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PubMed2000

A prospective multicenter clinical trial comparing one- and two-stage titanium screw-shaped fixtures with one-stage plasma-sprayed solid-screw fixtures.

BACKGROUND: Brånemark fixtures were originally placed in two stages, whereas titanium plasma-sprayed (TPS) solid-screws are placed in one stage. Long-term survival rates for both types of implants are excellent. Excellent survival rates have also been reported for machined screw-shaped (MS) titanium implants placed in one stage. A small number of studies have compared different implant systems and methods of implant placement. PURPOSE: The purpose of this study is to report clinical outcomes from a prospective longitudinal, multicenter study comparing Brånemark MS fixtures (Nobel Biocare, Yorba Linda, California, USA) placed in either one or two stages with a one-stage TPS system (ITI Straumann, Waldenburg, Switzerland). METHODS: A protocol was designed to compare implant survival rates, changes in crestal bone for titanium MS fixtures placed in one and two stages, and plasma-sprayed solid-screw fixtures placed in one surgical stage. Twenty-nine patients ranging in age from 24 to 82 years received MS fixtures in one stage. The average age for males was 58 years (n = 11), whereas the ages for females (n = 18) ranged from 15 to 84 years (average 58 years). Twenty-nine patients received machined titanium fixtures placed in two stages. There were 20 females ranging in age from 23 to 74 years (average 54 years) and 9 females ranging from 24 to 74 years (average 46 years). Twenty-five patients received TPS fixtures. There were 15 males, ranging in age from 57 to 79 (average 70), and 10 females, ranging in age from 40 to 83 years (average 62 years). Bone quality and quantity were determined from radiographs and during site preparation. Patient age, sex, location of implant placement according to jaw, length of fixtures, and number of lost fixtures were entered onto computer code sheets and continuously entered into a locked computer system. For one- and two-stage MS fixtures, nonstandardized periapical radiographs were taken at abutment connection and follow-up. Solid screws were x-rayed at prostheses connection and follow-up. The average time between implant restoration and radiographic follow-up was 15 months. The x-rays were scanned into a computer, and a program designed to measure radiographs was used to determine changes in crestal bone. Measurements for one- and two-stage MS fixtures were made from the top of the implant shoulder to the first bone to implant contact mesial and distally. Plasma-sprayed screws were measured from the bottom of the implant to the coronal most bone to implant contacts mesial and distally. Mesial-distal radiographic measurements were averaged and changes were compared using the t-test for related samples. RESULTS: This report presents data from the 2- to 3-year follow-up examinations. Twenty-nine patients received 80 one-stage MS fixtures. Between 0 and 1 year, two fixtures were lost, resulting in a 97.5% cumulative survival rate (CSR). The CSR remained unchanged through the 2- to 3-year follow-up. Twenty-eight patients received 78 two-stage MS fixtures. One implant was lost prior to loading and two were lost between 0- and 1-year follow-up, yielding a 96.2% CSR at the end of 1 year. The CSR remained unchanged through the 2- to 3-year follow-up. Twenty-three patients received 78 solid-screw plasma-sprayed screws. One implant was lost prior to loading and one between the 0- to 1-year follow-up, accounting for a 97.4% CSR at the 2- to 3-year follow-up. Changes in bone crest measurements for one-stage titanium threaded fixtures were insignificant (-0.11 mm, p = .08, maxillary; 0.07 mm, p = .42, mandibular). For two-stage MS fixtures, crestal bone loss was insignificant in maxillae (-0.16 mm, p = .92) and significant in mandibles (-0.43 mm, p = .000). There was significant bone loss for TPS implants in maxillae and mandibles (maxillae, 1.31 mm, p = .04; mandibles, 0.98 mm, p = .000). CONCLUSIONS: Cumulative survival rates for MS fixtures placed in one and two stages as well as one-stage TPS screws up to the 2- to 3-year follow-up examination were similar, indicating excellent clinical results. Radiographic measurements for changes in crestal bone loss were clinically insignificant for fixtures placed in one stage. For two-stage fixtures, maxillary changes were insignificant, whereas mandibular bone loss was statistically significant but clinically insignificant. Changes in crestal bone loss for TPS implants were statistically significant.

Adolescent↗
PubMed2002

Properties of titanium dioxide films prepared by reactive electron-beam evaporation from various starting materials.

