Smooth Titanium Research Articles

Biofunctionalization of Microgroove Surfaces with Antibacterial Nanocoatings.

Objectives To investigate the physical properties of the modified microgroove (MG) and antibacterial nanocoated surfaces. In addition, the biological interactions of the modified surfaces with human gingival fibroblasts (HGFs) and the antibacterial activity of the surfaces against Porphyromonas gingivalis were studied. Methods The titanium nitride (TiN) and silver (Ag) coatings were deposited onto the smooth and MG surfaces using magnetron sputtering. A smooth titanium surface (Ti-S) was used as the control. The physicochemical properties including surface morphology, roughness, and hydrophilicity were characterized using scanning electron microscopy, atomic force microscopy, and an optical contact angle analyzer. The “contact guidance” morphology was assessed using confocal laser scanning microscopy. Cell proliferation was analyzed using the Cell Counting Kit-8 assay. The expression level of the main focal adhesion-related structural protein vinculin was compared using quantitative reverse transcription PCR and Western blotting. The antibacterial activity against P. gingivalis was evaluated using the LIVE/DEAD BacLight™ Bacterial Viability Kit. Results The Ag and TiN antibacterial nanocoatings were successfully deposited onto the smooth and MG surfaces using magnetron sputtering technology. TiN coating on a grooved surface (TiN-MG) resulted in less nanoroughness and greater surface hydrophilicity than Ag coating on a smooth surface (Ag-S), which was more hydrophobic. Cell proliferation and expression of vinculin were higher on the TiN-MG surface than on the Ag-coated surfaces. Ag-coated surfaces showed the strongest antibacterial activity, followed by TiN-coated surfaces. Conclusion Nano-Ag coating resulted in good antimicrobial activity; however, the biocompatibility was questionable. TiN nanocoating on an MG surface showed antibacterial properties with an optimal biocompatibility and maintained the “contact guidance” effects for HGFs.

Epigenetic changes of osteoblasts in response to titanium surface characteristics.

We aimed to investigate the influence of titanium surface characteristics on epigenetic mechanisms and DNA damage/repair pathways. Osteoblast-like cells (MG63) were incubated on glass, smooth titanium, and minimally rough titanium discs, respectively, for 0, 1, 6, and 24 hr. The presence of double-stranded DNA damage (γH2AX), DNA repair (Chk2), and epigenetic markers (AcH3 & DNMT1) were investigated using immunofluorescence. There were no Chk2-positive cells on the minimally rough titanium surfaces at all-time points, in comparison to glass and smooth titanium. Total γH2AX-positive cells on minimally rough titanium gradually decreased as incubation time increased, on the contrary to smooth titanium. Minimally rough titanium surfaces induced cytoplasmic staining of DNMT1 up to 99% at 24 hr. For epigenetic markers related to the DNA damage/repair pathway, minimally rough titanium surfaces showed the lower percentage of AcH3-positive cells compared to glass and smooth titanium surface. The findings in the current study show that titanium surface characteristics indeed influence DNA damage and the DNA repair pathway, including epigenetic factors.

Antimicrobial properties of antibiotic-loaded implants.

The aim of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement, and smooth titanium alloy to inhibit staphylococci in an in vitro environment, based on the evaluation of the zone of inhibition (ZOI). The hypothesis was that there would be no significant difference in the inhibition of methicillin-sensitive or methicillin-resistant Staphylococcus aureus (MSSA/MRSA) between the two groups. A total of 30 beads made of three different materials (tantalum/3D porous titanium and smooth titanium alloy) were bathed for one hour in a solution of 1 g vancomycin in 20 ml of sterile water for injection (bath concentration: 50 mg/mL). Ten 1 cm3 cylinders of antibiotic-loaded cement were also created by mixing standard surgical cement with 1 g of vancomycin in standardized sterile moulds. The cylinders were then placed on agar plates inoculated with MSSA and MRSA. The ZOIs were measured each day and the cylinders were transferred onto a new inoculated plate. For MSSA and MRSA, no inhibitory effect was found in the control group, and antibiotic-loaded smooth titanium alloy beads showed a short inhibitory effect until day 2. For MSSA, both tantalum and 3D porous titanium beads showed significantly larger mean ZOIs than cement beads (all p < 0.01) each day until day 7 for tantalum and until day 3 for 3D porous titanium. After six days, antibiotic-loaded cement had significantly larger mean ZOIs than the 3D porous titanium (p = 0.027), but no significant difference was found with tantalum (p = 0.082). For MRSA, both tantalum and 3D porous titanium beads had significantly larger mean ZOIs than antibiotic-loaded cement each day until day 6 for tantalum (all p < 0.01) and until day 3 for 3D porous titanium (all p < 0.04). Antibiotic-loaded cement had significantly larger mean ZOIs than tantalum and 3D porous titanium from day 7 to 9 (all p < 0.042). These results show that porous metal implants can deliver local antibiotics over slightly varying time frames based on in vitro analysis. Cite this article: Bone Joint J 2020;102-B(6 Supple A):158-162.

