alloys↗
PubMed2003

Stress-relieving and porcelain firing cycle influence on marginal fit of commercially pure titanium and titanium-aluminum-vanadium copings.

OBJECTIVES: This study evaluated: (1) the marginal fit of copings fabricated from commercially pure titanium (cp Ti) and titanium-aluminum-vanadium alloy (Ti-6Al-4V) after each firing cycle for a recommended porcelain; and (2) the effectiveness of a stress-relieving treatment on the fit. The results were compared with copings made with Pd-Ag alloy submitted to the recommended porcelain firing protocol. METHODS: Bovine teeth were machined for metal-ceramic crowns and die casts were obtained for waxing patterns. The firing cycle of titanium porcelain was performed on cp Ti and Ti-6Al-4V copings obtained using the Rematitan System. A stress-relieving treatment (cp Ti treated and Ti-6Al-4V treated groups) was performed on original invested castings at the first porcelain firing temperature (800 degrees C). Fit (microm) was measured in the 'as cast' condition and after each porcelain firing cycle with a traveling microscope. The values were compared using the analysis of variance and Tukey's test (P<0.05), the Pd-Ag group was compared to titanium groups using Dunnett's test (P<0.05). RESULTS: The marginal fit values in the as-cast condition (initial) were 84.43 microm for Ti-6Al-4V not treated, 76.35 microm for Ti-6Al-4V treated, 86.09 microm for cp Ti not treated, 97.66 microm for cp Ti treated and 58.11 microm for Pd-Ag group. The Ti-6Al-4V, cp Ti, and Pd-Ag groups exhibit significant differences in marginal fit values when the as-cast condition (initial) was compared with those after the recommended porcelain firing protocol (by Tukey's test at 5% probability level). No significant differences were observed between stress-relieving treated and not treated groups.Significance. The firing cycles used for porcelain build-up may worsen the fit of titanium copings to values that suggest no inferences to the detriment of clinical applications.

Alloys↗
PubMed2006

Early results of titanium ossiculoplasty using the Kurz titanium prosthesis--a UK perspective.

Titanium has been shown to be a highly biocompatible material and recently interest has been raised by its use as a prosthetic material in the ear. Our objective was to prospectively assess the early results of titanium partial and total ossicular replacement prostheses in chronic ear disease. Thirty-three consecutive patients (20 titanium partials and 13 total ossicular replacement prostheses) were analysed and data from pre and post-operative pure tone audiograms were collected and compared at six months over a four frequency range (0.5-4 kHz) as well as using the American Academy of Otolaryngology-Head and Neck Surgery criteria (0.5-3 kHz). Closure of the air-bone gap and improvement in air conduction at six months was also calculated. 69% of patients obtained an air-bone gap of < or = 20 dB, with titanium partial ossicular replacement prostheses (85 per cent) doing better than total ossicular replacement prostheses (46 per cent). There have been no cases of sensorineural hearing loss or extrusion. In conclusion, titanium prostheses are easy to use, allow good visibility and have shown good short-term results in our hands.

Adolescent↗
PubMed1998

Quantitative and qualitative investigations of surface enlarged titanium and titanium alloy implants.

Screw shaped implants of commercially pure (c.p.) titanium and titanium-6aluminum-4vanadium (Ti6A14V) were blasted with particles of TiO2 of mean sizes of 25 microns (Group I) and 75 microns (Group II) and inserted in rabbit bone for 3 months. The surface roughness of the implants was examined and quantified with an optical scanning 3-dimensional instrument (TopScan 3D system), revealing the two alloy surfaces in each group had similar surface roughness. Biomechanical (removal torque) tests showed the c.p. titanium implants to be significantly more stable in the bone bed than those of Ti6A14V. In Group I, the c.p. titanium implants demonstrated a mean removal torque of 38 N cm while the Ti6A14V demonstrated a mean removal torque of 27 N cm (P = 0.004). Group II implants revealed a mean removal torque of 70 N cm for the c.p. ti and 50 N cm for the alloy samples (P = 0.003). The removal torque values were converted to shear forces/strengths by three calculation methods, based on (a) the entire length of the implant surface in the cortical region, (b) the thickness of the cortical bone measured in close vicinity to the thread peaks and (c) the bone-metal contact length measured on the non-unscrewed neighbouring implants. Group I: (a) the c.p. ti implants revealed a mean shear force of 4 vs a mean of 3 N/mm2 for the alloy samples. Shear strengths based on (b); were 8 for c.p. ti vs 6 N/mm2 for the alloy. The mean shear strength/force if calculated according to (c) revealed 23 for c.p. ti vs 18 N/mm2 for the alloy. Corresponding numbers for Group II; (a) c.p. ti 8 compared to 6 N/mm2 for the alloy, (b) c.p. ti demonstrated a mean value of 17 vs 11 N/mm2 for the alloy. According to method (c); c.p. ti had a mean shear strength of 26 vs 22 N/mm2 for the alloy samples. Histomorphometrical comparisons were performed on 10 microns thick undecalcified ground sections in the light microscope. In both Group I and Group II, the calculations of the mean bone-to-metal contact demonstrated more bone in contact to the c.p. titanium implants than to the Ti6A14V ones. Whereas comparisons of the bone volume inside the threads demonstrated slightly higher bone volumes around the alloy samples, no statistically significant difference was obtained between the two materials histomorphometrically.

