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Research Interests: Electron Microscopy, Biomaterials, Scanning Electron Microscopy, Polymers, Multidisciplinary, and 17 moreAnimals, Skull, Calcium Phosphates, Bone Cement, Calcium Phosphate, Mechanical Stress, Rats, Particle Size, Time Factors, Shear Strength, Wistar Rats, Osteogenesis, Bone Cements, Materials Testing, Calcium Phosphate Cement, Biocompatible Materials, and Lactic Acid
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AbstractThe aim of this study was to investigate the biological and mechanical response of bone to titanium plasma-sprayed implants of different roughnesses. Three types of titanium plasma-spray coating were applied to beam-shaped... more
AbstractThe aim of this study was to investigate the biological and mechanical response of bone to titanium plasma-sprayed implants of different roughnesses. Three types of titanium plasma-spray coating were applied to beam-shaped implants: Ti2, Ti3, and Ti4, with a Ra of 16.5, 21.4, and 37.9 μm, respectively. An Al2O3 grit-blasted implant (Ti-un) with a Ra of 4.7 μ was used as a control. In total, 72 implants were inserted in the tibial cortical bone of nine adult female goats. These implants were evaluated histologically and mechanically 3 months after implantation. At the end of the experiment, of the 72 inserted implants, two implants (one Ti2 and one Ti4) were lost. Histological evaluation of the other retrieved implants revealed a uniform bone reaction for all implants. The unloaded plasma-spray coatings showed no signs of delamination at the implant–coating interface. Occasionally, particles of the Ti4 coating broke free and were found near the implant. Histomorphometry revealed no difference in bone contact for the different implants (P > 0.05). Furthermore, the push-out test showed no significant difference (P > 0.05). Linear regression showed no interaction between the push-out values and the roughness values (r = 0.5). On the basis of these results, it may be concluded that the used surface roughnesses did not lead to differences in bone response or mechanical attachment strength in goat cortical bone. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 41–48, 1998.
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This study looks for grounds to alter the chemical composition (phosphate, calcium, silica and carbonate), dissolution properties, structure and nanotopography of the biomimetically processed surfaces on bioactive ceramics to optimize... more
This study looks for grounds to alter the chemical composition (phosphate, calcium, silica and carbonate), dissolution properties, structure and nanotopography of the biomimetically processed surfaces on bioactive ceramics to optimize their shown ability to influence bone cell behaviour and production of new bone. In the bone environment desirable characteristic of these materials is their ability to be remodeled by natural osteoclastic resorption. Different silica and carbonate containing calcium phosphate layers were prepared on bioactive glasses 9 (S53P4) and 1-98 (S53P2) and sol-gel processed pure silica SiO2 in C- and R-SBF (conventional and revised simulated body fluid) for varying periods of time. It was shown that in R-SBF the CaP layer formed faster compared to C-SBF. The CaP layer in the R-SBF contained more carbonate (CO3(2-)) compared to that formed with the same immersion time in C-SBF. The CaP so formed in R-SBF with faster precipitation is more amorphous than the bonelike HCA formed in C-SBF. The results indicate that the most suitable surface for both osteoblasts and osteoclasts was found to be an amorphous CaP having mesoporous nanotopography and proper dissolution rate of calcium and silica.
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Research Interests: Dentistry, Biomedical Engineering, Crystallography, Osseointegration, Scanning Electron Microscopy, and 18 moreTitanium, Trabecular Bone, Femur, Female, Animals, Calcium Phosphates, Follow-up studies, Magnetron Sputtering, Goats, Electromagnetic phenomena, Mechanical Stress, X ray diffraction, Microwaves, Surface Properties, Osteogenesis, Torque, Biocompatible Materials, and Bone and Bones
ABSTRACT
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Research Interests:
Fractured coronal fragments of incisors can be adhered to the remaining tooth with resin composite, but are prone to failure. This study explores whether mini fibre-reinforced composite (FRC) anchors increase fracture resistance of... more
Fractured coronal fragments of incisors can be adhered to the remaining tooth with resin composite, but are prone to failure. This study explores whether mini fibre-reinforced composite (FRC) anchors increase fracture resistance of reattached fragments. Forty-five extracted incisors were randomly divided into three groups. In Groups A and B coronal fragments were reattached to the remaining tooth, with additionally two anchors placed in Group B. In Group C resin composite buildups were made. Specimens were statically loaded until failure occurred. Failure modes were characterized as intact remaining tooth substrate (adhesive or cohesive failure of coronal fragment) or fractured remaining tooth substrate (fracture limited to enamel or extending into dentin). Mean fracture loads were 255N (SD=108N) for Group A, 599N (SD=465N) for Group B and 786N (SD=197N) for Group C (values significantly different, all p values <0.05). Group A showed purely adhesive failures, while Groups B and C showed 73 and 53% fractures of remaining tooth substrate (p<0.05). Mini FRC anchors increase fracture resistance of reattached coronal fragments, but induce more remaining tooth substrate fractures.