Effect of textured DLC coatings on tribological properties of titanium alloy under grease lubrication

To improve the tribological properties of titanium alloy surface and promote the functional application of titanium alloy, the synergistic anti-friction and wear-resistant effect of laser micro-textures and diamond-like carbon (DLC) coatings on titanium alloy surface under grease lubrication were investigated in this paper. Micro-textures and DLC coatings were fabricated on the surface of titanium alloy by Nd:YAG laser and magnetron sputtering technology. Effects of different surface treatment methods and micro-textures parameters on tribological properties of titanium alloy samples was studied. The results showed that, compared with the smooth titanium alloy sample, the friction coefficient of micro-textured sample, DLC coated sample and textured DLC coated sample decreased by 43.7%, 75.8%, 80.6% respectively. The surface of textured coated titanium alloy had the best tribological properties with a friction coefficient of 0.0799. The wear on the surface of the titanium alloy sample treated by laser micro-textures and DLC coatings was obviously improved. Compared with the severe adhesive wear on the surface of the titanium alloy sample, the surface of the textured coated titanium alloy sample was slightly scratched, and the wear volume was decreased by 97.5%. Meanwhile, DLC coatings with 30% textures density and 20 μm textures depth showed the best anti-friction effect as well as the optimal hydrodynamic lubrication effect. Under the condition of grease lubrication, the surface of textured DLC coated titanium alloy substrate presented favorable anti-friction and wear-resistance effects, which revealed that reasonable micro-textures density and depth could more effectively exert the lubricating and anti-friction properties of textured DLC coatings.

Do trabecular metal and cancellous titanium implants reduce the risk of late haematogenous infection? An experimental study in rabbits.

This study evaluated the late resistance to haematogenous contamination by microbial pathogens of implants and bone-implant interface and the development of late clinical infection when cementless components with different surface or structural properties are implanted. 50 adult male New Zealand white rabbits were divided into 5 groups of 10 animals each. In Group A smooth titanium, in Group B grit blasted titanium, in Group C HA-coated titanium, in Group D trabecular metal and in group E cancellous titanium rods were implanted in the right proximal tibia. Four weeks later, 1 ml of inoculum of a standardised CA-MRSA strain (3 × 108 cfu/ml) was injected through a femoral artery catheter (groups B, C, D, E) while in group A, 1 ml of sterile saline was injected in a similar way (control group). Subjects were killed 8 weeks after the initial procedure and 3 samples of each tibial specimen were subjected to conventional cultures and PCR studies. The number of the specimens (conventional cultures and PCR studies) contaminated by the standardized pathogen was as follows: Group A: 0/10, Group B: 7/10, Group C: 6/10, Group D; 5/10 and Group E: 5/10. Comparing the number of colony form units isolated from the implant samples, Group B (GB titanium) showed statistically significantly higher values (Mann-Whitney test) compared to Group C (p = 0.044), Group D (p = 0.040) and Group E (p = 0.038). Local active infection was observed in 6 animals: 3 in Group B; 1 in Group C, 1 in Group D, and 1 in Group E. Modern cementless implants (trabecular metal and cancellous titanium) showed a lower risk of implant contamination and late clinical haematogenous infection.

