Positive effect of strontium-oxide layer on the osseointegration of moderately rough titanium surface in non-osteoporotic rabbits.

OBJECTIVES: To evaluate the effect of strontium-oxide layer on new bone formation and osseointegration of sandblasted large-grit double-acid-etched (SLA) implant. MATERIAL AND METHODS: Strontium-oxide layer on the SLA surface was produced by hydrothermal treatment using a Sr-containing solution. The surface topographies, roughness, hardness values, chemical elements and ionic release of SLA and the strontium-containing SLA (Sr-SLA) surface were measured by special instruments separately. Sixty-four SLA and Sr-SLA implants were inserted into the proximal tibiae and femoral condyles of sixteen non-osteoporotic New Zealand white rabbits. The biological effects were evaluated by removal torque (RTQ) testing and histomorphometric analysis after 3 and 6 weeks of implantation. RESULTS: The surface characteristics showed Sr-SLA surfaces with dotted nanostructures can release appropriate amount of strontium ions into surrounding tissue till 14 days. In vivo, the Sr-SLA implants presented significantly higher RTQ than SLA implants at 3 and 6 weeks (P < 0.05). The Sr-SLA implants presented higher bone-to-implant contact (BIC) than SLA implants in cortical bone at 3 and 6 weeks (P < 0.05). The bone area was slightly higher for the Sr-SLA implants at 3 and 6 weeks (P > 0.05). CONCLUSIONS: The strontium-oxide layer on the SLA surface has the potential to improve implant osseointegration in non-osteoporotic rabbits.

Long-term outcomes of osteotome sinus floor elevation without bone grafts: a clinical retrospective study of 4-9 years.

OBJECTIVE: To evaluate the long-term clinical and radiographic outcomes of dental implant placed using osteotome sinus floor elevation (OSFE) without bone grafts, and to analyze the potential influence factors of implant survival and endo-sinus bone remodeling. MATERIAL AND METHODS: A retrospective study design was adopted. The clinical and radiographic data of 96 implants in 80 patients were collected after 4-9 (mean 5.40) years follow-up. Implant failures, peri-implant marginal bone loss (MBL), and endo-sinus bone remodeling on the radiographs were evaluated. A life-table analysis was used to assess the implant survival. Statistical models were established to investigate the potential influence factors of implant survival and endo-sinus bone gain (ESBG). RESULTS: In total, nine implants in seven patients failed, giving the 9-year cumulative survival rates of 90.6% and 91.3% for implant-based analysis and patient-based analysis, respectively. The mean MBL between implant installation and the 4- and 9-year follow-up visit was 0.46 ± 0.88 and 0.50 ± 1.69 mm, respectively. The average ESBG on radiographs was 2.95 ± 1.25 and 2.16 ± 1.13 mm at the 4- and 9-year follow-up. The final ESBG was found to be positively correlated to implant protrusion length after surgery without any other factors related. The implant survival rate was significantly lower in severe atrophic site (residual bone height <5 mm). CONCLUSION: Osteotome sinus floor elevation without bone grafts is a predictable treatment modality in the long run. But it should be used with caution when the initial bone height of the edentulous site is lower than 5 mm. The final endo-sinus bone height was found to be positively correlated to implant protrusion length measured on radiographs immediately after implant installation.

Bone response to the multilayer BMP-2 gene coated porous titanium implant surface.