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Research Interests: Biomedical Engineering, Scanning Electron Microscopy, Heat Treatment, Biomedical Materials, Calcium Phosphates, and 17 moreMagnetron, Biomaterial, Calcium Phosphate, Magnetics, X ray diffraction, Fourier transform infrared spectroscopy, Surface Properties, Infrared Radiation, Radiofrequency, Radio Waves, Materials Testing, Rf-Magnetron Sputtering, Biocompatible Materials, Sputter, Body Fluids, Infrared Rays, and *Hot Temperature(Magnetron, Biomaterial, Calcium Phosphate, Magnetics, X ray diffraction, Fourier transform infrared spectroscopy, Surface Properties, Infrared Radiation, Radiofrequency, Radio Waves, Materials Testing, Rf-Magnetron Sputtering, Biocompatible Materials, Sputter, Body Fluids, Infrared Rays, and *Hot Temperature)
(Magnetron, Biomaterial, Calcium Phosphate, Magnetics, X ray diffraction, Fourier transform infrared spectroscopy, Surface Properties, Infrared Radiation, Radiofrequency, Radio Waves, Materials Testing, Rf-Magnetron Sputtering, Biocompatible Materials, Sputter, Body Fluids, Infrared Rays, and *Hot Temperature)
ABSTRACT
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To assess whether dentin pins increase shear resistance of extensive composite restorations and to compare performance of mini fiber-reinforced composite (FRC) anchors with metal dentin pins in the laboratory. 30 extracted sound molars... more
To assess whether dentin pins increase shear resistance of extensive composite restorations and to compare performance of mini fiber-reinforced composite (FRC) anchors with metal dentin pins in the laboratory. 30 extracted sound molars were randomly divided into three groups. Occlusal surfaces were ground flat with a standard surface area and resin composite restorations were made in Group A. In Groups B and C similar restorations were made, with additionally four metal pins placed in Group B and four FRC pins in Group C. Specimens were statically loaded until failure occurred. Failure modes were characterized as intact remaining tooth substrate (adhesive or cohesive failure of restoration) or fractured remaining tooth substrate. Mean failure stresses were 6.5 MPa (SD 3.2 MPa) for Group A, 9.7 MPa (SD 2.6 MPa) for Group B and 9.2 MPa (SD 2.6 MPa) for Group C. Difference in mean failure stresses between Group A and Groups B and C was statistically significant (P = 0.01), while the difference between Groups B and C was not (P = 0.63). Failures of the restoration without fracture of tooth substrate were seen for 80% of specimens in Group A and 20% in Groups B and C (P = 0.04).
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Objectives: To understand the influence of the Young's modulus of the implant on peri-implant bone remodelling, by means of FEA. Materials and Methods: 16 Saanen goats, each receiving 1 Ti implant (Young's mod. 110 GPa) and 1... more
Objectives: To understand the influence of the Young's modulus of the implant on peri-implant bone remodelling, by means of FEA. Materials and Methods: 16 Saanen goats, each receiving 1 Ti implant (Young's mod. 110 GPa) and 1 high-density polyethylene (PE) implant (Young's mod. 1 GPa) in one femoral condyle were selected. A 100 nm Ti coating was applied on both implants. The implants protruded in the knee joint space and were directly weight bearing for 6 w. and 6 m. respectively. Histological sectioning and 3D trabecular bone parameters were calculated. An axisymmetric finite element (2095 linear (4-noded) quadrilateral elements and 2478 nodes/ Marc 2005 (MSC Software Corporation, Santa Ana, USA) model was created to compare peri-implant bone strains and relative motion between a Ti and a HDPE implant for the experimental loading condition, and to assess the influence of different bone-implant interface (contact) conditions. Results: The PE implants showed significantly...