There is a wide choice of starting materials for the production of titanium dioxide films by reactive electron-beam evaporation. We have investigated the specific merits of these materials in terms of refractive index, stress, and abrasion resistance of the resultant titanium dioxide films. The suboxides TiO, Ti2O3, and Ti3O5 as well as titanium dioxide and titanium metal were reactively evaporated, and titanium dioxide films free of absorption were obtained on substrates at 25 and 250 degrees C. On unheated substrates the refractive index, which varies from 2.06 to 2.22, the stress, and the abrasion resistance all depend on the starting material used. On substrates heated to 250 degrees C the refractive indices of all films lie closely about 2.4, and all films show high tensile stress and good abrasion resistance.

Journal Article↗
PubMed1979

Bioassay of titanium dioxide for possible carcinogenicity.

A bioassay of titanium dioxide for possible carcinogenicity was conducted by administering the test chemical in feed to Fischer 344 rats and B6C3F1 mice. Groups of 50 rats of each sex and 50 mice of each sex were administered titanium dioxide in the diet at one of two doses, either 25,000 or 50,000 ppm, for 103 weeks and then observed for 1 additional week. Matched controls consisted of 50 untreated rats of each sex and 50 untreated mice of each sex. All surviving rats and mice were killed at 104 weeks. Administration of the titanium dioxide had no appreciable effect on the mean body weights of rats or mice of either sex. With the exception of white feces, there was no other clinical sign that was judged to be related to the administration of titanium dioxide. Survival of the rats and the male mice at the end of the bioassay was not affected by the test chemical; mortality in female mice was dose related. Sufficient numbers of dosed and control rats and mice of each sex were at risk for development of late-appearing tumors. In the female rats, C-cell adenomas or carcinomas of the thyroids occurred at incidences that were dose related (P=0.013), but were not high enough (P=0.043 for direct comparison of the high-dose group with the control group) to meet the level of P=0.025 required by the Bonferroni criterion (controls 1/48, low-dose 0/47, high-dose 6/44). Thus, these tumors of the thyroid were not considered to be related to the administration of the test chemical. In male and female mice, no tumors occurred in dosed groups at incidences that were significantly higher than those for corresponding control groups. It is concluded that under the conditions of this bioassay, titanium dioxide was not carcinogenic by the oral route for Fischer 344 rats or B6C3F1 mice.

Journal Article↗
PubMed2003

Penetration depth of nickel titanium and stainless steel finger spreaders in curved root canals.

OBJECTIVE: To compare, radiographically, the differences in the penetration depths of nickel titanium and stainless steel finger spreaders in curved root canals. DESIGN: A comparative study. PLACE AND DURATION OF STUDY: The study was carried out at Armed Forces Institute of Dentistry, Rawalpindi, Pakistan, from September 2001 to June 2002. MATERIALS AND METHODS: Fifty patients with curved mesial canals of their mandibular first molars were randomly selected for the study. The angle of curvature for each root canal was radiographically determined before instrumentation. Canals were prepared by K flexo file using the step back preparation technique. The apical preparation was done upto no. 30 and cervical flaring upto no. 45. Gates Glidden drills nos. 2-4 were used in the cervical 2-3 mms of the canal.A no. 20 stainless steel and a fine medium nickel titanium finger spreader were inserted alternately into the same prepared canal and radiographed using the paralleling technique. The distance from the tip of the spreader to the apex of the root was measured radiographically by vernier calliper. RESULTS: Penetration of nickel-titanium finger spreader was significantly (p<0.05) deeper than the stainless steel spreader of comparable size. The ease of stainless steel penetration decreased with increasing angle of curvature of the canal. CONCLUSION: Nickel-titanium spreaders may give better results for lateral condensation in curved canals because of their deeper penetration.

Adolescent↗
PubMed1996

Evolution of the bone-titanium interface on implants coated/noncoated with xenogeneic bone particles: quantitative microscopic analysis.

Titanium cylinders having a sandblasted surface were implanted in holes drilled in the internal condyles of rabbit femurs. The right side received a titanium implant coated with xenogeneic bone particles and the left side received a titanium cylinder alone and was used as control. The femoral extremities were removed at 1, 2, and 3 months postsurgery and embedded undecalcified in methacrylic resins. Sections were studied by quantitative analysis and the interface contact between bone and titanium was measured at two microscopic magnifications due to the fractal dimension of this parameter. In addition the amount of bone volume in a given referent volume provided automatically by the image analyzer was obtained. No differences could be evidenced between the two series of implants, supporting the view that xenogeneic particles were ineffective in improving the attachment of bone to the implant. The bone-to-implant interface measured at the low magnification reflected the anchorage of the implant. In both series a progressive increase upon time of the bone-to-implant interface at the highest microscopic magnification evidenced the importance of late remodeling changes responsible for bone bonding and the fractal characteristics of this interface, related to surface quality of the implant responsible for stress transfer.

