This study focused at the potential of transforming growth factor b1 (TGF-b1) loaded gelatin micr... more This study focused at the potential of transforming growth factor b1 (TGF-b1) loaded gelatin microparticles to enhance the bone response and mechanical strength of rabbit femoral defects filled with injectable calcium phosphate (CaP)/gelatin microparticle composites. Therefore, TGF-b1 loaded composites and non-loaded controls were injected in circular defects as created in the femoral condyles of rabbits and were left in place for 4, 8 and 12 weeks. The specimens were evaluated mechanically (push-out test), and morphologically (scanning electron microscopy (SEM), histology, and histomorphometry). The results showed a gradual increase in mechanical strength with increasing implantation periods. Histological and histomorphometrical evaluation showed similar results for both composite formulations regarding histological aspect, new bone formation and bone/implant contact. However, TGF-b1 loading of the composites demonstrated a significant effect on composite degradation after twelve weeks of implantation. The results of this study showed that CaP/gelatin composites show excellent osteogenic properties and a rapid increase in mechanical strength. The addition of TGF-b1 significantly enhances the bone remodeling process. r
In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorpora... more In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorporated with 20 wt% poly (DL-lactic-coglycolic acid) (PLGA) microparticles were investigated in a rat cranial defect. After 2, 4 and 8 weeks of implantation, implants were evaluated mechanically (push-out test) and morphologically (Scanning Electron Microscopy (SEM) and histology). The results of the push-out test showed that after 2 weeks the shear strength of the implants was 0.4470.44 MPa (average7sd), which increased to 1.3471.05 MPa at 4 weeks and finally resulted in 2.6072.78 MPa at 8 weeks. SEM examination showed a fracture plane at the bone-cement interface at 2 weeks, while the 4-and 8-week specimens created a fracture plane into the CaP/PLGA composites, indicating an increased strength of the bone-cement interface. Histological evaluation revealed that the two weeks implantation period resulted in minimal bone ingrowth, while at 4 weeks of implantation the peripheral PLGA microparticles were degraded and replaced by deposition of newly formed bone. Finally, after 8 weeks of implantation the degradation of the PLGA microparticles was almost completed, which was observed by the bone ingrowth throughout the CaP/PLGA composites.
Journal of Materials Science Materials in Medicine, Nov 22, 2006
This study looks for grounds to alter the chemical composition (phosphate, calcium, silica and ca... 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.
Journal of Biomedical Materials Research Part a, Sep 1, 2007
In this study bone regeneration between porous btricalcium phosphate (Conduit TM TCP) and biphasi... more In this study bone regeneration between porous btricalcium phosphate (Conduit TM TCP) and biphasic calcium phosphate ceramic (Biosel 1 ), with a hydroxyapatite/b-TCP ratio of 75/25, was compared. The ceramic particles were implanted in sheep trabecular bone for 3, 12, and 26 weeks. Histomorphometrical analysis revealed that Conduit TM degraded significantly during time and only 36% of the material was left at 26 weeks implantation time. Biosel 1 , in contrast, remained nearly intact. The degradation of Conduit TM was due to dissolution as well as cell-mediated. Biosel 1 showed a high cellular intervention, although this material did not degrade. Both materials were osteoconductive. The amount of newly formed bone appeared greater in the Con-duit TM group after 26 weeks (46% 6 8% as compared to 37% 6 8% for Biosel 1 ), but this difference was not significant. Bone distribution over the defect was homogeneous in Conduit TM , whereas Biosel 1 showed significantly more bone in the periphery of the defect after 26 weeks in comparison to the center. In conclusion, both ceramics are biocompatible and osteoconductive. Degradation showed a difference in amount and in cellular events, with more degraded Conduit TM TCP with less cellular intervention as compared to Biosel 1 .
Fractured coronal fragments of incisors can be adhered to the remaining tooth with resin composit... 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.
To assess whether dentin pins increase shear resistance of extensive composite restorations and t... 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).
Objectives: To understand the influence of the Young's modulus of the implant on peri-implant... 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...
ABSTRACT Bioceramic coatings, including calcium phosphate coatings composed of hydroxyapatite (HA... 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.
A single- or multi-unit fixed dental prosthesis can be attached to the abutment teeth through mec... 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 ...
