Time-dependent degradation of titanium osteoconductivity: an implication of biological aging of implant materials

Enhanced functionality and migration of human gingival fibroblasts on vacuum ultraviolet light-treated titanium: An implication for mitigating cellular stress to improve peri-implant cellular reaction

PURPOSE

The maintenance of peri-implant health relies significantly on the integrity of the peri-implant seal, particularly vulnerable at the interface between implant abutment and soft tissue. Early healing stages around implants involve cellular exposure to oxidative stress. This study aimed to investigate whether vacuum ultraviolet (VUV)-treated titanium augments the growth and functionality of human gingival fibroblasts while mitigating cellular stress.

METHODS

Machined titanium plates underwent treatment with 172 nm VUV light for one minute, with untreated plates as controls. Human gingival fibroblasts were cultured on treated and untreated plates, and their behavior, growth, and functionality were assessed. Functionally impaired fibroblasts, treated with hydrogen peroxide, were also cultured on these titanium plates, and plate-to-plate transmigration ability was evaluated.

RESULTS

Fibroblasts on VUV-treated titanium exhibited a 50% reduction in intracellular reactive oxygen species production compared to controls. Additionally, glutathione, an antioxidant, remained undepleted in cells on VUV-treated titanium. Furthermore, the expression levels of inflammatory cytokines IL-1β and IL-8 decreased by 40-60% on VUV-treated titanium. Consequently, fibroblast attachment and proliferation doubled on VUV-treated titanium compared to those in the controls, leading to enhanced cell retention. Plate-to-plate transmigration assays demonstrated that fibroblasts migrated twice as far on VUV-treated surfaces compared to those in the controls. In particular, the transmigration ability, impaired in functionally impaired fibroblasts on the controls, was preserved on VUV-treated titanium.

CONCLUSIONS

VUV-treated titanium promotes the growth, function, and migration of human gingival fibroblasts by reducing cellular stress and enhancing antioxidative capacity. Notably, the transmigration ability significantly improved on VUV-treated titanium.

Beyond microroughness: novel approaches to navigate osteoblast activity on implant surfaces

Considering the biological activity of osteoblasts is crucial when devising new approaches to enhance the osseointegration of implant surfaces, as their behavior profoundly influences clinical outcomes. An established inverse correlation exists between osteoblast proliferation and their functional differentiation, which constrains the rapid generation of a significant amount of bone. Examining the surface morphology of implants reveals that roughened titanium surfaces facilitate rapid but thin bone formation, whereas smooth, machined surfaces promote greater volumes of bone formation albeit at a slower pace. Consequently, osteoblasts differentiate faster on roughened surfaces but at the expense of proliferation speed. Moreover, the attachment and initial spreading behavior of osteoblasts are notably compromised on microrough surfaces. This review delves into our current understanding and recent advances in nanonodular texturing, meso-scale texturing, and UV photofunctionalization as potential strategies to address the "biological dilemma" of osteoblast kinetics, aiming to improve the quality and quantity of osseointegration. We discuss how these topographical and physicochemical strategies effectively mitigate and even overcome the dichotomy of osteoblast behavior and the biological challenges posed by microrough surfaces. Indeed, surfaces modified with these strategies exhibit enhanced recruitment, attachment, spread, and proliferation of osteoblasts compared to smooth surfaces, while maintaining or amplifying the inherent advantage of cell differentiation. These technology platforms suggest promising avenues for the development of future implants.

Nanofeatured surfaces in dental implants: contemporary insights and impending challenges

Dental implant therapy, established as standard-of-care nearly three decades ago with the advent of microrough titanium surfaces, revolutionized clinical outcomes through enhanced osseointegration. However, despite this pivotal advancement, challenges persist, including prolonged healing times, restricted clinical indications, plateauing success rates, and a notable incidence of peri-implantitis. This review explores the biological merits and constraints of microrough surfaces and evaluates the current landscape of nanofeatured dental implant surfaces, aiming to illuminate strategies for addressing existing impediments in implant therapy. Currently available nanofeatured dental implants incorporated nano-structures onto their predecessor microrough surfaces. While nanofeature integration into microrough surfaces demonstrates potential for enhancing early-stage osseointegration, it falls short of surpassing its predecessors in terms of osseointegration capacity. This discrepancy may be attributed, in part, to the inherent "dichotomy kinetics" of osteoblasts, wherein increased surface roughness by nanofeatures enhances osteoblast differentiation but concomitantly impedes cell attachment and proliferation. We also showcase a controllable, hybrid micro-nano titanium model surface and contrast it with commercially-available nanofeatured surfaces. Unlike the commercial nanofeatured surfaces, the controllable micro-nano hybrid surface exhibits superior potential for enhancing both cell differentiation and proliferation. Hence, present nanofeatured dental implants represent an evolutionary step from conventional microrough implants, yet they presently lack transformative capacity to surmount existing limitations. Further research and development endeavors are imperative to devise optimized surfaces rooted in fundamental science, thereby propelling technological progress in the field.

Optimizing implant osseointegration, soft tissue responses, and bacterial inhibition: A comprehensive narrative review on the multifaceted approach of the UV photofunctionalization of titanium

Titanium implants have revolutionized restorative and reconstructive therapy, yet achieving optimal osseointegration and ensuring long-term implant success remain persistent challenges. In this review, we explore a cutting-edge approach to enhancing implant properties: ultraviolet (UV) photofunctionalization. By harnessing UV energy, photofunctionalization rejuvenates aging implants, leveraging and often surpassing the intrinsic potential of titanium materials. The primary aim of this narrative review is to offer an updated perspective on the advancements made in the field, providing a comprehensive overview of recent findings and exploring the relationship between UV-induced physicochemical alterations and cellular responses. There is now compelling evidence of significant transformations in titanium surface chemistry induced by photofunctionalization, transitioning from hydrocarbon-rich to carbon pellicle-free surfaces, generating superhydrophilic surfaces, and modulating the electrostatic properties. These changes are closely associated with improved cellular attachment, spreading, proliferation, differentiation, and, ultimately, osseointegration. Additionally, we discuss clinical studies demonstrating the efficacy of UV photofunctionalization in accelerating and enhancing the osseointegration of dental implants. Furthermore, we delve into recent advancements, including the development of one-minute vacuum UV (VUV) photofunctionalization, which addresses the limitations of conventional UV methods as well as the newly discovered functions of photofunctionalization in modulating soft tissue and bacterial interfaces. By elucidating the intricate relationship between surface science and biology, this body of research lays the groundwork for innovative strategies aimed at enhancing the clinical performance of titanium implants, marking a new era in implantology.

Efficacy of plasma treatment for surface cleansing and osseointegration of sandblasted and acid-etched titanium implants

PURPOSE

This study was conducted to evaluate the effects of plasma treatment of sandblasted and acid-etched (SLA) titanium implants on surface cleansing and osseointegration in a beagle model.

MATERIALS AND METHODS

For morphological analysis and XPS analysis, scanning electron microscope and x-ray photoelectron spectroscopy were used to analyze the surface topography and chemical compositions of implant before and after plasma treatment. For this animal experiment, twelve SLA titanium implants were divided into two groups: a control group (untreated implants) and a plasma group (implants treated with plasma). Each group was randomly located in the mandibular bone of the beagle dog (n = 6). After 8 weeks, the beagle dogs were sacrificed, and volumetric analysis and histometric analysis were performed within the region of interest.

RESULTS

In morphological analysis, plasma treatment did not alter the implant surface topography or cause any physical damage. In XPS analysis, the atomic percentage of carbon at the inspection point before the plasma treatment was 34.09%. After the plasma treatment, it was reduced to 18.74%, indicating a 45% reduction in carbon. In volumetric analysis and histometric analysis, the plasma group exhibited relatively higher mean values for new bone volume (NBV), bone to implant contact (BIC), and inter-thread bone density (ITBD) compared to the control group. However, there was no significant difference between the two groups (P > .05).

CONCLUSION

Within the limits of this study, plasma treatment effectively eliminated hydrocarbons without changing the implant surface.

Coatless modification of 3D-printed Ti6Al4V implants through tailored Cu ion implantation combined with UV photofunctionalization to enhance cell attachment, osteogenesis and angiogenesis

The three-dimensional-printed Ti6Al4V implant (3DTi) has been widely accepted for the reconstruction of massive bone defects in orthopedics owing to several advantages, such as its tailored shape design, avoiding bone graft and superior bone-implant interlock. However, the osteoinduction activity of 3DTi is inadequate when applied clinically even though it exhibits osteoconduction. This study developes a comprehensive coatless strategy for the surface improvement of 3DTi through copper (Cu) ion implantation and ultraviolet (UV) photofunctionalization to enhance osteoinductivity. The newly constructed functional 3DTi (UV/Ti-Cu) achieved stable and controllable Cu doping, sustained Cu2+ releasing, and increased surface hydrophilicity. By performing cellular experiments, we determined that the safe dose range of Cu ion implantation was less than 5×1016 ions/cm2. The implanted Cu2+ enhanced the ALP activity and the apatite formation ability of bone marrow stromal cells (BMSCs) while slightly decreasing proliferation ability. When combined with UV photofunctionalization, cell adhesion and proliferation were significantly promoted and bone mineralization was further increased. Meanwhile, UV/Ti-Cu was conducive to the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro, theoretically facilitating vascular coupling osteogenesis. In conclusion, UV/Ti-Cu is a novel attempt to apply two coatless techniques for the surface modification of 3DTi. In addition, it is considered a potential bone substrate for repairing bone defects.

