The initial attachment and subsequent behavior regulation of osteoblasts by dental implant surface modification

Electrophoretically deposited titanium and its alloys in biomedical engineering: Recent progress and remaining challenges

Over the past decade, titanium implants have gained popularity as the number of performed implantation operations has significantly increased. There are a number of methods for modifying the surface of biomaterials, which are aimed at extending the life of titanium implants. The developments in this field in recent years have required a comprehensive discussion of all the properties of electrophoretically deposited coatings on titanium and its alloys, taking into account their bioactivity. The development that took place in this field in recent years required a comprehensive discussion of all the properties of coatings electrophoretically deposited on titanium and its alloys, with particular emphasis on their bioactivity. Herein, we attempt to assess the influence of the electrophoretic deposition (EPD) process parameters on these coatings' biological and mechanical properties. Particular attention has been addressed to the in-vitro and in-vivo studies conducted hitherto. We have seen an increased interest in using titanium alloys without the addition of toxic compounds and gaps in the EPD field such as the uncommon endeavors to develop a "Design of experiments" approach as well as the lack of assessment of the surface free energy and detailed topography of electrophoretically deposited coatings. The exact correlation of coating properties with EPD process parameters still seems explicitly not understood, necessitating more future investigations. Ipso facto, the exact mechanism of particle agglomeration and Hamaker's law need to be fathomable.

A comparison of human dental pulp stem cell activity cultured on sandblasted titanium discs decontaminated with Er:YAG laser and air-powder abrasion: an in vitro study

Decontamination of implant surfaces is important to the treatment of peri-implantitis. Er:YAG laser and air-powder abrasion system are regarded as the most effective means of decontamination of implant surfaces. The aim of this in vitro study was to compare the activity of human dental pulp stem cells (hDPSCs) cultured on decontaminated sandblasted titanium discs using Er:YAG laser irradiation and air-powder abrasion. Forty-five titanium discs were contaminated with Escherichia coli (E. coli) bacteria and fifteen titanium discs served as sterile control groups. Thirty contaminated titanium discs were decontaminated with Er:YAG laser or air-powder abrasion system and fifteen contaminated discs were used as contaminated control group. Afterwards, hDPSCs were seeded on all sixty experimental titanium discs. The effects of two decontamination tools on hDPSCs viability were evaluated by MTT assay. Alkaline phosphatase (ALP) activity assay, quantitative real-time PCR analysis and alizarin red staining method were performed to assess hDPSCs osteogenic differentiation. Scanning microscope electron (SEM) was also used to evaluate the effects of two different decontaminated methods on cellular morphology. Our study showed that decontamination using Er:YAG laser caused maximum cell viability. However, the ALP activity was not different in laser and air-abrasion groups. The significant expression of an osteoblastic marker and stronger Alizarin red staining were observed in laser irradiation groups. In addition, SEM observation indicated that grown cells were more stretched and more filopodia in Er:YAG-treated discs. In the present study, Er:YAG laser and air-powder abrasion improved the activity of the cells cultured on the decontaminated titanium discs. However, in comparison with air-powder abrasion, Er:YAG laser was more effective.

Direct-Deposited Graphene Oxide on Dental Implants for Antimicrobial Activities and Osteogenesis

Objective

To determine the effects of graphene oxide (GO) deposition (on a zirconia surface) on bacterial adhesion and osteoblast activation.

Methods

An atmospheric pressure plasma generator (PGS-300) was used to coat Ar/CH₄ mixed gas onto zirconia specimens (15-mm diameter × 2.5-mm thick disks) at a rate of 10 L/min and 240 V. Zirconia specimens were divided into two groups: uncoated (control; Zr) group and GO-coated (Zr-GO) group. Surface characteristics and element structures of each specimen were evaluated by field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and contact angle. Additionally, crystal violet staining was performed to assess the adhesion of Streptococcus mutans. WST-8 and ALP (Alkaline phosphatase) assays were conducted to evaluate MC3T3-E1 osteoblast adhesion, proliferation, and differentiation. Statistical analysis was calculated by the Mann–Whitney U-test.

Results

FE–SEM and Raman spectroscopy demonstrated effective GO deposition on the zirconia surface in Zr-GO. The attachment and biofilm formation of S. mutans was significantly reduced in Zr-GO compared with that of Zr (P < 0.05). While no significant differences in cell attachment of MC3T3-1 were observed, both proliferation and differentiation were increased in Zr-GO as compared with that of Zr (P < 0.05).

Significance

GO-coated zirconia inhibited the attachment of S. mutans and stimulated proliferation and differentiation of osteoblasts. Therefore, GO-coated zirconia can prevent peri-implantitis by inhibiting bacterial adhesion. Moreover, its osteogenic ability can increase bone adhesion and success rate of implants.

Greater Osseointegration Potential with Nanostructured Surfaces on TiZr: Accelerated vs. Real-Time Ageing

Surface chemistry and nanotopography of dental implants can have a substantial impact on osseointegration. The aim of this investigation was to evaluate the effects of surface chemistry and nanotopography on the osseointegration of titanium-zirconium (TiZr; Roxolid^®) discs, using a biomechanical pull-out model in rabbits. Two discs each were placed in both the right and left tibiae of 16 rabbits. Five groups of sandblasted acid etched (SLA) discs were tested: (1) hydrophobic without nanostructures (dry/micro) (n = 13); (2) hydrophobic with nanostructures, accelerated aged (dry/nano/AA) (n = 12); (3) hydrophilic without nanostructures (wet/micro) (n = 13); (4) hydrophilic with nanostructures, accelerated aged (wet/nano/AA; SLActive^®) (n = 13); (5) hydrophilic with nanostructures, real-time aged (wet/nano/RTA). The animals were sacrificed after four weeks and the biomechanical pull-out force required to remove the discs was evaluated. Adjusted mean pull-out force was greatest for group wet/nano/RTA (64.5 ± 17.7 N) and lowest for group dry/micro (33.8 ± 10.7 N). Multivariate mixed model analysis showed that the pull-out force was significantly greater for all other disc types compared to the dry/micro group. Surface chemistry and topography both had a significant effect on pull-out force (p < 0.0001 for both), but the effect of the interaction between chemistry and topography was not significant (p = 0.1056). The introduction of nanostructures on the TiZr surface significantly increases osseointegration. The introduction of hydrophilicity to the TiZr implant surface significantly increases the capacity for osseointegration, irrespective of the presence or absence of nanotopography.