Effect of implant surface material and roughness to the susceptibility of primary gingival fibroblasts to inflammatory stimuli

ObjectivesThe impact of the implant surface material and roughness on inflammatory processes in peri-implantitis is not entirely clear. Hence, we investigated how titanium and zirconia surfaces with different roughness influence the susceptibility of primary human gingival fibroblasts to different inflammatory stimuli. MethodsPrimary human gingival fibroblasts were isolated from 8 healthy individuals and cultured on following surfaces: smooth titanium machined surface (TiM), smooth zirconia machined surface (ZrM), moderately rough titanium surface (SLA), or moderately rough zirconia surface (ZLA). Subsequently, stimulation with one of the following stimuli was performed: Porphyromonas gingivalis lipopolysaccharide (LPS), tumor necrosis factor (TNF)-α, interleukin (IL)-1β. The resulting production of IL-6, IL-8, and monocyte chemoattractant protein (MCP)-1 was measured by qPCR and ELISA. ResultsP. gingivalis LPS induced IL-6 and MCP-1 production was slightly higher on titanium surfaces compared to zirconia surfaces. IL-1β induced IL-6 production was not affected by any surface characteristic. The production of MCP-1 in response to IL-1β was higher on smooth compared to rough surfaces and was not affected by the material. The production of IL-6 and MCP-1 in response to TNF-α was most strongly affected by surface characteristics. Higher production of these cytokine was observed on smooth compared to rough surfaces and on titanium compared to zirconia surfaces. Surface characteristics had only minor effects on IL-8 production. SignificanceThe susceptibility of primary gingival fibroblasts to inflammation depends on various factors, such as surface material, surface roughness and the nature of inflammatory stimuli. All these factors might determine susceptibility to peri-implantitis.

Effects of titania nanotubes with different diameters on human gingival fibroblast

Objective: To study the effects of titania nanotubes with three different diameters on human gingival fibroblast (HGF). Methods: Three groups of specimens were prepared. Titania nanotubes with diameters of 30, 100, and 200 nm were synthesized on titanium surfaces through electrochemical anodization at 10, 30, and 60 V, respectively. Specimens were assigned into the three groups according to the diameter of the titania nanotubes. Pure smooth titanium without any treatment was set as the control group. HGF were seeded on the surface of the samples. The cell morphology on the specimens was observed with immunofluorescence staining after 2 h, the cell adhesion after 2 d and cell proliferation after 1, 3, and 7 d were detected using methyl thiazolyl tetrazolium assay, and the secretion of type Ⅰ collagen after 7 d was determined using enzyme-linked immunosorbent assay (each group has three samples for each experiment). Results: HGF on the control group exhibited an oval shape without noticeable extensions. HGF on titania nanotubes with a diameter of 30 nm and titania nanotubes with a diameter of 100 nm elongated further and were arranged orderly. HGF on titania nanotubes with a diameter of 200 nm were sparsely distributed without noticeable extensions. Titania nanotubes with a diameter of 30 nm and titania nanotubes with a diameter of 100 nm could enhance the cell attachment (0.603±0.021 and 0.773±0.045), and secretion of type Ⅰ collagen [(36.5±9.5) and (47.7±4.5) μg/ml, respectively] compared with the control group whose cell attactment was 0.427±0.057, and secretion of type Ⅰ collagen was (22.2±5.9) μg/ml (P<0.05). Furthermore, titania nanotubes with a diameter of 100 nm showed more cell attchment than titania nanotubes with a diameter of 30 nm did (P<0.05). Ttania nanotubes with a diameter of 200 nm clearly impaired the cell adhesion (0.250±0.046) and secretion of type Ⅰ collagen [(10.1±3.7) μg/ml] compared with the control group (P<0.05). At each time point, titania nanotubes with a diameter of 100 nm showed the highest cell proliferation, and the amount of cell proliferation was significantly higher than that on the titania nanotubes with a diameter of 200 nm and the control group at each time point (P<0.05), and was also significantly higher than that on the titania nanotubes with a diameter of 30 nm at day three (P<0.05). At each time point, titania nanotubes with a diameter of 200 nm showed the lowest cell proliferation, which was significantly lower than that on the control group at each time point (P<0.05), except that there was no significant difference in the amount of cell proliferation between titania nanotubes with a diameter of 200 nm and the control group at day one (P>0.05). Conclusions: Titania nanotubes with a diameter of 100 nm can improve the HGF attachment, proliferation, and secretion of type Ⅰ collagen.