Bone-to-Implant Contact in Implants with Plasma-Treated Nanostructured Calcium-Incorporated Surface (XPEEDActive) Compared to Non-Plasma-Treated Implants (XPEED): A Human Histologic Study at 4 Weeks

Titanium implants undergo an aging process through surface hydrocarbon deposition, resulting in decreased wettability and bioactivity. Plasma treatment was shown to significantly reduce surface hydrocarbons, thus improving implant hydrophilicity and enhancing the osseointegration process. This study investigates the effect of plasma surface treatment on bone-to-implant contact (BIC) of implants presenting a nanostructured calcium-incorporated surface (XPEED®). Following a Randomized Controlled Trial (RCT) design, patients undergoing implant surgery in the posterior maxilla received additional plasma-treated (n = 7) or -untreated (n = 5) 3.5 × 8 mm implants that were retrieved after a 4-week healing period for histological examination. Histomorphometric analysis showed that plasma-treated implants exhibited a 38.7% BIC rate compared to 22.4% of untreated implants (p = 0.002), indicating enhanced osseointegration potential. Histological images also revealed increased bone formation and active osteoblastic activity around plasma-treated implants when compared to untreated specimens. The findings suggest that plasma treatment improves surface hydrophilicity and biological response, facilitating early bone formation around titanium implants. This study underscores the importance of surface modifications in optimizing implant integration and supports the use of plasma treatment to enhance osseointegration, thereby improving clinical outcomes in implant dentistry and offering benefits for immediate and early loading protocols, particularly in soft bone conditions.

Enhancement of in vitro antibacterial activity and bioactivity of iodine-loaded titanium by micro-scale regulation using mixed-acid treatment

Postoperative infection and subsequent device loss are serious complications in the use of titanium dental implants and plates for jawbone reconstruction. We have previously reported that NaOH-CaCl2 -thermal-ICl3 -treated titanium (NaCaThIo) has a nano-scale surface and exhibits antibacterial activity against Staphylococcus aureus. The present study examined the surface properties of mixed-acid treated and then iodine-treated titanium (MA-NaCaThIo), and evaluated oral antibacterial activity and cytotoxicity compared with the results obtained with NaCaThIo. MA-NaCaThIo formed a surface layer with a nano-scale network structure having microscale irregularities, and both the thickness of the surface layer (1.49 ± 0.16 μm) and the average surface roughness (0.35 ± 0.03 μm) were significantly higher than those of NaCaThIo. Furthermore, MA-NaCaThIo maintained high hydrophilicity with a contact angle of 7.5 ± 1.7° even after 4 weeks, as well as improved apatite formation, iodine ion release, and antibacterial activity against Prevotella intermedia compared to NaCaThIo. Cell culture test revealed that MA-NaCaThIo exhibited no cytotoxicity against MG-63 and Vero cells, while increased cell proliferation, ALP activity and mineralization of MG-63 compared to NaCaThIo. This treated titanium is expected to be useful for the development of next-generation titanium devices having both bone-bonding and antibacterial properties.

3D bioprinting approaches for spinal cord injury repair

Regenerative healing of spinal cord injury (SCI) poses an ongoing medical challenge by causing persistent neurological impairment and a significant socioeconomic burden. The complexity of spinal cord tissue presents hurdles to successful regeneration following injury, due to the difficulty of forming a biomimetic structure that faithfully replicates native tissue using conventional tissue engineering scaffolds. 3D bioprinting is a rapidly evolving technology with unmatched potential to create 3D biological tissues with complicated and hierarchical structure and composition. With the addition of biological additives such as cells and biomolecules, 3D bioprinting can fabricate preclinical implants, tissue or organ-like constructs, andin vitromodels through precise control over the deposition of biomaterials and other building blocks. This review highlights the characteristics and advantages of 3D bioprinting for scaffold fabrication to enable SCI repair, including bottom-up manufacturing, mechanical customization, and spatial heterogeneity. This review also critically discusses the impact of various fabrication parameters on the efficacy of spinal cord repair using 3D bioprinted scaffolds, including the choice of printing method, scaffold shape, biomaterials, and biological supplements such as cells and growth factors. High-quality preclinical studies are required to accelerate the translation of 3D bioprinting into clinical practice for spinal cord repair. Meanwhile, other technological advances will continue to improve the regenerative capability of bioprinted scaffolds, such as the incorporation of nanoscale biological particles and the development of 4D printing.

Bone Tissue Engineering and Nanotechnology: A Promising Combination for Bone Regeneration

Large bone defects are the leading contributor to disability worldwide, affecting approximately 1.71 billion people. Conventional bone graft treatments show several disadvantages that negatively impact their therapeutic outcomes and limit their clinical practice. Therefore, much effort has been made to devise new and more effective approaches. In this context, bone tissue engineering (BTE), involving the use of biomaterials which are able to mimic the natural architecture of bone, has emerged as a key strategy for the regeneration of large defects. However, although different types of biomaterials for bone regeneration have been developed and investigated, to date, none of them has been able to completely fulfill the requirements of an ideal implantable material. In this context, in recent years, the field of nanotechnology and the application of nanomaterials to regenerative medicine have gained significant attention from researchers. Nanotechnology has revolutionized the BTE field due to the possibility of generating nanoengineered particles that are able to overcome the current limitations in regenerative strategies, including reduced cell proliferation and differentiation, the inadequate mechanical strength of biomaterials, and poor production of extrinsic factors which are necessary for efficient osteogenesis. In this review, we report on the latest in vitro and in vivo studies on the impact of nanotechnology in the field of BTE, focusing on the effects of nanoparticles on the properties of cells and the use of biomaterials for bone regeneration.

Surface characteristics and in vitro biocompatibility of titanium preserved in a vitamin C-containing saline storage solution

The purpose of this study is to explore a storage solution for titanium implants and investigate its osteogenic properties. The commercial pure titanium (cp-Ti) surface and double-etched (SLA) titanium surface specimens were preserved in air, saline, 10 mM Vitamin C (VitC)-containing saline and 100 mM VitC-containing saline storage solutions for 2 weeks. The surface microtopography of titanium was observed by scanning electron microscopy (SEM), the surface elemental compositions of the specimens were analyzed by Raman and X-ray photoelectron spectroscopy (XPS), and water contact angle and surface roughness of the specimens were tested. The protein adsorption capacity of two titanium surfaces after storage in different media was examined by BCA kit. The MC3T3-E1 osteoblasts were cultured on two titanium surfaces after storage in different media, and the proliferation, adhesion and osteogenic differentiation activity of osteoblasts were detected by CCK-8, laser confocal microscope (CLSM) and Western blot. The SEM results indicated that the titanium surfaces of the air group were relatively clean while scattered sodium chloride or VitC crystals were seen on the titanium surfaces of the other three groups. There were no significant differences in the micromorphology of the titanium surfaces among the four groups. Raman spectroscopy detected VitC crystals on the titanium surfaces of two experimental groups. The XPS, water contact angle and surface roughness results suggested that cp-Ti and SLA-Ti stored in 0.9% NaCl and two VitC-containing saline storage solutions possessed less carbon contamination and higher surface hydrophilicity. Moreover, the protein adsorption potentials of cp-Ti and SLA-Ti surfaces were significantly improved under preservation in two VitC-containing saline storage solutions. The results of in vitro study showed that the preservation of two titanium surfaces in 100 mM VitC-containing saline storage solution upregulated the cell adhesion, proliferation, osteogenic related protein expressions of MC3T3-E1 osteoblasts. In conclusion, preservation of cp-Ti and SLA-Ti in 100 mM VitC-containing saline storage solution could effectively reduce carbon contamination and enhance surface hydrophilicity, which was conducive to osteogenic differentiation of osteoblasts.

Study on Surface Roughness, Morphology, and Wettability of Laser-Modified Powder Metallurgy-Processed Ti-Graphite Composite Intended for Dental Application

In this study, the surface laser treatment of a new type of dental biomaterial, a Ti-graphite composite, prepared by low-temperature powder metallurgy, was investigated. Different levels of output laser power and the scanning speed of the fiber nanosecond laser with a wavelength of 1064 nm and argon as a shielding gas were used in this experiment. The surface integrity of the machined surfaces was evaluated to identify the potential for the dental implant's early osseointegration process, including surface roughness parameter documentation by contact and non-contact methods, surface morphology assessment by scanning electron microscopy, and surface wettability estimation using the sessile drop technique. The obtained results showed that the surface roughness parameters attributed to high osseointegration relevance (Rsk, Rku, and Rsm) were not significantly influenced by laser power, and on the other hand, the scanning speed seems to have the most prevalent effect on surface roughness when exhibiting statistical differences in all evaluated profile roughness parameters except Rvk. The obtained laser-modified surfaces were hydrophilic, with a contact angle in the range of 62.3° to 83.2°.