Localization of Integrin Beta-4 Subunit at Soft Tissue-Titanium or Zirconia Interface

Currently, along with titanium (Ti), zirconia is widely used as an abutment material for dental implants because it makes it possible to avoid gingival discoloration; however, the epithelial sealing capability of zirconia remains unknown. The purpose of the present study is to elucidate the localization of integrin β4 subunit (Inβ4), one of the main proteins in the attachment structure between gingival junctional epithelial (JE) cells and substrata. Maxillary first molars were extracted from rats, and implants were placed with Ti or zirconia transgingival parts; then, the localization of Inβ4 was observed. Morphological and functional changes in rat oral epithelial cells (OECs) cultured on a culture dish (Dish) and Ti and zirconia plates were also evaluated with Inβ4 immunofluorescence histochemistry and Western blotting. After four weeks of implant placement, the morphology of the peri-implant epithelium (PIE) and the localization of Inβ4 around the Ti and zirconia transgingival parts were similar. However, both exhibited markedly shorter Inβ4-positive bands in the PIE than in the JE around natural teeth. Decreased expression levels of Inβ4 were observed in OECs cultured on Ti and zirconia plates compared with those cultured on Dish. In conclusion, although inferior to natural teeth, zirconia implants are thought to have epithelial sealing properties comparable to those of titanium.

Nano-scale modification of titanium implant surfaces to enhance osseointegration

The main aim of this review study was to report the state of art on the nano-scale technological advancements of titanium implant surfaces to enhance the osseointegration process. Several methods of surface modification are chronologically described bridging ordinary methods (e.g. grit blasting and etching) and advanced physicochemical approaches such as 3D-laser texturing and biomimetic modification. Functionalization procedures by using proteins, peptides, and bioactive ceramics have provided an enhancement in wettability and bioactivity of implant surfaces. Furthermore, recent findings have revealed a combined beneficial effect of micro- and nano-scale modification and biomimetic functionalization of titanium surfaces. However, some technological developments of implant surfaces are not commercially available yet due to costs and a lack of clinical validation for such recent surfaces. Further in vitro and in vivo studies are required to endorse the use of enhanced biomimetic implant surfaces. STATEMENT OF SIGNIFICANCE: Grit-blasting followed by acid-etching is currently used for titanium implant modifications, although recent technological biomimetic physicochemical methods have revealed enhanced osteoconductive and anti-microbial outcomes. An improvement in wettability and bioactivity of titanium implant surfaces has been accomplished by combining micro and nano-scale modification and functionalization with protein, peptides, and bioactive compounds. Such morphological and chemical modification of the titanium surfaces induce the migration and differentiation of osteogenic cells followed by an enhancement of the mineral matrix formation that accelerate the osseointegration process. Additionally, the incorporation of bioactive molecules into the nanostructured surfaces is a promising strategy to avoid early and late implant failures induced by the biofilm accumulation.

Atypical Mesenchymal Stromal Cell Responses to Topographic Modifications of Titanium Biomaterials Indicate Cytoskeletal- and Genetic Plasticity-Based Heterogeneity of Cells

Titanium (Ti) is widely used as a biomaterial for endosseous implants due to its relatively inert surface oxide layer that enables implanted devices the ability of assembling tissue reparative components that culminate in osseointegration. Topographic modifications in the form of micro- and nanoscaled structures significantly promote osseointegration and enhance the osteogenic differentiation of adult mesenchymal stromal cells (MSCs). While the biological mechanisms central to the differential responses of tissues and cells to Ti surface modifications remain unknown, adhesion and morphological adaptation are amongst the earliest events at the cell-biomaterial interface that are highly influenced by surface topography and profoundly impact the regulation of stem cell fate determination. This study correlated the effects of Ti topographic modifications on adhesion and morphological adaptation of human MSCs with phenotypic change. The results showed that modified Ti topographies precluded the adhesion of a subset of MSCs while incurring distinct morphological constraints on adherent cells. These effects anomalously corresponded with a differential expression of stem cell pluripotency and Wnt signalling-associated markers on both modified surfaces while additionally differing between hydrophobic and hydrophilic surface modifications—though extent of osteogenic differentiation induced by both modified topographies yielded similarly significant higher levels of cellular mineralisation in contrast to polished Ti. These results suggest that in the absence of deposited proteins and soluble factors, both modified topographies incur the selective adhesion of a subpopulation of progenitors with relatively higher cytoskeletal plasticity. While the presence of deposited proteins and soluble factors does not significantly affect adherence of cells, nanotopographic modifications enhance expression of pluripotency markers in proliferative conditions, which are conversely overridden by both modified topographies in osteogenic inductive conditions. Further deciphering the mechanisms underlying cellular selectivity and Ti topographic responsiveness will improve our understanding of stem cell heterogeneity and advance the potential of MSCs in regenerative medicine.

Laser Surface Texturing of Alumina/Zirconia Composite Ceramics for Potential Use in Hip Joint Prosthesis

The use of metal shell to fix an acetabular cup to bone in hip joint prosthesis carries some limitations, including restrictions in prosthetic femur ball diameter and in patient’s range of motion. These drawbacks could be ideally overcome by using a monolithic ceramic acetabular cup, but the fixation of such an implant to host bone still remains a challenge. Since porous surfaces are known to promote more bone tissue interlocking compared to smooth materials, in this work the surfaces of sintered alumina/zirconia composite ceramics were treated by a pulsed laser radiation at 1064 nm with a pulse width in the nanosecond range, in order to impart controlled textural patterns. The influence of laser process parameters (e.g., energy per pulse, repetition rate, scanning speed, repetition number, angle of laser beam, and number of cycles) on the roughness and texture orientation was systematically investigated. The obtained surface topographies were inspected by optical and scanning electron microscopy, and the roughness was assessed by contact profilometry. Surface roughness could be modulated in the range of 3 to 30 µm by varying the processing parameters, among which the number of cycles was shown to play a major role. The laser treatment was also successfully adapted and applied to ceramic acetabular cups with a curved profile, thus demonstrating the feasibility of the proposed approach to process real prosthetic components.

Biological responses of human bone mesenchymal stem cells to Ti and TiZr implant materials

BACKGROUND

Titanium-zirconium alloy (TiZr1317) is a new material used for biological implants. There are several studies on the effects of TiZr implants on the biological characteristics of human bone mesenchymal stem cells (hBMSCs).

PURPOSE

The purpose of this study was to investigate the biological responses of hBMSCs to implant holes affected by the physicochemical properties of oral implants (Ti_SLA , Ti_SLActive , TiZr_SLA , and TiZr_SLActive ).

MATERIALS AND METHODS

Grade 4 Ti and TiZr (13-17% Zr) substrates were modified by sand-blasted large-grit acid-etched (SLA) or hydrophilic sand-blasted large-grit acid-etched (SLActive), resulting in four types of surface with complex microstructures corresponding to the commercially-available implants SLA, RoxolidSLA, SLActive, and RoxolidSLActive (Institute Straumann AG, Basel, Switzerland). Physicochemical properties were detected and the biological responses of hBMSCs were observed.