Analysis of Variance↗
PubMed1997

Blast coating method: new method of coating titanium surface with hydroxyapatite at room temperature.

When a titanium plate was blasted with hydroxyapatite [HAP; Ca10[x](HPO4)[x](PO4)[6-x](OH)[2-x]] powder at room temperature using an ordinary sandblaster, the surface of the titanium plate was found to be coated with HAP homogeneously and completely. The coated layer was examined with energy dispersive X-ray spectroscopy and X-ray diffraction and was found to be the same as the HAP powder used with respect to composition and crystallographic structure. The coated HAP layer was tightly attached to the surface of the titanium plate, at least at the level of scanning electron microscopy. Interestingly, the HAP particles stuck together at room temperature as if they were sintered. The coating was stable against ultrasonication in water for at least 5 min, and it was difficult to remove by nail scratching. Thus, the bonding strength between the HAP powder and the titanium plate was much higher than that achieved with currently employed room temperature coating processes such as dipping, electrophoretic deposition, and electrochemical deposition. Therefore, the blast coating method is potentially valuable for the fabrication of useful biomaterials for hard tissue replacement.

Biocompatible Materials↗
PubMed1998

Chemical modification of titanium surfaces for covalent attachment of biological molecules.

The surface of implantable biomaterials is in direct contact with the host tissue and plays a critical role in determining biocompatibility. In order to improve the integration of implants, it is desirable to control interfacial reactions such that nonspecific adsorption of proteins is minimized and tissue-healing phenomena can be controlled. In this regard, our goal has been do develop a method to functionalize oxidized titanium surfaces by the covalent immobilization of bioactive organic molecules. Titanium first was chemically treated with a mixture of sulfuric acid and hydrogen peroxide to eliminate surface contaminants and to produce a consistent and reproducible titanium oxide surface layer. An intermediary aminoalkylsilane spacer molecule was then covalently linked to the oxide layer, followed by the covalent binding of either alkaline phosphatase or albumin to the free terminal NH2 groups using glutaraldehyde as a coupling agent. Surface analyses following coating procedures consisted of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Enzymatic activity of coupled alkaline phosphatase was assayed colorimetrically, and surface coverage by bound albumin was evaluated by SEM visualization of colloidal gold immunolabeling. Our results indicate that the linkage of the aminoalkylsilane to the oxidized surface is stable and that bound proteins such alkaline phosphatase and albumin retain their enzymatic activity and antigenicity, respectively. The density of immunolabeling for albumin suggests that the binding and surface coverage obtained is in excess of what would be expected for inducing biological activity. In conclusion, this method offers the possibility of covalently linking selected molecules with known biological activity to oxidized titanium surfaces in order to guide and promote the tissue healing that occurs during implant integration in bone and soft tissues.

Biological Factors↗
PubMed1998

Quasi-biological apatite film induced by titanium in a simulated body fluid.

Commercially pure titanium (c.p.Ti) is capable of inducing the formation of a carbonated apatite onto its surface in a simulated body fluid (SBF) comprised of calcium ions, phosphate ions, and other inorganic species present in the body fluid. In addition to the incorporation of carbonate ions, such formed apatite has other important characteristics of the bone mineral phase, such as a small crystal size and ionic substitution by Mg2+ and Cl-. Thus, we call this apatite a quasi-biological apatite. The formation of the quasi-biological apatite is proposed to be related to TiOH groups that develop on the titanium surface through interaction with the SBF. The results suggest that titanium implants may be activated such that they can form a strong bond with bone tissue through the in vivo formation of apatite. Since the solution can reach any open space, the process discussed in this study is very suitable for coating porous titanium implants with a quasi-biological apatite film.

Apatites↗
PubMed1999

Enhancement of bone-bonding strengths of titanium alloy implants by alkali and heat treatments.