Genome-wide transcriptional responses of osteoblasts to different titanium surface topographies

This is the first genome-wide transcriptional profiling study using RNA-sequencing to investigate osteoblast responses to different titanium surface topographies, specifically between machined, smooth and acid-etched, microrough surfaces. Rat femoral osteoblasts were cultured on machine-smooth and acid-etched microrough titanium disks. The culture system was validated through a series of assays confirming reduced osteoblast attachment, slower proliferation, and faster differentiation on microrough surfaces. RNA-sequencing analysis of osteoblasts at an early stage of culture revealed that gene expression was highly correlated (r = 0.975) between the two topographies, but 1.38 % genes were upregulated and 0.37 % were downregulated on microrough surfaces. Upregulated transcripts were enriched for immune system, plasma membrane, response to external stimulus, and positive regulation to stimulus processes. Structural mapping confirmed microrough surface-promoted gene sharing and networking in signaling pathways and immune system/responses. Target-specific pathway analysis revealed that Rho family G-protein signaling pathways and actin genes, responsible for the formation of stress fibers, cytoplasmic projections, and focal adhesion, were upregulated on microrough surfaces without upregulation of core genes triggered by cell-to-cell interactions. Furthermore, disulfide-linked or -targeted extracellular matrix (ECM) or membranous glycoproteins such as laminin, fibronectin, CD36, and thrombospondin were highly expressed on microrough surfaces. Finally, proliferating cell nuclear antigen (PCNA) and cyclin D1, whose co-expression reduces cell proliferation, were upregulated on microrough surfaces. Thus, osteoblasts on microrough surfaces were characterized by upregulation of genes related to a wide range of functions associated with the immune system, stress/stimulus responses, proliferation control, skeletal and cytoplasmic signaling, ECM-integrin receptor interactions, and ECM-membranous glycoprotein interactions, furthering our knowledge of the surface-dependent expression of osteoblastic biomarkers on titanium.

Optimization of blood and protein flow around superhydrophilic implant surfaces by promoting contact hemodynamics

PURPOSE

We examined blood and protein dynamics potentially influenced by implant threads and hydrophilic/hydrophobic states of implant surfaces.

METHODS

A computational fluid dynamics model was created for a screw-shaped implant with a water contact angle of 70° (hydrophobic surface) and 0° (superhydrophilic surface). Movements and density of blood and fibrinogen as a representative wound healing protein were visualized and quantified during constant blood inflow.

RESULTS

Blood plasma did not occupy 40-50% of the implant interface or the inside of threads around hydrophobic implants, whereas such blood voids were nearly completely eliminated around superhydrophilic implants. Whole blood field vectors were disorganized and random within hydrophobic threads but formed vortex nodes surrounded by stable blood streams along the superhydrophilic implant surface. The averaged vector within threads was away from the implant surface for the hydrophobic implant and towards the implant surface for the superhydrophilic implant. Rapid and massive whole blood influx into the thread zone was only seen for the superhydrophilic implant, whereas a line of conflicting vectors formed at the entrance of the thread area of the hydrophobic implant to prevent blood influx. The fibrinogen density was up to 20-times greater at the superhydrophilic implant interface than the hydrophobic one. Fibrinogen density was higher at the interface than outside the threads only for the superhydrophilic implant.

CONCLUSIONS

Implant threads and surface hydrophilicity have profound effects on vector and distribution of blood and proteins. Critically, implant threads formed significant biological voids at the interface that were negated by superhydrophilicity-induced contact hemodynamics.

Gas Plasma Treatment Improves Titanium Dental Implant Osseointegration-A Preclinical In Vivo Experimental Study

Recent technological advancements led to the development of various plasma-based technologies for post-packaging modifications. The purpose of the present preclinical in vivo study was to assess the safety and efficacy of a novel chairside nonthermal gas plasma treatment for enhancing osseointegration of titanium implants. Six male mixed foxhounds underwent extraction of mandibular premolars and first molars, and the sockets healed for 42 days. Canine mandibles were randomized to receive either plasma-treated (test) or non-plasma-treated (control) dental implants. A total of 36 implants were placed in six animals, and they were sacrificed at 2 weeks (two animals), 4 weeks (two animals), and 6 weeks (two animals) after the implant surgery. When the radiographic analysis was performed, the changes in bone level were not statistically significant between the two groups at 2 weeks and 4 weeks. The difference became significant at 6 weeks (p = 0.016), indicating more bone loss from baseline to 6 weeks for the control group. The bone-to-implant contact (BIC) appeared to be higher for the test groups at all time points, and the BIC was significantly higher for the test group at 4 weeks (p = 0.046). In conclusion, this study underscored the potential of nonthermal plasma treatment in enhancing implant osseointegration.

Influence of Surface Contaminants and Hydrocarbon Pellicle on the Results of Wettability Measurements of Titanium

Hydrophilicity/hydrophobicity-or wettability-is a key surface characterization metric for titanium used in dental and orthopedic implants. However, the effects of hydrophilicity/hydrophobicity on biological capability remain uncertain, and the relationships between surface wettability and other surface parameters, such as topography and chemistry, are poorly understood. The objective of this study was to identify determinants of surface wettability of titanium and establish the reliability and validity of the assessment. Wettability was evaluated as the contact angle of ddH2O. The age of titanium specimens significantly affected the contact angle, with acid-etched, microrough titanium surfaces becoming superhydrophilic immediately after surface processing, hydrophobic after 7 days, and hydrorepellent after 90 days. Similar age-related loss of hydrophilicity was also confirmed on sandblasted supra-micron rough surfaces so, regardless of surface topography, titanium surfaces eventually become hydrophobic or hydrorepellent with time. On age-standardized titanium, surface roughness increased the contact angle and hydrophobicity. UV treatment of titanium regenerated the superhydrophilicity regardless of age or surface roughness, with rougher surfaces becoming more superhydrophilic than machined surfaces after UV treatment. Conditioning titanium surfaces by autoclaving increased the hydrophobicity of already-hydrophobic surfaces, whereas conditioning with 70% alcohol and hydrating with water or saline attenuated pre-existing hydrophobicity. Conversely, when titanium surfaces were superhydrophilic like UV-treated ones, autoclaving and alcohol cleaning turned the surfaces hydrorepellent and hydrophobic, respectively. UV treatment recovered hydrophilicity without exception. In conclusion, surface roughness accentuates existing wettability and can either increase or decrease the contact angle. Titanium must be age-standardized when evaluating surface wettability. Surface conditioning techniques significantly but unpredictably affect existing wettability. These implied that titanium wettability is significantly influenced by the hydrocarbon pellicle and other contaminants inevitably accumulated. UV treatment may be an effective strategy to standardize wettability by making all titanium surfaces superhydrophilic, thereby allowing the characterization of individual surface topography and chemistry parameters in future studies.

Evaluation of UV photofunctionalization effect on ultrastructural properties of SLA titanium disks: An in vitro study

Background

The success rate of dental implants diminishes over time; the lack of osseointegration and infection are the major causes of most implant failures. One of the effective methods to improve the surface properties is to irradiate ultraviolet (UV) light. This study investigated the effect of UV photofunctionalization on the ultrasuperficial properties of sandblasted, large-grit, acid-etched (SLA) titanium discs.

Methods

In this in vitro study, 24 sandblasted and acid-etched titanium discs, with a lifespan of more than four weeks, were categorized into three groups (n=8): control, ultraviolet C (UVC), and ultraviolet B (UVB). Then, they were exposed to a UV light source for 48 hours at a 1-cm distance. In addition to measuring the contact angle between the liquid and the disc surface in each of the three groups, the atomic concentrations of carbon, oxygen, and nitrogen atoms were measured at three different sites on each disc. One-way ANOVA and post hoc Tukey tests were used to analyze data.

Results

The mean concentration of carbon atoms significantly differed in the control, UVC, and UVB groups (P<0.001). The mean concentrations of nitrogen atoms differed significantly between the three groups (P<0.001). However, the mean concentrations of oxygen atoms were not significantly different between the three groups. In examining the contact angle, wettability was higher in the UVC group than in the UVB group and higher in the UBV group than in the control group.

Conclusion

Photofunctionalization with UV light significantly decreased carbon and nitrogen concentrations on the surface of titanium implants, indicating that the implant's superficial hydrocarbons were eliminated. It was observed that UVC photofunctionalization was more effective than UVB photofunctionalization in reducing superficial contamination and improving wettability.

Improvement implant osseointegration through nonthermal Ar/O2 plasma

This study investigated the effects of nonthermal Ar/O₂ plasma on the osseointegration of titanium implants. Through 8 weeks' in vivo evaluation of implants inserted into femoral bones of male Sprague-Dawley rats, the new bone mineralization apposition rate (MAR) is increased by 1.87 and 2.14 times for implants of smooth machined (SM) and sand-blasted and acid-etched (SLA) after plasma treatment. The bone volume fraction (bone volume/total volume, BV/TV) and bone-implant contact (BIC) ratios are improved by 1.31, 1.26 times and 1.35, 1.15 times after 90 s plasma treatment. The improved hydrophilicity rather than implant surface morphology is believed to play a critical role for the osseointegration improvement.