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ABSTRACT Bioceramic coatings, including calcium phosphate coatings composed of hydroxyapatite (HA), represent a common surface modification for metallic bone implants. In view of the mismatch in material properties between the ceramic... more
ABSTRACT Bioceramic coatings, including calcium phosphate coatings composed of hydroxyapatite (HA), represent a common surface modification for metallic bone implants. In view of the mismatch in material properties between the ceramic coating material and the metallic substrate material, this study aimed to evaluate the residual stress within an HA-coating deposited using RF magnetron sputtering via two different analyses, based on either the Stoney formula (i.e. based on curvature measurements of the substrate [Stoney, 1909]) or the sin2 ψ method (i.e. based on X-ray diffraction patterns of the coating). Additionally, the effect of HA-coating thickness (i.e. 1 or 4 μm) on residual stress and surface topography were addressed. We hypothesized that: (i) both methods to determine residual stress would show similar results, and (ii) residual stress would varied between coating thicknesses. The curvature measurements showed low residual stress values (ranging from − 60 to 80 MPa) and indicated relaxation upon post-deposition heat treatment at 650 °C. Similarly, lattice-based measurements of residual stress showed relaxation of HA coatings upon post-deposition heat treatment. Coating thickness variation in the micrometer scale showed no major effects on residual stress magnitude. For reasons of accuracy and similarity to the actual conditions, determination of residual stress via lattice-based techniques is preferable.
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A single- or multi-unit fixed dental prosthesis can be attached to the abutment teeth through mechanical retention and gap sealing or by adhesion. For sealing the gap, water-soluble cements are appropriate, such as zinc phosphate,... more
A single- or multi-unit fixed dental prosthesis can be attached to the abutment teeth through mechanical retention and gap sealing or by adhesion. For sealing the gap, water-soluble cements are appropriate, such as zinc phosphate, polycarboxylate, and (resin-modified) glasionomer cement. Attachment through adhesion can be performed with composite cement. If the hard tooth tissue is prepared adequately, composite cement provides sufficient adhesion, but self-adhesive composite cement is now also available. For the adhesion of the composite cement to the restorative materials of the single- or multi-unit fixed dental prosthesis, surface sandblasting, silanizing, and tin coating and the application of a metal primer or chemically active composite are available. Cementing a single- or multi-unit dental prosthesis involves 3 phases: 1. Cleansing the single- or multi-unit dental prosthesis and the abutment tooth/teeth; 2. Preparing the hard tooth tissue, mixing the cement and placing the ...
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Four different implant materials were installed into the mandibular corner of goats to investigate the trabecular bone response in a mainly unloaded model. The implants were installed using a standardized technique and were left in situ... more
Four different implant materials were installed into the mandibular corner of goats to investigate the trabecular bone response in a mainly unloaded model. The implants were installed using a standardized technique and were left in situ for 12 weeks. One goat had to be sacrificed after surgery because of a broken rib; the other animals healed uneventfully. After sacrifice of the animals, the bone response to the uncoated and the three different Ca-P implants was evaluated histologically and histomorphometrically. Four sections of each implant were evaluated; two were located in the cortical and two in the trabecular bone. Of the 44 retrieved implants, 20 implants appeared to be installed partially in the mandibular canal, as clearly visible on the X-rays. These implants were not used in the histomorphometrical measurements. Histological evaluation showed that the trabecular and cortical bone reactions were similar; there was no significant difference in the percentage of bone contac...
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Page 275. 17 Bone Sectioning Using a Modified Inner Diamond Saw Joop GC Wolke, 1 Jan-Paul CM van der Waerden, 1 Christel PAT Klein. 2 and John A. Jansen1 1Department of Biomaterials. ... Also in this area. remodeling lacunae with... more
Page 275. 17 Bone Sectioning Using a Modified Inner Diamond Saw Joop GC Wolke, 1 Jan-Paul CM van der Waerden, 1 Christel PAT Klein. 2 and John A. Jansen1 1Department of Biomaterials. ... Also in this area. remodeling lacunae with osteoblasts were visible. ...
Calcium phosphate ceramics are the main mineral constituents of bone and teeth and have therefore been extensively investigated for bone regenerative applications. In the current study, the effect of disk material, surface geometry, and... more
Calcium phosphate ceramics are the main mineral constituents of bone and teeth and have therefore been extensively investigated for bone regenerative applications. In the current study, the effect of disk material, surface geometry, and SBF volume on mineralization capacity was investigated. Hemispherical concavities were created on the surfaces of disks made of different materials (i.e., hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP) and titanium (Ti)) which were sintered at 1200°C. Mineralization of CaP was assessed on disk surfaces after immersion of the samples in different volumes of simulated body fluid (SBF) up to 14 days by means of calcium assay and scanning electron microscopy (SEM). This study showed that different SBF volumes have different effects on mineralization, with an optimum material/liquid ratio of 5 ml of SBF per cm(2) . Additionally, at this volume, apparent differences based on disk material became obvious. Evidently, su...
