Evaluation of New Bone Formation and Osseointegration Around Subperiosteal Titanium Implants with Histometry and Nanoindentation
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To assess the quality and quantity of newly formed bone around rough-surfaced titanium subperiosteal implants stabilized with two different fixation techniques and to investigate nanoindentation as a method for measuring the elastic properties of the bone around these implants.Ten 6-month-old white rabbits were used in this study. One femur received a subperiosteal implant fixed to the bone with screws. The other femur received a subperiosteal implant stabilized with a trough (bed) in the bone area, plus fixation screws. After a 3-month healing period, the animals were sacrificed and each titanium plate was resected along with the surrounding bone. Histometric measurements of osseointegration were performed on 16 titanium plates, and 16 titanium plates were evaluated qualitatively (hardness and modulus of elasticity) with nanoindentation. A regression model was used to analyze the data.Subperiosteal implants placed into a trough performed significantly better than those placed on top of the cortical bone in terms of percentage of bone in direct contact with the titanium plate, length of new bone, and percentage of area of new bone. The mechanical properties (modulus of elasticity, hardness) of the newly formed bone above the plate measured at the microstructural level were significantly inferior to those of the mature cortical bone below the plate.Subperiosteal implants placed into a trough performed better than those placed on top of the cortical bone, but it seems that 3 months of healing is not enough to achieve optimal integration and bone maturation around them. Nanoindentation can offer valuable insight into the elastic properties of the microstructural component of the bone.Keywords:
Stress shielding
To assess the quality and quantity of newly formed bone around rough-surfaced titanium subperiosteal implants stabilized with two different fixation techniques and to investigate nanoindentation as a method for measuring the elastic properties of the bone around these implants.Ten 6-month-old white rabbits were used in this study. One femur received a subperiosteal implant fixed to the bone with screws. The other femur received a subperiosteal implant stabilized with a trough (bed) in the bone area, plus fixation screws. After a 3-month healing period, the animals were sacrificed and each titanium plate was resected along with the surrounding bone. Histometric measurements of osseointegration were performed on 16 titanium plates, and 16 titanium plates were evaluated qualitatively (hardness and modulus of elasticity) with nanoindentation. A regression model was used to analyze the data.Subperiosteal implants placed into a trough performed significantly better than those placed on top of the cortical bone in terms of percentage of bone in direct contact with the titanium plate, length of new bone, and percentage of area of new bone. The mechanical properties (modulus of elasticity, hardness) of the newly formed bone above the plate measured at the microstructural level were significantly inferior to those of the mature cortical bone below the plate.Subperiosteal implants placed into a trough performed better than those placed on top of the cortical bone, but it seems that 3 months of healing is not enough to achieve optimal integration and bone maturation around them. Nanoindentation can offer valuable insight into the elastic properties of the microstructural component of the bone.
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Ultraviolet (UV)-mediated photofunctionalization has earned considerable attention for the enhancement of the biologic capabilities of titanium. The effects of photofunctionalization on bone augmentation and gap closure were examined using titanium implants and mesh in a rat femur model.An acid-etched titanium implant (4-mm length, 1-mm diameter) was placed in the gluteal tuberosity that resembles a knife-edge-like edentulous ridge. The lower half of the implant was located in a 2-mm-diameter defect created in the bone without cortical bone support; the upper half was exposed and covered with a titanium mesh to provide augmentation space. After 12 and 24 days of healing, specimens were subjected to microcomputed tomography (micro-CT)- and histology-based bone morphometry in three zones of analysis: augmentation, cortical bone-implant gap, and bone marrow. A biomechanical push-in test was performed to examine the strength of bone-implant integration. Photofunctionalization was performed by treating titanium implants and mesh with UV light for 12 minutes.Photofunctionalized titanium mesh and implants were hydrophilic, whereas untreated controls were hydrophobic. Bone volume was significantly greater in photofunctionalized implants and mesh than in untreated implants in all zones on days 12 and 24. Bone-to-implant contact of photofunctionalized implants was greater than that of untreated implants, not just in the bone marrow but also in the gap and augmented zones. The strength of osseointegration was three times greater for photofunctionalized implants than for untreated implants.Use of photofunctionalized titanium mesh and implants effectively enhanced vertical bone augmentation, cortical bone-implant gap closure, and osseointegration without innate bone support.