In vitro and in vivo evaluation of surface functionalization of titanium with H2 O2 hydrothermal treatment and FGF-2

The goals of the study were to investigate the effects on bone bioactivity of a titanium dioxide layer formed by hydrothermal oxidation of a titanium surface with hydrogen peroxide (H₂ O₂ ) and loading with fibroblast growth factor-2 (FGF-2) in vitro and in vivo. Ti-6Al-4V discs were hydrothermally oxidized with H₂ O₂ and then loaded with FGF-2. After cytotoxicity testing, Ti-6Al-4V mini-implants were subjected to the same treatment, and their osteogenic potential was evaluated histologically in a rat model. H₂ O₂ hydrothermal oxidation resulted in a dense porous network structure and hydrophilic changes, which improved retention of FGF-2. Morphologically, the cell density was higher, cell elongation was more pronounced, and the cell adhesion area was significantly higher in FGF-2-loaded cells than in those without FGF-2. In a cell proliferation assay using mouse osteoblast-like cells, absorbance tended to increase over time, especially in the FGF-2 group after 7 and 14 days, and in a bone differentiation assay based on ALP activity, there was a significant increase in the FGF-2 group after 14 days. In the rat model, H₂ O₂ hydrothermal oxidation and FGF-2 loading both resulted in more laminar bone tissue in the bone marrow around the mini-implant. These results suggest that titanium surface functionalization by H₂ O₂ hydrothermal oxidation and FGF-2 may promote initial cell adhesion, proliferation, and osteodifferentiation, and enhance bone bioactivity. These effects all contribute to early bonding of an implant with the surrounding bone.

Biological MWCNT/chitosan composite coating with outstanding anti-corrosion property for implants

Biocompatible coatings that can protect metal implants have great potential in tissue engineering. In this work, MWCNT/chitosan composite coatings with hydrophobic-hydrophilic asymmetric wettability were facilely prepared by one-step in situ electrodeposition. The resultant composite coating exhibits excellent thermal stability and mechanical strength (0.76 MPa), benefiting from the compact internal structure. The thickness of the coating can be controlled precisely by the amounts of transferred charges. The MWCNT/chitosan composite coating demonstrates a lower corrosion rate due to its hydrophobicity and compact internal structure. Compared with exposed 316 L stainless steel, its corrosion rate is reduced by two orders of magnitude from 3.004 × 10^-1 mm/yr to 5.361 × 10^-3 mm/yr. The content of iron released from 316 L stainless steel into the simulated body fluid drops to 0.1 mg/L under the protection of the composite coating. In addition, the composite coating enables efficient calcium enrichment from simulated body fluids and promotes the formation of bioapatite layers on the coating surface. This study contributes to furthering the practical application of chitosan-based coatings in implant anticorrosion.

In-Vitro Evaluation of Photofunctionalized Implant Surfaces in a High-Glucose Microenvironment Simulating Diabetics

The present study aimed to assess the efficacy of photofunctionalization on commercially available dental implant surfaces in a high-glucose environment. Discs of three commercially available implant surfaces were selected with various nano- and microstructural alterations (Group 1—laser-etched implant surface, Group 2—titanium–zirconium alloy surface, Group 3—air-abraded, large grit, acid-etched surface). They were subjected to photo-functionalization through UV irradiation for 60 and 90 min. X-ray photoelectron spectroscopy (XPS) was used to analyze the implant surface chemical composition before and after photo-functionalization. The growth and bioactivity of MG63 osteoblasts in the presence of photofunctionalized discs was assessed in cell culture medium containing elevated glucose concentration. The normal osteoblast morphology and spreading behavior were assessed under fluorescence and phase-contrast microscope. MTT (3-(4,5 Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and alizarin red assay were performed to assess the osteoblastic cell viability and mineralization efficiency. Following photofunctionalization, all three implant groups exhibited a reduced carbon content, conversion of Ti4+ to Ti3+, increased osteoblastic adhesion, viability, and increased mineralization. The best osteoblastic adhesion in the medium with increased glucose was seen in Group 3. Photofunctionalization altered the implant surface chemistry by reducing the surface carbon content, probably rendering the surfaces more hydrophilic and conducive for osteoblastic adherence and subsequent mineralization in high-glucose environment.

Effect of Hydrogen Peroxide on the Surface and Attractiveness of Various Zirconia Implant Materials on Human Osteoblasts: An In Vitro Study

The aim of this in vitro study was to investigate the effect of hydrogen peroxide (H₂O₂) on the surface properties of various zirconia-based dental implant materials and the response of human alveolar bone osteoblasts. For this purpose, discs of two zirconia-based materials with smooth and roughened surfaces were immersed in 20% H₂O₂ for two hours. Scanning electron and atomic force microscopy showed no topographic changes after H₂O₂-treatment. Contact angle measurements (1), X-ray photoelectron spectroscopy (2) and X-ray diffraction (3) indicated that H₂O₂-treated surfaces (1) increased in hydrophilicity (p < 0.05) and (2) on three surfaces the carbon content decreased (33-60%), while (3) the monoclinic phase increased on all surfaces. Immunofluorescence analysis of the cell area and DNA-quantification and alkaline phosphatase activity revealed no effect of H₂O₂-treatment on cell behavior. Proliferation activity was significantly higher on three of the four untreated surfaces, especially on the smooth surfaces (p < 0.05). Within the limitations of this study, it can be concluded that exposure of zirconia surfaces to 20% H₂O₂ for 2 h increases the wettability of the surfaces, but also seems to increase the monoclinic phase, especially on roughened surfaces, which can be considered detrimental to material stability. Moreover, the H₂O₂-treatment has no influence on osteoblast behavior.

A Novel High-Energy Vacuum Ultraviolet Light Photofunctionalization Approach for Decomposing Organic Molecules around Titanium

Titanium undergoes biological aging, represented by increased hydrophobicity and surface accumulation of organic molecules over time, which compromises the osseointegration of dental and orthopedic implants. Here, we evaluated the efficacy of a novel UV light source, 172 nm wavelength vacuum UV (VUV), in decomposing organic molecules around titanium. Methylene blue solution used as a model organic molecule placed in a quartz ampoule with and without titanium specimens was treated with four different UV light sources: (i) ultraviolet C (UVC), (ii) high-energy UVC (HUVC), (iii) proprietary UV (PUV), and (iv) VUV. After one minute of treatment, VUV decomposed over 90% of methylene blue, while there was 3-, 3-, and 8-fold more methylene blue after the HUVC, PUV, and UVC treatments, respectively. In dose-dependency experiments, maximal methylene blue decomposition occurred after one minute of VUV treatment and after 20-30 min of UVC treatment. Rapid and effective VUV-mediated organic decomposition was not influenced by the surface topography of titanium or its alloy and even occurred in the absence of titanium, indicating only a minimal photocatalytic contribution of titanium dioxide to organic decomposition. VUV-mediated but not other light source-mediated methylene blue decomposition was proportional to its concentration. Plastic tubes significantly reduced methylene blue decomposition for all light sources. These results suggest that VUV, in synergy with quartz ampoules, mediates rapid and effective organic decomposition compared with other UV sources. This proof-of-concept study paves the way for rapid and effective VUV-powered photofunctionalization of titanium to overcome biological aging.

Photo-functionalized TiO2 film for facile immobilization of EpCAM antibodies and efficient enrichment of circulating tumor cells

The highly efficient capture of circulating tumor cells (CTCs) in the blood is essential for the screening, treatment, and assessment of the risk of metastasis or recurrence of cancer. Immobilizing specific antibodies, such as EpCAM antibodies, on the material's surface is currently the primary method for efficiently capturing CTCs. However, the strategies for immobilizing antibodies usually have the disadvantages of requiring multiple chemical reagents and a complex pre-treatment process. Herein we developed a simple strategy for the immobilization of EpCAM antibodies without additional chemical reagents. By utilizing the positive charge property of the photo-functionalized titanium dioxide (TiO₂), the negatively charged carboxyl terminal of EpCAM antibodies was immobilized by electrostatic interaction, allowing the antibodies to expose the antigen binding site fully. The experimental results showed that the photo-functionalized TiO₂ surface had a marked positive charge and super-hydrophilic properties that could immobilize large amounts of EpCAM antibodies and keep excellent activity. CTCs capture experiments in vitro showed that the EpCAM antibodies-modified photo-functionalized TiO₂ could efficiently capture CTCs. The results of blood circulation experiments in rabbits showed that the EpCAM antibodies-modified photo-functionalized TiO₂ could accurately capture CTCs from the whole body's blood. It was foreseen that the strategy of simple immobilization of EpCAM antibodies based on photo-functionalized TiO₂ is expected to serve in the efficient capture of CTCs in the future.