RESULTS

Surface morphology characterization by scanning electron microscopy and atomic force microscopy revealed differences between the four groups. SLA_ctive had higher surface energy/wettability than SLA, indicating that increased surface energy/wettability can promote the absorption of osteogenic proteins and enhance osseointegration. hBMSCs seeded on SLActive substrates exhibited better performance in terms of cell attachment, proliferation and osteoblastic differentiation than cells seeded on SLA.

CONCLUSION

Because of their more suitable physicochemical properties, Ti_SLActive and TiZr_SLActive materials demonstrated more pronounced effects on the biological responses of hBMSCs compared with Ti_SLA and TiZr_SLA .

Bone healing dynamics associated with 3 implants with different surfaces: histologic and histomorphometric analyses in dogs

Purpose

This study evaluated differences in bone healing and remodeling among 3 implants with different surfaces: sandblasting and large-grit acid etching (SLA; IS-III Active^®), SLA with hydroxyapatite nanocoating (IS-III Bioactive^®), and SLA stored in sodium chloride solution (SLActive^®).

Methods

The mandibular second, third, and fourth premolars of 9 dogs were extracted. After 4 weeks, 9 dogs with edentulous alveolar ridges underwent surgical placement of 3 implants bilaterally and were allowed to heal for 2, 4, or 12 weeks. Histologic and histomorphometric analyses were performed on 54 stained slides based on the following parameters: vertical marginal bone loss at the buccal and lingual aspects of the implant (b-MBL and l-MBL, respectively), mineralized bone-to-implant contact (mBIC), osteoid-to-implant contact (OIC), total bone-to-implant contact (tBIC), mineralized bone area fraction occupied (mBAFO), osteoid area fraction occupied (OAFO), and total bone area fraction occupied (tBAFO) in the threads of the region of interest. Two-way analysis of variance (3 types of implant surface×3 healing time periods) and additional analyses for simple effects were performed.

Results

Statistically significant differences were observed across the implant surfaces for OIC, mBIC, tBIC, OAFO, and tBAFO. Statistically significant differences were observed over time for l-MBL, mBIC, tBIC, mBAFO, and tBAFO. In addition, an interaction effect between the implant surface and the healing time period was observed for mBIC, tBIC, and mBAFO.

Conclusions

Our results suggest that implant surface wettability facilitates bone healing dynamics, which could be attributed to the improvement of early osseointegration. In addition, osteoblasts might become more activated with the use of HA-coated surface implants than with hydrophobic surface implants in the remodeling phase.

Effect of donor variation on osteogenesis and vasculogenesis in hydrogel cocultures

To introduce a functional vascular network into tissue-engineered bone equivalents, human endothelial colony forming cells (ECFCs) and multipotent mesenchymal stromal cells (MSCs) can be cocultured. Here, we studied the impact of donor variation of human bone marrow-derived MSCs and cord blood-derived ECFCs on vasculogenesis and osteogenesis using a 3D in vitro coculture model. Further, to make the step towards cocultures consisting of cells derived from a single donor, we tested how induced pluripotent stem cell (iPSC)-derived human endothelial cells (iECs) performed in coculture models. Cocultures with varying combinations of human donors of MSCs, ECFCs, or iECs were prepared in Matrigel. The constructs were cultured in an osteogenic differentiation medium. Following a 10-day culture period, the length of the prevascular structures and osteogenic differentiation were evaluated for up to 21 days of culture. The particular combination of MSC and ECFC donors influenced the vasculogenic properties significantly and induced variation in osteogenic potential. In addition, the use of iECs in the cocultures resulted in prevascular structure formation in osteogenically differentiated constructs. Together, these results showed that close attention to the source of primary cells, such as ECFCs and MSCs, is critical to address variability in vasculogenic and osteogenic potential. The 3D coculture model appeared to successfully generate prevascularized constructs and were sufficient in exceeding the ~200 μm diffusion limit. In addition, iPSC-derived cell lineages may decrease variability by providing a larger and potentially more uniform source of cells for future preclinical and clinical applications.

Biological and Physicochemical Characteristics of 2 Different Hydrophilic Surfaces Created by Saline-Storage and Ultraviolet Treatment

OBJECTIVES

Hydrophilicity/hydrophobicity of titanium surfaces may affect osseointegration. Ordinary titanium surfaces are hydrophobic. Recently, 2 different methods of storing titanium in saline solution or treating it with ultraviolet (UV) light were introduced to generate surface hydrophilicity. This study compared biological and physicochemical properties of 2 different hydrophilic titanium surfaces created by these methods.

MATERIALS

Acid-etched control, saline-stored, and UV-treated titanium surfaces were assessed by scanning electron microscopy, energy dispersive spectroscopy, and x-ray photoelectron spectroscopy. The attachment, spreading behaviors, mineralization, and gene expression of osteoblasts were examined.

RESULTS

Similar microroughness was found on control and UV-treated surfaces, whereas foreign deposits were observed on saline-stored surfaces. Control and UV-treated surfaces consisted of Ti, O, and C, whereas saline-stored surfaces showed Na and Cl in addition to these 3 elements. Atomic percentage of surface carbon was higher in order of control, saline-stored, and UV-treated surfaces. Osteoblasts cultured on saline-stored surfaces showed higher levels of calcium deposition and collagen I expression than control. Osteoblasts on UV-treated surfaces showed significantly increased levels for all parameters related to cell attachment, cell spreading, the expression of adhesion and cytoskeletal proteins, mineralization, and gene expression compared with control, outperforming saline-stored surfaces for most parameters.

CONCLUSION

Despite similar hydrophilicity, saline-stored and UV light-treated surfaces showed substantially different biological effects on osseointegration, associated with different surface chemistry and morphology.

A critical review of multifunctional titanium surfaces: New frontiers for improving osseointegration and host response, avoiding bacteria contamination

Evolution of metal implants progressively shifted the focus from adequate mechanical strength to improved biocompatibility and absence of toxicity and, finally, to fast osseointegration. Recently, new frontiers and challenges of Ti implants have been addressed to improvement of bioactivity, fighting of bacterial infection and biofilm formation, as well as modulation of inflammation. This is closely related to the clinical demand of multifunctional implants able to simultaneously have a number of specific responses with respect to body fluids, cells (osteoblasts, fibroblasts, macrophages) and pathogenic agents (bacteria, viruses). This complex system of multiple biological stimuli and surface responses is a major arena of the current research on biomaterials and biosurfaces. This review covers the strategies explored to this purpose since 2010 in the case of Ti and Ti alloys, considering that the number of related papers doubled about in the last seven years and no review has comprehensively covered this engaging research area yet. The different approaches followed for producing multifunctional Ti-based surfaces involve the use of thick and thin inorganic coatings, chemical surface treatments, and functionalization strategies coupled with organic coatings.

