Connective tissue grafts are used successfully in periodontal therapy for root coverage. However,... more Connective tissue grafts are used successfully in periodontal therapy for root coverage. However, reports on the histologic interface between the root surface and the grafted tissue have been few in number. This report describes a case study in which a subepithelial connective tissue graft was placed in a 27-year-old female on the maxillary left side. The graft (15 mm long, 10 mm wide, 1.5 mm thick) included palatal periosteum and was placed with the periosteal side facing the exposed bone and root surfaces. 15 weeks after grafting, the teeth presented with residual recessions of 1 mm, and buccal probing depths were approximately 1 mm. 14 months post-surgery, the 1st maxillary premolars on both sides were extracted for orthodontic therapy. Clinical parameters at the graft site remained as at 15 weeks. Histologic analysis of tooth #24 showed that the sulcular epithelium was keratinized; epithelium lining the dentin exhibited rete ridges projecting into the gingival connective tissue; and junctional epithelium extended over new cementum. New connective tissue attachment was also observed, including periodontal ligament. Biological width was comparable pre- and post-surgery, indicating a real gain in attachment of 3.9 mm.
Transactions - 7th World Biomaterials Congress, 2004
INTRODUCTION: Osteoblasts are sensitive to surface microtopography, exhibiting a more differentia... more INTRODUCTION: Osteoblasts are sensitive to surface microtopography, exhibiting a more differentiated morphology on rougher surfaces. Surface effects are mediated through cell surface receptors (e.g. integrins or transmembrane proteoglycans) that recognize and bind to a specific motif in cell attachment proteins. Thus, not only the topography but also the (bio)chemistry of a surface plays an important role. Recently, we demonstrated that the assembly of peptide-functionalized poly-L-lysine-gpoly(ethylene glycol) (PLL-g-PEG) polymers on titanium surfaces is a promising approach for manufacturing protein-resistant surfaces presenting peptide moieties at controlled surface density to interact directly with integrin cell receptors.
Studies showing that osteoblasts exhibit a more differentiated phenotype on rough titanium (Ti) s... more Studies showing that osteoblasts exhibit a more differentiated phenotype on rough titanium (Ti) surfaces and osteoclast-resorbed bone surfaces used materials characterized by average peak to valley distance (Ra). Other surface features impacting the cells include distance between peaks, curvature of the valleys, and relative distribution of flat and smooth regions. We used novel Ti surfaces prepared by electrochemical micromachining as models to examine specific contributions of individual design features to osteoblast response. Results show that micron-scale topography modulates cell number, cell morphology and prostaglandin E2 (PGE2). In the presence of the appropriate microtopography, submicron-scale rugosity modulates differentiation and transforming growth factor-beta1 (TGF-beta1) levels. In this study, we examined the role of different types of submicron-scale structures. Thirty micrometer diameter craters on Ti disks were produced by photolithography resulting in an electropolished smooth surface, and arranged so that inside crater area vs. outside flat area was 6 (30/6). Submicron-scale structures were superposed by acid etching and porous anodization. Ra's were 700, 400, 60 nm on acid-etched, porous anodized and smooth 30/6 surfaces, respectively. MG63 osteoblast-like cells were sensitive to submicron-scale architecture. Cell morphology on anodized surfaces was similar to morphology on smooth surfaces, whereas on etched surfaces, cells had a more elongated differentiated shape. Cell number was greatest on smooth surfaces > anodized > etched. Osteocalcin and PGE2 were affected in a reverse manner. Active TGF-beta1 was greatest on etched 30/6 surfaces > anodized > smooth; latent TGF-beta1 was elevated on all rough surfaces. These results support our previous observations that submicron-scale structures modulate osteoblastic phenotype and show that the physical properties of the submicron-scale structures are important variables in determining osteoblast response to substrate topography.