The Bio-Aging of Biofilms on Behalf of Various Oral Status on Different Titanium Implant Materials

The properties of titanium implants are affected by bio-aging due to long-term exposure to the oral microenvironment. This study aimed to investigate probable changes in titanium plates after different biofilm bio-aging processes, representing various oral status. Titanium plates with different surface treatments were used, including polish, sandblasted with large grit and acid etched (SLA), microarc oxidation (MAO), and hydroxyapatite coating (HA). We established dual-species biofilms of Staphylococcus aureus (S. aureus)-Candida albicans (C. albicans) and saliva biofilms from the healthy and patients with stage III-IV periodontitis, respectively. After bio-aging with these biofilms for 30 days, the surface morphology, chemical composition, and water contact angles were measured. The adhesion of human gingival epithelial cells, human gingival fibroblasts, and three-species biofilms (Streptococcus sanguis, Porphyromonas gingivalis, and Fusobacterium nucleatum) were evaluated. The polished specimens showed no significant changes after bio-aging with these biofilms. The MAO- and SLA-treated samples showed mild corrosion after bio-aging with the salivary biofilms. The HA-coated specimens were the most vulnerable. Salivary biofilms, especially saliva from patients with periodontitis, exhibited a more distinct erosion on the HA-coating than the S. aureus-C. albicans dual-biofilms. The coating became thinner and even fell from the substrate. The surface became more hydrophilic and more prone to the adhesion of bacteria. The S. aureus-C. albicans dual-biofilms had a comparatively mild corrosion effect on these samples. The HA-coated samples showed more severe erosion after bio-aging with the salivary biofilms from patients with periodontitis compared to those of the healthy, which emphasized the importance of oral hygiene and periodontal health to implants in the long run.

Decomposing Organic Molecules on Titanium with Vacuum Ultraviolet Light for Effective and Rapid Photofunctionalization

Ultraviolet (UV) photofunctionalization counteracts the biological aging of titanium to increase the bioactivity and osseointegration of titanium implants. However, UV photofunctionalization currently requires long treatment times of between 12 min and 48 h, precluding routine clinical use. Here, we tested the ability of a novel, xenon excimer lamp emitting 172 nm vacuum UV (VUV) to decompose organic molecules coated on titanium as a surrogate of photofunctionalization. Methylene blue as a model organic molecule was coated on grade 4 commercially pure titanium and treated with four UV light sources: (i) ultraviolet C (UVC), (ii) high-energy UVC (HUVC), (iii) proprietary UV (PUV), and (iv) VUV. After one minute of treatment, VUV decomposed 57% of methylene blue compared with 2%, 36%, and 42% for UVC, HUVC, and PUV, respectively. UV dose-dependency testing revealed maximal methylene blue decomposition with VUV within one minute. Equivalent decomposition was observed on grade 5 titanium alloy specimens, and placing titanium specimens in quartz ampoules did not compromise efficacy. Methylene blue was decomposed even on polymethyl methacrylate acrylic specimens at 20-25% lower efficiency than on titanium specimens, indicating a relatively small contribution of titanium dioxide-mediated photocatalytic decomposition to the total decomposition. Load-testing revealed that VUV maintained high efficacy of methylene blue decomposition regardless of the coating density, whereas other UV light sources showed low efficacy with thin coatings and plateauing efficacy with thicker coatings. This study provides foundational data on rapid and efficient VUV-mediated organic decomposition on titanium. In synergy with quartz ampoules used as containers, VUV has the potential to overcome current technical challenges hampering the clinical application of UV photofunctionalization.

Effects of Excimer Laser Treatment of Zirconia Disks on the Adhesion of L929 Fibroblasts

The adhesion of zirconia and soft tissue is very important for the success of zirconia implants. The aim of this study was to characterize the effects of excimer laser treatment of zirconia on the adhesion of L929 fibroblasts. In this study, polished zirconia disks treated with an excimer laser were the experimental group and untreated zirconia disks were the control group. Surface roughness and contact angles of zirconia disks were measured. mRNA expression levels of integrin β1 and collagen type I α1 in L929 fibroblasts cultured on zirconia disks were measured using qRT-PCR. Cell morphology was evaluated using 3D laser microscopy and the expression of vinculin was characterized using confocal microscopy. There was no significant difference in the surface roughness of zirconia disks, but contact angles were significantly lower. mRNA expression of integrin β1 was significantly higher at 3, 6 and 24 h and of collagen type I α1 was significantly higher at 6 and 24 h. L929 fibroblasts tended to form elongated microspikes and vinculin colocalization in those microspikes. Furthermore, vinculin was strongly expressed in filopodia of L929 fibroblasts at 24 h. These results suggest that excimer laser treatment improves adhesion between zirconia disks and L929 fibroblasts.

Ultraviolet Light Treatment of Titanium Microfiber Scaffolds Enhances Osteoblast Recruitment and Osteoconductivity in a Vertical Bone Augmentation Model: 3D UV Photofunctionalization

Vertical bone augmentation to create host bone prior to implant placement is one of the most challenging regenerative procedures. The objective of this study is to evaluate the capacity of a UV-photofunctionalized titanium microfiber scaffold to recruit osteoblasts, generate intra-scaffold bone, and integrate with host bone in a vertical augmentation model with unidirectional, limited blood supply. Scaffolds were fabricated by molding and sintering grade 1 commercially pure titanium microfibers (20 μm diameter) and treated with UVC light (200-280 nm wavelength) emitted from a low-pressure mercury lamp for 20 min immediately before experiments. The scaffolds had an even and dense fiber network with 87% porosity and 20-50 mm inter-fiber distance. Surface carbon reduced from 30% on untreated scaffold to 10% after UV treatment, which corresponded to hydro-repellent to superhydrophilic conversion. Vertical infiltration testing revealed that UV-treated scaffolds absorbed 4-, 14-, and 15-times more blood, water, and glycerol than untreated scaffolds, respectively. In vitro, four-times more osteoblasts attached to UV-treated scaffolds than untreated scaffolds three hours after seeding. On day 2, there were 70% more osteoblasts on UV-treated scaffolds. Fluorescent microscopy visualized confluent osteoblasts on UV-treated microfibers two days after seeding but sparse and separated cells on untreated microfibers. Alkaline phosphatase activity and osteocalcin gene expression were significantly greater in osteoblasts grown on UV-treated microfiber scaffolds. In an in vivo model of vertical augmentation on rat femoral cortical bone, the interfacial strength between innate cortical bone and UV-treated microfiber scaffold after two weeks of healing was double that observed between bone and untreated scaffold. Morphological and chemical analysis confirmed seamless integration of the innate cortical and regenerated bone within microfiber networks for UV-treated scaffolds. These results indicate synergy between titanium microfiber scaffolds and UV photofunctionalization to provide a novel and effective strategy for vertical bone augmentation.

Osseointegration Properties of Titanium Implants Treated by Nonthermal Atmospheric-Pressure Nitrogen Plasma

Pure titanium is used in dental implants owing to its excellent biocompatibility and physical properties. However, the aging of the material during storage is detrimental to the long-term stability of the implant after implantation. Therefore, in this study, we attempted to improve the surface properties and circumvent the negative effects of material aging on titanium implants by using a portable handheld nonthermal plasma device capable of piezoelectric direct discharge to treat pure titanium discs with nitrogen gas. We evaluated the osteogenic properties of the treated samples by surface morphology and elemental analyses, as well as in vitro and in vivo experiments. The results showed that nonthermal atmospheric-pressure nitrogen plasma can improve the hydrophilicity of pure titanium without damaging its surface morphology while introducing nitrogen-containing functional groups, thereby promoting cell attachment, proliferation, and osseointegration to some extent. Therefore, nitrogen plasma treatment may be a promising method for the rapid surface treatment of titanium implants.

Positive Effects of UV-Photofunctionalization of Titanium Oxide Surfaces on the Survival and Differentiation of Osteogenic Precursor Cells-An In Vitro Study

INTRODUCTION

The UVC-irradiation ("UV-photofunctionalization") of titanium dental implants has proved to be capable of removing carbon contamination and restoring the ability of titanium surfaces to attract cells involved in the process of osteointegration, thus significantly enhancing the biocompatibility of implants and favoring the post-operative healing process. To what extent the effect of UVC irradiation is dependent on the type or the topography of titanium used, is still not sufficiently established.

OBJECTIVE

The present study was aimed at analyzing the effects of UV-photofunctionalization on the TiO₂ topography, as well as on the gene expression patterns and the biological activity of osteogenic cells, i.e., osteogenic precursors cultured in vitro in the presence of different titanium specimens.

METHODOLOGY

The analysis of the surface roughness was performed by atomic force microscopy (AFM) on machined surface grade 2, and sand-blasted/acid-etched surface grades 2 and 4 titanium specimens. The expression of the genes related with the process of healing and osteogenesis was studied in the MC3T3-E1 pre-osteoblastic murine cells, as well as in MSC murine stem cells, before and after exposure to differently treated TiO₂ surfaces.

RESULTS

The AFM determinations showed that the surface topographies of titanium after the sand-blasting and acid-etching procedures, look very similar, independently of the grade of titanium. The UVC-irradiation of the TiO₂ surface was found to induce an increase in the cell survival, attachment and proliferation, which was positively correlated with an increased expression of the osteogenesis-related genes Runx2 and alkaline phosphatase (ALP).