STATEMENT OF SIGNIFICANCE

According to the clinical demand of multifunctional implants able to simultaneously have a number of specific responses with respect to body fluids, cells and pathogenic agents, new frontiers of Ti implants have been addressed to improvement of bioactivity, fighting of bacterial infection and biofilm formation, as well as modulation of inflammation. Literature since 2010 is here reviewed. Several strategies for getting bioactive and antibacterial actions on Ti surfaces have been suggested, but they still need to be optimized with respect to several concerns. A further step will be to combine on the same surface a proven ability of modulation of inflammatory response. The achievement of multifunctional surfaces able to modulate inflammation and to promote osteogenesis is a grand challenge.

Osteogenic differentiation of mesenchymal stem cells modulated by a chemically modified super-hydrophilic titanium implant surface

This study investigated the osteogenic functionality of multipotent mesenchymal stem cells (MSCs) modulated by a chemically modified super-hydrophilic titanium (Ti) bone implant surface to elucidate the biological mechanism underlying the bone healing capacity of this modified Ti surface. A microstructured Ti surface incorporating bioactive ions (in this study, phosphate (P) ions) was prepared by wet chemical treatment. The results showed that the hydrothermally obtained crystalline P-incorporated Ti surface (P surface) displayed long-term super-hydrophilicity (water contact angles <5°) during a 36-week observation period. The hydrophilic P surface enhanced early cellular functions and osteogenic differentiation of multipotent MSCs derived from mouse bone marrow and human adipose tissue. The expression of critical integrins affecting subsequent osteoblast function and osteoblast phenotype genes was notably upregulated in multipotent MSCs grown on the P surface compared with the commercially available grit-blasted microrough clinical oral implant surface. The P surface supported better cell spreading, focal adhesion and ALP activity of MSCs. These results indicate that a super-hydrophilic P-incorporated Ti surface accelerates implant bone healing by enhancing the early osteogenesis functions of multipotent MSCs.

The impact of photofunctionalized gold nanoparticles on osseointegration

OBJECTIVES

The aims of this study were to create a new surface topography using simulated body fluids (SBF) and Gold Nanoparticles (GNPs) and then to assess the influence of UV Photofunctionalization (PhF) on the osteogenic capacity of these surfaces.

MATERIALS AND METHODS

Titanium plates were divided into six groups All were acid etched with 67% Sulfuric acid, 4 were immersed in SBF and 2 of these were treated with 10 nm GNPs. Half of the TiO2 plates were photofunctionalized to be compared with the non-PhF ones. Rat's bone marrow stem cells were seeded into the plates and then CCK8 assay, cell viability assay, immunofluorescence, and Scanning electron microscopy (SEM) were done after 24 hours. Gene expression analysis was done using real time quantitative PCR (qPCR) one week later to check for the mRNA expression of Collagen-1, Osteopontin and Osteocalcin. Alkaline phosphatase (ALP) activity was assessed after 2 weeks of cell seeding.

RESULTS

Our new topography has shown remarkable osteogenic potential. The new surface was the most biocompatible, and the 10 nm GNPs did not show any cytotoxicity. There was a significant increase in bioactivity, enhanced gene expressions and ALP activity.

CONCLUSIONS

GNPs enhances osteogenic differentiation of stem cells and Photofunctionalizing GNPs highly increases this. We have further created a novel highly efficient topography which highly enhances the speed and extent of osseointegration. This may have great potential for improving treatment outcomes for implant, maxillofacial as well as orthopedic patients.

Nanoscale Topographical Characterization of Orbital Implant Materials

The search for an ideal orbital implant is still ongoing in the field of ocular biomaterials. Major limitations of currently-available porous implants include the high cost along with a non-negligible risk of exposure and postoperative infection due to conjunctival abrasion. In the effort to develop better alternatives to the existing devices, two types of new glass-ceramic porous implants were fabricated by sponge replication, which is a relatively inexpensive method. Then, they were characterized by direct three-dimensional (3D) contact probe mapping in real space by means of atomic force microscopy in order to assess their surface micro- and nano-features, which were quantitatively compared to those of the most commonly-used orbital implants. These silicate glass-ceramic materials exhibit a surface roughness in the range of a few hundred nanometers (S_q within 500–700 nm) and topographical features comparable to those of clinically-used “gold-standard” alumina and polyethylene porous orbital implants. However, it was noted that both experimental and commercial non-porous implants were significantly smoother than all the porous ones. The results achieved in this work reveal that these porous glass-ceramic materials show promise for the intended application and encourage further investigation of their clinical suitability.

Osteoblastic differentiating potential of dental pulp stem cells in vitro cultured on a chemically modified microrough titanium surface

Titanium surface modification is critical for dental implant success. Our aim was to determine surfaces influence on dental pulp stem cells (DPSCs) viability and differentiation. Implants were divided into sandblasted/acid-etched (control) and sandblasted/acid-etched coated with calcium and magnesium ions (CaMg), supplied as composite (test). Proliferation was evaluated by MTT, differentiation checking osteoblastic gene expression, PGE2 secretion and matrix formation, inflammation by Interleukin 6 (IL-6) detection. MTT and IL-6 do not modify on test. A PGE2 increase on test is recorded. BMP2 is higher on test at early experimental points, Osterix and RUNX2 augment later. Alizarin-red S reveals higher matrix production on test. These results suggest that test surface is more osteoinductive, representing a start point for in vivo studies aiming at the construction of more biocompatible dental implants, whose integration and clinical performance are improved and some undesired effects, such as implant stability loss and further surgical procedures, are reduced.

The effect of strontium-loaded rough titanium surface on early osseointegration

It is not clear whether surface bioactive chemistry plays an important role in the early osseointegration of micro-structured titanium implants that have the same surface topography at the micrometer and submicrometer scales. In this study, magnetron sputtering methodology was employed for the preparation of Sr coating on sandblasted and acid-etched (SLA) titanium implant without changing the surface characteristics. The study of the surface morphology of the coating was carried out with the use of scanning electron microscopy, and the chemical composition of the surface was examined by X-ray energy-dispersive spectrometry. Twenty SLA implants together with 20 Sr-SLA implants were randomly inserted into the proximal tibia of 20 rats. The early osseointegration of the Sr-SLA implant was compared with SLA implant by removal torque test and histological analysis following two and eight weeks of implantation, correspondingly. As revealed by the surface characteristics, both Sr-SLA and SLA surfaces exhibited similar typical isotropic irregular indentations. The strontium ions were effectively incorporated into the SLA surface (the atomic ratio is 2%). Following two and eight weeks of healing, significant increases in removal torque values ( p < 0.05) were taken into observation in respect of Sr-SLA implant. Histologically, the Sr-SLA implants displayed significantly higher bone-to-implant contact percentages and bone area ratio in comparison with the SLA implant at eight weeks ( p < 0.05). At two weeks, the bone-implant contact percentages, together with bone area ratio of Sr-SLA surface appeared to be a little bit slightly greater than that of SLA surface. But the statistical difference was not significant. These results indicated that the chemical modification with Sr incorporated by magnetron sputtering treatment in moderately rough surfaced implants remarkably increases early bone apposition.