OBJECTIVES: Evaluate hBMP-2 expression following gene delivery from plasmid multilayers formed on sandblasted titanium in vitro and bone formation around similarly prepared implant surfaces in vivo. MATERIALS AND METHODS: Multilayers of cationic lipid/rhBMP-2 plasmid DNA complex (LDc) and anionic hyaluronic acid (HA) was assembled on sandblasted-dual acid etched pure titanium disks or implant surfaces using layer-by-layer (LBL) assembly. Gene delivery and hBMP-2 expression in cells exposed to the LDc multilayers was measured in vitro. To determine the effect of BMP delivery from such multilyaers in vivo, roughened implants coated with BMP-2 LDc multilayers or uncoated control implants (n = 15 for both) were implanted in the femurs of NZW rabbits. After 2, 4, 8 weeks, femurs were retrieved and prepared for histomorphometric evaluation (n = 5 rabbits per time point). RESULTS: MC3T3-E1 cells cultured directly on the BMP-2 LDc coated titanium disks showed EGFP and hBMP-2 expression after 48 h in culture. Increased gene delivery occurred by increasing the number of assembly layers when cells were cultured for 48 h. Cells cultured on LDc coated surfaces had significantly higher cell viability than control cells cultured on uncoated porous titanium surfaces. Histologic observation of the implants showed that after 4 weeks healing, the bone to implant contact (BIC) on the LDc coated surface was much lower than that on the control surface, but didn't reach significant. In contrast, the percentage of bone within the implant's threads was significantly higher than the control group (P = 0.047). CONCLUSION: The BMP-2 gene coated sandblasted dual acid etched titanium implants slightly accelerated early bone formation around implants.

Mechanical and histomorphometric evaluations of rough titanium implants treated with hydrofluoric acid/nitric acid solution in rabbit tibia.

PURPOSE: The aim of this study was to investigate the bone response to rough titanium implants treated with hydrofluoric acid/nitric acid (HF/HNO3) solution. MATERIALS AND METHODS: Implants were treated with HF/HNO3 solution (test implants) or without HF/HNO3 solution (control implants). Forty-five test and 45 control implants were inserted into both tibias of 15 rabbits. After 2, 4, and 8 weeks in situ, tibias were retrieved and prepared for removal torque testing and histomorphometric evaluation. The removed implants were prepared and observed with an electron microscope. RESULTS: Mechanical tests showed that mean removal torque values for the test implants were higher than those of the control implants after 8 weeks (33.1 Ncm versus 25.7 Ncm, P = .012). Histomorphometric analysis showed that the bone area in the threads of the cortical bone region was significantly higher for test implants (81.99% and 86.38%) than for control implants (75.33% and 81.62%) after 4 and 8 weeks of healing, respectively. The implant-bone contact rate in the cortical region was higher for test implants than for control implants after 8 weeks in situ (79.56% versus 68.45%, P = .003). CONCLUSIONS: The treatment with HF/HNO3 solution promotes bone formation and osseointegration after 4 and 8 weeks of bone healing in the rabbit tibia model.

In vivo comparison of bone formation on titanium implant surfaces coated with biomimetically deposited calcium phosphate or electrochemically deposited hydroxyapatite.

PURPOSE: The purpose of this study was to investigate and compare bone formation on titanium implant surfaces coated with biomimetically deposited calcium phosphate (BDCaP) or electrochemically deposited hydroxyapatite (EDHA). MATERIALS AND METHODS: The implants were separated into three groups: a control group, a BDCaP group, and an EDHA group. Surface analysis was performed by field-emission scanning electron microscopy, x-ray diffractometry, and Fourier transform infrared spectroscopy. Implants were inserted in a randomized arrangement into rabbit tibiae. After 2, 4, and 8 weeks, the tibiae were retrieved and prepared for histomorphometric evaluation. RESULTS: Field-emission scanning electron microscopy showed that the BDCaP crystals were flakelike and the EDHA crystals were rodlike with a hexagonal cross section. X-ray diffractometric patterns and Fourier transform infrared spectroscopy spectra showed that the BDCaP coating consisted of HA and octacalcium phosphate, whereas the EDHA coating consisted of HA. Histologic observation showed that new bone on the EDHA-coated implant became mature after 4 weeks, while new bone on the control and BDCaP-coated implants was mature after 8 weeks. The EDHA implant showed significantly greater BIC and bone area compared to the control and BDCaP implants during 4 to 8 weeks. The BDCaP coating failed to show increased bone formation during the test period. CONCLUSION: The present EDHA coating has good bone formation properties, while the BDCaP coating has weaker bone formation properties.