CONCLUSION

Overall, our findings expand and further support the current view that UV-photofunctionalization can indeed restore biocompatibility and osteointegration of TiO₂ implants, and suggest that this at least in part occurs through a stimulation of the osteogenic differentiation of the precursor cells.

Improvement of osseointegration efficacy of titanium implant through plasma surface treatment

A novel plasma treatment source for generating cylindrical plasma on the surface of titanium dental implants is developed herein. Using the titanium implant as an electrode and the packaging wall as a dielectric barrier, a dielectric barrier discharge (DBD) plasma was generated, allowing the implant to remain sterile. Numerical and experimental investigations were conducted to determine the optimal discharge conditions for eliminating hydrocarbon impurities, which are known to degrade the bioactivity of the implant. XPS measurement confirmed that plasma treatment reduced the amount of carbon impurities on the implant surface by approximately 60%. Additionally, in vitro experiments demonstrated that the surface treatment significantly improved cell adhesion, proliferation, and differentiation. Collectively, we proposed a plasma treatment source for dental implants that successfully removes carbon impurities and facilitate the osseointegration of SLA implants.

Human Gingival Fibroblast Attachment to Smooth Titanium Disks with Different Surface Roughnesses

Peri-implantitis is a significant problem associated with dental implants. It has been hypothesized that creating a soft-tissue seal around the implant neck prevents peri-implantitis. This study aims to clarify the effects of the surface smoothness of titanium disks on soft tissues. Thus, titanium disks were prepared through electrolytic composite polishing (ECP), sisal buffing (SB), hairline polishing (HP), and laser cutting (LC). The surface roughness values of seven items was measured. For ECP, SB, HP, and LC samples, the Ra values were 0.075, 0.217, 0.671, and 1.024 μm and the Sa values were 0.005, 0.115, 0.500, and 0.676, respectively, indicating that the surface roughness was remarkably lower with ECP. Moreover, the Wsk values for ECP, SB, HP, and LC were 0.521, 1.018, -0.678, and -0.558, respectively. The smooth surfaces produced by ECP and SB were biased toward the concave surface, whereas those produced by HP and LC were biased toward the convex surface. The Rku values for ECP, SB, HP, and LC were 2.984, 11.774, 14.182, and 26.232, respectively. Only the ECP exhibited a moderate bias peak and produced an extremely smooth surface. The contact angles in the cases of ECP, SB, HP, and LC were 60.1°, 66.3°, 68.4°, and 79.3°, respectively, indicating the hydrophobicity of the titanium disks. Human oral fibroblasts were then incubated on each disk for 24 and 48 h to measure cell attachment, and no significant differences were observed. The differences in Ra and Sa did not affect cell attachment. Therefore, by applying ECP to the abutment or implant neck, the cell attachment required for soft-tissue formation while preventing bacterial adhesion can be achieved.

Effectiveness of photofunctionalized titanium alloy on osseointegration in rats with type 2 diabetes

Background

Ultraviolet (UV) light-mediated photofunctionalization improves the osseointegration of pure titanium and titanium alloy (Ti6Al4V). However, little is known about the effect of UV irradiation on Ti6Al4V, used frequently in orthopedic surgery, in diabetic patients. We examined the effect of UV irradiation on Ti6Al4V in rats with type 2 diabetes.

Methods

Cylinder Ti6Al4V implants were used. Half the animals were Sprague Dawley rats (the control group), and the other half were Spontaneously Diabetic Torii fatty rats (the diabetes mellitus model). For radiological analysis, bone density was observed and calculated using 3D microcomputed tomography. Histological analysis was performed to calculate the bone–implant contact (BIC) ratio. We used Pearson correlation to analyze the correlation between average blood glucose level and BIC ratio, and between average blood glucose level and bone volume (BV) ratio.

Results

In the UV light-treated group, the BIC ratios of the normal and diabetic rats increased significantly compared with those in the untreated group at 2 weeks; at 4 weeks, the BIC ratio of the diabetic rats increased significantly, but there was no significant increase in the control animals. In both the control and diabetic groups, there was no significant difference in the BV ratios between the UV-treated and untreated implants at 2 or 4 weeks. The average blood glucose level in the 4-week group negatively correlated with the BIC and BV ratios. The average blood glucose level in the UV-treated group negatively correlated with the BIC ratio.

Conclusion

Photofunctionalization of Ti6Al4V implants may promote osseointegration in the early stages in rats with type 2 diabetes.

Advances in the superhydrophilicity-modified titanium surfaces with antibacterial and pro-osteogenesis properties: A review

In recent years, the rate of implant failure has been increasing. Microbial infection was the primary cause, and the main stages included bacterial adhesion, biofilm formation, and severe inhibition of implant osseointegration. Various biomaterials and their preparation methods have emerged to produce specific implants with antimicrobial or bactericidal properties to reduce implant infection caused by bacterial adhesion and effectively promote bone and implant integration. In this study, we reviewed the research progress of bone integration promotion and antibacterial action of superhydrophilic surfaces based on titanium alloys. First, the adverse reactions caused by bacterial adhesion to the implant surface, including infection and bone integration deficiency, are briefly introduced. Several commonly used antibacterial methods of titanium alloys are introduced. Secondly, we discuss the antibacterial properties of superhydrophilic surfaces based on ultraviolet photo-functionalization and plasma treatment, in contrast to the antibacterial principle of superhydrophobic surface morphology. Thirdly, the osteogenic effects of superhydrophilic surfaces are described, according to the processes of osseointegration: osteogenic immunity, angiogenesis, and osteogenic related cells. Finally, we discuss the challenges and prospects for the development of this superhydrophilic surface in clinical applications, as well as the prominent strategies and directions for future research.

Impact of nano-scale trabecula size on osteoblastic behavior and function in a meso-nano hybrid rough biomimetic zirconia model

PURPOSE

A novel implant model consisting of meso-scale cactus-inspired spikes and nano-scale bone-inspired trabeculae was recently developed to optimize meso-scale roughness on zirconia. In this model, the meso-spike dimension had a significant impact on osteoblast function. To explore how different nano-textures impact this model, here we examined the effect of different nano-trabecula sizes on osteoblast function while maintaining the same meso-spike conformation.

METHODS

Zirconia disks with meso-nano hybrid surfaces were created by laser etching. The meso-spikes were fixed to 40 μm high, whereas the nano-texture was etched as large and small trabeculae of average Feret diameter 237.0 and 134.1 nm, respectively. A polished surface was also prepared. Rat bone marrow-derived and human mesenchymal stromal cell-induced osteoblasts were cultured on these disks.

RESULTS

Hybrid rough surfaces, regardless of nano-trabecula dimension, robustly promoted the osteoblastic differentiation of both rat and human osteoblasts compared to those on polished surfaces. Hybrid surfaces with small nano-trabeculae further enhanced osteoblastic differentiation compared with large nano-trabeculae. However, the difference in osteoblastic differentiation between small and large nano-trabeculae was much smaller than the difference between the polished and hybrid rough surfaces. The nano-trabecula size did not influence osteoblast attachment and proliferation, or protein adsorption. Both hybrid surfaces were hydro-repellent. The atomic percentage of surface carbon was lower on the hybrid surface with small nano-trabeculae.

CONCLUSIONS

Small nano-trabeculae promoted osteoblastic differentiation more than large nano-trabeculae when combined with meso-scale spikes. However, the biological impact of different nano-trabeculae was relatively small compared with that of different dimensions of meso-spikes.

A Novel Cell Delivery System Exploiting Synergy between Fresh Titanium and Fibronectin

Delivering and retaining cells in areas of interest is an ongoing challenge in tissue engineering. Here we introduce a novel approach to fabricate osteoblast-loaded titanium suitable for cell delivery for bone integration, regeneration, and engineering. We hypothesized that titanium age influences the efficiency of protein adsorption and cell loading onto titanium surfaces. Fresh (newly machined) and 1-month-old (aged) commercial grade 4 titanium disks were prepared. Fresh titanium surfaces were hydrophilic, whereas aged surfaces were hydrophobic. Twice the amount of type 1 collagen and fibronectin adsorbed to fresh titanium surfaces than aged titanium surfaces after a short incubation period of three hours, and 2.5-times more fibronectin than collagen adsorbed regardless of titanium age. Rat bone marrow-derived osteoblasts were incubated on protein-adsorbed titanium surfaces for three hours, and osteoblast loading was most efficient on fresh titanium adsorbed with fibronectin. The number of osteoblasts loaded using this synergy between fresh titanium and fibronectin was nine times greater than that on aged titanium with no protein adsorption. The loaded cells were confirmed to be firmly attached and functional. The number of loaded cells was strongly correlated with the amount of protein adsorbed regardless of the protein type, with fibronectin simply more efficiently adsorbed on titanium surfaces than collagen. The role of surface hydrophilicity of fresh titanium surfaces in increasing protein adsorption or cell loading was unclear. The hydrophilicity of protein-adsorbed titanium increased with the amount of protein but was not the primary determinant of cell loading. In conclusion, the osteoblast loading efficiency was dependent on the age of the titanium and the amount of protein adsorption. In addition, the efficiency of protein adsorption was specific to the protein, with fibronectin being much more efficient than collagen. This is a novel strategy to effectively deliver osteoblasts ex vivo and in vivo using titanium as a vehicle.