Effect of enamel matrix derivative on the angiogenic behaviors of human umbilical vein endothelial cells on different titanium surfaces

Angiogenesis play a crucial role in the regeneration of hard and soft tissue around dental titanium (Ti) implant. Enamel matrix derivative (EMD) promotes tissue regeneration and stimulates angiogenesis but its effect on the angiogenesis on Ti surfaces was never investigated. The effect of EMD on the angiogenic activity of endothelial cells cultured on pre-treated smooth Ti (PT), acidetched (A), coarse-grit blasted and acid-etched (SLA) surfaces and tissue culture plastic (TCP) in the presence or absence of EMD was investigated. EMD inhibited the proliferation/viability of human umbilical vein endothelial cells (HUVECs) growing on A and SLA Ti surfaces. EMD induced an increase in the expression of all these genes in HUVECs grown on SLA surface but not on other surfaces. Summarizing, our data show that EMD influences proliferation and expression of angiogenesis associated gene in HUVECs grown on moderately rough SLA surfaces, suggesting that EMD might promote angiogenesis following implantation.

Temporal sequence of hard and soft tissue healing around titanium dental implants

The objective of the present review was to summarize the evidence available on the temporal sequence of hard and soft tissue healing around titanium dental implants in animal models and in humans. A search was undertaken to find animal and human studies reporting on the temporal dynamics of hard and soft tissue integration of titanium dental implants. Moreover, the influence of implant surface roughness and chemistry on the molecular mechanisms associated with osseointegration was also investigated. The findings indicated that the integration of titanium dental implants into hard and soft tissue represents the result of a complex cascade of biological events initiated by the surgical intervention. Implant placement into alveolar bone induces a cascade of healing events starting with clot formation and continuing with the maturation of bone in contact with the implant surface. From a genetic point of view, osseointegration is associated with a decrease in inflammation and an increase in osteogenesis-, angiogenesis- and neurogenesis-associated gene expression during the early stages of wound healing. The attachment and maturation of the soft tissue complex (i.e. epithelium and connective tissue) to implants becomes established 6-8 weeks following surgery. Based on the findings of the present review it can be concluded that improved understanding of the mechanisms associated with osseointegration will provide leads and targets for strategies aimed at enhancing the clinical performance of titanium dental implants.

The use of heparin chemistry to improve dental osteogenesis associated with implants

In this study, we designed a hybrid Ti by heparin modifying the Ti surface followed by Growth/differentiation factor-5 (GDF-5) loading. After that, products were characterized by physicochemical analysis. Quantitative analysis of functionalized groups was also confirmed. The release behavior of GDF-5 grafted samples was confirmed for up to 21days. The surface modification process was found to be successful and to effectively immobilize GDF-5 and provide for its sustained release behavior. As an in vitro test, GDF-5 loaded Ti showed significantly enhanced osteogenic differentiation with increased calcium deposition under nontoxic conditions against periodontal ligament stem cells (PDLSc). Furthermore, an in vivo result showed that GDF-5 loaded Ti had a significant influence on new bone formation in a rabbit model. These results clearly confirmed that our strategy may suggest a useful paradigm by inducing osseo-integration as a means to remodeling and healing of bone defects for restorative procedures in dentistry.

Proliferation, behavior, and differentiation of osteoblasts on surfaces of different microroughness

OBJECTIVES

Titanium surface roughness is recognized as an important parameter influencing osseointegration. However, studies concerning the effect of well-defined surface topographies of titanium surfaces on osteoblasts have been limited in scope. In the present study we have investigated how Ti surfaces of different micrometer-scale roughness influence proliferation, migration, and differentiation of osteoblasts in-vitro.

METHODS

Titanium replicas with surface roughnesses (Ra) of approximately 0, 1, 2, and 4μm were produced and MG-63 osteoblasts were cultured on these surfaces for up to 5 days. The effect of surface micrometer-scale roughness on proliferation, migration in time-lapse microscopy experiments, as well as the expression of alkaline phosphatase, osteocalcin, vascular-endothelial growth factor (VEGF), osteoprotegerin (OPG), and receptor activator of nuclear factor kappa-B ligand (RANKL) were investigated.

RESULTS

Proliferation of MG-63 cells was found to decrease gradually with increasing surface roughness. However, the highest expression of alkaline phosphatase, osteocalcin and VEGF was observed on surfaces with Ra values of approximately 1 and 2μm. Further increase in surface roughness resulted in decreased expression of all investigated parameters. The cell migration speed measured in time-lapse microscopy experiments was significantly lower on surfaces with a Ra value of about 4μm, compared to those with lower roughness. No significant effect of surface roughness on the expression of OPG and RANKL was observed.

SIGNIFICANCE

Thus, surfaces with intermediate Ra roughness values of 1-2μm seem to be optimal for osteoblast differentiation. Neither proliferation nor differentiation of osteoblasts appears to be supported by surfaces with higher or lower Ra values.

Effective incorporation of rhBMP-2 on implantable titanium disks with microstructures by using electrostatic spraying deposition

Electrostatic spraying deposition was applied to construct a biodegradable coating loaded with rhBMP-2 on hydrophilic SLA-treated titanium disks.

A Key Role of Autophagy in Osteoblast Differentiation on Titanium-Based Dental Implants

Autophagy plays an important role in embryogenesis, for the maintenance of tissue homeostasis and the elimination of damaged subcellular structures. Furthermore, autophagy could be a mode of physiological cell death and also be implicated in cell differentiation. Thus, we hypothesized that autophagy may have an impact on the differentiation of osteoblast cells influenced by various titanium-based surfaces. Interactions between smooth, commercially available pure titanium (Ti cp), rough Ticer, acid-etched Ti cp (SS) and M1-M3 (comprised of the monoclinic phase of sodium-titanium oxides and rutile; M2 contains amorphous calcium phosphates) and human osteoblast cells were investigated. Immunofluorescent staining was used for detecting autophagy, cell cluster formation and collagen type I (Col-1) expression. Flow cytometry was employed to identify autophagy, the production of endogenous nitric oxide (NO) and the size and granularity of the cells. Rough surfaces caused osteoblast differentiation via the autophagic-dependent PI3/Akt signalling pathway. These surfaces induced the formation of discrete populations of large, granular cells, i.e. mature osteoblasts. In addition, M1-M3 provoked the development of a third population of small, granular cells, responsible for cell cluster formation, which are important for the formation of bone noduli and mineralisation. The same surfaces induced faster osteoblast maturation and enhanced NO production, a hallmark of the already mentioned processes. Neither the mature osteoblasts nor the small cells appeared after the inhibition of autophagy. Inhibition of autophagy also prevented cell cluster formation. We demonstrate that autophagy plays an essential role in the osteoblast differentiation on titanium-based surfaces with rough topography.