Effects of the Origin and Deacetylation Degree of Chitosan on Properties of Its Coatings on Titanium

The properties of chitosan coatings on titanium surfaces may be influenced by a variety of factors, including their chemical characteristics and the deposition method. The aim of this research was to determine the influence of a chitosan’s origin (a type of shrimp) and deacetylation degree (DD), when deposited on a very smooth titanium surface, on adhesion and biological behavior. The tests were performed using chitosan of a degree of 87% or 84% of deacetylation and that originated from armor crabs or shrimp armor. The technology of fabrication of chitosan coatings was by surface polishing to a smooth surface, oxidation in air, and immersion in a chitosan solution. The surface topographies were analyzed with an atomic force microscope and their water contact angles were measured by a falling drop method with a goniometer. The bioactivity tests were done in in vitro on osteogenic cells, type MC3T3-E1, with a biological microscope. The abrasion of the coatings was examined using a nano tribotester. The obtained results revealed that the adhesion of the coatings onto a smooth, oxidized titanium surface is appropriate as they remain sufficiently adjacent to the surface after wear tests. The source of chitin has a significant influence on biological properties, and the deacetylation degree is much less critical. The performed tests demonstrated the crucial role that the source of chitosan and the applicability of the applied surface treatment play in the preparation of chitosan coatings.

Effects of different implant materials and surface microgrooves on the biological behavior of gingival fibroblasts

Objective: To study the effect of microgroove surface modification of titanium and zirconia on the biological behavior of gingival fibroblasts in order to find suitable surface materials for the transmucosal part of the dental implant. Methods: Twenty specimens were divided into four groups: smooth titanium (Ti-S), smooth zirconia (ZC-S), microgroove titanium (Ti-MG) and microgroove zirconia (ZC-MG) (five specimens in each group). Microgroove modification of titanium and zirconia surfaces was carried out by using fine machining chip system in the last two groups. The width of groove ridge was 60 μm, the width of groove was 60 μm, the depth of groove was 10 μm. The surface morphologies (the groove width and depth) were observed by scanning electron microscope (SEM), the surface roughness, static contact angle and elemental of specimens in each group were detected by SEM, atomic force microscope (AFM), optical contact angle measuring device and energy-dispersion X-ray analysis (EDX). Morphology of human gingival fibroblast (HGF) that arranged along the groove was analyzed using laser scanning confocal microscope by immunofluorescence staining. Differences in cell proliferation were analyzed and compared using cell counting kit. Expression level of intergrin α(5), β(1) and collagen Ⅰ mRNA were compared among different groups by quantitative real-time PCR for 6 h and 3 d. Results: The surface roughness of smooth titanium group and smooth zirconia group was (63.23± 2.55) and (26.78±3.11) nm, respectively. Microgroove zirconia group showed the best hydrophilicity: the static contact angle was 51.2°±2.0°. HGF was arranged along the groove surface, and cell proliferation results showed that proliferation on microgroove zirconia was more significant than that on other groups from 6 h to 7 d (P<0.05). Intergrin α(5) mRNA has the highest expression in microgroove zirconia (P<0.05) in the early adhesion (6 h), and there was no significant difference in the surface expression of intergrin β(1) and collagen Ⅰ mRNA in the early adhesion (6 h) of each group. However, in the late adhesion (3 d), intergrin α(5), β(1) and collagenⅠ mRNA expression in microgroove surface groups were higher than those of the smooth groups (P<0.05). Conclusions: Microgroove zirconia surface has small roughness and good hydrophilicity, which can guide HGF to line up in the groove, and this is beneficial to the HGF proliferation and the expression of structural proteins and functional proteins.

Osteoblast Responses to Titanium-Coated Subcellular Scaled Microgrooves.