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Mechanical fixation of the implant to host bone is an important contributor to orthopedic implant survivorship. The relative importance of bone-implant contact, trabecular bone architecture, and cortical bone geometry to implant fixation strength has never been directly tested, especially in the settings of differential implant surface properties. Thus, using a rat model where titanium rods were placed into the intramedullary canal of the distal femur, we determined the relative contribution of bone-implant contact and peri-implant bone architecture to the fixation strength in implants with different surface roughness: highly polished and smooth (as-received) and dual acid-etched (DAE) implants. Using a training set that maximized variance in implant fixation strength, we initially examined correlation between implant fixation strength and outcome parameters from microcomputed tomography and found that osseointegration volume per total volume (OV/TV), trabecular bone volume per total volume (BV/TV), and cortical thickness (Ct.Th) were the single best compartment-specific predictors of fixation strength. We defined separate regression models to predict implant fixation strength for as-received and DAE implants. When the training set models were applied to independent validation sets, we found strong correlations between predicted and experimentally measured implant fixation strength, with r2 = .843 in as received and r2 = .825 in DAE implants. Interestingly, for as-received implants, OV/TV explained more of the total variance in implant fixation strength than the other variables, whereas in DAE implants, Ct.Th had the most explanatory power, suggesting that surface topography of implants affects which bone compartment is most important in providing implant fixation strength.
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Unsuccessful implant integration leads to pain and implant mobility. Implant photo-functionalization by ultraviolet (UV) light has been suggested as a method that may stimulate osseointegration.This study was conducted to analyze the histopathological feature of the titanium implant surface upon treatment with UV-C wave.In this interventional study, twenty rabbits were enrolled. In the treatment groups, the titanium implants, irradiated earlier with UV-C for four hours laterally, were inserted in one of the femur bones. In the control group, the titanium implants without irradiation were inserted in the other femur bone of the rabbits. After two and four weeks, the animals were sacrificed, and then the samples were histologically and histo-morphometrically analyzed. In addition, the amounts of new bone formation, bleeding, and inflammation were recorded, and the data were subjected to statistical analysis.The results confirmed that UV-C irradiation to titanium implants significantly improved new bone formation (p< 0.001). However, no significant new bone formation was observed between two and four weeks after implant insertion (p< 0.098).The study results showed that irradiating titanium implants with UV-C for four hours significantly improves osseointegration and new bone formation but does not considerably affect inflammation or bleeding around the implant. The study suggests that UV-C radiation can increase the success rate of implant treatment.
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Abstract An osseointegrated stepped screw dental implant was evaluated using 2-dimensional finite element analysis (FEA). The implant was modeled in a cross section of the posterior human mandible digitized from a computed tomography (CT) generated patient data set. A 15-mm regular platform (RP) Branemark implant with equivalent length and neck diameter was used as a control. The study was performed under a number of clinically relevant parameters: loading at the top of the transmucosal abutment in vertical, horizontal, and 45° oblique 3 orientations. Elastic moduli of the mandible varied from a normal cortical bone level (13.4 GPa) to a trabecular bone level (1.37 GPa). The study indicated that an oblique load and elastic moduli of the cortical bone are important parameters to the implant design optimization. Compared with the cylindrical screw implant, the maximum von Mises stress of the stepped screw implant model was 17.9% lower in the trabecular bone-implant area. The study also showed that the stepped screw implant is suitable for the cortical bone modulus from 10 to 13.4 GPa, which is not necessarily as strict as the Branemark implant, for which a minimum 13.4 GPa cortical bone modulus is recommended.