Microscale surface roughness has been shown to enhance osseointegration of titanium implants thro... more Microscale surface roughness has been shown to enhance osseointegration of titanium implants through increased osteoblast differentiation while osteoblast proliferation remains greater on smooth titanium. Taking advantage of these phenomena, we developed a shape memory (meth)acrylate copolymer with thermomechanical properties that created a time-dependent dynamic surface change from smooth to rough under in vitro cell culture conditions and evaluated the effect of the shape recovery on osteoblast response. Rough topographies were created using soft lithography techniques to mimic those found on clinically-used Ti surfaces (machined smooth; acid-etched; grit-blasted). The surface roughness was then reduced to smooth via compression and shown to fully recover within 24 h in culture conditions. When grown under static conditions, osteoblast number, alkaline phosphatase specific activity (ALP), and osteoprotegerin (OPG) and vascular endothelial growth factor (VEGF) production were unaffected by polymer surface roughness, but osteocalcin (OCN) was increased on the grit-blasted polymer mimic. Under dynamic conditions, DNA was reduced but OCN and OPG were increased on the compressed grit-blasted polymer at 3 days compared to static surfaces. The present study indicates that responses to polymer surface are sensitive to time-dependent changes in topography. The use of a shape memory polymer with dynamic surface roughness may improve osseointegration.
Osteoblasts are attachment-dependent cells that interact with their surface through integrin-medi... more Osteoblasts are attachment-dependent cells that interact with their surface through integrin-mediated mechanisms. Their differentiation is regulated by 1,25-dihydroxyvitamin D3 [1alpha,25(OH)(2)D(3)] and is affected by substrate chemistry and microtopography, suggesting that 1alpha,25(OH)(2)D(3) may regulate integrin expression in a surface-specific manner. To test this hypothesis, osteoblast-like human MG63 cells were grown on tissue culture plastic and on grit-blasted and acid-etched titanium disks with a complex microtopography to induce osteoblast differentiation. Expression of alpha(2), alpha(5), alpha(v), beta(1), and beta(3) integrins were quantified by real-time polymerase chain reaction (PCR) as a function of time in culture and treatment with 1alpha,25(OH)(2)D(3). Results were correlated with expression of osteocalcin, a marker of a differentiated osteoblast. Osteocalcin mRNA increased with time and 1alpha,25(OH)(2)D(3) treatment and these changes were greater in cultures on the titanium disks. Integrin expression varied with time in culture and this was also surface dependent. At each time point, beta(1) and alpha(2) mRNAs were greater on titanium than on plastic, whereas alpha(5) expression was reduced and alpha(v),beta(3) expression was unaffected. 1alpha,25(OH)(2)D(3) increased beta(1) mRNA on both surfaces at all time points, but it increased alpha(2) expression only in 8-d cultures. 1alpha,25(OH)(2)D(3) caused reduced alpha(5) expression only in cultures grown on plastic for 8 d, and had no effect on either alpha(v) or beta(3) expression regardless of surface. These results show that integrin expression in human osteoblast-like cells is differentially modulated by 1alpha,25(OH)(2)D(3) in a time-dependent manner that is sensitive to the surface on which the cells are grown.
