Fixation Of Titanium Implants Research Articles

The circadian clock component BMAL1 regulates osteogenesis in osseointegration.

Congenital and developmental craniofacial deformities often cause bone defects, misalignment, and soft tissue asymmetry, which can lead to facial function and morphologic abnormalities, especially among children born with cleft lip and palate. Joint efforts from oral maxillofacial surgery, oral implantology, and cosmetic surgery are often required for diagnosis and treatment. As one of the most widely performed treatment methods, implant-supported cranio-maxillofacial prostheses have been widely applied in the course of treatment. Therefore, stability of peri-implant bone tissue is crucial for the long-term success of treatment and patients' quality of life. The circadian clock component brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) was found to be involved in the cell fate of bone marrow mesenchymal stem cells, which were essential in the fixation of titanium implants. This study aimed to investigate the effect of BMAL1 on osteogenesis in osseointegration, providing a brand new solution to increase bone implant conjunction efficiency and implant stability, paving the way for a long-term satisfactory therapy outcome.

In vitro characterization of primary osteoblasts on titanium surfaces processed with wire-type electric discharge machining.

The fixation of titanium implants in bone tissue is affected by the presence of a passive titanium oxide (TiO2) layer. Specifically, oxidation products in the amorphous TiO2 matrix enhance the mechanical properties of mineralized tissues. In addition, in vitro mineralization mediated by primary osteoblasts on amorphous TiO2 generates stiff tissues in a process that resembles pathological mechanisms connected with tumors and proceeds through hydrogen peroxide-inducible clone-5 (Hic-5) expression. However, the relationship between surface-based peroxidation and stiff mineralized tissue formation remains unclear. In this study, titanium samples were processed using wire electrical discharge machining to generate oxidation products in amorphous TiO2. The gene expression profiles of primary osteoblasts cultured on these specimens were characterized. Increased expression of Hic-5 was correlated with the presence of peroxidation products. The crystallization of amorphous TiO2 in these samples reduced the expression of both Hic-5 and lysyl oxidase, an enzyme that promotes matrix cross-linking.

The role of USP34 in the fixation of titanium implants in murine models.

Ubiquitin-specific protease 34 (USP34), a member of the ubiquitin-specific protease family, regulates osteogenic differentiation of bone marrow mesenchymal stem cells via bone morphogenetic protein signaling. This study aimed to investigate the role of USP34 in fixation of titanium implants in mouse models. Eight-week-old Usp34-knockout (Prx1-Cre;Usp34f/f ) mice and their Usp34 wild-type (Usp34f/f ) control littermates were used. Experimental titanium implants were inserted into the distal ends of femurs and the edentulous area of maxillae. Two and four weeks after surgery, samples of femur and maxilla were obtained, and micro-computed tomography scanning, histomorphometric analyses, and push-in tests were performed on the samples. Compared with controls, Prx1-Cre;Usp34f/f mice showed reduced bone volume for both femurs and maxillae; a decreased femoral bone-implant contact ratio (BIC) at 2wk [mean (standard error of the mean): 62.17% (2.15%) vs. 44.06% (3.45%)] and 4wk [72.46% (1.61%) vs. 64.53% (1.93%)]; decreases in femoral bone volume fraction (BV/TV) and push-in resistance; and lower BIC and BV/TV of the maxillae. Taken together, our data demonstrate that specific deletion of Usp34 in mesenchymal stem cells impairs fixation of titanium implants in mice.

Plasma-Sprayed Titanium Patterns for Enhancing Early Cell Responses

Titanium coating has been widely used as a biocompatible metal in biomedical applications. However, the early cell responses and long-term fixation of titanium implants are not satisfied. To obviate these defects, in this paper, micro-post arrays with various widths (150-1000 μm) and intervals (100-300 μm) were fabricated on the titanium substrate by template-assisted plasma spraying technology. In vitro cell culture experiments showed that MC3T3-E1 cells exhibited significantly higher osteogenic differentiation as well as slightly improved adhesion and proliferation on the micro-patterned coatings compared with the traditional one. The cell number on the pattern with 1000 µm width reached 130% after 6 days of incubation, and the expressions of osteopontin (OPN) as well as osteocalcin (OC) were doubled. No obvious difference was found in cell adhesion on various size patterns. The present micro-patterned coatings proposed a new modification method for the traditional plasma spraying technology to enhance the early cell responses and convenience for the bone in-growth.