Statistical data have consistently shown that implant loosening is a significant causative factor for revision surgeries. Both in vivo and in vitro studies have confirmed the positive influences of microgrooved titanium implant surfaces on improving orthopedic titanium implants compared with a smooth titanium surface. Complete cell-groove adhesion is a prerequisite for rapid and robust osseointegration. For the first time, this work has quantified the influence of the titanium groove width at the subcellular scale (5-20 μm) on osteoblast responses, using titanium-coated microgrooved silicon wafer specimens (surface roughness, Ra = ∼1.5 nm), which can avoid the latent influence of variations in surface roughness from the use of normal titanium substrates. The cell-groove adhesion increased from 53.07% to 98.55% with an increasing groove width from 5 to 20 μm. In addition, both the cell spreading area and cell width were proportional to groove width. However, no statistically significant influence (p > 0.05) of groove width was identified on cell proliferation and differentiation. An exponential model was proposed to predict the groove geometries that can facilitate complete cell-groove adhesion. The underlying mechanisms were discussed. The experimental findings of this study provide a unique basis for the design of titanium implant surfaces.

Effects of micro/nano strontium-loaded surface implants on osseointegration in ovariectomized sheep.

Poor osseointegration of dental implants often occurs in osteoporotic patients and processed implant surfaces could help to improve the dilemma. This study aimed to compare the effects of different titanium (Ti) surfaces on bone-implant osseointegration in ovariectomized (OVX) sheep. Four groups were included: smooth titanium (ST) was merely polished Ti; micro titanium (MT) was treated with hydrofluoric acid (HF) for 30 minutes; strontium-loaded nano titanium (NT-Sr) was formed by magnetron sputtering; strontium-loaded micro/nano titanium (MNT-Sr) was fabricated by HF etching combined with magnetron sputtering. The biological responses were evaluated by human bone marrow-derived mesenchymal stem cells (hBMMSCs) experiments in vitro. Osseointegration was evaluated in vivo after each surface implant was inserted into OVX sheep' mandibles. The numbers of adhered and mineralized hBMMSCs increased significantly in the MNT-Sr group. The bone-implant contact and the maximal pull-out force increased significantly with MNT-Sr surface. The bone volume ratio and trabecular number of the MNT-Sr group were significantly higher than others, whereas trabecular separation decreased. These results indicated that an MNT-Sr surface promotes the differentiation of hBMMSCs in vitro and enhances bone-implant osseointegration in vivo, which may be a promising option for clinical implants in osteoporotic patients.

Zirconium Nitride Coating Reduced Staphylococcus epidermidis Biofilm Formation on Orthopaedic Implant Surfaces: An In Vitro Study.

One of the most commonly identified pathogens responsible for orthopaedic implant infection is Staphylococcus epidermidis, which can form biofilms on surfaces. Currently, orthopaedic implants made of various surface materials are available, each with features influencing osseointegration, biocompatibility, and adherence of bacteria to the surface, which is the first step in biofilm formation. The aim of this experimental study was to investigate the effect of a high tribologic-resistant 2.5-µm zirconium nitride top coat on an antiallergic multilayer ceramic-covered cobalt-chromium-molybdenum surface on the formation of S. epidermidis biofilm compared with other commonly used smooth and rough orthopaedic implant surface materials. (1) When evaluating the surfaces of a cobalt-chromium-molybdenum (CoCrMo) alloy with a zirconium (Zr) nitride coating, a CoCrMo alloy without a coating, titanium alloy, a titanium alloy with a corundum-blasted rough surface, and stainless steel with a corundum-blasted rough surface, does a Zr coating reduce the number of colony-forming units of S. epidermidis in an in vitro setting? (2) Is there quantitatively less biofilm surface area on Zr-coated surfaces than on the other surfaces tested in this in vitro model? To determine bacterial adhesion, five different experimental implant surface discs were incubated separately with one of 31 different S. epidermidis strains each and subsequently sonicated. Twenty test strains were obtained from orthopaedic patients undergoing emergency hip prosthesis surgeries or revision of implant infection and 10 further strains were obtained from the skin of healthy individuals. Additionally, one reference strain, S. epidermidis DSM 3269, was tested. After serial dilutions, the number of bacteria was counted and expressed as colony-forming units (CFUs)/mL. For biofilm detection, discs were stained with 0.1% Safranin-O for 15 minutes, photographed, and analyzed with computer imaging software. The lowest bacterial count was found in the CoCrMo + Zr surface disc (6.6 x 10 CFU/mL ± 4.6 x 10 SD) followed by the CoCrMo surface (1.1 x 10 CFU/mL ± 1.9 x 10 SD), the titanium surface (1.36 x 10 CFU/mL ± 1.8 x 10 SD), the rough stainless steel surface (2.65 x 10 CFU/mL ± 3.8 x 10 SD), and the rough titanium surface (2.1 x 10 CFU/mL ± 3.0 x 10 SD). The mean CFU count was lower for CoCrMo + Zr discs compared with the rough stainless steel surface (mean difference: 2.0 x 10, p = 0.021), the rough titanium alloy surface (mean difference: 1.4 x 10, p = 0.002), and the smooth titanium surface (mean difference: 7.0 x 10, p = 0.016). The results of biofilm formation quantification show that the mean covered area of the surface of the CoCrMo + Zr discs was 19% (± 16 SD), which was lower than CoCrMo surfaces (35% ± 23 SD), titanium alloy surface (46% ± 20 SD), rough titanium alloy surface (66% ± 23 SD), and rough stainless steel surface (58% ± 18 SD). These results demonstrate that a multilayer, ceramic-covered, CoCrMo surface with a 2.5-µm zirconium nitride top coat showed less S. epidermidis biofilm formation compared with other surface materials used for orthopaedic implants. CoCrMo with a 2.5-µm zirconium nitride top coat seems to be a promising surface modification technology able to reduce bacterial attachment on the surface of an implant and, hence, may further prevent implant infection with S. epidermidis biofilm formation.