Previous studies have shown that costochondral cartilage cell cultures produce extracellular matr... more Previous studies have shown that costochondral cartilage cell cultures produce extracellular matrix vesicles which contain metalloproteinase activity. In the present study, we examined whether two matrix metalloproteinases (MMPs) known to be present in cartilage, stromelysin-1 and 72 kDa gelatinase, are expressed by fourth passage resting zone and growth zone costochondral chondrocytes and whether they are specifically incorporated into matrix vesicles produced by the cells. We also examined whether the cells synthesize tissue inhibitor of metalloproteinase-1 and -2 (TIMP-1 and TIMP-2). Oligonucleotide primers for stromelysin-1, 72 kDa gelatinase, tissue inhibitor of metalloproteinases-1 and -2 (TIMP-1 and TIMP-2), and GAPDH were synthesized and optimized for use in the reverse transcription-polymerase chain reaction (RT-PCR). It was found that both resting zone and growth zone chondrocytes produced mRNA for both MMPs and the two TIMPs. Further, immunostaining of cell layers with antibodies to 72 kDa gelatinase and stromelysin-1 showed that both cell types produced these MMPs in culture. Substrate gel electrophoresis and Western analysis were used to characterize MMP activity in matrix vesicles, media vesicles, or plasma membranes as well as in conditioned media produced by the chondrocyte cultures. It was found that matrix vesicles but not plasma membranes or media vesicles were selectively enriched in stromelysin-1. Also, 72 kDa gelatinase was found in matrix vesicles, but to a lesser extent than seen in media vesicles. The relative activity of each enzyme detected was cell maturation-dependent. No MMP activity was detected in conditioned media produced by either cell type. The results of this study show that MMPs are expressed by resting zone and growth zone chondrocytes in culture and differentially distributed among three different membrane compartments. This suggests that, in addition to the well-known activators and inhibitors of MMP activity in the matrix, differential membrane distribution may enable more precise control over the site, rate, and extent of matrix degradation by the cell.
Matrix vesicles (MVs) are nano-sized extracellular vesicles that are anchored in the extracellula... more Matrix vesicles (MVs) are nano-sized extracellular vesicles that are anchored in the extracellular matrix (ECM). In addition to playing a role in biomineralization, osteoblast-derived MVs were recently suggested to have regulatory duties. The aims of this study were to: establish the characteristics of osteoblast-derived MVs in the context of extracellular vesicles like exosomes, assess their role in modulating osteoblast differentiation, and examine their mechanism of uptake. MVs were isolated from the ECM of MG-63 human osteoblast-like cell cultures and characterized via enzyme activity, transmission electron microscopy, nanoparticle tracking analysis, western blot, and small RNA sequencing. Osteoblasts were treated with MVs from two different culture conditions (growth media [GM]; osteogenic media [OM]) to evaluate their effects on differentiation and production of inflammatory markers and on macrophage polarization. MV endocytosis was assessed using a lipophilic, fluorescent dye...
Reduced skeletal loading associated with many conditions, such as neuromuscular injuries, can lea... more Reduced skeletal loading associated with many conditions, such as neuromuscular injuries, can lead to bone fragility and may threaten the success of implant therapy. Our group has developed a botulinum toxin A (botox) injection model to imitate disease-reduced skeletal loading and reported that botox dramatically impaired the bone formation and osseointegration of titanium implants. Semaphorin 3A (sema3A) is an osteoprotective factor that increases bone formation and inhibits bone resorption, indicating its potential therapeutic role in improving osseointegration in vivo. We first evaluated the sema3A effect on whole bone morphology following botox injections by delivering sema3A via injection. We then evaluated the sema3A effect on the osseointegration of titanium implants with two different surface topographies by delivering sema3A to cortical bone defect sites prepared for implant insertion and above the implants after insertion using a copper-free click hydrogel that polymerizes...
Journal of Biomedical Materials Research Part B: Applied Biomaterials
Current standards in bone‐facing implant fabrication by metal 3D (M3D) printing require post‐manu... more Current standards in bone‐facing implant fabrication by metal 3D (M3D) printing require post‐manufacturing modifications to create distinct surface properties and create implant microenvironments that promote osseointegration. However, the biological consequences of build parameters and surface modifications are not well understood. This study evaluated the relative contributions of build parameters and post‐manufacturing modification techniques to cell responses that impact osseointegration in vivo. Biomimetic testing constructs were created by using a M3D printer with standard titanium–aluminum–vanadium (Ti6Al4V) print parameters. These constructs were treated by either grit‐blasting and acid‐etching (GB + AE) or GB + AE followed by hot isostatic pressure (HIP) (GB + AE, HIP). Next, nine constructs were created by using a M3D printer with three build parameters: (1) standard, (2) increased hatch spacing, and (3) no infill, and additional contour trace. Each build type was further ...