The response of bioactive titanium surfaces with different structure to UVC-irradiation to eliminate the negative effect on biological properties during aging time

The biological aging of titanium implants affects the service lifetime negatively in clinical applications, and UV irradiation is an applicable method to overcome the biological aging. This study investigated the changes in surface characteristics and biological properties of bioactive titanium surfaces with different structure and topography after UVC-irradiation. The bioactive titanium surfaces were prepared by anodizing (AO), sandblasting and acid-etching (SLA), acid-alkali etching (AA), alkali-heat etching (AH) methods. Samples were stored at dark for 7 weeks to simulate biological aging process and then irradiated by UVC for 2 hours. The results showed that the Ti-OH groups, which are crucial to enhance the biological properties, were easier to be generated on AO surfaces by UVC-irradiation, o owing to a mixture of anatase and rutile on surfaces. UVC-irradiation had the strongest effect on AO surfaces to enhance the bioactivity in bone-like apatite deposition and better biocompatibility in MSCs attachment and proliferation. Therefore, titanium surfaces with a mixture phase of anatase and rutile has the potential to effectively utilize the benefits of UVC-irradiation to overcome the negative effects of the biological aging and have a promising clinical application prospect.

Surface analysis of titanium disks with strontium coating

Peri-implantitis is one of the most common complications after dental implant placement. Researchers have demonstrated that the peri-implantitis tends to occur around dental implants with a rough surface rather than those with a smooth surface. We aimed to investigate the ability of a smooth titanium (Ti) surface containing strontium (Sr) to enhance bone formation as a result of strontium's capacity to support osteoblast proliferation and differentiation. A thin titanium oxide film was formed on an as-mirror polished Ti surface by dipping in 5% sodium hypochlorite (NaOCl) solution for 24 h, followed by thermal treatment at 350°C. The Ti surface was then treated with 1% strontium nitrate (Sr(NO₃)₂) solution and turned in spin coater. The surface morphology, chemical composition, and release of strontium ions (Sr²⁺) were evaluated. The results demonstrate that strontium in the form of Sr²⁺ was successfully doped into the titanium dioxide (TiO₂) film by this simple chemical treatment.

Surface properties and biocompatibility of sandblasted and acid-etched titanium-zirconium binary alloys with various compositions

Ti-Zr alloys have been investigated as an alternative to commercially pure Ti (c.p.Ti). According to our previous studies on the mechanical properties of Ti-Zr alloys, a Zr proportion in the range of 30-50 mol% has competitive advantages over Ti-10Zr and c.p.Ti. The aim of this study is to evaluate the biological response to Ti-Zr alloys with different compositions and their surface characteristics. Alloy surfaces are modified by sandblasting and sulfuric acid etching. As a result, similar surface structures are observed for c.p.Ti, Ti-10Zr, and Ti-30Zr, whereas Ti-50Zr does not form a micro-rough structure by the same treatment process. No significant difference is found in the viability of cells on c.p.Ti, Ti-10Zr, and Ti-30Zr, whereas lower cell attachment levels are detected on Ti-50Zr. In summary, Ti-30Zr reliably forms a micro-rough structure, which provides one evidence for its application in a new dental implant material.

Ultraviolet Treatment of Titanium to Enhance Adhesion and Retention of Oral Mucosa Connective Tissue and Fibroblasts

Peri-implantitis is an unsolved but critical problem with dental implants. It is postulated that creating a seal of gingival soft tissue around the implant neck is key to preventing peri-implantitis. The objective of this study was to determine the effect of UV surface treatment of titanium disks on the adhesion strength and retention time of oral connective tissues as well as on the adherence of mucosal fibroblasts. Titanium disks with a smooth machined surface were prepared and treated with UV light for 15 min. Keratinized mucosal tissue sections (3 × 3 mm) from rat palates were incubated for 24 h on the titanium disks. The adhered tissue sections were then mechanically detached by agitating the culture dishes. The tissue sections remained adherent for significantly longer (15.5 h) on the UV-treated disks than on the untreated control disks (7.5 h). A total of 94% of the tissue sections were adherent for 5 h or longer on the UV-treated disks, whereas only 50% of the sections remained on the control disks for 5 h. The adhesion strength of the tissue sections to the titanium disks, as measured by tensile testing, was six times greater after UV treatment. In the culture studies, mucosal fibroblasts extracted from rat palates were attached to titanium disks by incubating for 24, 48, or 96 h. The number of attached cells was consistently 15–30% greater on the UV-treated disks than on the control disks. The cells were then subjected to mechanical or chemical (trypsinization) detachment. After mechanical detachment, the residual cell rates on the UV-treated surfaces after 24 and 48 h of incubation were 35% and 25% higher, respectively, than those on the control surfaces. The remaining rate after chemical detachment was 74% on the control surface and 88% on the UV-treated surface for the cells cultured for 48 h. These trends were also confirmed in mouse embryonic fibroblasts, with an intense expression of vinculin, a focal adhesion protein, on the UV-treated disks even after detachment. The UV-treated titanium was superhydrophilic, whereas the control titanium was hydrophobic. X-ray photoelectron spectroscopy (XPS) chemical analysis revealed that the amount of carbon at the surface was significantly reduced after UV treatment, while the amount of TiOH molecules was increased. These ex vivo and in vitro results indicate that the UV treatment of titanium increases the adhesion and retention of oral mucosa connective tissue as a result of increased resistance of constituent fibroblasts against exogenous detachment, both mechanically and chemically, as well as UV-induced physicochemical changes of the titanium surface.

Aesthetic Outcomes of Early Occlusal Loaded SLA Dental Implants with Hydroxyl Ion Modified Surface-A 12 Months Prospective Study

Background: Many efforts have been made recently to arrange a newer, more hydrophilic and more osteoconductive implant surface. One of the possible options in this matter is modification with hydroxyl ion. Materials and Methods: Forty implants with the diameters 3.5 and 4.0 mm were inserted as a single missing tooth restoration protocol in the frontal aspect of the maxilla. All implants were loaded early in a 4 week period. Prior to and during the surgery, the following indices were considered: height of keratinized tissue, the thickness of soft tissue, and the initial level of bone tissue. After 12 months, the implant and the tissues in its direct vicinity were evaluated once more with the following indices: marginal bone loss (MBL), height of keratinized tissue (HKT), probing pocket depth (PPD), pink and white aesthetics scores (PES, WES), as well as pain sensations combined with the procedure (VAS). All results were related to the diameter of the implant and thickness of periodontal biotype. Results: High aesthetic outcomes were reported regardless of soft tissue thickness and implant diameter. The VAS score was higher for the 4.0 implant group, and the thickness of soft tissue had no influence on VAS. In case of implantation in thin or soft tissue, higher MBL levels were reported (0.26 mm), while in case of a thick phenotype, MBL was 0.06 mm. Conclusions: Hydrophilic surface implants can be used for a protocol of early functional occlusal loading. The initial thickness of soft tissue does not influence aesthetic outcomes and does not raise pain perception, although it may elevate crestal bone resorption.

Dual-Functional Nano-Functionalized Titanium Scaffolds to Inhibit Bacterial Growth and Enhance Osteointegration

Implantable biomaterials play a key role for the success of orthopedic surgery procedures. However, infections remain one of the most damaging post-operative complications that lead to the implant failure. Recently, several approaches have been proposed to avoid or manage implant-associated infections. Among these, an appropriate surface functionalization to confer intrinsic antibacterial properties preserving the osteo-integration ability represents an appealing strategy for the development of innovative implant materials. Titanium and its alloys are the most used materials for manufacturing of both articular and bone skull prostheses as well as dental implants. However, to date there is still a significant clinical need to improve their bioactivity, osseointegration and antibacterial activity. In this study, titanium biomimetic scaffolds are prepared by nano-functionalization with TiO₂ (Ti_TiO₂) and γFe₂O₃ (Ti_γFe₂O₃). Both cytocompatibility and antibacterial activity have been evaluated. Data show that both nano-functionalized scaffolds exhibit a good antibacterial activity towards Staphylococcus aureus, reducing colony number to 99.4% (Ti_TiO₂) and 99.9% (Ti_γFe₂O₃), respectively. In addition, an increase of both human adipose-derived mesenchymal stem cells (hADSCs) cell proliferation (up to 4.3-fold for Ti_TiO₂ and 3.7-fold for Ti_γFe₂O₃) and differentiation has been observed. These data suggest that these nano-functionalized titanium substrates represent promising prototypes for new antimicrobial and osteoconductive biomaterials to be used in the orthopedic field to reconstruct significant bone defect.

