The difference of fibroblast behavior on titanium substrata with different surface characteristics

The evaluation of the impact of titania nanotube covers morphology and crystal phase on their biological properties

The highly ordered titanium dioxide nanotube coatings were produced under various electrochemical conditions on the surface of titanium foil. The anodization voltage changes proved to be a main factor which directly affects the nanotube morphology, structure, and wettability. Moreover we have noticed a significant dependence between the size and crystallinity of TiO2 layers and the adhesion/proliferation of fibroblasts and antimicrobial properties. Cellular functionality were investigated for up to 3 days in culture using a cell viability assay and scanning electron microscopy. In general, results of our studies revealed that fibroblasts adhesion, proliferation, and differentiation on the titania nanotube coatings is clearly higher than on the surface of the pure titanium foil. The formation of crystallic islands in the nanotubes structure induced a significant acceleration in the growth rate of fibroblasts cells by as much as ~200 %. Additionally, some types of TiO2 layers revealed the ability to the reduce of the staphylococcal aggregates/biofilm formation. The nanotube coatings formed during the anodization process using the voltage 4 V proved to be the stronger S. aureus aggregates/biofilm inhibitor in comparison to the uncovered titanium substrate. That accelerated eukaryotic cell growth and anti-biofilm activity is believed to be advantageous for faster cure of dental and orthopaedic patients, and also for a variety of biomedical diagnostic and therapeutic applications. The highly ordered titanium dioxide nanotube coatings were produced under various electrochemical conditions on the surface of titanium foil. The anodization voltage changes proved to be a main factor which directly affects the nanotube morphology, structure, and wettability. Moreover we have noticed a significant dependence between the size and crystallinity of TiO2 layers and the adhesion/proliferation of fibroblasts and antimicrobial properties.

Regulation of matrix remodelling phenotype in gingival fibroblasts by substratum topography

Gingival connective tissue often has a composition resembling that of scar surrounding dental implant abutments. Increased cell adhesion, α-smooth muscle actin (α-SMA) expression and increased extracellular matrix deposition are a hallmark of fibrotic cells, but how topographic features influence gingival fibroblast adhesion and adoption of the α-SMA positive myofibroblast phenotype associated with scarring is unknown. The purpose of the present study was to demonstrate whether implant topographies that limit adhesion formation would reduce myofibroblast differentiation and extracellular matrix deposition. Human gingival fibroblasts were cultured on PT (smooth) and SLA (roughened) titanium discs for varying time-points. At 1 and 2 weeks after seeding, incorporation of α-SMA into stress-fibre bundles and fibronectin deposition was significantly higher on PT than SLA surfaces indicating differentiation of the cells towards a myofibroblast phenotype. Analysis of adhesion formation demonstrated that cells formed larger adhesions and more stable adhesions on PT, with more nascent adhesions observed on SLA. Gene expression analysis identified up-regulation of 15 genes at 24 hrs on SLA versus PT associated with matrix remodelling. Pharmacological inhibition of Src/FAK signalling in gingival fibroblasts on PT reduced fibronectin deposition and CCN2 expression. We conclude that topographical features that reduce focal adhesion stability could be applied to inhibit myofibroblast differentiation in gingival fibroblasts.

Effect of high-pressure torsion deformation on surface properties and biocompatibility of Ti-50.9 mol. %Ni alloys

Ti-50.9 mol. %Ni was subjected to high-pressure torsion (HPT) deformation for different number of rotations (N) of 0.25, 0.5, 1, 5, and 10. The structural changes induced by HPT were analyzed using x-ray diffractometer (XRD). The surfaces of the samples before and after cell culture were characterized using x-ray photoelectron spectroscopy (XPS). The biocompatibility of the samples was evaluated based on a colony formation assay, nickel ion release, and protein adsorption behavior. XRD analysis revealed the occurrence of grain refinement, phase transformation, and amorphization in the TiNi samples by HPT deformation due to high dislocation density. The changes in chemical composition and thickness of the passive film formed on the surface observed in XPS analysis reveals improvement in the stability of the passive film by HPT deformation. The microstructural change due to the deformation was found to influence the biocompatibility behaviors of TiNi. Plating efficiency and protein adsorption were found to be higher when the samples are in stress-induced martensitic or amorphous state. HPT deformation was found to alter the surface behavior of the TiNi, which effectively reduced the Ni ion release and improved its biocompatibility.