OBJECTIVES Increased wettability of titanium and titanium alloy surfaces due to processing and st... more OBJECTIVES Increased wettability of titanium and titanium alloy surfaces due to processing and storage methods increases osteoprogenitor cell differentiation and osseointegration compared to microroughness alone. Implants that are exposed to air have a hydrophobic surface due to adsorption of atmospheric hydrocarbons, which can limit overall implant success. Dielectric barrier discharge plasma (DBD) is one method to increase surface hydrophilicity. Although current DBD methods yield a hydrophilic surface, adsorbed hydrocarbons rapidly restore hydrophobicity. We demonstrated that application of DBD to implants previously packaged in a vacuum, generates a hydrophilic surface that supports osteoblastic differentiation in vitro and this can be done immediately prior to use. In the present study, we tested the hypothesis that DBD treatment to alter surface wettability at the time of implant placement will improve osseointegration in vivo. MATERIALS AND METHODS Twenty male and sixteen female rabbits were used in a preclinical trans-axial femur model of osseointegration. Control and DBD treatment implants were inserted randomized per hind limb in each rabbit (1 implant/hind-limb). At 6 weeks post-surgery, bone-to-implant contact, adjacent bone volume, and torque to failure were assessed by micro-CT, calcified histology, and mechanical testing. RESULTS DBD plasma treatment of vacuum-sealed implants increased surface wettability and did not change surface chemistry or roughness. Peak torque and torsional energy, and bone-to-implant contact increased with DBD treatment in males. In contrast, female rabbits showed increased osseointegration equal to DBD treated male implants regardless of DBD plasma treatment. CONCLUSION DBD treatment is an effective method to enhance osseointegration by increasing surface wettability; however, this response is sex dependent. In healthy female patients, DBD treatment may not be necessary but in older patients or patients with compromised bone, this treatment could be an effective measure to ensure implant success.
Connective tissue grafts are used successfully in periodontal therapy for root coverage. However,... more Connective tissue grafts are used successfully in periodontal therapy for root coverage. However, reports on the histologic interface between the root surface and the grafted tissue have been few in number. This report describes a case study in which a subepithelial connective tissue graft was placed in a 27-year-old female on the maxillary left side. The graft (15 mm long, 10 mm wide, 1.5 mm thick) included palatal periosteum and was placed with the periosteal side facing the exposed bone and root surfaces. 15 weeks after grafting, the teeth presented with residual recessions of 1 mm, and buccal probing depths were approximately 1 mm. 14 months post-surgery, the 1st maxillary premolars on both sides were extracted for orthodontic therapy. Clinical parameters at the graft site remained as at 15 weeks. Histologic analysis of tooth #24 showed that the sulcular epithelium was keratinized; epithelium lining the dentin exhibited rete ridges projecting into the gingival connective tissue; and junctional epithelium extended over new cementum. New connective tissue attachment was also observed, including periodontal ligament. Biological width was comparable pre- and post-surgery, indicating a real gain in attachment of 3.9 mm.
Transactions - 7th World Biomaterials Congress, 2004
INTRODUCTION: Osteoblasts are sensitive to surface microtopography, exhibiting a more differentia... more INTRODUCTION: Osteoblasts are sensitive to surface microtopography, exhibiting a more differentiated morphology on rougher surfaces. Surface effects are mediated through cell surface receptors (e.g. integrins or transmembrane proteoglycans) that recognize and bind to a specific motif in cell attachment proteins. Thus, not only the topography but also the (bio)chemistry of a surface plays an important role. Recently, we demonstrated that the assembly of peptide-functionalized poly-L-lysine-gpoly(ethylene glycol) (PLL-g-PEG) polymers on titanium surfaces is a promising approach for manufacturing protein-resistant surfaces presenting peptide moieties at controlled surface density to interact directly with integrin cell receptors.
