Hydrophilic surface of Ti6Al4V-ELI alloy improves the early bone apposition of sheep tibia

Full-arch prostheses supported by implants with different macrostructures: A multicenter randomized controlled trial

OBJECTIVES

This study evaluates the clinical performance of implants with hydrophilic surface and two different macrostructures: cylindrical with perforating triangular threads (CT) and cylindrical-tapered with the association of square and condensing and perforating triangular threads (TST).

MATERIALS AND METHODS

This was a multicenter split-mouth, simple-blinded, randomized, and controlled trial. Thirty patients with edentulous mandible received two CT and two TST implants. Primary stability was determined by insertion torque and resonance frequency analysis (RFA). Implants were loaded with full fixed-arch prostheses within 24 h after insertion. Clinical parameters (visible plaque index, marginal bleeding index; bleeding on probing; probing depth; and clinical attachment level) and the RFA were assessed at 2, 6, 12, and 24 months after implant loading. Marginal bone level changes were measured by comparison of standardized radiographs taken on the day of implant placement and 6, 12, and 24 months thereafter.

RESULTS

Twenty-eight patients completed the 2-year follow-up. The survival rates were 99.16% for CT implants and 100% for TST implants. One CT implant was lost until the 2 months follow-up. No significant differences were found between the two implant types for marginal bone level changes (CT 0.34 [0.24; 0.55 mm]; 0.33 [0.18; 0.55 mm]; 0.41 [0.12; 0.7 mm] vs TST 0.36 [0.14; 0.74 mm]; 0.33 [0.23; 0.63 mm]; 0.30 [0.20; 0.64 mm] at 6, 12, and 24 months, respectively) and other clinical parameters.

CONCLUSION

The macrostructure of the implants had no influence on survival rate, primary and secondary stability, marginal bone level changes, and peri-implant clinical parameters outcomes. Both implants can be predictably used for immediate loading of full-arch mandibular prostheses.

Comparative clinical evaluation of the stability of implants using double acid etching treatment with and without the addition of fluoride solution: A randomized clinical trial

Background

Osseointegration depends on primary stability, and further, implant surface modifications may improve secondary stability. This randomized clinical trial evaluates whether adding a fluoride solution enhances the implant stability.

Materials and Methods

Stability of dental implants with two different types of surface treatments was compared utilizing resonance frequency analysis (RFA). Twelve patients were recruited: eight females and four males with an average age of 58.3 years and they received either double acid etched implants (control: Porus Implant, Sistema Conexão) and double acid etched implants containing fluoride on their surfaces (test: Porus Nano Implant, Sistema Conexão). Each patient received one implant from the test category and another implant from the control category, resulting in 24 implants in this study. RFA, utilizing Osstell was used to assess the implant stability, immediately after the placement of implant and 15, 30 and 45 days post-implant placement.

Results

At the initial time, there was no difference between the test and control groups regarding the ISQ. However, after 15, 30, and 45 days, ISQ values for the test group were significantly higher than the control group. When using implants without fluoride addition, it was observed that after 15 days, the ISQ values were lower than those found at the initial time, but after 30 days, values matched the initial. Concerning the test group results, the ISQ values from T0 (immediately after implant placement) to T3 (45 days after implant placement) always increased from every period of evaluation.

Conclusions

It was concluded that double acid etched implants with surfaces containing fluoride solution increases the implant stability quotient, compared to implants with fluoride-free double acid etched surfaces.

Dental implants in large animal models with experimental systemic diseases: A systematic review