PROSPECTS OF USING TITANIUM IMPLANTS WITH PREDETERMINED OSTEOGENIC PROPERTIES

The paper discusses the benefits and drawbacks of using titanium implants in spine surgery. Improved fixation of titanium implants in bone tissue is achieved by applying a variety of textured and nano-based coatings on their surfaces. Coatings made of osteotropic hydroxyapatite (HA)- and tricalciumphosphate (TCP)-based materials prevail over allogenic materials in many features. This permits to achieve positive results in bone defect osteoplasty. However, HA and TCP do not completely meet the needs of clinicians due to the lack of apparent osteoinductive properties. The guided bone regeneration requires creation of initial conditions for the ordered proliferation of osteogenic cells and capillaries in a predetermined space. A prerequisite for this is the presence of biologically active substances providing osteoinduction of osteoplastic material to form a matrix on which the bone tissue will develop. Candidate substances are various fractions of bone morphogenetic protein (BMP) which induce bone regeneration. The advantages of various physicochemical treatments of titanium implants (plasma, ion, sandblasting, ablative, etc.) are still debated, but their clinical use requires further research.

Coralline hydroxyapatite granules inferior to morselized allograft around uncemented porous Ti implants: Unchanged fixation by addition of concentrated autologous bone marrow aspirate

We compared early fixation of titanium implants grafted with impacted allograft bone or coralline hydroxyapatite (HA) granules (Pro Osteon 200) with and without the addition of concentrated bone marrow cells (BMC). Autologous bone marrow aspirate was centrifuged to increase the BMC concentration. Four nonloaded cylindrical, porous coated titanium implants with a circumferential gap of 2.3 mm were inserted in the proximal humeri of eight dogs. Coralline HA granules +/- BMC were impacted around the two implants on one side, and allograft +/- BMC was impacted around the contra lateral implants. Observation time was 4 weeks. The implants surrounded by allograft bone had a three-fold better fixation than the HA-grafted implants. The concentration of BMC after centrifugation was increased with a factor 2.1. The addition of BMC to either of the bone graft materials had no statistically significant effects on implant fixation. The allografted implants were well osseointegrated, whereas the HA-grafted implants were largely encapsulated in fibrous tissue. The addition of concentrated autologous BMCs to the graft material had no effect on implant fixation. The HA-grafted implants were poorly anchored compared with allografted implants, suggesting that coralline HA granules should be considered a bone graft extender rather than a bone graft substitute.

Bisphosphonate coating on titanium screws increases mechanical fixation in rat tibia after two weeks

Recently published data indicate that immobilized N-bisphosphonate enhances the pullout force and energy uptake of implanted stainless steel screws at 2 weeks in rat tibia. This study compares titanium screws with and without a bisphosphonate coating in the same animal model. The screws were first coated with an approximately 100-nm thick crosslinked fibrinogen film. Pamidronate was subsequently immobilized into this film via EDC/NHS-activated carboxyl groups within the fibrinogen matrix, and finally another N-bisphosphonate, ibandronate, was physically adsorbed. The release kinetics of immobilized (14)C-alendronate was measured in buffer up to 724 h and showed a 60% release within 8 h. Mechanical tests demonstrated a 32% (p = 0.04) and 48% (p = 0.02) larger pullout force and energy until failure after 2 weeks of implantation, compared to uncoated titanium screws. A control study with physically adsorbed pamidronate showed no effect on mechanical fixation, probably due to a too small adsorbed amount. We conclude that the fixation of titanium implants in bone can be improved by fibrinogen matrix-bound bisphosphonates.