Epithelial cell adhesion efficacy of a novel peptide identified by panning on a smooth titanium surface

Epithelial attachment via the basal lamina on the tooth surface provides an important structural defence mechanism against bacterial invasion in combating periodontal disease. However, when considering dental implants, strong epithelial attachment does not exist throughout the titanium-soft tissue interface, making soft tissues more susceptible to peri-implant disease. This study introduced a novel synthetic peptide (A10) to enhance epithelial attachment. A10 was identified from a bacterial peptide display library and synthesized. A10 and protease-activated receptor 4-activating peptide (PAR4-AP, positive control) were immobilized on commercially pure titanium. The peptide-treated titanium showed high epithelial cell migration ability during incubation in platelet-rich plasma. We confirmed the development of dense and expanded BL (stained by Ln5) with pericellular junctions (stained by ZO1) on the peptide-treated titanium surface. In an adhesion assay of epithelial cells on A10-treated titanium, PAR4-AP-treated titanium, bovine root and non-treated titanium, A10-treated titanium and PAR4-AP-treated titanium showed significantly stronger adhesion than non-treated titanium. PAR4-AP-treated titanium showed significantly higher inflammatory cytokine release than non-treated titanium. There was no significant difference in inflammatory cytokine release between A10-treated and non-treated titanium. These results indicated that A10 could induce the adhesion and migration of epithelial cells with low inflammatory cytokine release. This novel peptide has a potentially useful application that could improve clinical outcomes with titanium implants and abutments by reducing or preventing peri-implant disease.

Surface Modification of Titanium Dental Implants: A Review

Osseointegration of titanium dental implants is the most important clinical parameter for an implant to be successful. One of most biocompatible material, titanium can be made to affix fast on to host bone via various modification of its surface. Machined and smooth titanium implant osseointegrate into living bone tissue but with a roughened surface, this is much more predictable as well as promising clinically. Surface modification allows for an increase in the surface area on to which the osteoblasts easily start laying bone. So, there have been various methods to roughen the surface of titanium implants. The article describes various methods used for modifying the surfaces of dental implants, giving a note on their clinical efficacy as well as advantages and disadvantages of these methods.

Topographical cues of direct metal laser sintering titanium surfaces facilitate osteogenic differentiation of bone marrow mesenchymal stem cells through epigenetic regulation.

