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PubMed1997

Modulation of the production of cytokines in titanium-stimulated human peripheral blood monocytes by pharmacological agents. The role of cAMP-mediated signaling mechanisms.

Cytokines secreted by activated macrophages play a role in the development of osteolysis adjacent to prosthetic joints. To determine whether the synthesis of cytokines can be inhibited by pharmacological agents, we studied the role of the cAMP-protein kinase A signal transduction pathway in the synthesis of interleukin-6 and tumor necrosis factor-alpha and examined the effect of potential pharmacological regulators of this pathway in human peripheral blood monocytes stimulated with titanium particles. Dibutyryl cAMP enhanced the synthesis of interleukin-6 by titanium-stimulated monocytes and resulted in a marked increase (maximum, seventyfold) in the synthesis of interleukin-6 even in the absence of titanium particles. However, the active analogs (agonists) of cAMP, dibutyryl cAMP and Sp cAMP, inhibited the production of tumor necrosis factor-alpha by titanium-stimulated monocytes (the maximum effects resulted in complete inhibition), while the cAMP antagonist, Rp cAMP, enhanced the production of tumor necrosis factor-alpha. Additional agents that alter the intracellular levels of cAMP were examined for their effects on the synthesis of cytokines. Prostaglandins E1 and E2 were potent inhibitors of the synthesis of tumor necrosis factor-alpha but stimulated the synthesis of interleukin-6. In contrast, indomethacin enhanced the stimulatory effects of titanium particles on tumor necrosis factor-alpha, resulting in a more than threefold increase in the maximum levels of tumor necrosis factor-alpha. Phosphodiesterase inhibitors, such as isobutyryl methylxanthine and pentoxifylline, which increase intracellular levels of cAMP, caused a decrease in the production of tumor necrosis factor-alpha and an increase in the production of interleukin-6. In contrast, the fluoroquinolone antibiotic ciprofloxacin, which is also a phosphodiesterase inhibitor, caused a dose-dependent inhibition of the synthesis of both tumor necrosis factor-alpha and interleukin-6 by titanium-stimulated monocytes, suggesting that ciprofloxacin suppresses the synthesis of interleukin-6 through a mechanism that is independent of cAMP.

Bucladesine↗
PubMed2001

Titanium particles stimulate bone resorption by inducing differentiation of murine osteoclasts.

BACKGROUND: Loosening of orthopaedic implants is mediated by cytokines that elicit bone resorption and are produced in response to phagocytosis of implant-derived wear particles. This accelerated bone resorption could be due to increased osteoclastic activity, survival, or differentiation. Although a number of in vitro studies have shown that wear particles increase osteoclastic activity, the increase was less than twofold in all cases. The objective of the current study was to test the hypothesis that wear particles stimulate bone resorption by inducing osteoclast differentiation. METHODS: Conditioned media were prepared from murine marrow cells or human peripheral blood monocytes incubated in the presence or absence of titanium particles. The effects of conditioned media on osteoclast differentiation were examined with use of a recently developed assay in which osteoclast precursors are co-cultured with mesenchymal support cells. RESULTS: The present study showed that titanium particles induced both murine marrow cells and human peripheral blood monocytes to produce factors that stimulated osteoclast differentiation. The mean increase in osteoclast differentiation was 29.3+/-9.4-fold. The stimulation of osteoclast differentiation led to a parallel increase in bone resorption. The amount of stimulation was regulated in a dose-dependent manner by the concentration of both titanium particles and conditioned media. The stimulation of osteoclast differentiation required interactions between the cells and the particles themselves and, therefore, was not due to metal ions, soluble contaminants released from the particles, or submicrometer particles. In contrast, conditioned media from control cells incubated in the absence of titanium particles had no detectable effect on any of the examined parameters. CONCLUSIONS: The present study showed that titanium particles stimulate in vitro bone resorption primarily by inducing osteoclast differentiation. In contrast, the titanium particles had only small effects on osteoclast activity or survival.

Adult↗
PubMed2005

[Effect of surface modification using laser on wear resistance of titanium].