Biomechanical comparison of biomimetically and electrochemically deposited hydroxyapatite-coated porous titanium implants.

PURPOSE: The purpose of this study was to investigate the effects of biomimetically and electrochemically deposited hydroxyapatite on the fixation of an implant with bone tissue. MATERIALS AND METHODS: Implants were separated into 3 groups: roughened group, biomimetically deposited calcium-phosphorus (BDCaP) group, and electrochemically deposited hydroxyapatite (EDHA) group. We randomly inserted 90 implants into the femurs of 45 rabbits. After 2, 4, and 8 weeks, the femurs were retrieved and prepared for removal torque tests (RTQs) and field-emission scanning electron microscopy observation. RESULTS: During the test period, the EDHA group showed significantly greater RTQ values than did the roughened group and BDCaP group. The BDCaP group failed to increase the RTQ values compared with the roughened group. Field-emission scanning electron microscopy observation showed that the amount of attached bone tissue on the EDHA-coated implant surface was more than that on the roughened and BDCaP-coated implant surfaces during the test period. CONCLUSION: The electrochemical hydroxyapatite coating contributes to the fixation between bone and implant compared with the roughened surface, whereas the biomimetic calcium-phosphorus coating has little effect on the fixation.

Effect of the Wnt signal-RANKL/OPG axis on the enhanced osteogenic integration of a lithium incorporated surface.

Bone remolding involves the formation of new bone by osteoblasts and the absorption of old bones by osteoclasts. Due to the vital role of osteoblasts and osteoclasts during bone regeneration, it might be feasible to promote osseointegration around the titanium implants by stimulating osteoblasts and inhibiting osteoclasts by modifying the surfaces of the implants. Lithium is used in the treatment of psychiatric patients, and it may be associated with osteogenesis. In this study, lithium was incorporated with sandblasted, large-grit and acid-etched titanium implants via a hydrothermal treatment. In vitro, the nano-scale surface enhanced the adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs). Moreover, the SLA-Li surface displayed a negative effect on the process of osteoclastogenesis. Further mechanism analysis indicated that the canonical Wnt/ß-catenin signaling pathway was activated according to the results of RT-PCR and western blotting. More importantly, the RANKL/OPG signaling axis was also involved in these effects on the SLA-Li surface. The experiments in vivo proved that the SLA-Li surface could induce the bone formation and osseointegration during the early osseointegration after the dental implant surgery. These results suggested that bone homeostasis could be manipulated by an SLA-Li surface, which implied that this new surface might serve as a promising material for clinical application in the future.

Effect of H2O2/HCl heat treatment of implants on in vivo peri-implant bone formation.

PURPOSE: To investigate the effect of H2O/HCl heat treatment on peri-implant bone formation in vivo. MATERIALS AND METHODS: Twenty Ti-6Al-4V implants and 30 Ti-6Al-4V discs were used in this study. The implants and discs were separated into 2 groups: sandblasted and dual acid-etched group (control group) and sandblasted, dual acid-etched and H2O2/HCl heat-treated group (test group). Surface morphology, roughness, and crystal structure of the discs were analyzed by field-emission scanning electron microscopy, atomic force microscopy, and low angle X-ray diffractometry. The implants were inserted into the femurs of 10 adult white rabbits. Animals were injected with fluorescent bone labels at 1, 5, and 7 weeks following surgery to monitor progress of bone formation. Animals were euthanized 8 weeks postsurgery, and block biopsies were prepared for histologic and histometric analysis. RESULTS: Microscopic evaluation showed the surfaces were quite irregular for both techniques; however, the test surface demonstrated consistently smaller surface irregularities. The differences in Sa values were significant (P = .022). No significant differences were found in the maximum peak-to-valley ratio values (P = .258). X-ray diffractometry analysis showed that titanium dioxide was found on the test surface. New bone was formed on both implant surfaces. The bone-implant contact pattern appeared to produce a broad-based direct contact. Test implants demonstrated 7.13% more bone to implant contact (P = .003) and 15.42% more bone to implant contact for 3 consecutive threads (P = .001) than control implants. Test implants demonstrated 37.04% more bone area 500 microm outside of implant threads (P = .004) and 51.97% more bone area within 3 consecutive threads (P = .001) than control implants. No significant differences were found in bone area within all implant threads between the two groups (P = .069). CONCLUSION: This study demonstrated that implants heat-treated with H2O2/HCl solution enhanced peri-implant bone formation.