This systematic review aims to identify and discuss the most used methodologies in pre-clinical studies for the evaluation of the implementation of dental implants in systemically compromised pigs and sheep. This study provides support and guidance for future research, as well as for the prevention of unnecessary animal wastage and sacrifice. Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) was used as a guideline; electronic searches were performed in PubMed, Scopus, Scielo, Web of Science, Embase, Science Direct, Brazilian Bibliography of Dentistry, Latin American and Caribbean Literature in Health Sciences, Directory of Open Access Journals, Database of Abstracts of Reviews of Effects, and gray literature until January 2022 (PROSPERO/CRD42021270119). Sixty-eight articles were chosen from the 2439 results. Most studies were conducted in pigs, mainly the Göttinger and Domesticus breeds. Healthy animals with implants installed in the jaws were predominant among the pig studies. Of the studies evaluating the effect of systemic diseases on osseointegration, 42% were performed in osteoporotic sheep, 32% in diabetic sheep, and 26% in diabetic pigs. Osteoporosis was primarily induced by bilateral ovariectomy and mainly assessed by X-ray densitometry. Diabetes was induced predominantly by intravenous streptozotocin and was confirmed by blood glucose analysis. Histological and histomorphometric analyses were the most frequently employed in the evaluation of osseointegration. The animal models presented unique methodologies for each species in the studies that evaluated dental implants in the context of systemic diseases. Understanding the most commonly used techniques will help methodological choices and the performance of future studies in implantology.

In vivo osseointegration evaluation of implants coated with nanostructured hydroxyapatite in low density bone

OBJECTIVE

This in vivo study, aimed to biomechanically, histomorphometrically and histologically evaluate an implant surface coated with nanostructured hydroxyapatite using the wet chemical process (biomimetic deposition of calcium phosphate coating) when compared to a dual acid-etching surface.

MATERIAL AND METHODS

Ten sheep (2-4 years old) received 20 implants, 10 with nanostructured hydroxyapatite coating (HAnano), and 10 with dual acid-etching surface (DAA). The surfaces were characterized with scanning electron microscopy and energy dispersive spectroscopy; insertion torque values and resonance frequency analysis were measured to evaluate the primary stability of the implants. Bone-implant contact (BIC) and bone area fraction occupancy (BAFo) were evaluated 14 and 28 days after implant installation.

RESULTS

The HAnano and DAA groups showed no significant difference in insertion torque and resonance frequency analysis. The BIC and BAFo values increased significantly (p<0.05) over the experimental periods in both groups. This event was also observed in BIC value of HAnano group. The HAnano surface showed superior results compared to DAA after 28 days (BAFo, p = 0.007; BIC, p = 0.01).

CONCLUSION

The results suggest that the HAnano surface favors bone formation when compared to the DAA surface after 28 days in low-density bone in sheep.

Evolution of implants and advancements for osseointegration: A narrative review

Since ancient times, reduction and internal fixation has been applied to restore skeletal integrity. Despite advances in the understanding of fracture healing, the risk of complication such as implant loosening or implant-related infection still depicts a challenging complication. Nowadays, a great deal of research is devoted to unreveal the impact of implant surface modifications on osteogenic processes to enhance bone consolidation and osseointegration. This narrative review is aimed to (1) show the evolution and already achieved milestones of implant optimization, and (2) to outline the key factors that contribute to an enhanced osseointegration. Different physical and chemical roughening techniques are currently applied in various studies. Surface patterning on the nanoscale has been found to be an essential factor for the biological response, achievable by e.g. anodisation or laser texturing. Besides surface roughening, also different coating methods are vastly investigated. Next to metal or inorganic compounds as coating material, a variety of biomolecules is currently studied for their osteosupportive capacities. Osseointegration can be improved by surface modification on the micro and nanoscale. Bioactive agents can further improve the osseointegration potential. Used agents at the moment are e.g. inorganic compounds, growth factors (BMPs and non-BMPs) and antiresorptive drugs. The advancement in research on new implant generations therefore aims at actively supporting osseointegration processing.

In Vitro and In Vivo Studies of Hydrogenated Titanium Dioxide Nanotubes with Superhydrophilic Surfaces during Early Osseointegration