PURPOSE: Severe wear of cast commercial pure (CP) titanium teeth was observed in a clinical survey. This study evaluated the wear resistance of cast CP titanium and titanium alloy teeth after the surface was modified using laser technology. METHODS: Teeth patterns were duplicated from artificial first molars (Livdent FB30, GC, Japan). All teeth specimens were cast with CP Ti grade 3 (T-Alloy H, GC) and Ti-6Al-7Nb (T-Alloy Tough, GC). After the occlusal surface was blasted with Al(2)O(3), the occlusal contact points were modified using a laser (Neo laser L, Girrbach, Germany) at the following irradiation conditions (voltage: 260 V; pulse: 7 ms; focus: 1.5 mm). These parameters were determined by preliminary study. As a control, Type IV gold alloy (PGA-3, Ishifuku, Japan) was also cast conventionally. Both maxillary and mandibular teeth were worn using an in vitro two-body wear testing apparatus that simulated chewing function (60 strokes/min; grinding distance: 2 mm under flowing water). Wear resistance was assessed as volume loss (mm(3)) at 5 kgf (grinding force) after 50,000 strokes. The results (n=5) were analyzed by ANOVA/Scheffé's test (alpha=0.05). RESULTS: The gold alloy showed the best wear resistance of all the metals tested. Of all the titanium specimens tested, the modified surface indicated significantly greater wear resistance than did conventional titanium teeth without surface modification (p<0.05). CONCLUSIONS: Wear resistance was increased by modification of the surface using a laser. If severe wear of titanium teeth was observed clinically, little wear occurred when the occlusal facets were irradiated using a laser.

Dental Materials↗
PubMed1987

Titanium implants in rabbit knee joints.

The subchondral bone, cartilage, and synovial tissue adjacent to nonalloyed titanium screws were morphologically evaluated 2, 4, and 6 weeks after insertion in rabbit knee joints. The titanium screws were in direct contact with the surrounding bone. Two weeks postoperatively, bone resorption, as well as formation of new bone on the titanium surface, was evident. The observed inflammatory process was transient, and the amount of bone within the screw threads increased progressively with time. The articular cartilage regenerated and covered the titanium screws. Synovial tissue also regenerated and covered the screws when inserted into a noncartilaginous area of the joint. These findings, together with recent findings in soft tissues, indicate that titanium provides an inert surface for the proliferation of differentiating tissues in vivo. These data, supported by the observation that no inflammation was present in the synovial tissue, suggest that nonalloyed titanium can be used safely intraarticularly.

Animals↗
PubMed2003

Ions released from dental amalgams in contact with titanium.

The ions released from conventional and high-copper amalgams in contact with titanium were quantitatively analyzed in a 0.9% NaCl solution at 37 degrees C when the surface area ratio of titanium/amalgam was set up as 1/10, 1/1, or 10/1. The corrosion potentials of the amalgams and titanium were measured under the same conditions. Surface analyses on the amalgams were also employed using SEM with WDS. Though the potential of the conventional amalgam was always lower than that of titanium, that of the high-copper amalgam was reversed during the early stage of immersion and remained lower. When the surface area ratio of titanium grew at 10/1, tin and copper ions released from the conventional and high-copper amalgam, respectively, increased significantly compared with those of each amalgam that was not in contact with titanium. The galvanic corrosion in such a large surface area of titanium possibly led to the heavy corrosion of the amalgams.

Copper↗
PubMed2005

Immobilization of octadecyl ammonium chloride on the surface of titanium and its effect on microbial colonization in vitro.

The aim of our study was twofold: to immobilize an organosilicon quaternary ammonium salt (3-(trimethoxysilyl)-propyldimethyl-octadecyl ammonium chloride, Si-QAC) on the surface of pure titanium and to investigate the antimicrobial activity of Si-QAC-immobilized titanium against microbial adherence and biofilm formation. The results of ToF-SIMS analysis of Si-QAC-titanium suggested the possibility of immobilizing Si-QAC on titanium surface through Ti-O-Si coupling, and that Si-QAC treatment significantly reduced both the adherence and colonization of Candida albicans and Streptococcus mutans isolates. The antimicrobial activity was achieved through at least two mechanisms: the first was attributed to the octadecyl alkyl chain which inhibited initial adherence, and the second was attributed to the quaternary ammonium salt which killed initial adherent cells as well as retarded or inhibited subsequent microbial growth. Further, thermocycling did not significantly reduce the antimicrobial activity of Si-QAC-titanium, and no significant cytotoxicity of Si-QAC-titanium was observed in either cell viability test or proinflammatory cytokine production test using human gingival fibroblasts. These results, taken together, favorably suggested that Si-QAC treatment would be a helpful means to inhibit dental plaque or denture plaque formation.