Alloys↗
PubMed2000

Interfacial oxidations of pure titanium and titanium alloys with investments.

External oxides of a commercially pure titanium (cpTi), Ti6Al4V alloy, and an experimental beta-type titanium alloy (Ti 53.4 wt%, Nb 29 wt%, Ta 13 wt%, and Zr 4.6 wt%) were characterized after heating to 600, 900, 1150, and 1400 degrees C in contact with three types of investments (alumina cement, magnesia cement, and phosphate-bonded) in air. XRD studies demonstrated that MgO, Li2TiO3 and/or Li2Ti3O7 were formed through reactions with the metal and the constituents in the magnesia cement-investment after heating to 900, 1150, and 1400 degrees C. Except for these conditions, TiO2 (rutile) was only formed on cpTi. For titanium alloys, the other components apart from Ti also formed simple and complex oxides such as Al2O3 and Al2TiO5 on Ti6Al4V, and Zr0.25Ti0.75Nb2O7 on the beta-type titanium alloy. However, no oxides containing V or Ta were formed. These results suggest that the constituents of titanium alloys reacted with the investment oxides and atmospheric oxygen to form external oxides due to the free energy of oxide formation and the concentration of each element on the metal surface.

Alloys↗
PubMedDate not supplied

Formation of mineralizing osteoblast cultures on machined, titanium oxide grit-blasted, and plasma-sprayed titanium surfaces.

Altering osseous responses at implant surfaces to enhance bone is a current goal of clinical therapy. Cell culture may be used to investigate surface-dependent responses of bone-forming cells. In this report, the ability of primary fetal bovine mandibular osteoblast cultures to form a mineralizing matrix on machined, titanium plasma-sprayed, and titanium oxide grit-blasted surfaces has been compared. Immunohistochemical markers associated with bone formation were used to define the differentiated state of the formed matrix using qualitative light microscopy, and von Kossa staining was used to demonstrate the presence of mineralization within this matrix. Compared to either titanium oxide grit-blasted or machined surfaces, titanium plasma-sprayed surfaces displayed a unique pattern of mineralized matrix formation. Scanning electron microscopy further revealed that each surface accumulated unique organic and inorganic deposits during matrix formation, suggesting that surface-dependent physicochemical and biochemical conditioning of implant surfaces takes place. Surface topographic features of commercially pure titanium substrates can alter cultured osteoblast extracellular matrix formation and mineralization. Similar molecular and cellular assessment of in vivo responses to implant surface topography may contribute to improved engineering of endosseous implants.

Animals↗
PubMed1990

Semiconductive properties of passivated titanium and titanium based hard coatings on metals for implants--an experimental approach.

Titanium is used in the field of dental implants on account of the fact that they are integrated into body tissue virtually reaction-free. This integration is made possible by the passivated layers which form within the body electrolyte, and which can be described in the terms of a semiconductive solid body. A prerequisite, however, is the prevention of relative movement between the implant and the tissue so that the passivated layer is not destroyed. The low resistance to shearing, and the oxide stoichiometry--which under in vivo conditions cannot be influenced--on repassivation following mechanical destruction strongly suggest that, during fabrication, implants should be provided with wear-resistant coatings having defined solid state properties which are similar to those of electrochemically passivated titanium surfaces. In the clinical test are already employed, a (Ti,Nb)ON- and a (Ti,Zr)O-coating on titanium and TiAl5Fe2.5. One of the most important parameters for the solid body-physical description of semiconductive hard coatings is the energy gap between conduction and valence band of the electronic structure, which are determinative for the physical-chemical behaviour of the implant surface within the body. The contribution describes the experimental procedure and the results of determinations of the energy gap at singularities in the Brillouin zone for titanium, the titanium alloys in clinical use, and some hard coatings in clinical test. The experimental method of choice for surfaces in contact with aqueous electrolytes is the electroreflectance spectroscopy.

Alloys↗
PubMed1995

[Morphological transformation of BHK-21 cells by nickel titanium shape memory alloy particles encapsulated by titanium oxide].

The special treatment process formed a compact titanium oxide thin film on the surface of medical nickel titanium shape memory alloy (NiTiSMA) particles (< or = 5 microns). The BHK-21 cells were cultivated in 10% infant calf serum containing NiTiSMA particles and NiTiSMA particles encapsulated by titanium oxide respectively, and morphological transformation clones were observed. The results showed that NiTiSMA particles induced obviously morphological transformation clones, and that NiTiSMA particles induced obviously morphorogical transformation of BHK-21 cells (the rate of morphological transformation clones was 13.46%), especially in TPA medium. The rate of morphological transformation in the group containing NiTiSMA particles was not more significantly different than that in the positive control group. The rate of morphological transformation in the group containing NiTiSMA particles encapsulated by titanium oxide was not more significantly different than that in the negative control group, but significantly different than that in the NiTiSMA particles group. Therefore, it is possible that NiTiSMA particles are directly carcinogenic and that NiTiSMA particles encapsulated by titanium oxide are not potentially carcinogenic.

Alloys↗