Titanium-based implants are often utilized in oral implantology and craniofacial reconstructions. However, the biological inertness of machined titanium commonly results in unsatisfactory osseointegration. To improve the osseointegration properties, we modified the titanium implants with nanotubular/superhydrophilic surfaces through anodic oxidation and thermal hydrogenation and evaluated the effects of the machined surfaces (M), nanotubular surfaces (Nano), and hydrogenated nanotubes (H-Nano) on osteogenesis and osseointegration in vitro and in vivo. After incubation of mouse bone marrow mesenchymal stem cells on the samples, we observed improved cell adhesion, alkaline phosphatase activity, osteogenesis-related gene expression, and extracellular matrix mineralization in the H-Nano group compared to the other groups. Subsequent in vivo studies indicated that H-Nano implants promoted rapid new bone regeneration and osseointegration at 4 weeks, which may be attributed to the active osteoblasts adhering to the nanotubular/superhydrophilic surfaces. Additionally, the Nano group displayed enhanced osteogenesis in vitro and in vivo at later stages, especially at 8 weeks. Therefore, we report that hydrogenated superhydrophilic nanotubes can significantly accelerate osteogenesis and osseointegration at an early stage, revealing the considerable potential of this implant modification for clinical applications.

Preventing Peri-implantitis: The Quest for a Next Generation of Titanium Dental Implants

Titanium and its alloys are frequently the biomaterial of choice for dental implant applications. Although titanium dental implants have been utilized for decades, there are yet unresolved issues pertaining to implant failure. Dental implant failure can arise either through wear and fatigue of the implant itself or peri-implant disease and subsequent host inflammation. In the present report, we provide a comprehensive review of titanium and its alloys in the context of dental implant material, and how surface properties influence the rate of bacterial colonization and peri-implant disease. Details are provided on the various periodontal pathogens implicated in peri-implantitis, their adhesive behavior, and how this relationship is governed by the implant surface properties. Issues of osteointegration and immunomodulation are also discussed in relation to titanium dental implants. Some impediments in the commercial translation for a novel titanium-based dental implant from "bench to bedside" are discussed. Numerous in vitro studies on novel materials, processing techniques, and methodologies performed on dental implants have been highlighted. The present report review that comprehensively compares the in vitro, in vivo, and clinical studies of titanium and its alloys for dental implants.

Osseointegration of a New, Ultrahydrophilic and Nanostructured Dental Implant Surface: A Comparative In Vivo Study

This study compared the osseointegration of acid-etched, ultrahydrophilic, micro- and nanostructured implant surfaces (ANU) with non-ultra-hydrophilic, microstructured (SA) and non-ultrahydrophilic, micro- and nanostructured implant surfaces (AN) in vivo. Fifty-four implants (n = 18 per group) were bilaterally inserted into the proximal tibia of New Zealand rabbits (n = 27). After 1, 2, and 4 weeks, bone-implant contact (BIC, %) in the cortical (cBIC) and spongious bone (sBIC), bone chamber ingrowth (BChI, %), and the supra-crestal, subperiosteal amount of newly formed bone, called percentage of linear bone fill (PLF, %), were analyzed. After one week, cBIC was significantly higher for AN and ANU when compared to SA (p = 0.01 and p = 0.005). PLF was significantly increased for ANU when compared to AN and SA (p = 0.022 and p = 0.025). After 2 weeks, cBIC was significantly higher in SA when compared to AN (p = 0.039) and after 4 weeks, no significant differences in any of the measured parameters were found anymore. Ultrahydrophilic implants initially improved osseointegration when compared to their non-ultrahydrophilic counterparts. In accordance, ultrahydrophilic implants might be appropriate in cases with a necessity for an accelerated and improved osseointegration, such as in critical size alveolar defects or an affected bone turnover.

Surface Characteristics and In-Vitro Studies of TiO2 Coatings by Plasma Electrolytic Oxidation in Potassium-Phosphate Electrolyte

Plasma electrolytic oxidation (PEO) was used to produce titanium oxide (TiO2) coatings on Ti surface in potassium - phosphate electrolyte. The morphology, wettability, phase, and chemical compositions were studied as a function of processing parameters. The bioactivity of the coating was assessed by the ability to form biomimetic apatite in-vitro using cell culture medium. In-vitro studies using human mesenchymal stem cells were also conducted to evaluate cells' proliferation and viability of the treated Ti. The results revealed that the produced TiO2 coatings comprised pore features with the pore size increasing with applied current density and treatment duration due to high energy discharge channels at higher potential. The PEO treated Ti exhibited superhydrophilic characteristics with a contact angle <1°. The findings indicated that the large actual surface area produced by the PEO treatment and the presence of negatively charge P O 4 3 - are the key factors for the superhydrophilic behavior. The in-vitro studies revealed that the PEO treated groups had higher amount of biomimetic apatite formation compared to the as-polished Ti. The PEO treatment significantly enhanced the cells' adhesion and growth after 24 and 72 hrs compared to the untreated Ti. A significant difference in the bioactivity was not observed between anatase and rutile.