Analysis of Variance↗
PubMed1989

[Study on biocompatibility of titanium alloys].

The biocompatibility of two different titanium alloys, Ti-6Al-4V ELI and Ti-5Al-2, 5Fe, and pure titanium were evaluated. The results were as follows: 1) Titanium alloys were implanted into the dorsal subcutaneous tissues of the Hartley guinea-pig for 12 weeks, immersed in calf serum or in Ringer's solution for 8 weeks. The surface changes of the titanium alloys were observed by SEM and the chemical composition was analyzed by XMA. No evident surface changes were found. 2) Three hundred mg, 200 mg and 100 mg of the powders of the tested materials were immersed in 2ml of Eagle's MEM, incubated for 1-7 days, 8-21 days and 22-70 days at 37 C degrees. The amount of metallic elements dissolved in the solutions was measured by ICP and AAS. The detected corrosion rates of V and Al contained in the solution, in which Ti-6Al-4V ELI 100 mg was immersed for 1-7 days, were 194.3 +/- 17.6 and 73.0 +/- 28, 1 pg/mg alloy/day, respectively. V was released more than Al. The amount of Ti was below the detectable limit. The solution Ti-5Al-2.5 Fe 100 mg immersed for 1-7 days contained 31.9 +/- 34.4 pg/mg alloy/day Fe and 25.7 +/- 6.3 pg/mg alloy/day Al. Only in the solution 300 mg immersed for 1-7 days was Ti detected at 1.4 pg/mg alloy/day. 3) By the bacterial mutation assay of Salmonella typhimurium TA 98, Salmonella typhimurium TA 100 and Escherichia coli WP2 uvrA, the solutions, in which the tested materials were immersed, were not found to be mutagenic. 4) By the UDS assay, the grain counts on autoradiography with the solutions, in which the tested materials were immersed, were not greater than the negative control. The results suggest an excellent corrosion resistance of the titanium alloys. Mutagenicity was negative by these mutation assays, indicating that the tested alloys and pure titanium are safe for humans and animals.

Animals↗
PubMed2004

[Development and evaluation of a new surface treatment method for titanium alloy implants].

We developed and evaluated a new method of titanium surface treatment for direct bone fixation of implants. This method consists of hydroxyapatite (HA) flame coating onto a porous titanium surface which is arc-sprayed with pure titanium material in argon gas at atmospheric pressure. The surface roughness of the porous layer was 360 μm, Rmax, and showed higher resistance to blast erosion in comparison with the conventional low-pressure plasma-sprayed porous layers of titanium. The thickness of the HA layer was between 20 and 40 μm considering the balance of bone conduction effect of HA and the possibility of mechanical detachment of the layers from the porous titanium. Short-term animal tests showed excellent results. This new surface treatment method was applied to cementless total hip joints which were used clinically. The results obtained from observations of the retrieved specimens show that the thickness of the HA coating layer is sufficient for the new bone formation after implantation. It was concluded that the new surface treatment method for titanium alloy implants is effective and successful for direct bone fixation.

Alloys↗
PubMedDate not supplied

Laser-welded titanium frameworks for implant-supported fixed prostheses: a 5-year report.

The 5-year results from a multicenter study of implant-supported, laser-welded titanium frameworks are reported here as a complement to earlier reported 2-year results. Implant survival rates were satisfactory for patients with titanium frameworks and for a control group of patients with gold-alloy frameworks. At the 5-year review, more patients with titanium frameworks had lost implants than the patients with gold-alloy frameworks, but this difference was not statistically significant. More fractures of the titanium frameworks occurred, compared to the gold-alloy frameworks; again, this difference was not statistically significant. No significant differences in marginal bone levels were found between the 2 groups of patients. Slightly more fractures of artificial teeth occurred in patients with titanium frameworks than in patients with gold-alloy frameworks. Overall results for the titanium frameworks after 5 years in function are encouraging.

Alveolar Process↗
PubMedDate not supplied

Cleaning and heat-treatment effects on unalloyed titanium implant surfaces.