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The current rapid progression in stem cell research has enhanced our knowledge of dental tissue regeneration. In this study, rat dental pulp cells were isolated and their differentiation ability was evaluated. First, dental pulp cells... more
The current rapid progression in stem cell research has enhanced our knowledge of dental tissue regeneration. In this study, rat dental pulp cells were isolated and their differentiation ability was evaluated. First, dental pulp cells were obtained from maxillary incisors of male Wistar rats. Immunochemistry by stem cell marker STRO-1 proved the existence of stem cells or progenitors in the isolated cell population. The dissociated cells were then cultured both on smooth surfaces and on three-dimensional (3-D) scaffold materials in medium supplemented with beta-glycerophosphate, dexamethasone, and L-ascorbic acid. Cultures were analyzed by light and scanning electron microscopy and, on proliferation, alkaline phosphatase activity and calcium content were determined and the polymerase chain reaction was performed for dentin sialophosphoprotein, osteocalcin, and collagen type I. These cells showed the ability to differentiate into odontoblast-like cells and produced calcified nodules, which had components similar to dentin. In addition, we found that the "odontogenic" properties of the isolated cells were supported by three-dimensional calcium phosphate and titanium scaffolds equally well.
Research Interests: Biomedical Engineering, Tissue Engineering, Calcium, Scanning Electron Microscopy, Titanium, and 19 moreStem Cell, Dexamethasone, Cell Differentiation, Animals, Male, Polymerase Chain Reaction, Calcium Phosphates, Tissue, alkaline phosphatase activity (APA), Calcium Phosphate, Ascorbic Acid, Rats, Three Dimensional, Wistar Rats, Cell Proliferation, Materials Testing, Biocompatible Materials, Biochemistry and cell biology, and Dental Pulp(Stem Cell, Dexamethasone, Cell Differentiation, Animals, Male, Polymerase Chain Reaction, Calcium Phosphates, Tissue, alkaline phosphatase activity (APA), Calcium Phosphate, Ascorbic Acid, Rats, Three Dimensional, Wistar Rats, Cell Proliferation, Materials Testing, Biocompatible Materials, Biochemistry and cell biology, and Dental Pulp)
(Stem Cell, Dexamethasone, Cell Differentiation, Animals, Male, Polymerase Chain Reaction, Calcium Phosphates, Tissue, alkaline phosphatase activity (APA), Calcium Phosphate, Ascorbic Acid, Rats, Three Dimensional, Wistar Rats, Cell Proliferation, Materials Testing, Biocompatible Materials, Biochemistry and cell biology, and Dental Pulp)
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ABSTRACT
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Calcium phosphate (CaP) coatings can be applied to improve the biological performance of polymeric medical implants. A strong interfacial bond between ceramic and polymer is required for clinical applications. Because the chemical... more
Calcium phosphate (CaP) coatings can be applied to improve the biological performance of polymeric medical implants. A strong interfacial bond between ceramic and polymer is required for clinical applications. Because the chemical structure of an interface plays an important role in the adhesion of a coating, we studied the formation of the interface between CaP and polystyrene (PS) and polytetrafluoroethylene
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This study looks for grounds to alter the chemical composition (phosphate, calcium, silica and carbonate), dissolution properties, structure and nanotopography of the biomimetically processed surfaces on bioactive ceramics to optimize... more
This study looks for grounds to alter the chemical composition (phosphate, calcium, silica and carbonate), dissolution properties, structure and nanotopography of the biomimetically processed surfaces on bioactive ceramics to optimize their shown ability to influence bone cell behaviour and production of new bone. In the bone environment desirable characteristic of these materials is their ability to be remodeled by natural osteoclastic resorption. Different silica and carbonate containing calcium phosphate layers were prepared on bioactive glasses 9 (S53P4) and 1-98 (S53P2) and sol-gel processed pure silica SiO2 in C- and R-SBF (conventional and revised simulated body fluid) for varying periods of time. It was shown that in R-SBF the CaP layer formed faster compared to C-SBF. The CaP layer in the R-SBF contained more carbonate (CO3(2-)) compared to that formed with the same immersion time in C-SBF. The CaP so formed in R-SBF with faster precipitation is more amorphous than the bonelike HCA formed in C-SBF. The results indicate that the most suitable surface for both osteoblasts and osteoclasts was found to be an amorphous CaP having mesoporous nanotopography and proper dissolution rate of calcium and silica.