To investigate the role of hierarchical micro/nanoscale topography of direct metal laser sintering (DMLS) titanium surfaces in osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), as well as the possible underlying epigenetic mechanism. Three groups of titanium specimens were prepared, including DMLS group, sandblasted, large-grit, acid-etched (SLA) group and smooth titanium (Ti) group. BMSCs were cultured on discs followed by surface characterization. Cell adhesion and proliferation were examined by SEM and CCK-8 assay, while osteogenic-related gene expression was detected by real-time RT-PCR. Immunofluorescence, western blotting and in vivo study were also performed to evaluate the potential for osteogenic induction of materials. In addition, to investigate the underlying epigenetic mechanisms, immunofluorescence and western blotting were performed to evaluate the global level of H3K4me3 during osteogenesis. The H3K4me3 and H3K27me3 levels at the promoter area of the osteogenic gene Runx2 were detected by ChIP assay. The DMLS surface exhibits greater protein adsorption ability and shows better cell adhesion performance than SLA and Ti surfaces. Moreover, both in vitro and in vivo studies demonstrated that the DMLS surface is more favourable for the osteogenic differentiation of BMSCs than SLA and Ti surfaces. Accordingly, osteogenesis-associated gene expression in BMSCs is efficiently induced by a rapid H3K27 demethylation and increase in H3K4me3 levels at gene promoters upon osteogenic differentiation on DMLS titanium surface. Topographical cues of DMLS surfaces have greater potential for the induction of osteogenic differentiation of BMSCs than SLA and Ti surfaces both in vitro and in vivo. A potential epigenetic mechanism is that the appropriate topography allows rapid H3K27 demethylation and an increased H3K4me3 level at the promoter region of osteogenesis-associated genes during the osteogenic differentiation of BMSCs.

In Vivo Periodontium Formation Around Titanium Implants Using Periodontal Ligament Cell Sheet.

Osseointegrated implants have been recognized as being very reliable and having long-term predictability. However, host defense mechanisms against infection have been known to be impaired around a dental implant because of the lack of a periodontal ligament (PDL). The purpose of our experimental design was to produce cementum and PDL on the implant surface adopting cell sheet technology. To this aim we used PDL-derived cells, which contain multipotential stem cells, as the cell source and we cultured them on an implant material constituted of commercially pure titanium treated with acid etching, blasting, and a calcium phosphate (CaP) coating to improve cell attachment. Implants with adhered human PDL cell sheets were transplanted into bone defects in athymic rat femurs as a xenogeneic model. Implants with adhered canine PDL-derived cell sheets were transplanted into canine mandibular bone as an autologous model. We confirmed that PDL-derived cells cultured with osteoinductive medium had the ability to induce cementum formation. The attachment of PDL cells onto the titanium surface with three surface treatments was accelerated, compared with that onto the smooth titanium surface, at 40 min after starting incubation. Results in the rat model showed that cementum-like and PDL-like tissue was partly observed on the titanium surface with three surface treatments in combination with adherent PDL-derived cell sheets. On the other hand, osseointegration was observed on almost all areas of the smooth titanium surface that had PDL-derived cell sheets, but did not have the three surface treatments. In the canine model, histological observation indicated that formation of cementum-like and PDL-like tissue was induced on the titanium surface with surface treatments and that the PDL-like tissue was perpendicularly oriented between the titanium surface with cementum-like tissue and the bone. Results demonstrate that a periodontal-like structure was formed around a titanium implant, which is similar to the environment existing around a natural tooth. The clinical application of dental implants combined with a cell sheet technique may be feasible as an alternative implant therapy. Furthermore, application of this methodology may play an innovative role in the periodontal, prosthetic, and orthodontic fields in dentistry.

Application of plasma sprayed zirconia coating in dental implant: study in implant

Objective: To investigate the osseointegration of a novel coating-plasma-sprayed zirconia in dental implant. Methods: Zirconia coating on non-thread titanium implant was prepared using plasma spraying, the implant surface morphology, surface roughness and wettability were measured. In vivo, zirconia coated implants were inserted in rabbit tibia and animals were respectively sacrificed at 2, 4, 8 and 12 weeks after implantation. The bond strength between implant and bone was measured by push-out test. The osseointegration was observed by scanning electron microscopy (SEM), micro CT and histological analyses. Quantified parameters including removal torque, and bone-implant contact (BIC) percentage were calculated. Results: The surface roughness (1.6 µm) and wettability (54.6°) of zirconia coated implant was more suitable than those of titanium implant (0.6 µm and 74.4°) for osseointegration. At 12 weeks, the push-out value of zirconia coated implant and titanium implant were (64.9±3.0) and (50.4±2.9) N, and BIC value of these two groups were (54.7±3.6)% and (41.5±3.6)%. All these differences had statistical significance. Conclusions: The surface characters of zirconia coated implant were more suitable for osseointegration and present better osseointegration than smooth titanium implant in vivo, especially at early stage.