This study tested the following hypotheses: (1) acid-cleaned and passivated unalloyed titanium implants have higher surface energies (which are considered desirable for bone implants) than ethanol-cleaned titanium; (2) higher temperatures of heat treatment of unalloyed titanium result in higher surface energies; and (3) these changes can be related to changes in surface composition and roughness. Thus, unalloyed titanium specimens were either acid-cleaned and passivated (CP) or ethanol-cleaned (Et). Each set was then divided into 3 groups and heat-treated for 1 hour at 316 degrees C (600 degrees F), 427 degrees C (800 degrees F), and 538 degrees C (1,000 degrees F), respectively. Surface roughness values for each of these groups were determined using atomic force microscopy, while surface compositions were determined using Auger electron, x-ray photoelectron, and Raman spectroscopic techniques. Surface energies were estimated using a 2-liquid geometric mean technique and correlated with surface roughness, elemental composition, and elemental thickness. The CP surfaces were slightly rougher than the Et specimens, which had greater oxide thickness and hydrocarbon presence. The surface oxides were composed of TiO2, Ti2O3, and possibly titanium peroxide; those heat-treated at 427 degrees C or above were crystalline. The CP specimens had carbonaceous coverage that was of a different composition from that on Et specimens. The CP specimens had significantly higher surface energies, which showed statistically significant correlations with oxide thickness and carbonaceous presence. In conclusion, ethanol cleaning of unalloyed titanium dental implants may not provide optimal surface properties when compared to cleaning with phosphoric acid followed by nitric acid passivation.

Analysis of Variance↗
PubMed2003

[The effect on anti-acid corrosion resistance of Ni-Cr alloy coating titanium].

OBJECTIVE: The aim of this study was to investigate the variation of the corrosion resistance of Ni-Cr alloy in acid environment before and after coating titanium in vitro. METHODS: 1. Surface treatment using sol-gel technique of coating titanium. The steps were as follows: (1) Pre-treatment: sanding, washing and activation in order to remove the oxidative product; (2) The preparation of sol: some small charged particles produced by the hydrolytic reaction, and formed sol. These particles would congeal into extremely small ones (diameter usually is 5 microns); (3) Coating; (4) Heat treatment: The organism was resolved and volatilizeed at high temperature, and the atoms of Ti were left. These atoms of Ti were very active and could combine firmly with the atoms on the surface awaiting of treatment. 2. CONDITIONS: artificial saliva; pH = 7.0 and pH = 5.6; temperature: 36.5 degrees C 3. Electrochemical test: polarization curve; instrument: ZF-3 poteniostat. RESULTS: Before coating titanium, when pH was 7.0, the electrode potential of Ni-Cr alloy was -160 mV, and the self-corrosion current density was 0.262 microA cm-2; when pH = 5.6, the data were -182 mV and 0.352 microA cm-2, respectively. This result showed that when pH value reduced, the potential and current density descended, too. This indicated that the material was easy to be corroded. After coating titanium, when pH value was 7.0, the potential was -71 mV, the self-corrosion current density was 0.152 microA cm-2; when pH = 5.6, the data were -89 mV and 0.174 microA cm-2. This indicated that the corrosion rate of material descended evidently after coating titanium in acid environment. CONCLUSION: (1) Not only before coating Ti but also after coating, the corrosion resistance of Ni-Cr alloy would descend in acid environment;(2) In acid environment, the corrosion resistance of Ni-Cr alloy after coating titanium was superior to that of the material before coating. So was in neutral environment.

Chromium↗
PubMed1992

The castability of unalloyed titanium in three different casting machines.

The general demand for a variety of fine detail work made of titanium has resulted in the development of equipment/systems for the casting of this metal. Dental casting machines suitable for the casting of titanium are now also available. The aim of the present study was therefore to evaluate the possibility of precision casting of dental crown restorations of unalloyed titanium. The three kinds of casting equipment currently used in Sweden were tested by evaluating the crown edge diameter of 10 titanium crowns processed by each one of the titanium casting machines. The results revealed that clinically acceptable margins can be obtained but also that further improvements in processing have to be achieved before titanium casting can be considered as uncomplicated as the casting of traditional dental gold alloys.