Implant-bone-interface: Reviewing the impact of titanium surface modifications on osteogenic processes in vitro and in vivo

Titanium is commonly and successfully used in dental and orthopedic implants. However, patients still have to face the risk of implant failure due to various reasons, such as implant loosening or infection. The risk of implant loosening can be countered by optimizing the osteointegration capacity of implant materials. Implant surface modifications for structuring, roughening and biological activation in favor for osteogenic differentiation have been vastly studied. A key factor for a successful stable long-term integration is the initial cellular response to the implant material. Hence, cell-material interactions, which are dependent on the surface parameters, need to be considered in the implant design. Therefore, this review starts with an introduction to the basics of cell-material interactions as well as common surface modification techniques. Afterwards, recent research on the impact of osteogenic processes in vitro and vivo provoked by various surface modifications is reviewed and discussed, in order to give an update on currently applied and developing implant modification techniques for enhancing osteointegration.

Comparative Study of Physicochemical Properties and Biocompatibility (L929 and MG63 Cells) of TiN Coatings Obtained by Plasma Nitriding and Thin Film Deposition

Ti6Al4V is one of the most lightweight, mechanically resistant, and appropriate for biologically induced corrosion alloys. However, surface properties often must be tuned for fitting into biomedical applications, and therefore, surface modification is of paramount importance to carry on its use. This work compares the interaction between two different cell lines (L929 fibroblasts and osteoblast-like MG63) and medical grade Ti6Al4V after surface modification by plasma nitriding or thin film deposition. We studied the adhesion of these two cell lines, exploring which trends are consistent for cell behavior, correlating with osseointegration and in vivo conditions. Modified surfaces were analyzed through several physicochemical characterization techniques. Plasma nitriding led to a more pronounced increase in surface roughness, a thicker aluminum-free layer, made up of diverse titanium nitride phases, whereas thin film deposition resulted in a single-phase pure titanium nitride layer that leveled the ridged topography. The selective adhesion of osteoblast-like cells over fibroblasts was observed in nitrided samples but not in thin film deposited films, indicating that the competitive cellular behavior is more pronounced in plasma nitrided surfaces. The obtained coatings presented an appropriate performance for its use in biomedical-aimed applications, including the possibility of a higher success rate in osseointegration of implants.

Antibiotic-loaded amphora-shaped pores on a titanium implant surface enhance osteointegration and prevent infections

Artificial prostheses for joint replacement are indispensable in orthopedic surgery. Unfortunately, the implanted surface is attractive to not only host cells but also bacteria. To enable better osteointegration, a mechanically stable porous structure was created on a titanium surface using laser treatment and metallic silver particles were embedded in a hydrophilic titanium oxide layer on top. The laser structuring resulted in unique amphora-shaped pores. Due to their hydrophilic surface conditions and capillary forces, the pores can be loaded preoperative with the antibiotic of choice/need, such as gentamicin. Cytotoxicity and differentiation assays with primary human osteoblast-like cells revealed no negative effect of the surface modification with or without gentamicin loading. An in vivo biocompatibility study showed significantly enhanced osteointegration as measured by push-out testing and histomorphometry 56 days after the implantation of the K-wires into rat femora. Using a S. aureus infection model, the porous, silver-coated K-wires slightly reduced the signs of bone destruction, while the wires were still colonized after 28 days. Loading the amphora-shaped pores with gentamicin significantly reduced the histopathological signs of bone destruction and no bacteria were detected on the wires. Taken together, this novel surface modification can be applied to new or established orthopedic implants. It enables preoperative loading with the antibiotic of choice/need without further equipment or post-coating, and supports osteointegration without a negative effect of the released dug, such as gentamicin.