The purpose of this study is to evaluate the bone-bonding ability of alkali- and heat-treated titanium alloys. Smoothed-surface rectangular plates of Ti6Al4V, Ti6Al2Nb1Ta, and Ti15Mo5Zr3Al were prepared. The plates were inserted transcortically into the proximal metaphyses of bilateral rabbit tibiae, with alkali- and heat-treated plates inserted on the right side, and untreated plates on the left. The tensile failure loads between the implants and the bones were measured after 8, 16, and 24 weeks by a detaching test. The untreated implants showed almost no bonding even at 16 weeks, and only weak bonding at 24 weeks. In contrast, treated implants showed bonding to bone at all time periods. Histological examination showed that alkali- and heat-treated alloys bonded directly to the bone. Conversely, the untreated implants had an intervening layer of fibrous tissue between the bone and the plate, or only partial direct contact with the bone. This study demonstrates that alkali and heat treatments enhance the bone-bonding strength of these titanium alloys. Although in this study even tentative conditions of the treatments enhance the bonding strength of the titanium alloys, further work is required to determine the optimum conditions for treatment to give the highest bonding strength. These new bioactive titanium alloys are available for weight-bearing and bone-bonding orthopedic devices.

Alkalies↗
PubMed1999

Early events associated with periodontal connective tissue attachment formation on titanium and hydroxyapatite surfaces.

Endosseous dental implants can support at least three types of biomaterial/connective tissue interfaces: osseointegration, fibro-osseous integration, and periodontal connective tissue attachment. Although a periodontal connective tissue attachment offers distinct advantages, only osseointegration and fibro-osseous integration are at present clinically achievable. Recent studies indicate a periodontal regeneration-competent cell population and an appropriate biomaterial substrate both are required for periodontal connective attachment formation on biomaterial surfaces. We therefore have developed an in vitro model to characterize the effects of various biomaterial substrates on the early events of periodontal connective tissue attachment formation. Primary cultures of periodontal ligament and gingival connective tissue cells were cultured on uncoated (control) and coated (titanium- and hydroxyapatite-coated) tissue culture plastic, and the level of cell proliferation, collagen, and noncollagen protein synthesis, alkaline phosphatase activity, and expression of a 42 kD cementum extracellular matrix protein were measured over 5, 7, and 9 days in culture. While all three substrates supported cell attachment, proliferation, and protein synthesis, only uncoated and titanium-coated tissue culture plastic supported expression of the cementum extracellular matrix protein after 9 days of culture. In addition, the levels of cell proliferation and collagen and noncollagen protein synthesis for cells grown on hydroxyapatite-coated surfaces lagged behind cells cultured on the control or titanium-coated surfaces at each of the three time points. These data suggest that biomaterial substrates markedly can influence the temporal sequence of extracellular matrix proteins associated with periodontal connective tissue attachment formation. In addition to surface composition (titanium versus hydroxyapatite), surface properties (e.g., topography) also may have an effect on periodontal connective tissue attachment formation. This model may be of use in designing biomaterials to support the formation of periodontal connective tissue attachment in vivo.

Animals↗
PubMed2000

Calcium phosphate deposition on titanium surfaces in the presence of fibronectin.

Titanium implants are known to nucleate spontaneously a calcium phosphate (apatite-like) layer when in contact with biological model fluids. The presence of proteins either in solution or pre-adsorbed on the titanium surface may influence the process of calcium phosphate deposition. The role of fibronectin, a protein known to promote cell adhesion in spite of its low concentration in biological fluids, was dissolved in Hanks' balanced salt solution (HBSS) and investigated. Several techniques of surface analysis, namely wettability, XPS, and SEM studies, were applied. The concentration of fibronectin in the HBSS solution was an important parameter in the process of calcium phosphate deposition. Concentrations as low as 0.01 mg/mL did not significantly affect the ionic precipitation; however, if the protein concentration was increased to 0.05 mg/mL, a value still far below the concentration in blood (0.2 mg/mL), the formation of a calcium phosphate layer was strongly inhibited. The influence of fibronectin pre-adsorbed on titanium surface also was investigated. It was found, as in the first case, that the extent of ionic precipitation that occurred during the immersion in HBSS depended on the protein concentration in the NaCl solution used to pre-immerse the titanium sample.

Animals↗
PubMed2000

Quantifying the adherence of fibroblasts to titanium and its enhancement by substrate-attached material.