Studies showing that osteoblasts exhibit a more differentiated phenotype on rough titanium (Ti) s... more Studies showing that osteoblasts exhibit a more differentiated phenotype on rough titanium (Ti) surfaces and osteoclast-resorbed bone surfaces used materials characterized by average peak to valley distance (Ra). Other surface features impacting the cells include distance between peaks, curvature of the valleys, and relative distribution of flat and smooth regions. We used novel Ti surfaces prepared by electrochemical micromachining as models to examine specific contributions of individual design features to osteoblast response. Results show that micron-scale topography modulates cell number, cell morphology and prostaglandin E2 (PGE2). In the presence of the appropriate microtopography, submicron-scale rugosity modulates differentiation and transforming growth factor-beta1 (TGF-beta1) levels. In this study, we examined the role of different types of submicron-scale structures. Thirty micrometer diameter craters on Ti disks were produced by photolithography resulting in an electropolished smooth surface, and arranged so that inside crater area vs. outside flat area was 6 (30/6). Submicron-scale structures were superposed by acid etching and porous anodization. Ra's were 700, 400, 60 nm on acid-etched, porous anodized and smooth 30/6 surfaces, respectively. MG63 osteoblast-like cells were sensitive to submicron-scale architecture. Cell morphology on anodized surfaces was similar to morphology on smooth surfaces, whereas on etched surfaces, cells had a more elongated differentiated shape. Cell number was greatest on smooth surfaces > anodized > etched. Osteocalcin and PGE2 were affected in a reverse manner. Active TGF-beta1 was greatest on etched 30/6 surfaces > anodized > smooth; latent TGF-beta1 was elevated on all rough surfaces. These results support our previous observations that submicron-scale structures modulate osteoblastic phenotype and show that the physical properties of the submicron-scale structures are important variables in determining osteoblast response to substrate topography.
Microscale surface roughness has been shown to enhance osseointegration of titanium implants thro... more Microscale surface roughness has been shown to enhance osseointegration of titanium implants through increased osteoblast differentiation while osteoblast proliferation remains greater on smooth titanium. Taking advantage of these phenomena, we developed a shape memory (meth)acrylate copolymer with thermomechanical properties that created a time-dependent dynamic surface change from smooth to rough under in vitro cell culture conditions and evaluated the effect of the shape recovery on osteoblast response. Rough topographies were created using soft lithography techniques to mimic those found on clinically-used Ti surfaces (machined smooth; acid-etched; grit-blasted). The surface roughness was then reduced to smooth via compression and shown to fully recover within 24 h in culture conditions. When grown under static conditions, osteoblast number, alkaline phosphatase specific activity (ALP), and osteoprotegerin (OPG) and vascular endothelial growth factor (VEGF) production were unaffected by polymer surface roughness, but osteocalcin (OCN) was increased on the grit-blasted polymer mimic. Under dynamic conditions, DNA was reduced but OCN and OPG were increased on the compressed grit-blasted polymer at 3 days compared to static surfaces. The present study indicates that responses to polymer surface are sensitive to time-dependent changes in topography. The use of a shape memory polymer with dynamic surface roughness may improve osseointegration.