Osseodensification enables bone healing chambers with improved low-density bone site primary stability: an in vivo study

Primary implant stability is a prerequisite for successful implant osseointegration. The osseodensification technique (OD) is a non-subtractive drilling technique that preserves the bone tissue, increases osteotomy wall density, and improves the primary stability. This study aimed to investigate the hypothesis that OD, through a wider osteotomy, produces healing chambers (HCs) at the implant-bone interface without impacting low-density bone primary stability. Twenty implants (3.5 × 10 mm) with a nanohydroxyapatite (nHA) surface were inserted in the ilium of ten sheep. Implant beds were prepared as follows: (i) 2.7-mm-wide using subtractive conventional drilling (SCD) technique (n = 10); (ii) 3.8-mm-wide using an OD bur system (n = 10). The sheep were randomized to two groups, with samples collected at either 14-(n = 5) or 28-days (n = 5) post-surgery and processed for histological and histomorphometric evaluation of bone-implant contact (BIC) and bone area fraction occupancy (BAFO). No significant group differences were found with respect to final insertion torque and implant stability quotient (p > 0.050). BIC values were higher for SCD after 14 and 28 days (p < 0.050); however, BAFO values were similar (p > 0.050). It was possible to conclude that the OD technique allowed a wider implant bed preparation without prejudice on primary stability and bone remodeling.

Wettability and in-vitro study of titanium surface profiling prepared by electrolytic plasma processing

Electrolytic plasma processing (EPP) was used to create hydrophilic surface profiles on titanium. The wettability, surface morphology characteristics and chemical composition of the treated samples were studied as a function of EPP processing parameters. The EPP profiled surfaces comprised of a characteristic "hills and valleys" morphology because of continuous surface melting and freezing cycles. A bimodal surface profile was produced with 2-3 μm height hills and valleys with nano-roughness (≤200 nm). The produced profile resulted in a significant contact angle decrease (from 38.7° to 5.4°). Ratios of actual surface area to projection area (r) and fraction of solid surface remaining dry (φ) were obtained from profilometry. The surface characteristics and large r values produced by EPP were able to induce hemi-wicking. Hence, EPP produced superhydrophilic surfaces on Ti. The bioactivity of EPP treated Ti was evaluated using cell free and MC3T3 cells in-vitro studies. The treated Ti surface significantly increased the bioactivity and formed stoichiometric hydroxyapatite after immersion in a bone cell culture medium for 21 days. Cells' attachment and proliferation studies indicated that EPP treated surface significantly enhances the cells' adhesion and growth after 24 and 48 h compared to the untreated surface. The results show that Ti surface profiling by EPP constitutes a promising method to potentially improve bone implant bonding.

Laser surface texturing of zirconia-based ceramics for dental applications: A review

Laser surface texturing is widely explored for modifying the surface topography of various materials and thereby tuning their optical, tribological, biological, and other surface properties. In dentistry, improved osseointegration has been observed with laser textured titanium dental implants in clinical trials. Due to several limitations of titanium materials, dental implants made of zirconia-based ceramics are now considered as one of the best alternatives. Laser surface texturing of zirconia dental implants is therefore attracting increasing attention. However, due to the brittle nature of zirconia, as well as the metastable tetragonal ZrO₂ phase, laser texturing in the case of zirconia is more challenging than in the case of titanium. Understanding these challenges requires different fields of expertise, including laser engineering, materials science, and dentistry. Even though much progress was made within each field of expertise, a comprehensive analysis of all the related factors is still missing. This review paper provides thus an overview of the common challenges and current status on the use of lasers for surface texturing of zirconia-based ceramics for dental applications, including texturing of zirconia implants for improving osseointegration, texturing of zirconia abutments for reducing peri-implant inflammation, and texturing of zirconia restorations for improving restoration retention by bonding.

Hydrophilic titanium surface modulates early stages of osseointegration in osteoporosis

OBJECTIVE

Using a mouse osteoporotic model, this study aimed to determine the influence of hydrophilic titanium surfaces on gene expression and bone formation during the osseointegration process.

BACKGROUND

Based on the previous evidence, it is plausible to assume that osteoporotic bone has a different potential of bone healing. Therefore, implant surface modification study that aims at enhancing bone formation to further improve short- and long-term clinical outcomes in osteoporosis is necessary.