Osteoblast responses to thin nanohydroxyapatite coated on roughened titanium surfaces deposited by an electrochemical process.

PURPOSE: The purpose of this study was to investigate in vitro osteoblast responses to the thin nano-hydroxyapatite (HA) coating on porous implant surfaces. MATERIALS AND METHODS: Surface characteristics of nano-HA coating were evaluated by x-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). Murine preosteoblast cell (MC3T3-E1) proliferation, alkaline phosphatase (ALP) activity, and osteocalcin release on nano-HA coated surfaces were compared with HA-coated surfaces. RESULTS: The XRD pattern demonstrated that the peak of nano-HA coating matched well with the standard HA patterns. FTIR spectra also showed that the coating consisted of pure HA crystals. Significant increases in cell proliferation, total protein on day 7, ALP activity on day 14 and day 21, and osteocalcin production on day 21 (P < .05) were observed for nano-HA coated surfaces. CONCLUSIONS: It was concluded that thin nano-HA coating, deposited by the electrochemical process, improved proliferation and differentiation of osteoblasts.

Effects of zinc-substituted nano-hydroxyapatite coatings on bone integration with implant surfaces.

OBJECTIVE: The purpose of this study was to investigate the effects of a zinc-substituted nano-hydroxyapatite (Zn-HA) coating, applied by an electrochemical process, on implant osseointegraton in a rabbit model. METHODS: A Zn-HA coating or an HA coating was deposited using an electrochemical process. Surface morphology was examined using field-emission scanning electron microscopy. The crystal structure and chemical composition of the coatings were examined using an X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). A total of 78 implants were inserted into femurs and tibias of rabbits. After two, four, and eight weeks, femurs and tibias were retrieved and prepared for histomorphometric evaluation and removal torque (RTQ) tests. RESULTS: Rod-like HA crystals appeared on both implant surfaces. The dimensions of the Zn-HA crystals seemed to be smaller than those of HA. XRD patterns showed that the peaks of both coatings matched well with standard HA patterns. FTIR spectra showed that both coatings consisted of HA crystals. The Zn-HA coating significantly improved the bone area within all threads after four and eight weeks (P<0.05), the bone to implant contact (BIC) at four weeks (P<0.05), and RTQ values after four and eight weeks (P<0.05). CONCLUSIONS: The study showed that an electrochemically deposited Zn-HA coating has potential for improving bone integration with an implant surface.

Fluorescence microscopic analysis of bone osseointegration of strontium-substituted hydroxyapatite implants.

The purpose of this study was to analyze the effect of strontium-substituted hydroxyapatite (Sr-HA) on bone osseointegration of the implants using fluorescence microscopy. We allocated 20 implants to two groups: Sr-HA group and HA group. Electrochemically deposited HA and Sr-HA coatings were applied onto the implants separately. All the implants were inserted into femur bone of rabbits. Oxytetracycline hydrochloride, alizarin-complexon, and calcein green were respectively administered 7, 28, and 46 d after the implantation. After eight weeks, femurs were retrieved and prepared for the fluorescence microscopy observation. We analyzed the bone mineral apposition rates (MARs), bone area ratios (BARs), and bone to implant contact (BIC) of the two groups. Fluorescence microscopic observation showed that all groups exhibited extensive early peri-implant bone formation. The MAR of the Sr-HA group was greater than that for pure HA from 7 to 28 d after implantation, but no significant difference was found at later stage. And the BIC showed difference at 7 and 28 d compared with pure HA. We concluded that Sr-HA coating can improve the bone osseointegration of the implant in the early stage compared with the HA coating.