Osteoblasts are attachment-dependent cells that interact with their surface through integrin-medi... more Osteoblasts are attachment-dependent cells that interact with their surface through integrin-mediated mechanisms. Their differentiation is regulated by 1,25-dihydroxyvitamin D3 [1alpha,25(OH)(2)D(3)] and is affected by substrate chemistry and microtopography, suggesting that 1alpha,25(OH)(2)D(3) may regulate integrin expression in a surface-specific manner. To test this hypothesis, osteoblast-like human MG63 cells were grown on tissue culture plastic and on grit-blasted and acid-etched titanium disks with a complex microtopography to induce osteoblast differentiation. Expression of alpha(2), alpha(5), alpha(v), beta(1), and beta(3) integrins were quantified by real-time polymerase chain reaction (PCR) as a function of time in culture and treatment with 1alpha,25(OH)(2)D(3). Results were correlated with expression of osteocalcin, a marker of a differentiated osteoblast. Osteocalcin mRNA increased with time and 1alpha,25(OH)(2)D(3) treatment and these changes were greater in cultures on the titanium disks. Integrin expression varied with time in culture and this was also surface dependent. At each time point, beta(1) and alpha(2) mRNAs were greater on titanium than on plastic, whereas alpha(5) expression was reduced and alpha(v),beta(3) expression was unaffected. 1alpha,25(OH)(2)D(3) increased beta(1) mRNA on both surfaces at all time points, but it increased alpha(2) expression only in 8-d cultures. 1alpha,25(OH)(2)D(3) caused reduced alpha(5) expression only in cultures grown on plastic for 8 d, and had no effect on either alpha(v) or beta(3) expression regardless of surface. These results show that integrin expression in human osteoblast-like cells is differentially modulated by 1alpha,25(OH)(2)D(3) in a time-dependent manner that is sensitive to the surface on which the cells are grown.
Previous studies have shown that costochondral cartilage cell cultures produce extracellular matr... more Previous studies have shown that costochondral cartilage cell cultures produce extracellular matrix vesicles which contain metalloproteinase activity. In the present study, we examined whether two matrix metalloproteinases (MMPs) known to be present in cartilage, stromelysin-1 and 72 kDa gelatinase, are expressed by fourth passage resting zone and growth zone costochondral chondrocytes and whether they are specifically incorporated into matrix vesicles produced by the cells. We also examined whether the cells synthesize tissue inhibitor of metalloproteinase-1 and -2 (TIMP-1 and TIMP-2). Oligonucleotide primers for stromelysin-1, 72 kDa gelatinase, tissue inhibitor of metalloproteinases-1 and -2 (TIMP-1 and TIMP-2), and GAPDH were synthesized and optimized for use in the reverse transcription-polymerase chain reaction (RT-PCR). It was found that both resting zone and growth zone chondrocytes produced mRNA for both MMPs and the two TIMPs. Further, immunostaining of cell layers with antibodies to 72 kDa gelatinase and stromelysin-1 showed that both cell types produced these MMPs in culture. Substrate gel electrophoresis and Western analysis were used to characterize MMP activity in matrix vesicles, media vesicles, or plasma membranes as well as in conditioned media produced by the chondrocyte cultures. It was found that matrix vesicles but not plasma membranes or media vesicles were selectively enriched in stromelysin-1. Also, 72 kDa gelatinase was found in matrix vesicles, but to a lesser extent than seen in media vesicles. The relative activity of each enzyme detected was cell maturation-dependent. No MMP activity was detected in conditioned media produced by either cell type. The results of this study show that MMPs are expressed by resting zone and growth zone chondrocytes in culture and differentially distributed among three different membrane compartments. This suggests that, in addition to the well-known activators and inhibitors of MMP activity in the matrix, differential membrane distribution may enable more precise control over the site, rate, and extent of matrix degradation by the cell.
Matrix vesicles (MVs) are nano-sized extracellular vesicles that are anchored in the extracellula... more Matrix vesicles (MVs) are nano-sized extracellular vesicles that are anchored in the extracellular matrix (ECM). In addition to playing a role in biomineralization, osteoblast-derived MVs were recently suggested to have regulatory duties. The aims of this study were to: establish the characteristics of osteoblast-derived MVs in the context of extracellular vesicles like exosomes, assess their role in modulating osteoblast differentiation, and examine their mechanism of uptake. MVs were isolated from the ECM of MG-63 human osteoblast-like cell cultures and characterized via enzyme activity, transmission electron microscopy, nanoparticle tracking analysis, western blot, and small RNA sequencing. Osteoblasts were treated with MVs from two different culture conditions (growth media [GM]; osteogenic media [OM]) to evaluate their effects on differentiation and production of inflammatory markers and on macrophage polarization. MV endocytosis was assessed using a lipophilic, fluorescent dye...