Comparison and preparation of multilayered polylactic acid fabric strengthen calcium phosphate-based bone substitutes for orthopedic applications

An attempt to maintain the three-dimensional space into restorative sites through the conveniently pack porous fillers are general used strategy. Advancement in the manufacturing protective shells in the scaffolds, which would be filled with brittle ceramic grafts for the development of highly connective pores provides the approach to solve crack problem for generating the tissues. Therefore, multilayered braided and alkalized poly(lactic acid) (PLA) composites with calcium phosphate bone cement (CPC) were synthesized and compared. The PLA/CPC composites were divided into various groups according to a series of heat-treatment temperatures (100-190 °C) and periods (1-3 h) and then characterized. The effects of 24-h immersion on the strength decay resistance of the samples were compared. Results showed that the residual oil capped on the surfaces of alkalized PLA braid was removed, and the structure was unaltered. However, the reduced tensile stress of alkalized PLA braids was due to ester-group formation by hydrolysis. Mechanical test results of PLA/CPC composites showed that the strength significantly increased after heat treatment, except when the heating temperature was higher than the PLA melting point at approximately 160-170 °C. The degree of PLA after recrystallization became higher than that of unheated composites, thereby leading to reduced strength and toughness of the specimen. Braiding fibers of biodegradable PLA reinforced and toughened the structure particularly of the extra-brittle material of thin-sheet CPC after implantation.

The in vitro and in vivo performance of a strontium-containing coating on the low-modulus Ti35Nb2Ta3Zr alloy formed by micro-arc oxidation

The β-titanium alloy is thought to be a promising alloy using as orthopedic or dental implants owing to its characteristics, which contains low elastic modulus, high corrosion resistance and well biocompatibility. Our previous study has reported that a new β-titanium alloy Ti35Nb2Ta3Zr showed low modulus close to human bone, equal tissue compatibility to a traditional implant alloy Ti6Al4V. In this study, micro-arc oxidation (MAO) was applied on the Ti35Nb2Ta3Zr alloy to enhance its surface characteristics and biocompatibility and osseointegration ability. Two different coatings were formed, TiO2 doped with calcium-phosphate coating (Ca-P) and calcium-phosphate-strontium coating (Ca-P-Sr). Then we evaluated the effects of the MAO coatings on the Ti35Nb2Ta3Zr alloy through in vitro and in vivo tests. As to the characteristics of the coatings, the morphology, chemical composition, surface roughness and contact angle of MAO coatings were tested by scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, and video contact-angle measurement system respectively. Besides, we performed MTT assay, ALP test and cell morphology-adhesion test on materials to evaluate the MAOed coating materials' biocompatibility in vitro. The in vivo experiment was performed through rabbit model. Alloys were implanted into rabbits' femur shafts, then we performed micro-CT, histological and sequential fluorescent labeling analysis to evaluate implants' osseointegration ability in vivo. Finally, the Ca-P specimens and Ca-P-Sr specimens exhibited a significant enhancement in surface roughness, hydrophilicity, cell proliferation, cell adhesion. More new bone was found around the Ca-P-Sr coated alloy than Ca-P coated alloy and Ti35Nb2Ta3Zr alloy. In conclusion, the MAO treatment improved in vitro and in vivo performance of Ti35Nb2Ta3Zr alloy. The Ca-P-Sr coating may be a promising modified surface formed by MAO for the novel β-titanium alloy Ti35Nb2Ta3Zr.

Effect of laser-dimpled titanium surfaces on attachment of epithelial-like cells and fibroblasts

PURPOSE

The objective of this study was to conduct an in vitro comparative evaluation of polished and laserdimpled titanium (Ti) surfaces to determine whether either surface has an advantage in promoting the attachment of epithelial-like cells and fibroblast to Ti.

MATERIALS AND METHODS

Forty-eight coin-shaped samples of commercially pure, grade 4 Ti plates were used in this study. These discs were cleaned to a surface roughness (Ra: roughness centerline average) of 180 nm by polishing and were divided into three groups: SM (n=16) had no dimples and served as the control, SM15 (n=16) had 5-µm dimples at 10-µm intervals, and SM30 (n=16) had 5-µm dimples at 25-µm intervals in a 2 × 4 mm(2) area at the center of the disc. Human gingival squamous cell carcinoma cells (YD-38) and human lung fibroblasts (MRC-5) were cultured and used in cell proliferation assays, adhesion assays, immunofluorescent staining of adhesion proteins, and morphological analysis by SEM. The data were analyzed statistically to determine the significance of differences.

RESULTS

The adhesion strength of epithelial cells was higher on Ti surfaces with 5-µm laser dimples than on polished Ti surfaces, while the adhesion of fibroblasts was not significantly changed by laser treatment of implant surfaces. However, epithelial cells and fibroblasts around the laser dimples appeared larger and showed increased expression of adhesion proteins.

CONCLUSION

These findings demonstrate that laser dimpling may contribute to improving the periimplant soft tissue barrier. This study provided helpful information for developing the transmucosal surface of the abutment.

Plasma-electrochemical deposition of porous zirconia on titanium-based dental material and in vitro interactions with primary osteoblasts cells

Three new porous zirconia-coated titanium materials using anodic plasma-electrochemical oxidation have been fabricated and characterized by scanning electron microscopy, electron probe microanalysis and X-ray diffraction. These ZrO2/TiO2 surfaces contained up to 43 wt% of ZrO2, 49 wt% TiO2 (M1–M3) and 8 wt% P2O5 (M2, M3). Zirconium titanate was detected as dominant microcrystalline phase. Primary human osteoblast cells were used for in vitro investigations. Cell proliferation and immunohistochemical analyses of morphology and expression of bone sialoprotein and osteocalcin were performed. Novel coatings M2 and M3 were shown to induce proliferation and expression of osteocalcin and bone sialoprotein to the extent comparable to that of Ticer, a material already employed in clinical practice.