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BACKGROUND: At present, metal implants are widely used in neuro-orthopedics, of which titanium alloys are of particular interest. A team of authors developed an original combined implant for posterior spinal fusion as an import substitution, which can be used from one-way access during minimally invasive operations on the lumbar spine. The implant was manufactured at the Endocarbon Enterprise in Penza. For better osseointegration, it is made of VT6 alloy and titanium nickelide. The middle part of the implant is laser-treated to create an uneven surface in the hope of better integration in the tissues of the body. This study was conducted to assess the cytotoxicity and biocompatibility of this implant for its further application in clinical practice.
AIM: To determine the cytotoxicity of an interspinous implant made of titanium alloys for its further introduction into spinal surgery.
MATERIALS AND METHODS: To determine the cytotoxicity of titanium samples of interspinous implants, a methyltetrazolium test was conducted to assess the viability of stromal cells in the presence of a nutrient medium after incubation with the test material. The biocompatibility of the material was analyzed using scanning electron microscopy of samples 1 and 7 days after cell culture.
RESULTS: The viability of cells cultured in the presence of a nutrient medium after incubation with samples of titanium VT6 was 105% and that of titanium nickelide was 98%, which were comparable to the viability of cells in a standard nutrient medium. With electron microscopy, after 1 day of cultivation, cells form a monolayer on a titanium surface, all cells were well spread out and formed intercellular contacts, and after 7 days of cultivation, the number of cells increased and they formed a dense monolayer.
CONCLUSIONS: The interspinous implant, which includes alloys of titanium VT6 and titanium nickelide, is biocompatible with cultured cells and can be introduced into spinal surgery.
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Abstract Healing chambers present at the interface between implant and bone have become a target for improving osseointegration. The objective of the present study was to compare osseointegration of several implant healing chamber configurations at early time points and regions of interest within bone using an in vivo animal femur model. Six implants, each with a different healing chamber configuration, were surgically implanted into each femur of six skeletally mature beagle dogs ( n = 12 implants per dog, total n = 72). The implants were harvested at 3 and 5 weeks post‐implantation, non‐decalcified processed to slides, and underwent histomorphometry with measurement of bone‐to‐implant contact (BIC) and bone area fraction occupied (BAFO) within healing chambers at both cortical and trabecular bone sites. Microscopy demonstrated predominantly woven bone at 3 weeks and initial replacement of woven bone by lamellar bone by 5 weeks. BIC and BAFO were both significantly increased by 5 weeks ( p < 0.001), and significantly higher in cortical than trabecular bone ( p < 0.001). The trapezoidal healing chamber design demonstrated a higher BIC than other configurations. Overall, a strong temporal and region‐specific dependence of implant osseointegration in femurs was noted. Moreover, the findings suggest that a trapezoidal healing chamber configuration may facilitate the best osseointegration. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1091–1097, 2016.
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Using implants for dental applications are well-accepted procedures as one of the solutions for periodontal defect repair. Suitable design and materials, their reaction with the surrounding hard tissues and interfacial biomechanical properties are still considered to be the primary criteria which need to be addressed. The purpose of present study was to evaluate the bone repair around pure titanium implants and porous surface using anodic oxidation technique, after their insertion in tibiae of rats (n = 15). Five animals received pure titanium-surface implants in tibia, 5 rough-surface implants (TiO2/Ti) in tibia and last five acted as control group. The interfacial integrity and compositional variation along the interface were studied using scanning electron microscope (SEM) with energy dispersive analysis of X-ray (EDX) and histopathology after 2 months. The rats were sacrificed 8 weeks after surgery and fragments of the tibiae containing the implants were submitted to histological analyses to evaluate new bone formation at the implant-bone interface as well as the tibiae were radio graphed. The SEM-EDX results confirmed the initial stability for the Ti implant, but the regeneration of new bone formation was faster in the case of TiO2/Ti implant, and hence could be used for faster healing. The results of the histological analysis showed that osseointegration occurred for both types of implants with similar quality of bone tissue. In conclusion, the porous-surface implants contributed to the osseointegration because they provide a larger contact area with surface roughness at implant-bone interface can help into the formation of physico-chemical bondage with the surrounding hard tissues.
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