Normal human skin fibroblasts were cultured on tissue culture polystyrene and on commercially pure titanium. In addition, substrate-attached material that remained on the surfaces after detachment of fibroblasts with a chelating agent was examined. The force required to detach 50% of the fibroblasts from each substrate was assessed by centrifugation. The results showed a time-dependent decrease in the force required to detach fibroblasts from titanium not seen on tissue culture polystyrene. Nearly all cells detached from the titanium surfaces at 7.85 x 10(x3) dynes/cell after 3 or 5 days in culture, whereas few cells detached from tissue culture polystyrene. Cells freshly seeded onto titanium substrates that had been coated with substrate-attached material by prior culture of fibroblasts for 3 or 5 days showed an approximately sixfold increased adherence. The results of immunofluorescence staining for fibronectin and its receptor suggest that the nature of the interaction between this extracellular matrix ligand and the substrate may be important in determining cellular stiffness at the cell-extracellular matrix interface.

Biocompatible Materials↗
PubMed2000

Combined effect of titanium particles and TNF-alpha on the production of IL-6 by osteoblast-like cells.

To clarify the role of tumor necrosis factor (TNF)-alpha on osteoblast functions in the presence of metal particles, two human osteoblast-like cell lines (MG-63 and SaOS-2) were cultured with TNF-alpha in the presence or absence of titanium particles in vitro. A combination of TNF-alpha and titanium particles showed additive effects on inhibition of cell proliferation and alkaline phosphatase production. On the other hand, production of interleukin-6, which is well known to induce osteoclastogenesis and to directly stimulate bone resorption, was additively stimulated by the combination of TNF-alpha and titanium particles. These results suggest that the association of TNF-alpha and titanium particles may play an important role in the pathogenesis of periprosthetic osteolysis through two different pathways: a reduced periprosthetic bone formation due to inhibition of osteoblast proliferation and alkaline phosphatase production, and osteoblast-mediated activation of osteoclastic bone resorption as suggested by the enhancement of interleukin-6 production.

Biocompatible Materials↗
PubMed2001

Interactions between calcium, phosphate, and albumin on the surface of titanium.

The deposition of calcium phosphate on chemically polished commercially pure titanium immersed in Hank's balanced salt solution (HBSS) with bovine serum albumin (BSA) (concentrations 0 and 4 mg/mL) has been investigated. Electrochemical techniques, 125I labeling of albumin, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used. A tricalcium phosphate layer with a thickness of ca. 1 microm was formed for periods of immersion in HBSS ranging between 1 and 2 weeks. A concentration of 4 mg/mL of BSA prevented its formation, even for periods as long as 1 month. In the absence of BSA, the electrochemical behavior of titanium specimens was significantly affected by the length of immersion time, reflecting the changes that slowly occur on their surface. In the presence of BSA, the surfaces maintained most of their original electrochemical activity. Surface studies have shown that calcium and phosphate become incorporated in the surface at very early stages of immersion. Albumin, which was rapidly adsorbed on titanium, was slowly desorbed when titanium was placed in HBSS. Protein and phosphate may coexist on the same surface, but initially adsorbed albumin molecules prevent the precipitation of a thick layer of tricalcium phosphate.

Animals↗
PubMed1995

Treatment of patients with cirrhosis and refractory ascites using LeVeen shunt with titanium tip: comparison with therapeutic paracentesis.

It has recently been suggested that insertion of a titanium tip at the venous end of the LeVeen shunt drastically reduces the rate of shunt obstruction. To assess whether the LeVeen shunt with titanium tip improves the results obtained with therapeutic paracentesis, 81 patients with cirrhosis and refractory ascites were randomly assigned to therapy with paracentesis plus intravenous albumin (42 patients) or LeVeen shunt with titanium tip (39 patients). If patients were readmitted for ascites during follow-up, those in the first group were treated with paracentesis, and those in the LeVeen shunt group by the insertion of a new valve or a new shunt if obstruction was demonstrated. During first hospitalization, both treatments were equally effective in removing ascites. Complications were similar in both groups except for a higher rate of severe bacterial infection in the LeVeen shunt group. The mean duration of hospitalization was shorter in the paracentesis group than in the shunt group. During follow-up, the total number of readmissions and the number of readmissions for ascites were higher in the paracentesis group than in the shunt group (252 vs. 99, P < .001; and 193 vs. 43, P < .001, respectively). The total time in hospital, however, was similar (38 +/- 38 vs. 39 +/- 43 days, P = NS). Three patients had obstruction of the shunt during first hospitalization and 14 patients had a total of 22 obstructions during follow-up. Long-term survival was similar in both groups. The insertion of a titanium tip at the venous end of the LeVeen shunt does not prevent obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Influence of fluoride on titanium in an acidic environment measured by polarization resistance technique.