Effect of strontium-substituted nanohydroxyapatite coating of porous implant surfaces on implant osseointegration in a rabbit model.

PURPOSE: This study investigated the effects of a strontium-substituted nanohydroxyapatite (Sr-HA) coating, deposited onto porous implant surfaces using an electrochemical process, on implant osseointegration in a rabbit model. MATERIALS AND METHODS: The surfaces were analyzed by field-emission scanning electron microscopy, x-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), a portable surface roughness tester, and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Thirty implants (half HA-coated and half Sr-HA-coated) were inserted into femurs of 15 rabbits. After 2, 4, and 8 weeks, the femurs were retrieved and prepared for histomorphometric evaluation. RESULTS: Microscopic examination showed a surface topography of rodlike crystals on both surfaces. XRD and FT-IR showed that the phase of the deposits was HA. No differences were found in surface roughness between the two groups. ICP-AES showed that the Sr/(Ca+Sr) molar ratio of Sr-HA coating was 10.1 mol%. Histologic observation showed that new bone appeared on both surfaces after 2 weeks and became mature after 8 weeks. Histomorphometric analysis showed no differences between the two groups in bone-to-implant contact at 2 weeks or in bone area within all threads at 2 and 4 weeks. The Sr-HA coated group had significantly higher bone-to-implant contact at 4 and 8 weeks. Significant differences were also found in bone area at 8 weeks. CONCLUSION: The present study showed that this Sr-HA coating, deposited using an electrochemical process, has the potential to enhance implant osseointegration.

Influence of multilayer rhBMP-2 DNA coating on the proliferation and differentiation of MC3T3-E1 cells seeded on roughed titanium surface.

For bone morphogenetic protein (BMP) gene therapy to be a viable approach for enhancing implant osseointegration clinically, requires the development of efficient nonviral delivery vectors that can coat the implant. This study evaluated a multilayer cationic liposome-DNA complex (LDc) coating as a delivery vehicle for recombinant human BMP-2 (rhBMP-2). Multilayered coatings, comprising hyaluronic acid (HA) and LDc, were fabricated onto titanium using a layer-by-layer (LBL) assembly technique. Preosteoblastic MC3T3-E1 cells were cultured on the roughened titanium surfaces coated with multilayers of HA/LDc, or on uncoated or HA/liposome only surfaces as controls. The amount of rhBMP-2 secreted by the MC3T3-E1 cells and the effect of the various surfaces on cell viability, proliferation, alkaline phosphatase (ALP) activity, osteocalcin (OC) secretion, and calcium deposition were evaluated. Messenger RNA levels of OC, ALP, Runx2, and Osx were also investigated. The results demonstrated that rhBMP-2 protein secreted into culture medium at 3 days was significantly higher than control groups. MC3T3-E1 cells cultured on the HA/LDc coating displayed significantly higher ALP activity and OC secretion at 7 days and 14 days culture, respectively. MC3T3-E1 cells cultured on HA/LDc upregulated expression of the osteoblast differentiation markers, especially on days 12 for OC and on days 6 and 12 for ALP and Osx. In conclusion, MC3T3-E1 cell cultured on the multilayer HA/LDc coating surface can secret rhBMP-2 protein and the protein levels were effective in inducing early osteogenic differentiation.

Osteoblast response to porous titanium surfaces coated with zinc-substituted hydroxyapatite.

BACKGROUND: The aims of this study were to deposit a zinc-hydroxyapatite (Zn-HA) coating on titanium surfaces by using the electrochemical process and investigate the cell response to the Zn-HA-coated titanium surface. STUDY DESIGN: Surface characteristics were evaluated by scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Murine preosteoblast cell (MC3T3-E1) proliferation, alkaline phosphatase (ALP) activity, and osteocalcin release on Zn-HA-coated surfaces were compared with HA-coated surfaces. RESULTS: Field-emission SEM observation showed rod-like HA crystals with a hexagonal cross-section on the HA-coated surface, although the hexagon of the cross-section of Zn-HA crystals became irregular. ICP-AES analysis showed that Zn was present in the Zn-HA coatings at a Zn/(Ca+Zn) molar ratio of 1.04%. Significant increases in cell proliferation, ALP activity on day 7, and osteocalcin production on day 14 (P < .05) were observed for Zn(2+)-containing HA-coated surfaces. CONCLUSIONS: The present study showed that a Zn-HA coating deposited by using the electrochemical process enhances proliferation and differentiation of osteoblasts, which has the potential benefit to enhance implant osseointegration.