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The aim of this study was to investigate in vitro bioactivity of different thermoplastic biodegradable barrier membranes. Three experimental GBR membranes were fabricated using Poly(epsilon-caprolactone-co-D: ,L-lactide) P(CL/DL-LA) and... more
The aim of this study was to investigate in vitro bioactivity of different thermoplastic biodegradable barrier membranes. Three experimental GBR membranes were fabricated using Poly(epsilon-caprolactone-co-D: ,L-lactide) P(CL/DL-LA) and particulate bioactive glass S53P4 (BAG; granule size 90-315 microm): (A) composite membrane with 60-wt.% of BAG, (B) membrane coated with BAG; and (C) copolymer membrane without BAG. Membranes were immersed in simulated body fluid (SBF), and their surfaces were characterized with SEM, XRD and EDS after 6 and 12 h and after 1, 3, 5, 7, and 14 days. Calcium phosphate (Ca-P) surface formation was observed on both composite membranes (A and B) but not on the copolymer membrane without bioactive glass (C). The Ca-P precipitation appeared to be initiated on the bioactive glass followed by growth of the layer along the polymer surface. In 6-12 h ion dissolution of the bioactive glass led to formation of the silica rich layer on the surface of the exposed glass granules on composite membrane B whereas only small amounts of silica was observed on the polymer surface of the composite membrane A. At 24 h nucleation of Ca-P precipitation was observed, and by 3-5 days membrane surface was covered with a uniform Ca-P layer transforming from amorphous to low crystalline structure. At 7 days composition and structure of the apatite surface resembled the apatite in bone. Once nucleated, the surface topography seemed to have significant effect on the growth of the apatite layer.
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Fractured coronal fragments of incisors can be adhered to the remaining tooth with resin composite, but are prone to failure. This study explores whether mini fibre-reinforced composite (FRC) anchors increase fracture resistance of... more
Fractured coronal fragments of incisors can be adhered to the remaining tooth with resin composite, but are prone to failure. This study explores whether mini fibre-reinforced composite (FRC) anchors increase fracture resistance of reattached fragments. Forty-five extracted incisors were randomly divided into three groups. In Groups A and B coronal fragments were reattached to the remaining tooth, with additionally two anchors placed in Group B. In Group C resin composite buildups were made. Specimens were statically loaded until failure occurred. Failure modes were characterized as intact remaining tooth substrate (adhesive or cohesive failure of coronal fragment) or fractured remaining tooth substrate (fracture limited to enamel or extending into dentin). Mean fracture loads were 255N (SD=108N) for Group A, 599N (SD=465N) for Group B and 786N (SD=197N) for Group C (values significantly different, all p values <0.05). Group A showed purely adhesive failures, while Groups B and C showed 73 and 53% fractures of remaining tooth substrate (p<0.05). Mini FRC anchors increase fracture resistance of reattached coronal fragments, but induce more remaining tooth substrate fractures.
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To investigate the short term effects of gamma-irradiation and conventional freezing on the hardness of human dentine. Twenty-one dentine disks were produced by transverse sectioning 21 sound extracted human permanent molar teeth. The 2.1... more
To investigate the short term effects of gamma-irradiation and conventional freezing on the hardness of human dentine. Twenty-one dentine disks were produced by transverse sectioning 21 sound extracted human permanent molar teeth. The 2.1 mm thick disks were wet polished using 4000 grit polishing paper. Three lines were drawn dividing each disk into six symmetrical areas. Seven disks were randomly assigned for freezing in water at -18 degrees C for 12 days; seven were exposed to a single dose of 25.2 kGy gamma radiation in water; seven were kept in water at 20 degrees C for 12 days (control). Before treatment, three Vicker's indentations at a load of 30 kg and a dwelling time of 20 s were made in one half of each disk, at equal distances from its edge and centre. Using light microscopy and image analysis software, the indentation diagonals were measured 4 h after preparation. Vicker's hardness values (VHN = kg/mm2) were calculated for each indentation. Following the treatment, VHNs were calculated again, for three symmetrical indentations in the second half of each disk. A statistical analysis was performed using the Wilcoxon rank sum test. The frozen group showed no changes following the treatment (VHN = 58 +/- 6 before vs. 57 +/- 6 after). The irradiation and control groups showed some hardening (VHN = 53 +/- 7 vs. 59 +/- 8; 57 +/- 3 vs. 63 +/- 6, respectively), however all values were within the normal variation. Both conventional freezing at -18 degrees C for 12 days in water, and a single gamma-irradiation dose of 25.2 kGy in water, appeared to have no short term effects on the hardness of human coronal dentine.