In vivo and in vitro studies of epithelial cell behavior around titanium implants with machined and rough surfaces

BACKGROUND

The surface roughness of a dental implant affects the epithelial wound healing process and may significantly enhance implant prognosis.

PURPOSE

We explored the influence of surface roughness on peri-implant epithelium (PIE) sealing and down-growth by comparing machine-surfaced (Ms) and rough-surfaced (Rs) implants.

MATERIALS AND METHODS

(1) Maxillary first molars were extracted from rats and replaced with Ms or Rs implants. (2) We also compared changes in the morphology of cultured rat oral epithelial cells (OECs) grown on Ms or Rs titanium (Ti) plates.

RESULTS

(1) After 4 weeks, the PIE around Ms and Rs implants showed a similar structure to junctional epithelium (JE). At 16 weeks, Rs implants appeared to form a weak epithelial seal at the tissue-implant interface and exhibited markedly less PIE down-growth than Ms implants but was deeper than that observed in natural teeth. (2) We observed less expression of adhesion proteins in OECs cultured on Rs plates than in cells grown on Ms plates. Additionally, cell adherence, migration, and proliferation on Rs plates were lower, whereas apoptosis was reduced on Ms plates.

CONCLUSION

Ms implants are a better choice for integration with an epithelial wound healing process.

Therapeutic interaction of systemically-administered mesenchymal stem cells with peri-implant mucosa

OBJECTIVES

The objective of this study was to investigate the effect of systemically transplanted mesenchymal stem cells (MSCs) on the peri-implant epithelial sealing around dental implants.

MATERIALS AND METHODS

MSCs were isolated from bone marrow of donor rats and expanded in culture. After recipient rats received experimental titanium dental implants in the bone sockets after extraction of maxillary right first molars, donor rat MSCs were intravenously transplanted into the recipient rats.

RESULTS

The injected MSCs were found in the oral mucosa surrounding the dental implants at 24 hours post-transplantation. MSC transplantation accelerated the formation of the peri-implant epithelium (PIE)-mediated mucosa sealing around the implants at an early stage after implantation. Subsequently, enhanced deposition of laminin-332 was found along the PIE-implant interface at 4 weeks after the replacement. We also observed enhanced attachment and proliferation of oral mucous epithelial cells.

CONCLUSION

Systemically transplanted MSCs might play a critical role in reinforcing the epithelial sealing around dental implants.

Viability of Titanium-Titanium Boride Composite as a Biomaterial

The use of reinforcements to enhance mechanical properties of titanium such as hardness has been adopted by many researchers. Of these reinforcements, titanium boride has emerged as one of the most suitable reinforcements for titanium which is both chemically and mechanically compatible with the titanium matrix. Despite the extensive work conducted on these types of composites, very little is known about their biocompatibility which has so far precluded their use in bioapplications. The present paper investigates, for the first time, the biocompatibility of powder-processed titanium-titanium boride () composites for use in medical and dental implants and basic studies on fibroblast attachment conducted to assess for this application. The work is intended to serve as an initial step towards understanding the bioresponse of these composites by evaluating cytotoxicity, cellular attachment and morphology, and hemolytic potential. Results indicate that fibroblasts attach, proliferate, and achieve confluency when in contact with the composites, exhibiting normal morphology. Furthermore, the cells show a favorable growth rate when cultured with the composite for 48 hours. The composite demonstrated excellent blood biocompatibility, with a low hemolysis level (0.12% ) when compared with CP Ti (0.17%) and Ti-6Al-4V (0.36%). These findings suggest that composite is biocompatible and further investigation into its suitability as a biomaterial should be considered.