Simvastatin-loaded porous implant surfaces stimulate preosteoblasts differentiation: an in vitro study.

OBJECTIVE: Recent studies demonstrate that simvastatin stimulates bone formation, suggesting the potential application in dental implantology. In this study, our lab developed a simvastatin-loaded titanium porous surface. The aim was to investigate the effect of simvastatin-loaded titanium surfaces on the promotion of osteogenesis in preosteoblasts (MC3T3-E1) in vitro. STUDY DESIGN: The control group consisted of cells cultured on titanium disks without any intervention for different time intervals (4, 7, and 14 days), and the experimental groups (simvastatin-loaded groups) consisted of cells cultured on titanium disks that were preincubated in varying concentration (10(-7) mol/L, 10(-6) mol/L, 10(-5) mol/L, and 10(-4) mol/L) of simvastatin for the same time intervals of the control group. Alkaline phosphatase (ALP) activity, type I collagen synthesis, and osteocalcin release were used to measure the cellular osteoblastic activities. RESULTS: All simvastatin-loaded groups showed increased ALP activity compared with the control group at every time point, especially the 10(-7) mol/L group, which significantly increased the activity almost fourfold at 4 days (P < .05). In the type I collagen synthesis assay, all simvastatin-loaded groups showed an increase, and the effect was inverse dose dependent (maximal at 10(-7) mol/L). This stimulatory effect of simvastatin was also observed in the osteocalcin release assay (P < .05; at 10(-7) mol/L, 10(-6) mol/L, maximal at 10(-7) mol/L). CONCLUSION: These results indicate that simvastatin-loaded porous implant surfaces promote accelerated osteogenic differentiation of preosteoblasts, which have the potential to improve the nature of osseointegration.

Fabrication, characterization, and biological assessment of multilayer DNA coatings on sandblasted-dual acid etched titanium surface.

As local gene therapy has received attention, immobilizing functional gene onto irregular oral implant surface has become an advanced challenge. Electrostatic layer-by-layer (LBL) assembly technique could achieve this goal and allow local and efficient administration of genes to the target cells. In this study, multilayers of cationic lipid/plasmid DNA (pEGFP-C1) complex (LDc) and anionic hyaluronic acid were assembled onto sandblasted-dual acid etched titanium disks by the LBL technique. Surface characteristics of the coatings were performed by x-ray photospectroscopy (XPS), contact angle measurements, and scanning electron microscopy (SEM). The cell biological characteristics of the coatings were evaluated by in vitro experiments. SEM results demonstrated that the porous titanium surface was gradually flattened with the increase of the multilayer. The XPS survey indicated that the N element was found from the coating. The coating degradation and pEGFP-C1 releasing kinetics showed that the more assembled layer numbers were, the larger the amount of DNA released in the first 30 h. MC3T3-E1 cells were cultured directly on the DNA-loaded surface. Higher enhanced green fluorescent protein (EGFP) expression efficiency was achieved by increasing the number of layers when cells were cultured after 24 or 72 h. The MC3T3-E1 cell viability on the surface of multilayer DNA coatings was significantly higher than that on control porous titanium surface. It was concluded that the approach established by the LBL technique had great potential in immobilizing gene coatings onto the porous titanium surface and subsequently influenced the function of the cultured cell.

Effects of biomimetically and electrochemically deposited nano-hydroxyapatite coatings on osseointegration of porous titanium implants.