Research Interests: Dentistry, Water, Microscopy, Gamma Rays, Humans, and 4 moreHardness, Time Factors, Dentin, and Freezing
Osteoporotic conditions are anticipated to affect the osseointegration of dental implants. This study aimed to evaluate the effect of a radiofrequent magnetron-sputtered calcium phosphate (CaP) coating on dental implant integration upon... more
Osteoporotic conditions are anticipated to affect the osseointegration of dental implants. This study aimed to evaluate the effect of a radiofrequent magnetron-sputtered calcium phosphate (CaP) coating on dental implant integration upon installment in the femoral condyles of both healthy and osteoporotic rats. At 8 weeks post-implantation, bone volume and histomorphometric bone area were lower around non-coated implants in osteoporotic rats compared with healthy rats. Interestingly, push-out tests revealed significantly enhanced implant fixation for CaP-coated compared with non-coated implants in both osteoporotic (i.e., 2.9-fold) and healthy rats (i.e., 1.5-fold), with similar implant fixation for CaP-coated implants in osteoporotic conditions compared with that of non-coated implants in healthy conditions. Further, the presence of a CaP coating significantly increased bone-to-implant contact compared with that in non-coated implants in both osteoporotic (i.e., 1.3-fold) and healthy rats (i.e., 1.4-fold). Sequential administration of fluorochrome labels showed significantly increased bone dynamics close to CaP-coated implants at 3 weeks of implantation in osteoporotic conditions and significantly decreased bone dynamics in osteoporotic compared with healthy conditions. In conclusion, analysis of the data obtained demonstrated that dental implant modification with a thin CaP coating effectively improves osseointegration in both healthy and osteoporotic conditions.
Research Interests: Dentistry, Osseointegration, Titanium, Fluorescent Dyes and Reagents, Dental Materials, and 19 moreDental Implants, Humans, Femur, Female, Animals, Osteoclasts, Dental, Bone Density, Mechanical Stress, Rats, Time Factors, Surface Properties, Dental Prosthesis Design, Wistar Rats, Bone remodeling, Osteoblasts, Durapatite, X Ray Microtomography, and Ovariectomy
The aim of this study was to investigate the physicochemical and biological properties of a newly developed calcium phosphate cement (CPC). The novel cement was compared with two other commercially available CPCs. After mixing the powder... more
The aim of this study was to investigate the physicochemical and biological properties of a newly developed calcium phosphate cement (CPC). The novel cement was compared with two other commercially available CPCs. After mixing the powder and liquid phase, the CPCs were injected as a paste into a rabbit distal femoral defect model. The CPCs were evaluated after 24 h, 6 weeks, 26 weeks, and 52 weeks. The novel CPC was easy to handle and was fast setting. X-ray diffraction (XRD) and Fourier Transform Infrared Spectrometry (FTIR) at the different implantation periods showed that the cement had converted to carbonated hydroxyapatite and remained stable over time. Histological evaluation showed bone apposition on the cement surface without any inflammatory response or fibrous encapsulation. At later time points, all CPCs were completely covered by a thin layer of bone. Osteoclast-like cells present at the interface resorbed parts of the cement mass. Histological and histomorphometrical analyses did not show any significant differences between the three implanted CPCs. The results indicate that the investigated CPC is biocompatible, osteoconductive, as well as osteotransductive and seems to be both biologically safe and effective as a bone void filler.
Research Interests: Biomedical Engineering, Hydroxyapatite, Bone Regeneration, FTIR, Femur, and 16 moreFemale, Animals, Calcium Phosphates, Osteoclasts, Animal Model, XRD, X ray diffraction, Fourier transform infrared spectroscopy, Time Factors, Bone Cements, Rabbits, Materials Testing, Calcium Phosphate Cement, Fourier transform infrared, Inflammatory response, and Thin Layer
Calcium phosphate cements (CPCs) are significant alternatives to autologous bone grafting. CPCs can be composed of biphasic or multiphase calcium phosphate (CaP) compounds. A common way to process CPCs is by ball milling. Ball milling can... more
Calcium phosphate cements (CPCs) are significant alternatives to autologous bone grafting. CPCs can be composed of biphasic or multiphase calcium phosphate (CaP) compounds. A common way to process CPCs is by ball milling. Ball milling can be used for grinding or mechanosynthesis. The aim of this study was to determine the effect of well-defined ball milling grinding parameters, applied via different milling pathways, on the properties of CPCs. Starting CaP compounds used included α-tricalcium phosphate, dicalcium phosphate anhydrous and precipitated hydroxyapatite. Scanning electron microscopy showed changes in the powder morphology, which were related to the behavior of the starting CaP materials. Specific surface area (SSA) and particle size (PS) measurements exposed the effect of ball milling on the CaP compounds and CPC powders. X-ray diffraction revealed no effect of ball milling pathways or milling time on the composition of CPCs or the starting materials, but affected their crystallographic properties. No contamination of the milling media or transformation into an amorphous calcium phosphate compound was found. The milling pathways affected setting and cohesion. Fourier transform infrared spectroscopy (FTIR) revealed differences on the CPC v₄-PO₄³⁻ bands according to the interaction, created between the CaP compounds by the milling pathways. FTIR confirmed that the milling pathways changed the crystallographic properties. This study demonstrates that the pathways used for milling grinding modify the PS, SSA, and crystallographic properties of the powders, without affecting their composition. These modifications affected the bulk and reactivity properties of the CPCs by creating different setting and cohesion behaviors.