Crowns↗
PubMedDate not supplied

Improved retention and bone-tolmplant contact with fluoride-modified titanium implants.

PURPOSE: The purpose of the present study was to investigate whether a fluoride modification of the titanium surface would have an effect on bone response after implantation. MATERIALS AND METHODS: Titanium-oxide-blasted titanium implants with and without fluoride modification were investigated in a rabbit tibia model. Quantitative analysis of surface roughness, biomechanical interlocking, and in vivo tissue reactions in rabbit bone at 1 and 3 months after placement were compared. RESULTS: The fluoride-modified test implants had a slightly smoother surface (Sa: 0.91 +/- 0.14 microm) than the unmodified control implants (Sa: 1.12 +/- 0.24 microm). Significantly higher removal torque values (85 +/- 16 Ncm vs 54 +/- 12 Ncm) and shear strength between bone and implants (23 +/- 9 N/mm2 vs 15 +/- 5 N/mm2) were measured for the fluoride-modified implants after 3 months. The histomorphometric evaluations demonstrated higher bone-to-implant contact for test implants at 1 month (35% +/- 14% vs 26% +/- 8%) and 3 months (39% +/- 11% vs 31% +/- 6%) after placement. DISCUSSION: Implant surface modification with fluoride may result in morphologic and physiochemical phenomena that are of significance for the bone response. Another possible explanation for the findings in the present study is that a surface modification changes the surface chemical structures to be more suitable for bone bonding. CONCLUSION: Based on the biomechanical and histomorphometric data, the fluoride-modified titanium implants demonstrated a firmer bone anchorage than the unmodified titanium implants. These implants achieved greater bone integration than unmodified titanium implants after a shorter healing time.

Animals↗
PubMedDate not supplied

Different titanium surfaces modulate the bone phenotype of SaOS-2 osteoblast-like cells.

Commercially pure titanium implants presenting a relatively smooth, machined surface or a roughened endosseous surface show a large percentage of clinical success. Surface properties of dental implants seem to affect bone cells response. Implant topography appears to modulate cell growth and differentiation of osteoblasts affecting the bone healing around the titanium implant. The aim of the present study was to examine the effects of 1cm diameter and 1mm thick titanium disks on cellular morphology, adhesion and bone phenotypic expression of human osteoblast-like cells, SaOS-2. SaOS-2 cells were cultured on commercially 1 cm pure titanium disks with three different surface roughness: smooth (S), sandblasted (SB) and titanium plasma sprayed (TPS). Differences in the cellular morphology were found when they were grown on the three different surfaces. An uniform monolayer of cells recovered the S surface, while clusters of multilayered irregularly shaped cells were distributed on the rough SB and TPS surfaces. The adhesion of SaOS-2 cells, as measured after 3h of culture, was not affected by surface roughness. ECM components such as Collagen I (CoI), Fibronectin (FN), Vitronectin (VN) and Tenascin (TN) were secreted and organized only on the SB and TPS surfaces while they remained into the cytoplasm on the S surfaces. Osteopontin and BSP-II were largely detected on the SB and TPS surfaces, while only minimal production was observed on the S ones. These data show that titanium surface roughness affects bone differentiation of osteoblast like-cells, SaOS-2, indicating that surface properties may be able to modulate the osteoblast phenotype. These observations also suggest that the bone healing response around dental implants can be affected by surface topography.

Bone and Bones↗
PubMedDate not supplied

Attachment of oral gram-negative anaerobic rods to a smooth titanium surface: an electron microscopy study.

PURPOSE: Attachment of bacteria to titanium may differ not only between bacterial species but also between strains within a species. The aim of the present in vitro study was to examine differences in bacterial attachment using 4 gram-negative anaerobic species of bacteria that are considered potential periodontal pathogens. MATERIALS AND METHODS: The attachment of clinical and laboratory strains (n = 23) representing 2 Fusobacterium nucleatum subspecies, Porphyromonas gingivalis, and Prevotella intermedia to smooth, commercially pure titanium was examined using scanning electron microscopy. RESULTS: All bacterial strains were attached to the smooth titanium surface by their outer membrane. F nucleatum cells were poorly attached to the titanium, unlike P gingivalis or P intermedia cells, but only slight differences were observed in the quantity of attached cells between the strains within each bacterial group. DISCUSSION: In favorable conditions, some anaerobes can attach directly to an inert titanium surface. Microbial adhesion and subsequent colonization on the dental implant surface can lead to infection of the peri-implant tissue. CONCLUSION: The results indicated that the avidity of bacterial attachment to a smooth titanium surface varies between species of oral gram-negative anaerobes but not between strains.