This study focused at the potential of transforming growth factor b1 (TGF-b1) loaded gelatin micr... more This study focused at the potential of transforming growth factor b1 (TGF-b1) loaded gelatin microparticles to enhance the bone response and mechanical strength of rabbit femoral defects filled with injectable calcium phosphate (CaP)/gelatin microparticle composites. Therefore, TGF-b1 loaded composites and non-loaded controls were injected in circular defects as created in the femoral condyles of rabbits and were left in place for 4, 8 and 12 weeks. The specimens were evaluated mechanically (push-out test), and morphologically (scanning electron microscopy (SEM), histology, and histomorphometry). The results showed a gradual increase in mechanical strength with increasing implantation periods. Histological and histomorphometrical evaluation showed similar results for both composite formulations regarding histological aspect, new bone formation and bone/implant contact. However, TGF-b1 loading of the composites demonstrated a significant effect on composite degradation after twelve weeks of implantation. The results of this study showed that CaP/gelatin composites show excellent osteogenic properties and a rapid increase in mechanical strength. The addition of TGF-b1 significantly enhances the bone remodeling process. r
In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorpora... more In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorporated with 20 wt% poly (DL-lactic-coglycolic acid) (PLGA) microparticles were investigated in a rat cranial defect. After 2, 4 and 8 weeks of implantation, implants were evaluated mechanically (push-out test) and morphologically (Scanning Electron Microscopy (SEM) and histology). The results of the push-out test showed that after 2 weeks the shear strength of the implants was 0.4470.44 MPa (average7sd), which increased to 1.3471.05 MPa at 4 weeks and finally resulted in 2.6072.78 MPa at 8 weeks. SEM examination showed a fracture plane at the bone-cement interface at 2 weeks, while the 4-and 8-week specimens created a fracture plane into the CaP/PLGA composites, indicating an increased strength of the bone-cement interface. Histological evaluation revealed that the two weeks implantation period resulted in minimal bone ingrowth, while at 4 weeks of implantation the peripheral PLGA microparticles were degraded and replaced by deposition of newly formed bone. Finally, after 8 weeks of implantation the degradation of the PLGA microparticles was almost completed, which was observed by the bone ingrowth throughout the CaP/PLGA composites.
Journal of Materials Science Materials in Medicine, Nov 22, 2006
This study looks for grounds to alter the chemical composition (phosphate, calcium, silica and ca... 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.
Journal of Biomedical Materials Research Part a, Sep 1, 2007
In this study bone regeneration between porous btricalcium phosphate (Conduit TM TCP) and biphasi... more In this study bone regeneration between porous btricalcium phosphate (Conduit TM TCP) and biphasic calcium phosphate ceramic (Biosel 1 ), with a hydroxyapatite/b-TCP ratio of 75/25, was compared. The ceramic particles were implanted in sheep trabecular bone for 3, 12, and 26 weeks. Histomorphometrical analysis revealed that Conduit TM degraded significantly during time and only 36% of the material was left at 26 weeks implantation time. Biosel 1 , in contrast, remained nearly intact. The degradation of Conduit TM was due to dissolution as well as cell-mediated. Biosel 1 showed a high cellular intervention, although this material did not degrade. Both materials were osteoconductive. The amount of newly formed bone appeared greater in the Con-duit TM group after 26 weeks (46% 6 8% as compared to 37% 6 8% for Biosel 1 ), but this difference was not significant. Bone distribution over the defect was homogeneous in Conduit TM , whereas Biosel 1 showed significantly more bone in the periphery of the defect after 26 weeks in comparison to the center. In conclusion, both ceramics are biocompatible and osteoconductive. Degradation showed a difference in amount and in cellular events, with more degraded Conduit TM TCP with less cellular intervention as compared to Biosel 1 .
Fractured coronal fragments of incisors can be adhered to the remaining tooth with resin composit... 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.
To assess whether dentin pins increase shear resistance of extensive composite restorations and t... 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).
Objectives: To understand the influence of the Young's modulus of the implant on peri-implant... 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...
ABSTRACT Bioceramic coatings, including calcium phosphate coatings composed of hydroxyapatite (HA... 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.
A single- or multi-unit fixed dental prosthesis can be attached to the abutment teeth through mec... 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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