The relationship between substrate morphology and biological performances of nano-silver-loaded dopamine coatings on titanium surfaces.

Biomedical device-associated infection (BAI) and lack of osseointegration are the main causes of implant failure. Therefore, it is imperative for implants not only to depress microbial activity and biofilm colonization but also to prompt osteoblast functions and osseointegration. As part of the coating development for implants, the interest of in vitro studies on the interaction between implant substrate morphology and the coating's biological performances is growing. In this study, by harnessing the adhesion and reactivity of bioinspired polydopamine, nano-silver was successfully anchored onto micro/nanoporous as well as smooth titanium surfaces to analyse the effect of substrate morphology on biological performances of the coatings. Compared with the smooth surface, a small size of nano-silver and high silver content was found on the micro/nanoporous surface. More mineralization happened on the coating on the micro/nanoporous structure than on the smooth surface, which led to a more rapid decrease of silver release from the micro/nanoporous surface. Antimicrobial tests indicated that both surfaces with resulting coating inhibit microbial colonization on them and growth around them, indicating that the coating eliminates the shortcoming of the porous structure which render the implant extremely susceptible to BAI. Besides, the multiple osteoblast responses of nano-silver-loaded dopamine coatings on both surfaces, i.e. attachment, proliferation and differentiation, have deteriorated, however the mineralized surfaces of these coatings stimulated osteoblast proliferation and differentiation, especially for the micro/nanoporous surface. Therefore, nano-silver-loaded dopamine coatings on micro/nanoporous substratum may not only reduce the risk of infection but also facilitate mineralization during the early post-operative period and then promote osseointegration owing to the good osteoblast-biocompatibility of the mineralized surface. These results clearly highlight the influence of the substrate morphology on the biological performances of implant coating.

Molecular Layering Synthesis of TiO2 Nanolayer with Developed Roughness on Silicon as a Promising Basis for Biosensors

Conditions for the synthesis of dispersion titanium dioxide with a developed roughness by molecular layering on the silicon surface were determined and structural characteristics of the resulting layer were studied. Electroactive surface area of the titanium dioxide nano-roughened films obtained by the proposed method is higher than those of the reference (smooth) titanium oxide film and the reference silicon electrode by factors 1.1 and 1.2, respectively.

Osteogenic nanostructured titanium surfaces with antibacterial properties under conditions that mimic the dynamic situation in the oral cavity.

The study aim was to assess the impact of different surface nanofeatures on otherwise smooth titanium surfaces on bacterial adhesion as well as on their osteogenic potential. Bacterial adhesion was assessed in the presence of saliva under static and dynamic conditions to approximate both sub- and supragingival conditions in the oral cavity as the gingival seal will be affected by implantation. The ultimate goal was to develop a surface that will reduce biofilm formation but still support osseointegration in vivo. To this end nanotubular or nanopitted surfaces were created on electropolished titanium via electrochemical anodization procedures. Sandblasted/acid etched surfaces (SBAE) were used as a microrough reference. Bacterial adhesion was studied using saliva-precoated samples with S. sanguinis as a typical early colonizer of the oral cavity; osteogenic differentiation was assessed with human bone marrow stromal cells. While bacterial adhesion was reduced on all microsmooth surfaces to an average of 17% surface coverage compared to 61% on SBAE under static conditions, under dynamic conditions the nanopitted surface had a significant impact on bacterial adhesion. Here fluid flow removed all bacteria. By comparison, the reduction on the nanotubular surface was only similar to that of the SBAE reference. We hypothesise the underlying cause to be an effect of the surface morphology on the structure and composition of the saliva precoating that reduces its stability, giving rise to a self-cleaning effect. In addition, no negative influence on the osteogenic potential of the nanopitted surface could be determined by alkaline phosphatase activity, mineralization behaviour or gene expression; it remained on a par with the tissue culture plastic control. Thus, nanopitting seems to be a promising surface treatment candidate for dental implants to reduce infection related complications without compromising the implant integration.