Osteoblast Attachment Compromised by High and Low Temperature of Titanium and Its Restoration by UV Photofunctionalization

Titanium implants undergo temperature fluctuations during manufacturing, transport, and storage. However, it is unknown how this affects their bioactivity. Herein, we explored how storage (six months, dark conditions) and temperature fluctuations (5-50 °C) affected the bioactivity of titanium implants. Stored and fresh acid-etched titanium disks were exposed to different temperatures for 30 min under wet or dry conditions, and their hydrophilicity/hydrophobicity and bioactivity (using osteoblasts derived from rat bone marrow) were evaluated. Ultraviolet (UV) treatment was evaluated as a method of restoring the bioactivity. The fresh samples were superhydrophilic after holding at 5 or 25 °C under wet or dry conditions, and hydrophilic after holding at 50 °C. In contrast, all the stored samples were hydrophobic. For both fresh and stored samples, exposure to 5 or 50 °C reduced osteoblast attachment compared to holding at 25 °C under both wet and dry conditions. Regression analysis indicated that holding at 31 °C would maximize cell attachment (p < 0.05). After UV treatment, cell attachment was the same or better than that before temperature fluctuations. Overall, titanium surfaces may have lower bioactivity when the temperature fluctuates by ≥20 °C (particularly toward lower temperatures), independent of the hydrophilicity/hydrophobicity. UV treatment was effective in restoring the temperature-compromised bioactivity.

Surface treatment of 3D printed porous Ti6Al4V implants by ultraviolet photofunctionalization for improved osseointegration

Three-dimensional (3D)-printed porous Ti6Al4V implants play an important role in the reconstruction of bone defects. However, its osseointegration capacity needs to be further improved, and related methods are inadequate, especially lacking customized surface treatment technology. Consequently, we aimed to design an omnidirectional radiator based on ultraviolet (UV) photofunctionalization for the surface treatment of 3D-printed porous Ti6Al4V implants, and studied its osseointegration promotion effects in vitro and in vivo, while elucidating related mechanisms. Following UV treatment, the porous Ti6Al4V scaffolds exhibited significantly improved hydrophilicity, cytocompatibility, and alkaline phosphatase activity, while preserving their original mechanical properties. The increased osteointegration strength was further proven using a rabbit condyle defect model in vivo, in which UV treatment exhibited a high efficiency in the osteointegration enhancement of porous Ti6Al4V scaffolds by increasing bone ingrowth (BI), the bone-implant contact ratio (BICR), and the mineralized/osteoid bone ratio. The advantages of UV treatment for 3D-printed porous Ti6Al4V implants using the omnidirectional radiator in the study were as follows: 1) it can significantly improve the osseointegration capacity of porous titanium implants despite the blocking out of UV rays by the porous structure; 2) it can evenly treat the surface of porous implants while preserving their original topography or other morphological features; and 3) it is an easy-to-operate low-cost process, making it worthy of wide clinical application.

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An omnidirectional radiator based on ultraviolet photofunctionalization was invented..

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The omnidirectional radiator can evenly treat the surface of the porous implants..

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The present method can enhance osteoinetegration of porous Ti6Al4V implants in a convenient way with a low cost.

Analysis of Surface Roughness and Three-dimensional Scanning Topography of Zirconia Implants before and after Photofunctionalization by Atomic Force Microscopy: An In Vitro Study

Aim:

To analyze surface roughness and three-dimensional (3D) scanning topography parameters of zirconia implants before and after photofunctionalization by atomic force microscopy (AFM).

Materials and Methods:

Ten commercially available zirconia implants five each in the study and control group were taken. The study group was subjected to ultraviolet (UV) radiation for 48 h using the shorter wavelength of 254 nm. After washing all the implants with 70% alcohol and drying, 3D surface topography and roughness parameters were analyzed using CSC 17 probe AFM at three different magnifications 25 μm, 50 μm, and 80 μm, respectively.

Results:

The surface topography and calculated mean amplitude, spatial, and hybrid parameters of the study group were higher than the control group (P < 0.05) in all three magnifications. Up to scale depth and peak value for the study and control group were (−0.4–0.4: −2-1) (−0.75 to 0.6:−1–1.3) (−0.75-−0.5: −1.5-1.3) for the study and control group at 25, 50, and 80 μm magnification, respectively. This indicates that photofunctionalization increased surface roughness of Zirconia implants to desirable extent.

Conclusion:

There is a definite difference in the quantitative topographic characteristics with zirconia implants being microroughned after photofunctionalization (UV treatment).

Strontium-incorporated titanium implant surfaces treated by hydrothermal treatment enhance rapid osseointegration in diabetes: A preclinical vivo experimental study

OBJECTIVES

The aim of the current study was to explore effects of strontium-incorporated titanium implant surfaces by hydrothermal treatment on osseointegration in diabetic rats.

MATERIALS AND METHODS

The surface characteristics of SLA and SLA-Sr surfaces were detected by related instruments. Thirty-six male Sprague-Dawley rats were induced into diabetes, and thirty-six rats were normal. SLA and SLA-Sr implants were, respectively, inserted into bilateral tibial metaphysis of each rat. Percentage of bone-to-implant contact (BIC%) and percentage of bone area (BA%) were analyzed at 4 and 8 weeks after implantation. Immunohistochemistry of osteoprotegerin (OPG) and Wnt5a were conducted at 1 and 4 weeks. Gene expression levels of inflammatory cytokines and related signaling molecules in peri-implant bone tissue were detected at 3 and 7 days.

RESULTS

Strontium was uniformly distributed on SLA-Sr surfaces, and it was released in an effective concentration range. SLA-Sr surfaces showed significantly higher BIC% in diabetic rats at 4 (p < .05) and 8 weeks (p < .05). Besides, it displayed higher BIC% at 4 weeks (p < .05) in normal rats. Also, SLA-Sr surfaces upregulated expression of OPG at 4 weeks (p < .05) in diabetic rats. What's more, SLA-Sr surfaces downregulated inflammation (TNF-α, IL-1β, and IL-6; p < .01) in diabetic rats at 3 days. In addition, expression of Wnt5a and ROR2 was upregulated (p < .05) at 7 days after implantation under diabetes.

CONCLUSION

It is suggested that strontium-incorporated titanium implant surfaces by hydrothermal treatment could enhance implant osseointegration as compared with SLA implant surfaces in diabetic rats.

Influence of surface modification of titanium implants on improving osseointegration: An in vitro study

STATEMENT OF PROBLEM

The effect of aging and the surface treatment of implants on osseointegration needs to be evaluated.

PURPOSE

The purpose of this in vitro study was to evaluate the effects of aging and the surface treatment of titanium with ultraviolet (UV) radiation and fibroblast growth factor (FGF) on hydrophilicity and cell growth and thus on osseointegration.

MATERIAL AND METHODS

A total of 28 specimens were divided into 2 groups to measure hydrophilicity (n=14) and cell growth (n=14). Each group was further divided into 4 groups according to surface modification. These include the control group (CG) (nascent specimens), aged group (AG) (nascent specimens aged for 4 weeks), photofunctionalized group (PG) (aged specimens UV-A treated), and mimed group (MG) (aged specimens UV-A and FGF2 treated). The PG and MG specimens were treated with UV-A light for 40 minutes. The biomimetic surface modification was performed for MG. Hydrophilicity was measured by using the contact angle in relation to the surface of titanium disks with the help of a drop shape analyzing device (KRUSS), and cell growth was measured by calculating the number of stem cells per cm² with the help of a scanning electron microscope (SEM). The data obtained were subjected to statistical analysis with a statistical software program (α=.05).

RESULTS

The lowest contact angle values were found in PG (13.52 ±0.90 degrees) and the highest in AG (70.54 ±1.72 degrees). The highest number of cells per cm² (2880 ±99.33) were found for MG, and the lowest number of cells per cm² (760 ±9.17) for AG.

CONCLUSIONS

Aging decreased the hydrophilicity and cell adhesion, migration, and growth on the titanium surface. UV treatment improved the hydrophilicity, cell adhesion, migration, and growth for both CG and AG. FGF2 treatment increased the cell adhesion, migration, and growth for CG, AG, and PG.

Research to Clinics: Clinical Translation Considerations for Anodized Nano-Engineered Titanium Implants

Titania nanotubes (TNTs) fabricated on titanium orthopedic and dental implants have shown significant potential in "proof of concept" in vitro, ex vivo, and short-term in vivo studies. However, most studies do not focus on a clear direction for future research towards clinical translation, and there exists a knowledge gap in identifying key research challenges that must be addressed to progress to the clinical setting. This review focuses on such challenges with respect to anodized titanium implants modified with TNTs, including optimized fabrication on clinically utilized microrough surfaces, clinically relevant bioactivity assessments, and controlled/tailored local release of therapeutics. Further, long-term in vivo investigations in compromised animal models under loading conditions are needed. We also discuss and detail challenges and progress related to the mechanical stability of TNT-based implants, corrosion resistance/electrochemical stability, optimized cleaning/sterilization, packaging/aging, and nanotoxicity concerns. This extensive, clinical translation focused review of TNTs modified Ti implants aims to foster improved understanding of key research gaps and advances, informing future research in this domain.