Reduced skeletal loading associated with many conditions, such as neuromuscular injuries, can lea... more Reduced skeletal loading associated with many conditions, such as neuromuscular injuries, can lead to bone fragility and may threaten the success of implant therapy. Our group has developed a botulinum toxin A (botox) injection model to imitate disease-reduced skeletal loading and reported that botox dramatically impaired the bone formation and osseointegration of titanium implants. Semaphorin 3A (sema3A) is an osteoprotective factor that increases bone formation and inhibits bone resorption, indicating its potential therapeutic role in improving osseointegration in vivo. We first evaluated the sema3A effect on whole bone morphology following botox injections by delivering sema3A via injection. We then evaluated the sema3A effect on the osseointegration of titanium implants with two different surface topographies by delivering sema3A to cortical bone defect sites prepared for implant insertion and above the implants after insertion using a copper-free click hydrogel that polymerizes...
Journal of Biomedical Materials Research Part B: Applied Biomaterials
Current standards in bone‐facing implant fabrication by metal 3D (M3D) printing require post‐manu... more Current standards in bone‐facing implant fabrication by metal 3D (M3D) printing require post‐manufacturing modifications to create distinct surface properties and create implant microenvironments that promote osseointegration. However, the biological consequences of build parameters and surface modifications are not well understood. This study evaluated the relative contributions of build parameters and post‐manufacturing modification techniques to cell responses that impact osseointegration in vivo. Biomimetic testing constructs were created by using a M3D printer with standard titanium–aluminum–vanadium (Ti6Al4V) print parameters. These constructs were treated by either grit‐blasting and acid‐etching (GB + AE) or GB + AE followed by hot isostatic pressure (HIP) (GB + AE, HIP). Next, nine constructs were created by using a M3D printer with three build parameters: (1) standard, (2) increased hatch spacing, and (3) no infill, and additional contour trace. Each build type was further ...
OBJECTIVES Increased wettability of titanium and titanium alloy surfaces due to processing and st... more OBJECTIVES Increased wettability of titanium and titanium alloy surfaces due to processing and storage methods increases osteoprogenitor cell differentiation and osseointegration compared to microroughness alone. Implants that are exposed to air have a hydrophobic surface due to adsorption of atmospheric hydrocarbons, which can limit overall implant success. Dielectric barrier discharge plasma (DBD) is one method to increase surface hydrophilicity. Although current DBD methods yield a hydrophilic surface, adsorbed hydrocarbons rapidly restore hydrophobicity. We demonstrated that application of DBD to implants previously packaged in a vacuum, generates a hydrophilic surface that supports osteoblastic differentiation in vitro and this can be done immediately prior to use. In the present study, we tested the hypothesis that DBD treatment to alter surface wettability at the time of implant placement will improve osseointegration in vivo. MATERIALS AND METHODS Twenty male and sixteen female rabbits were used in a preclinical trans-axial femur model of osseointegration. Control and DBD treatment implants were inserted randomized per hind limb in each rabbit (1 implant/hind-limb). At 6 weeks post-surgery, bone-to-implant contact, adjacent bone volume, and torque to failure were assessed by micro-CT, calcified histology, and mechanical testing. RESULTS DBD plasma treatment of vacuum-sealed implants increased surface wettability and did not change surface chemistry or roughness. Peak torque and torsional energy, and bone-to-implant contact increased with DBD treatment in males. In contrast, female rabbits showed increased osseointegration equal to DBD treated male implants regardless of DBD plasma treatment. CONCLUSION DBD treatment is an effective method to enhance osseointegration by increasing surface wettability; however, this response is sex dependent. In healthy female patients, DBD treatment may not be necessary but in older patients or patients with compromised bone, this treatment could be an effective measure to ensure implant success.
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Papers by Barbara Boyan