Cellular responses evoked by different surface characteristics of intraosseous titanium implants

The properties of biomaterials, including their surface microstructural topography and their surface chemistry or surface energy/wettability, affect cellular responses such as cell adhesion, proliferation, and migration. The nanotopography of moderately rough implant surfaces enhances the production of biological mediators in the peri-implant microenvironment with consequent recruitment of differentiating osteogenic cells to the implant surface and stimulates osteogenic maturation. Implant surfaces with moderately rough topography and with high surface energy promote osteogenesis, increase the ratio of bone-to-implant contact, and increase the bonding strength of the bone to the implant at the interface. Certain features of implant surface chemistry are also important in enhancing peri-implant bone wound healing. It is the purpose of this paper to review some of the more important features of titanium implant surfaces which have an impact on osseointegration.

Influence of various superhydrophilic treatments of titanium on the initial attachment, proliferation, and differentiation of osteoblast-like cells

The purpose of this study was to investigate the influence of superhydrophilic treatments of titanium on the behavior of osteoblastlike cells. Superhydrophilic specimens were prepared with sandblast and acid-etching (DW), oxygen plasma (Plasma) and ultraviolet light (UV), and were stored in distilled water for 3 days immediately after these treatments. Specimens stored in air for 3 weeks were used as a control Air group. Initial cell attachment, proliferation, alkaline phosphatase activity, and osteocalcin secretion of mouse osteoblast-like cells MC3T3-E1 were enhanced more on superhydrophilic groups than were Air specimens. On confocal laser scanning microscope images of cell morphology, the expression of actin filaments was observed on the superhydrophilic groups, whereas relatively little actin filament expression was seen on the Air surfaces on all culture periods. These results indicate that DW, Plasma, or UV treatment has potential for the creation and maintenance of superhydrophilic surfaces and the enhancement of the initial attachment, proliferation, and differentiation of osteoblast-like cells.

Cementum and Periodontal Ligament Regeneration

The unique anatomy and composition of the periodontium make periodontal tissue healing and regeneration a complex process. Periodontal regeneration aims to recapitulate the crucial stages of wound healing associated with periodontal development in order to restore lost tissues to their original form and function and for regeneration to occur, healing events must progress in an ordered and programmed sequence both temporally and spatially, replicating key developmental events. A number of procedures have been employed to promote true and predictable regeneration of the periodontium. Principally, the approaches are based on the use of graft materials to compensate for the bone loss incurred as a result of periodontal disease, use of barrier membranes for guided tissue regeneration and use of bioactive molecules. More recently, the concept of tissue engineering has been integrated into research and applications of regenerative dentistry, including periodontics, to aim to manage damaged and lost oral tissues, through reconstruction and regeneration of the periodontium and alleviate the shortcomings of more conventional therapeutic options. The essential components for generating effective cellular based therapeutic strategies include a population of multi-potential progenitor cells, presence of signalling molecules/inductive morphogenic signals and a conductive extracellular matrix scaffold or appropriate delivery system. Mesenchymal stem cells are considered suitable candidates for cell-based tissue engineering strategies owing to their extensive expansion rate and potential to differentiate into cells of multiple organs and systems. Mesenchymal stem cells derived from multiple tissue sources have been investigated in pre-clinical animal studies and clinical settings for the treatment and regeneration of the periodontium.

Behavior of osteoblasts on TI surface with two different coating designed for orthodontic devices

In the present study we coated Ti surfaces with polytetrafluorethylene (PTFE) and titanium nitride (TiN) and investigated in vitro the behavior of osteoblasts on these surfaces. MG-63 osteoblasts were cultured on titanium discs with different surface treatment: uncoated Ti6Al4V, TiN-coated, PTFE-coated. Cell viability/proliferation was detected by MTT assay. Gene-expression levels of alkaline phosphatase (ALP), osteocalcin (OC), type I collagen, receptor activator of nuclear factor-kappa-B ligand (RANKL), and osteoprotegerin (OPG) were determined by qPCR. Cell behavior on different surfaces was observed by time-lapse microscopy. Cells grown on PTFE-coated Ti surface exhibited delayed surface attachment and decreased proliferation after 48 h. However, after 168 h of culture cells grown on PTFE-coated surface exhibited higher viability/proliferation, higher expression levels of ALP and OC, and higher OPG/RANKL ratio compared to uncoated surface. No effect of TiN-coating on any investigated parameter was found. Our results shows that PTFE coating exhibits no toxic effect on MG-63 cells and slightly stimulates expression of several genes associated with osteogenesis. We propose that PTFE coating could be considered as a possible choice for a surface treatment of temporary skeletal anchorage devices in orthodontics.

Bioactive coatings for orthopaedic implants-recent trends in development of implant coatings

Joint replacement is a major orthopaedic procedure used to treat joint osteoarthritis. Aseptic loosening and infection are the two most significant causes of prosthetic implant failure. The ideal implant should be able to promote osteointegration, deter bacterial adhesion and minimize prosthetic infection. Recent developments in material science and cell biology have seen the development of new orthopaedic implant coatings to address these issues. Coatings consisting of bioceramics, extracellular matrix proteins, biological peptides or growth factors impart bioactivity and biocompatibility to the metallic surface of conventional orthopaedic prosthesis that promote bone ingrowth and differentiation of stem cells into osteoblasts leading to enhanced osteointegration of the implant. Furthermore, coatings such as silver, nitric oxide, antibiotics, antiseptics and antimicrobial peptides with anti-microbial properties have also been developed, which show promise in reducing bacterial adhesion and prosthetic infections. This review summarizes some of the recent developments in coatings for orthopaedic implants.

Differential expression of osteo-modulatory molecules in periodontal ligament stem cells in response to modified titanium surfaces

This study assessed differential gene expression of signaling molecules involved in osteogenic differentiation of periodontal ligament stem cells (PDLSCs) subjected to different titanium (Ti) surface types. PDLSCs were cultured on tissue culture polystyrene (TCPS), and four types of Ti discs (PT, SLA, hydrophilic PT (pmodPT), and hydrophilic SLA (modSLA)) with no osteoinductive factor and then osteogenic activity, including alkaline phosphatase (ALP) activity, mRNA expression of runt-related gene 2, osterix, FOSB, FRA1, and protein levels of osteopontin and collagen type IA, were examined. The highest osteogenic activity appeared in PDLSCs cultured on SLA, compared with the TCPS and other Ti surfaces. The role of surface properties in affecting signaling molecules to modulate PDLSC behavior was determined by examining the regulation of Wnt pathways. mRNA expression of the canonical Wnt signaling molecules, Wnt3a and β-catenin, was higher on SLA and modSLA than on smooth surfaces, but gene expression of the calcium-dependent Wnt signaling molecules Wnt5a, calmodulin, and NFATc1 was increased significantly on PT and pmodPT. Moreover, integrin α2/β1, sonic hedgehog, and Notch signaling molecules were affected differently by each surface modification. In conclusion, surface roughness and hydrophilicity can affect differential Wnt pathways and signaling molecules, targeting the osteogenic differentiation of PDLSCs.