Bacterial Adhesion↗
PubMed2005

[Influence of different-sized titanium particles loading on osteoblastic differentiation and mineralization].

Studies have recently suggested that the coupling mechanism of bone formation and bone resorption are affected by particulate wear debris inducing aseptic loosening around the bone-prosthesis microenviroment. There may be direct impacts on osteoblasts, resulting in net decrease in bone formation. In addition, the influences of particulate wear debris in different size on the osteogenesis should be various. In order to investigate the hypothesis that particulate wear debris derived from prosthetic biomaterials affects the osteogenesis of osteblasts, we studied the influence of different-sized titanium particles loading on the osteoblastic differentiation by assaying the secretion of alkaline phosphatase (ALP), osteocalcin (OCN), N-terminal type I procollagen (PINP), and on the osteoblastic mineralization with the use of calcified node number, calcified node area and Alizarin Red S (ARS) concentration. Upon in vitro culture in the absence of titanium particles, we observed that cultures of osteoblasts isolated from newborn Japanese rabbits' cranium were excellently capable of differentiation and mineralization. Phi6.9 microm titanium particles did not evidently alter osteoblastic differentiation and mineralization. In comparison, phi2.7 microm and phi0.9 microm titanium particles, especially phi0.9 microm (submicron), significantly suppressed ALP expression, reduced PINP production, decreased OCN secretion and inhibited matrix mineralization. Results of transmission electron microscopy (TEM) of titanium particles-loaded osteoblastic cultures revealed that osteoblasts phagocytized titanium particles and exhibited ultrastructional changes consistent with cellular dysfuction. Combined with our previous studies in vitro findings, these results suggest that particles size play a key role in the process of aseptic loosening, which submicron particles are closely associated with inhibition of bone formation while bigger particles with enhancement of bone resorption. Further understanding the nature of osteoblastic bioreactivity to different-size wear particles should provide additional insights into mechanisms underlying aseptic loosening.

Animals↗
PubMed2005

[Radiotherapy for immediate reconstruction of mandibular defects with the titanium plate after tumor resection of mandible].

OBJECTIVE: To study the influence of radiotherapy on immediate reconstruction with the titanium plate after resection of mandible in oral cancer patients. METHODS: Fifty-eight cases (radiation group, 30 patients and control group, 28 patients) with titanium plate for immediate reconstruction of mandibular defects were observed from January, 1997 to May, 2002. The patients of radiation group underwent radiotherapy with total doses of 4,050 - 6,540 cGy (mean 5,495 cGy). The titanium plate was in radiation fields and was irradiated during the radiation therapy. RESULTS: Local infection and fistula accounted for 6 cases and plate exposure accounted for 5 in radiation group. Local infection and plate exposure happened in 4 and 3 patients in control group respectively. Titanium plates were taken in six cases in radiation group and 4 cases in control group by re-surgery 4 - 15 months after primary surgery because of local infection. The success rates of immediate reconstruction with the titanium plate were 80.0% (24/30) in radiation group and 85.7% (24/28) in control group (P > 0.05). CONCLUSIONS: The cases of immediate reconstruction with the titanium plate after resection of mandible in oral cancer patients can accept postoperative radiotherapy.

Aged↗
PubMedDate not supplied

Nonalloyed titanium as a bioinert metal--a review.

Titanium is used for many dental applications and instruments, such as orthodontic wires, endodontic files, dental implants, and cast restorations. The popularity of titanium is primarily due to its good mechanical properties, its high corrosion resistance, and its excellent biocompatibility. A thorough review of the medical and dental literature reveals, however, that titanium can also cause chemical-biological interactions. Tissue discoloration and allergic reactions in patients who have come in contact with titanium have been reported. The biostability of titanium is becoming increasingly questioned. At the same time, new technologies and materials, such as high-performance ceramics, are emerging which could replace titanium in dentistry in the not-too-distant future.

Allergens↗