MATERIAL AND METHODS

Fifty female, 3-month-old mice were included in this study. Osteoporosis was induced by ovariectomy (OVX, test group) in 25 mice. The further 25 mice had ovaries exposed but not removed (SHAM, control group). Seven weeks following the ovariectomy procedures, one customized implant (0.7 × 8 mm) of each surface was placed in each femur for both groups. Implants had either a hydrophobic surface (SAE) or a hydrophilic treatment surface (SAE-HD). Calcium (Ca) and phosphorus (P) content was measured by energy-dispersive X-ray spectroscopy (EDS) after 7 days. The femurs were analyzed for bone-to-implant contact (BIC) and bone volume fraction (BV) by nano-computed tomography (nano-CT) after 14 and 28 days. Same specimens were further submitted to histological analysis. Additionally, after 3 and 7 days, implants were removed and cells were collected around the implant to access gene expression profile of key osteogenic (Runx2, Alp, Sp7, Bsp, Sost, Ocn) and inflammatory genes (IL-1β, IL-10, Tnf-α, and Nos2) by qRT-PCR assay. Statistical analysis was performed by ANOVA and paired t test with significance at P < .05.

RESULTS

The amount of Ca and P deposited on the surface due to the mineralization process was higher for SAE-HD compared to SAE on the intra-group analysis. Nano-CT and histology revealed more BV and BIC for SAE-HD in SHAM and OVX groups compared to SAE. Analysis in OVX group showed that most genes (ie, ALP, Runx2) involved in the bone morphogenetic protein (BMP) signaling were significantly activated in the hydrophilic treatment.

CONCLUSION

Both surfaces were able to modulate bone responses toward osteoblast differentiation. SAE-HD presented a faster response in terms of bone formation and osteogenic gene expression compared to SAE. Hydrophilic surface in situations of osteoporosis seems to provide additional benefits in the early stages of osseointegration.

The Influence of Nanostructured Hydroxyapatite Surface in the Early Stages of Osseointegration: A Multiparameter Animal Study in Low-Density Bone

Background and Objective

The success rates of dental implants in low-density bone have been reported as a challenge, especially for early or immediate loading in the maxilla posterior area. Nanoscale architecture affects the roughness, surface area, surface energy of the implant and can enhance osseointegration. This study aimed to evaluate the implant-surface topography and biomechanical, histomorphometric, and histological bone responses to a new nanostructured hydroxyapatite surface placed in the iliac crest of sheep.

Methods

Ten female sheep (2–4 years) received 30 implants (n=10/group): HAnano^® coated (Epikut Plus^®, S.I.N. Implant System, Sao Paulo, SP, Brazil), SLActive (BLX^®, Straumann, Basel, Switzerland), and TiUnite (NobelActive^®, Nobel Biocare, Göteborg, Sweden) surfaces. Scanning electron microscopy with energy-dispersive spectroscopy evaluated the implant surface topography, the insertion torque value, and resonance frequency analysis evaluated the primary stability, bone-implant contact, and bone-area fraction occupancy were evaluated after 14 and 28 days after implant placement.

Results

The surface morphology was considerably comparable between the implant groups’; however, the TiUnite^® group presented a remarkable different surface. The SLActive^® and TiUnite^® groups presented an insertion torque average of 74 (±8.9) N/cm that was similar to that of HAnano^® 72 (±8.3) N/cm (p >0.05). The resonance frequency evaluated with Osstell^®/SmartPeg^® or Penguin^®/MulTipeg^® showed similar results when assessing implants from the same group. BIC and BAFO significantly increased (p<0.05) throughout the experimental periods to all groups, but BIC and BAFO values were similar among the implants at the same time point. After 4 weeks, bone-implant contact was higher than 80% of the total length analyzed. New bone occupies around 60% of analyzed area around the implants.

Conclusion

HAnano^® coated surface promoted comparable osseointegration as SLActive and TiUnite in the sheep model. The three tested surfaces showed comparable osseointegration at the early stages of low-density bone repair in the sheep model.