Monitoring bone morphogenetic protein-2 and -7, soluble receptor activator of nuclear factor-κB ligand and osteoprotegerin levels in the peri-implant sulcular fluid during the osseointegration of hydrophilic-modified sandblasted acid-etched and sandblasted acid-etched surface dental implants

BACKGROUND AND OBJECTIVE

The implant surface plays a major role in the biological response to titanium dental implants. The aim of this study was to investigate levels of soluble receptor activator of nuclear factor-κB ligand (sRANKL), osteoprotegerin (OPG), bone morphogenetic protein-2 (BMP-2) and -7 (BMP-7) in the peri-implant crevicular fluid (PICF) of different implants during the osseointegration period.

MATERIAL AND METHODS

Forty-seven patients (22 females and 25 males, mean age 47.34 ± 10.11) were included in this study. Forty-seven implants from two implant systems (group A1 (sandblasted acid-etched [SLA]-16), group A2 (hydrophilic-modified SLA [SLActive]-16), and group B (sandblasted acid-etched [SLA]-15) were placed using standard surgical protocols. PICF samples, plaque index, gingival index and probing depth measurements were obtained at 1 and 3 mo after surgery. PICF levels of sRANKL, OPG, BMP-2/-7 were analyzed by ELISA.

RESULTS

No complications were observed during the healing period. No significant differences were observed in the PICF levels of sRANKL, OPG, BMP-2 and BMP-7 for all groups at any time point (p > 0.05). A significant decrease was observed in BMP-2 levels in group A1 (p < 0.05). A significant increase in BMP-7 levels was observed only for group A2 (p < 0.05). There was a strong negative correlation between OPG and gingival index and a negative correlation between BMP-7 and plaque index (p < 0.05).

CONCLUSION

Considering the correlations between clinical and biochemical parameters, the levels of these cytokines in PICF during early healing of implants reflects the degree of peri-implant inflammation, rather than differences in the implant surfaces.

In vitro adhesion of fibroblastic cells to titanium alloy discs treated with sodium hydroxide

OBJECTIVE

Adhesion of osteogenic cells on titanium surfaces is a prerequisite for osseointegration. Alkali treatment can increase the hydrophilicity of titanium implant surfaces, thereby supporting the adhesion of blood components. However, it is unclear if alkali treatment also supports the adhesion of cells with a fibroblastic morphology to titanium.

MATERIALS AND METHODS

Here, we have used a titanium alloy (Ti-6AL-4V) processed by alkali treatment to demonstrate the impact of hydrophilicity on the adhesion of primary human gingival fibroblast and bone cells. Also included were the osteosarcoma and fibroblastoma cell lines, MG63 and L929, respectively. Cell adhesion was determined by scanning electron microscopy. We also measured viability, proliferation, and protein synthesis of the adherent cells.

RESULTS

Alkali treatment increased the adhesion of gingival fibroblasts, bone cells, and the two cell lines when seeded onto the titanium alloy surface for 1 h. At 3 h, no significant changes in cell adhesion were observed. Cells grown for 1 day on the titanium alloy surfaces processed by alkali treatment behave similarly to untreated controls with regard to viability, proliferation, and protein synthesis.

CONCLUSION

Based on these preliminary In vitro findings, we conclude that alkali treatment can support the early adhesion of cells with fibroblastic characteristics to a titanium alloy surface.

The bone tissue compatibility of a new Ti35Nb2Ta3Zr alloy with a low Young's modulus

Titanium (Ti) alloys of the β-type are highly attractive metallic materials for biomedical applications due to their low elastic modulus, high corrosion resistance and notable biocompatibility. A new β-type Ti35Nb2Ta3Zr alloy with a low Young's modulus of approximately 48 GPa was previously fabricated. In the present study, the biocompatibility of this alloy was evaluated. In an in vitro assay, the Ti35Nb2Ta3Zr alloy did not markedly affect the adhesion of MG63 osteoblast cells, but it increased their proliferation, alkaline phosphatase (ALP) activity, calcium deposition and mRNA expression of osteogenic genes (i.e., ALP, osteocalcin, osteopontin). In an in vivo study, no marked histological differences were observed between the new bone formed on the surface of Ti35Nb2Ta3Zr and that formed on the surface of control Ti6Al4V rods placed in the medullary canal of rabbit femurs. Additionally, no significant differences were observed in the failure load of Ti35Nb2Ta3Zr and Ti6Al4V in pull-out tests. In conclusion, the Ti35Nb2Ta3Zr alloy with a lower elastic modulus closer to that of human bone has significant bone tissue compatibility equal to that of Ti6Al4V, which has been widely used in orthopedic applications.

Initial attachment, subsequent cell proliferation/viability and gene expression of epithelial cells related to attachment and wound healing in response to different titanium surfaces

OBJECTIVES

A tight seal between the epithelium and the dental implant surface is required to prevent bacterial inflammation and soft tissue recession and therefore to demonstrate a long-term success. Surface hydrophilicity was recently shown to promote osseointegration. The aim of this study was to investigate the influence of surface hydrophilicity in combination with surface topography of Ti implant surfaces on the behavior and activation/differentiation of epithelial cells using a set of in vitro experiments mimicking the implant-soft tissue contact.

METHODS

Hydrophobic acid-etched (A) and coarse-grit-blasted, acid-etched (SLA) surfaces and hydrophilic acid-etched (modA) and modSLA surfaces were produced. The behavior of an oral squamous cell carcinoma cell line (HSC-2) grown on all surfaces was compared through determination of cell attachment and proliferation/viability (CCK-8 and MTT assay), time-lapse microscopy of fluorescence labeled cells and determination of gene expression by real time polymerase chain reaction.

RESULTS

Within the surfaces with similar wettability cell spreading and cell movements observed by time-lapse microscopy after one day of incubation were most pronounced on smoother (A and modA) surfaces compared to rougher (SLA and modSLA) surfaces. Within the surfaces with similar roughness the hydrophilic surfaces (modA and modSLA) showed more cell spreading and cell activity compared to the hydrophobic surfaces (A and SLA). The relative gene expressions of cytokeratin14, integrin α6, integrin β4, vinculin, transforming growth factor (TGF)-β, TGF-β1, and TGF-β3 were decreased in HSC-2 on all four types of Ti surfaces compared to control surfaces (tissue culture polystyrene; p<0.01) and there was no significant difference of gene expression on the four different implant-surfaces.

SIGNIFICANCE

We have demonstrated that for proliferation and spreading of HSC-2 cells the smoother and hydrophilic surface is optimal (modA). These results suggest that surface hydrophilicity might positively influence the epithelial seal around dental implants. All tested titanium surfaces downregulate cell attachment, cell proliferation, expression of adhesion promoters, and cytokines involved in wound healing in HSC-2 cells compared to control surfaces.