OBJECTIVE: The objective of this study was to evaluate and compare the effects of biomimetically and electrochemically deposited nano-hydroxyapatite (HA) coatings on the osseointegration of porous titanium implants after 6 and 12 weeks of insertion in a rabbit bone model. STUDY DESIGN: Forty-two roughened implants were separated into 3 groups: roughened group, biomimetically deposited CaP (BDCaP) group, and electrochemically deposited HA (EDHA) group. Implant surface morphology of 3 groups (n = 6) was performed by field-emission scanning electron microscope (FSEM). Thirty-six implants were randomly inserted into tibias of 18 rabbits. After 6 and 12 weeks, tibias were retrieved and prepared for histomorphometric evaluation. RESULTS: FSEM showed the BDCaP crystals were flakelike, whereas the EDHA crystals were rodlike with a hexagonal cross section. Histological observation showed bone growth along the surfaces after 6 weeks. New bones were also seen on the BDCaP and EDHA implant surfaces in the marrow space. New bone on the roughened and EDHA implants became mature after 12 weeks. The EDHA implant showed significantly greater BIC and bone area compared with the roughened and BDCaP implants during 6 to 12 weeks (P < .05). The BDCaP implants did not evidently increase BIC and bone area compared to the roughened implants during the test period (P > .05). CONCLUSION: These results suggest that the EDHA coating has a better bone integration potential than does the BDCaP coating.

In vivo evaluation of bone-bonding ability of RGD-coated porous implant using layer-by-layer electrostatic self-assembly.

RGD has been demonstrated to improve implant osseointegration. However, few studies are known about an effect of RGD coating on a bone-bonding ability of screw-shaped porous implant. The aim of this study was to investigate the effect of RGD coating using the layer-by-layer self-assembly technique on the bone-bonding ability of porous implant. 60 implants of 10 mm in length (30 control and 30 RGD-coated) were inserted into femurs of 30 rabbits and 30 implants of 8 mm in length (15 control and 15 RGD-coated) were inserted into tibias of 15 rabbits. At 4, 8, and 12 weeks post-implantation, femurs and tibias were retrieved and prepared for removal torque tests (RTQ) and histomorphometric evaluation, respectively. No differences were found in the RTQ values between two implants at 4 weeks (p = 0.932). There were statistical significances in the RTQ values at 8 and 12 weeks (p = 0.002, 0.001, respectively). New bone was formed on both implant surfaces. The bone-implant contact pattern appeared to produce a broad-based direct contact in both implants. The RGD-coated implants showed a significantly greater BIC in the threads inside the cortical bone compared with the control implants at 4, 8, and 12 weeks (p = 0.024, 0.041, 0.022, respectively). No differences were found in the bone area within the same threads between two implants at 4 weeks (p = 0.806) whereas differences were found at 8 and 12 weeks (p = 0.009, 0.031, respectively). It was concluded that RGD coating using the layer-by-layer self-assembly technique has a positive effect on the bone-bonding ability of porous implant.

Bone responses to titanium implants surface-roughened by sandblasted and double etched treatments in a rabbit model.

OBJECTIVE: The objective of this study was to investigate bone responses to titanium implants surface-roughened by sandblasted and double-etched treatments in a rabbit model. STUDY DESIGN: Sixty implants of 10 mm in length (30 machined and 30 roughened) were inserted into femurs of 30 rabbits and 30 implants of 8 mm in length (15 machined and 15 roughened) were inserted into tibias of 15 rabbits. At 2, 4, and 8 weeks postimplantation, femurs and tibias were retrieved and prepared for removal torque tests (RTQ) and histomorphometric evaluation, respectively. RESULTS: The roughened implants showed 66.21%, 89.06%, and 115.00% greater RTQ values than did the machined implants at 2, 4, and 8 weeks. Histomorphometric evaluation demonstrated the roughened implants significantly increased bone-implant contact and peri-implant bone formation during all observation periods. CONCLUSION: These results suggest this surface-roughened approach provides the implant surface with a considerable osteoconductive potential promoting a high level of bone integration with bone.