Photo-activated implants: a triple-blinded, split-mouth, randomized controlled clinical trial on the resistance to removal torque at various healing intervals

OBJECTIVES

Hydrophilic implant surfaces promote faster osseointegration of dental implants with a higher bone-implant contact (BIC) rate. Animal and in vitro studies proved that ultraviolet (UV) irradiation of titanium implants regains hydrophilicity. Clinical impact is still unclear. The objective of this RCT was to assess the removal torque (RT) required to unfix a surface-treated implant (test group) versus the original surface implant (control group) performed at various points in time. The null hypothesis stated that test and control implants will show the same deliberation force at specific time points.

MATERIAL AND METHODS

One hundred eighty partially edentulous patients were randomly assigned to six groups. In single-stage surgery, each patient received one test and one control implant. In total, 180 test and 180 control implants were placed epicrestally. Test implants received a surface treatment with UV irradiation prior to insertion, in order to reduce carbon and enhance hydrophilicity and thus wettability. Maximum RT values for test and control implants were recorded with a torque measuring device at implant placement (T1), after 1 (group 1), 2 (group 2), 3 (group 3), 4 (group 4), 6 (group 5) (T2), and 8 weeks (group 6) of healing. Subsequently, implants were returned to their original position for the continuation of the healing process.

RESULTS

No implant was lost. Age, gender, smoking, implant position, and bone quality could be excluded as confounding factors because of the lack of statistical significance. At T2, RT values were higher for test implants compared with those for control implants, being statistically significant in groups 2, 3, 4, and 6 (p < 0.05).

CONCLUSIONS

Our data support rejection of the null hypothesis.

CLINICAL RELEVANCE

Photo-activation of the surface of titanium implants leads to higher resistance to RT forces compared with that of non-treated implants, indicating improved healing and implant stability especially in the early healing phase.

Bacteria Death and Osteoblast Metabolic Activity Correlated to Hydrothermally Synthesised TiO₂ Surface Properties

Orthopaedic surgery comes with an inherent risk of bacterial infection, prolonged antibiotic therapy and revision surgery. Recent research has focused on nanostructured surfaces to improve the bactericidal and osseointegrational properties of implants. However, an understanding of the mechanical properties of bactericidal materials is lacking. In this work, the surface properties of hydrothermal TiO₂ nanostructured surfaces are investigated for their effect on bactericidal efficiency and cellular metabolic activity of human osteoblast cells. TiO₂ nanostructures, approximately 307 nm in height and 14 GPa stiffness, were the most effective structures against both gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) bacteria. Statistical analysis significantly correlated structure height to the death of both bacteria strains. In addition, the surface contact angle and Young’s modulus were correlated to osteoblast metabolic activity. Hydrophilic surfaces with a contact angle between 35 and 50° produced the highest cellular metabolic activity rates after 24 h of incubation. The mechanical tests showed that nanostructures retain their mechanical stability and integrity over a long time-period, reaffirming the surfaces’ applicability for implants. This work provides a thorough examination of the surface, mechanical and wettability properties of multifunctional hydrothermally synthesised nanostructured materials, capable of killing bacteria whilst improving osteoblast metabolic rates, leading to improved osseointegration and antibacterial properties of orthopaedic implants.

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.

Bioactivity Studies on Titania Coatings and the Estimation of Their Usefulness in the Modification of Implant Surfaces

Morphologically different titania coatings (nanofibers (TNFs), nanoneedles (TNNs), and nanowires (TNWs)) were studied as potential biomedical materials. The abovementioned systems were produced in situ on Ti6Al4V substrates via direct oxidation processes using H₂O₂ and H₂O₂/CaCl₂ agents, and via thermal oxidation in the presence of Ar and Ar/H₂O₂. X-ray diffraction and Raman spectroscopy have been used to structurally characterize the produced materials. The morphology changes on the titanium alloy surface were investigated using scanning electron microscopy. The bioactivity of the samples has been estimated by the analysis of the produced titania coatings’ biocompatibility, and by the determination of their ability to reduce bacterial biofilm formation. The photoactivity of the produced nanocoatings was also analyzed, in order to determine the possibility of using titania coated implant surfaces in the sterilization process of implants. Photocatalytic activity was estimated using the methylene blue photodegradation kinetics, in the presence of UV light.