The effect of sodium fluoride on the polarization resistance of titanium was investigated. Titanium plates were exposed to sodium chloride solutions with increasing fluoride concentrations. This was done at pH 7 and 4 at 37 degrees C. The polarization resistance technique was chosen because it is the only electrochemical corrosion test procedure that allows sequential measurements of the same specimen and provides a quantitative basis to estimate corrosion currents unlike measurements of the potential. The results showed a large decrease in polarization resistance with increasing fluoride concentration at pH 4. The polarization resistance at pH 7 remained constant after a slight decrease at a very high value, even with a high fluoride concentration. The results clearly confirm that titanium is attacked by fluoride in an acidic environment. The clinical implications are that fluoride rinses or fluoride gels must have a neutral pH if there is a titanium containing device in the oral environment despite the less prophylactic effectiveness.

Biocompatible Materials↗
PubMed2002

Hydroxyapatite deposition by electrophoresis on titanium sheets with different surface finishing.

Hydroxyapatite coatings are commonly applied to metallic biomedical implants to accelerate osseointegration. These coatings, usually produced by plasma spray techniques, can be obtained by alternative processes, like biomimetic process, electrolytic deposition, or electrophoretic process as well. Electrophoretic deposition of hydroxyapatite exhibits several advantages like simplicity and low cost. In this article, titanium sheets with three different surface finishing were coated with hydroxyapatite by using electrophoresis. Surface treatments include: (1) abrading with SiC paper; (2) abrading with SiC paper plus electrolytic etch with H3PO4 solution; and (3) blasting with alumina powder followed by etch with a solution containing H2O2 and HF. Stoichiometric hydroxyapatite was used to coat titanium sheets. Blasted samples were also coated using a calcium-deficient hydroxyapatite. SEM, XRD, and FTIR were employed to characterize titanium substrates and coatings produced. Results show that electrophoretic process can produce a uniform thin layer, satisfactorily adhered, of hydroxyapatite on treated titanium samples. Furthermore, sintering at 800 degrees C do not promote the decomposition of calcium-deficient hydroxyapatite.

Biocompatible Materials↗
PubMed2002

Bone formation by rat bone marrow cells cultured on titanium fiber mesh: effect of in vitro culture time.

The objective of this study was to examine the effect of cell culture time on bone formation by rat bone marrow cells seeded in titanium fiber mesh. As a seeding technique, a high cell suspension was used (3 x 10(6) cells/mL). Therefore, 30 meshes were repeatedly rotated in a 10 mL tube (containing 30 x 10(6) cells) on a rotation plate (2 rpm) for 3 h. Osteogenic cells were cultured for 1, 4, and 8 days on titanium fiber mesh and finally implanted subcutaneously in rats. Meshes without cells were also implanted subcutaneously in rats. DNA and scanning electron microscopy (SEM) analyses and calcium measurements determined cellular proliferation and differentiation during the in vitro incubation period of the mesh implants. Four weeks after implant insertion, the animals were sacrificed. The implants, with their surrounding tissue, were retrieved and prepared for histologic evaluation and calcium measurements. DNA analysis of the in vitro experiment showed a lag phase from day 1 through day 4, but a 42% increase in DNA between days 4 and 8. SEM and calcium measurements indicated an increase in calcium from day 1 to day 4, yet only a small but significant increase from days 4 to 8. Histologic analysis demonstrated that bone was formed in all day 1 and day 4 implants, and that the bone-like tissue was present uniformly through the meshes. The bony tissue was morphologically characterized by osteocytes embedded in a mineralized matrix, with a layer of osteoid and osteoblasts at the surface. The day 8 implants showed only calcium phosphate deposition in the titanium fiber mesh. Calcium measurements of the implants revealed that calcification in day 1 implants was significantly higher (p < 0.05) compared to day 4 and day 8 implants. No significant difference in calcium content existed between day 4 and day 8 implants. On the basis of our results, we conclude that 1) bone formation was generated more effectively in osteogenic cells by a short culture time after seeding in titanium fiber mesh; 2) dynamic cell seeding is probably more effective than static cell seeding; and 3) selection of the right cells from the heterogenous bone marrow population remains a problem.

Animals↗