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The aim of this study was to investigate the biological and mechanical response of bone to titanium plasma-sprayed implants of different roughnesses. Three types of titanium plasma-spray coating were applied to beam-shaped implants: Ti2,... more
The aim of this study was to investigate the biological and mechanical response of bone to titanium plasma-sprayed implants of different roughnesses. Three types of titanium plasma-spray coating were applied to beam-shaped implants: Ti2, Ti3, and Ti4, with a Ra of 16.5, 21.4, and 37.9 microm, respectively. An Al2O3 grit-blasted implant (Ti-un) with a Ra of 4.7 microm was used as a control. In total, 72 implants were inserted in the tibial cortical bone of nine adult female goats. These implants were evaluated histologically and mechanically 3 months after implantation. At the end of the experiment, of the 72 inserted implants, two implants (one Ti2 and one Ti4) were lost. Histological evaluation of the other retrieved implants revealed a uniform bone reaction for all implants. The unloaded plasma-spray coatings showed no signs of delamination at the implant-coating interface. Occasionally, particles of the Ti4 coating broke free and were found near the implant. Histomorphometry revealed no difference in bone contact for the different implants (P > 0.05). Furthermore, the push-out test showed no significant difference (P > 0.05). Linear regression showed no interaction between the push-out values and the roughness values (r = 0.5). On the basis of these results, it may be concluded that the used surface roughnesses did not lead to differences in bone response or mechanical attachment strength in goat cortical bone.
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ABSTRACT In the search for a suitable bone graft substitute, a study was conducted using a material that combined a proven osteconductive composite, hydroxyapatite-calcium sulfate (HA/CS), with an osteoinductive factor, bovine osteogenic... more
ABSTRACT In the search for a suitable bone graft substitute, a study was conducted using a material that combined a proven osteconductive composite, hydroxyapatite-calcium sulfate (HA/CS), with an osteoinductive factor, bovine osteogenic factor (OF). The initial study demonstrated the osteoinductive potential of OF in the rabbit muscle model. Once satisfied that the OF was active, it was added to the HA/CS composite and placed in 8-mm trephine defects in the rabbit cranium. This HA/CS/OF was directly compared to HA/CS augmented with a control protein, rabbit serum albumin (RSA). Animals were sacrificed at 4 and 8 weeks. Results demonstrated increased bone formation with the addition of the OF to the composite with bridging of the defects, in most cases, by 4 weeks. No bridging was seen, at this time period, in the other defects left unfilled or filled with HA/CS/RSA. Osteogenic factor, with the appropriate delivery system, can induce bone formation in the rabbit muscle. It may also increase the rate of bone formation at early time periods in a bony defect site when the delivery system is the osteconductive composite HA/CS.
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Research Interests: Biomedical Engineering, Cell Adhesion, Scanning Electron Microscopy, Titanium, Cell Division, and 12 moreBiomedical Materials, Animals, Male, Calcium Phosphates, Magnetron Sputtering, Rats, X ray diffraction, Fourier transform infrared spectroscopy, Surface Properties, Wistar Rats, Osteoblasts, and Bone Marrow Cells
... They showed a linear increase for the two composites (C.50 in Fig. ... In the case of glass-ceramics the formation of a thin calcium phosphate layer by successive deposition of chemical reaction products at the interface ... 6b-d),... more
... They showed a linear increase for the two composites (C.50 in Fig. ... In the case of glass-ceramics the formation of a thin calcium phosphate layer by successive deposition of chemical reaction products at the interface ... 6b-d), this calcium was not measured by atomic absorption. ...