Promotive effect of insulin-like growth factor-1 for epithelial sealing to titanium implants

Improvement of oral epithelial adhesion to titanium (Ti) may significantly enhance the efficacy of dental implants. Here, we investigated whether insulin-like growth factor-1 (IGF-1) improved the sealing of the peri-implant epithelium (PIE) around the implant. Right maxillary first molars were extracted from rats and replaced with experimental implants. After 4 weeks of IGF-1 treatment, the implant-PIE interface exhibited a band of immunoreactive laminin-332 (Ln-5), similar to the tooth-junctional epithelium interface, that was partially absent in the untreated group. Immunoelectron microscopy showed a characteristic Ln-5-positive band including hemidesmosomes at both the apical and upper portions of the implant-PIE interface in the IGF-1-treated group. We also investigated the effects of IGF-1/PI3K inhibitors on the dynamics of rat oral epithelial cells (OECs) grown on Ti plates. In OECs cultured with IGF-1, adhesion protein expression increased, cell adherence to Ti plates was higher, and proliferation was faster, whereas migration and apoptosis were induced in the absence of IGF-1 or in the presence of both IGF-1 and a PI3K inhibitor. These data suggest that PI3K mediates the promotive effects of IGF-1, and that IGF-1 is effective at enhancing epithelial integration around Ti implants.

Effects of a new implant abutment design on peri-implant soft tissues

The purpose of this study was to assess the effects of a modified implant abutment design on peri-implant soft and hard tissues in dogs. Three months after extraction of mandibular premolar teeth, 3 dental implants were placed in each side of the jaw using a 1-stage approach. Implants on one side of the mandible received standard abutments (control), and implants on the contralateral side received modified, patented, grooved abutments (test). Two months after implant placement, animals were euthanized and specimens were prepared for histologic and histomorphometric assessment. The linear distance (in micrometers) was measured from the implant shoulder (IS) to the following landmarks: gingival margin (GM; distance IS-GM), most apical position of the junctional epithelium (JE; distance IS-JE), and bone crest (BC; distance IS-BC). Percent of bone-to-implant contact was also measured. Histologic assessment revealed that all implants were osseointegrated and that interimplant gingival fibers between test abutments appeared to be more numerous and organized than control abutments. The IS-GM and IS-JE distances in test implants were greater than the corresponding distances in control implants (P = .024 and P = .015, respectively), whereas crestal bone loss (IS-BC) was greater for control implants than test implants (P = .037). There were no differences between control and test implants in bone-to-implant contact (P = .69), which averaged close to 50%. These results suggest that the modified groove design incorporated in standard abutments confers both soft and hard tissue benefits.

Influence of Titanium Surface Topography on Peri-Implant Soft Tissue Integration

At the neck area of dental implant surface, machined surface (Ms) has been employed to avoid surface contamination. Recently, implants which have roughened surface texture (Rs) at their neck are also available. However, from the viewpoint of soft tissue integration, it remains to be elucidated whether or not surface topography affects the soft tissue attachment around implants. The aim of the present study was to clarify the influence of surface topography on peri-implant soft tissue integration. First, surface roughness of both surfaces was measured. Second, protein adsorption capability on both surfaces was examined. Then, as the rat implant model, titanium implants with each surface were inserted into the maxillae. Horseradish peroxidase (HRP) tracer was applied 4 weeks post implantation to the gingival sulci of implants or natural teeth (NT) to investigate the sealing capability of periodontal/peri-implant soft tissue. Collagen density was also observed by fluorescent staining. As a result, surface roughness (Sa) of Ms and Rs was 0.16 µm and 0.25 µm, respectively. Protein adsorption capability on both surface showed no significant differences. In the NT group of the rat implant model, presence of HRP was restricted only in the coronal portion of epithelium. In both implant groups, in contrast, more invasion of HRP was observed in the soft tissue around implants. Especially in the Ms group, more HRP was observed in the deeper area compared with Rs group. Stronger expression of collagen was observed around Rs compared to Ms at the connective tissue-implant interface. It could be speculated that, with dense collagen, Rs implants showed stronger soft tissue integration compared with Ms implants, but the integration is not as strong as NT’s.