Locally delivered TGF-β1 and IGF-1 enhance the fixation of titanium implants: A study in dogs

Background Osteogenic growth factors have been suggested to enhance the fixation of implants used in joint replacement. We examined the effect of locally delivered transforming growth factor-β1 and insulin-like growth factor-1 in a biodegradable poly (D, L-lactide) coating.Material and methods In a paired study using 9 dogs, unloaded titanium implants surrounded by a 1-mm gap were inserted into the proximal humerus. The growth factors were incorporated in a poly (D, L-lactide) coating at a 1% (w/w) ratio of TGF-β1 and a 5% (w/w) ratio of IGF-1. Control implants were uncoated. After 4 weeks, the implants were evaluated by mechanical push-out test and by histomorphometry.Results A twofold increase was seen in mechanical fixation (strength, stiffness, energy absorption) for the growth factor-treated implants (p = 0.04). Similar results were seen in histomorphometry, as bone ongrowth was 2.5 times higher (p = 0.02), and gap healing was 30–110% higher (p = 0.04) for the growth factor-treated implants than for the control implants. Ongrowth of fibrous tissue was eliminated by the treatment.Interpretation TGF-beta-1 and IGF-1, locally delivered in a biodegradable poly(D,L-lactide) coating, enhance the mechanical fixation and osseointegration of titanium implants in cancellous bone, and no fibrous tissue is produced in the growth factor treated implants.

In vivo effects of RGD‐coated titanium implants inserted in two bone‐gap models

RGD (Arg-Gly-Asp) coating has been suggested to enhance implant fixation by facilitating the adhesion of osteogenic cells to implant surfaces. Orthopedic implants are unavoidably surrounded partly by gaps, and these regions represent a challenging environment for osseointegration. We examined the effects of cyclic RGD-coated implants on tissue integration and implant fixation in two cancellous bone-gap models. In canines, we inserted loaded RGD-coated implants with 0.75-mm gap (n = 8) and unloaded RGD-coated implants with 1.5-mm gap (n = 8) into the distal femur and proximal tibia, respectively. Control gap implants without RGD were inserted contralaterally. The titanium alloy (Ti-6Al-4V) implants were plasma sprayed and cylindrical. The observation period was 4 weeks and the fixation was evaluated by push-out test and histomorphometry. Mechanical implant fixation was improved for RGD-coated implants. Unloaded RGD-coated implants showed a significant increase in bone whereas both loaded and unloaded implants showed a significant reduction in fibrous tissue anchorage. The results are encouraging, because RGD had an overall positive effect on the fixation of titanium implants in regions where gaps exist with the surrounding bone. RGD peptide coatings can potentially be used to enhance tissue integration in these challenging environments.

Does sodium fluoride in bone cement affect implant fixation. Part II: evaluation of the effect of sodium fluoride additions to acrylic bone cement and the fixation of titanium implants in ovariectomized rabbits.

Bone integration of threaded implants made of cured polymethylmethacrylate containing sodium fluoride or commercially pure (c.p.) titanium were studied in normal and estrogen deficient New Zealand white rabbits. Nine had been ovariectomized through laparoscopy and nine served as controls. Four weeks after the ovariectomy two threaded implants made of cured bone cement with or without sodium fluoride addition were inserted in each tibia. One threaded commercially pure titanium implant was inserted in each patello-femoral joint flush to the cartilage. Six weeks after implant insertion measurement of the peak removal torque necessary to loosen the implants and light microscopical histomorphometrical investigations of tissue integration were performed. In the ovariectomized rabbits addition of sodium fluoride to the cement resulted in increased area of bone in the threads (p=0.04), but no corresponding effect could be noted in the controls. The removal torque was lower in the ovariectomized rabbits compared to the non-ovariectomized when comparing implant with sodium fluoride addition (p=0.02). The bone tissue response and the removal torque of the titanium implants were not influenced by ovariectomy in these rabbits.