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The aim of this study was to investigate the physicochemical, biological, and handling properties of a new developed calcium phosphate (Ca-P) cement when implanted in trabecular bone. Ca-P cement consisting of a powder and a liquid phase... more
The aim of this study was to investigate the physicochemical, biological, and handling properties of a new developed calcium phosphate (Ca-P) cement when implanted in trabecular bone. Ca-P cement consisting of a powder and a liquid phase was implanted as a paste into femoral trabecular bone of goats for 3 days and 2, 8, 16, and 24 weeks. The cement was tested using three clinically relevant liquid-to-powder ratios. Polymethylmethacrylate bone cement, routinely used in orthopedics, was used as a control. The Ca-P cement was easy to handle and was fast setting with good cohesion when in contact with body fluids. X-ray diffraction at the different implantation periods showed that the cement had set as an apatite and remained stable over time. Histological evaluation after 2 weeks, performed on 10 microm un-decalcified sections, showed abundant bone apposition on the cement surface without any inflammatory reaction or fibrous encapsulation. At later time points, the Ca-P cement implants were totally covered by a thin layer of bone. Osteoclast-like cells, as present at the interface, had resorbed parts of the cement mass. At locations where Ca-P cement was resorbed, new bone was formed without loss of integrity between the bone bed and the cement. This demonstrated the osteotransductive property of the cement, i.e., resorption of the material by osteoclast-like cells, directly followed by the formation of new bone. Histological and histomorphometrical evaluation did not show any significant differences between the Ca-P cement implanted at the three different liquid/powder ratios. The results indicate that the investigated Ca-P cement is biocompatible, osteoconductive, as well as osteotransductive and is a candidate material for use as a bone substitute.
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In this study, we examined the effect of calcium phosphate (Ca-P) coating crystallinity and of surface roughness on growth and differentiation of osteogenic cells. Grit-blasted titanium substrates were provided with Ca-P coatings of... more
In this study, we examined the effect of calcium phosphate (Ca-P) coating crystallinity and of surface roughness on growth and differentiation of osteogenic cells. Grit-blasted titanium substrates were provided with Ca-P coatings of different crystallinities. Rat bone marrow (RBM) cells were cultured on these substrates and on noncoated rough and smooth titanium substrates. After specific culture times, expression of osteogenic markers by the cells was studied. Cells cultured on crystalline coatings and on titanium substrates proliferate, express alkaline phosphatase, osteocalcin (OC), and show mineralization of the extracellular matrix. Rough titanium substrates only express low OC levels. Significantly higher OC levels were expressed on smooth titanium, and even higher levels on the crystalline Ca-P coating. No difference was found in calcification between smooth and rough titanium. The crystalline coating showed more calcification than the titanium substrates. When substrates without cells were incubated in medium, precipitation of calcium was found. On the titanium substrates, this precipitate disappeared after prolonged incubation. The precipitate on the crystalline coating was stable and increased with longer incubation times. On the amorphous coatings, no proliferation and differentiation of RBM cells were found. After longer culture periods, substrates showed extensive dissolution. Cells on the amorphous coatings did express high levels of prostaglandin E2. In contrast, prostaglandin E2 expression was low for the other substrates. We conclude that crystalline Ca-P coatings stimulate differentiation of RBM cells, to a higher extent than titanium substrates. Surface roughness only has a limited effect on phenotype expression of the cells. In contrast, thin amorphous coatings show negative effects on the growth and differentiation of cultured RBM cells.
Research Interests: Biomedical Engineering, Scanning Electron Microscopy, Crystallization, Surface Roughness, Cell Division, and 14 moreCell Differentiation, Biomedical Materials, Animals, Male, Calcium Phosphates, Osteocalcin, Alkaline phosphatase, Calcium Phosphate, Rats, X ray diffraction, Fourier transform infrared spectroscopy, Surface Properties, Wistar Rats, and Bone Marrow Cells
The aim of this study was to investigate bone response to and biostability of three different hydroxyapatite (HA)-coatings. Therefore, coated and uncoated titanium implants were inserted into the tibia of rabbits. Implantation times were... more
The aim of this study was to investigate bone response to and biostability of three different hydroxyapatite (HA)-coatings. Therefore, coated and uncoated titanium implants were inserted into the tibia of rabbits. Implantation times were at 3 and 12 weeks. The histological evaluation included measurement of the amount of bone apposition to the various implant surfaces. The results demonstrated at 3 and 12 weeks no marked differences in bony reaction at the cortical level to the different implant materials. However, compared with the 3-week specimens, at 12 weeks extensive maturation of the woven bone callus had occurred. In addition, all 12-week implants induced bone formation in the medullary cavity. It was also noted that all HA-coatings showed loss of coating thickness. Quantitative determination of bone contact demonstrated that all 12-week implants showed the same high amount of bone apposition.