Reality of dental implant surface modification: a short literature review

Layer-by-layer self-assembly of PLL/CPP-ACP multilayer on SLA titanium surface: Enhancing osseointegration and antibacterial activity in vitro and in vivo

Dental Implants are expected to possess both excellent osteointegration and antibacterial activity because poor osseointegration and infection are two major causes of titanium implant failure. In this study, we constructed layer-by-layer self-assembly films consisting of anionic casein phosphopeptides-amorphous calcium phosphate (CPP-ACP) and cationic poly (L-lysine) (PLL) on sandblasted and acid etched (SLA) titanium surfaces and evaluated their osseointegration and antibacterial performance in vitro and in vivo. The surface properties were examined, including microstructure, elemental composition, wettability, and Ca2+ ion release. The impact the surfaces had on the adhesion, proliferation and differentiation abilities of MC3T3-E1 cells were investigated, as well as the material's antibacterial performance after exposure to the oral microorganisms such as Porphyromonas gingivalis (P. g) and Actinobacillus actinomycetemcomitans (A. a). For the in vivo studies, SLA and Ti (PLL/CA-3.0)10 implants were inserted into the extraction socket immediately after extracting the rabbit mandibular anterior teeth with or without exposure to mixed bacteria solution (P. g & A. a). Three rabbits in each group were sacrificed to collect samples at 2, 4, and 6 weeks of post-implantation, respectively. Radiographic and histomorphometry examinations were performed to evaluate the implant osseointegration. The modified titanium surfaces were successfully prepared and appeared as a compact nano-structure with high hydrophilicity. In particular, the Ti (PLL/CA-3.0)10 surface was able to continuously release Ca2+ ions. From the in vitro and in vivo studies, the modified titanium surfaces expressed enhanced osteogenic and antibacterial properties. Hence, the PLL/CPP-ACP multilayer coating on titanium surfaces was constructed via a layer-by-layer self-assembly technology, possibly improving the biofunctionalization of Ti-based dental implants.

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.

Overview of strategies to improve the antibacterial property of dental implants

The increasing number of peri-implant diseases and the unsatisfactory results of conventional treatment are causing great concern to patients and medical staff. The effective removal of plaque which is one of the key causes of peri-implant disease from the surface of implants has become one of the main problems to be solved urgently in the field of peri-implant disease prevention and treatment. In recent years, with the advancement of materials science and pharmacology, a lot of research has been conducted to enhance the implant antimicrobial properties, including the addition of antimicrobial coatings on the implant surface, the adjustment of implant surface topography, and the development of new implant materials, and significant progress has been made in various aspects. Antimicrobial materials have shown promising applications in the prevention of peri-implant diseases, but meanwhile, there are some shortcomings, which leads to the lack of clinical widespread use of antimicrobial materials. This paper summarizes the research on antimicrobial materials applied to implants in recent years and presents an outlook on the future development.

Vapor-Induced Pore-Forming Atmospheric-Plasma-Sprayed Zinc-, Strontium-, and Magnesium-Doped Hydroxyapatite Coatings on Titanium Implants Enhance New Bone Formation-An In Vivo and In Vitro Investigation

OBJECTIVES

Titanium implants are regarded as a promising treatment modality for replacing missing teeth. Osteointegration and antibacterial properties are both desirable characteristics for titanium dental implants. The aim of this study was to create zinc (Zn)-, strontium (Sr)-, and magnesium (Mg)-multidoped hydroxyapatite (HAp) porous coatings, including HAp, Zn-doped HAp, and Zn-Sr-Mg-doped HAp, on titanium discs and implants using the vapor-induced pore-forming atmospheric plasma spraying (VIPF-APS) technique.

METHODS

The mRNA and protein levels of osteogenesis-associated genes such as collagen type I alpha 1 chain (COL1A1), decorin (DCN), osteoprotegerin (TNFRSF11B), and osteopontin (SPP1) were examined in human embryonic palatal mesenchymal cells. The antibacterial effects against periodontal bacteria, including Porphyromonas gingivalis and Prevotella nigrescens, were investigated. In addition, a rat animal model was used to evaluate new bone formation via histologic examination and micro-computed tomography (CT).

RESULTS

The ZnSrMg-HAp group was the most effective at inducing mRNA and protein expression of TNFRSF11B and SPP1 after 7 days of incubation, and TNFRSF11B and DCN after 11 days of incubation. In addition, both the ZnSrMg-HAp and Zn-HAp groups were effective against P. gingivalis and P. nigrescens. Furthermore, according to both in vitro studies and histologic findings, the ZnSrMg-HAp group exhibited the most prominent osteogenesis and concentrated bone growth along implant threads.

SIGNIFICANCE

A porous ZnSrMg-HAp coating using VIPF-APS could serve as a novel technique for coating titanium implant surfaces and preventing further bacterial infection.

Effect of microtopography on osseointegration of implantable biomaterials and its modification strategies

Orthopedic implants are widely used for the treatment of bone defects caused by injury, infection, tumor and congenital diseases. However, poor osseointegration and implant failures still occur frequently due to the lack of direct contact between the implant and the bone. In order to improve the biointegration of implants with the host bone, surface modification is of particular interest and requirement in the development of implant materials. Implant surfaces that mimic the inherent surface roughness and hydrophilicity of native bone have been shown to provide osteogenic cells with topographic cues to promote tissue regeneration and new bone formation. A growing number of studies have shown that cell attachment, proliferation and differentiation are sensitive to these implant surface microtopography. This review is to provide a summary of the latest science of surface modified bone implants, focusing on how surface microtopography modulates osteoblast differentiation in vitro and osseointegration in vivo, signaling pathways in the process and types of surface modifications. The aim is to systematically provide comprehensive reference information for better fabrication of orthopedic implants.

How Porphyromonas gingivalis Navigate the Map: The Effect of Surface Topography on the Adhesion of Porphyromonas gingivalis on Biomaterials

The main purpose of this study is to develop an understanding of how Porphyromonas gingivalis responds to subperiosteal implant surface topography. A literature review was drawn from various electronic databases from 2000 to 2021. The two main keywords used were “Porphyromonas gingivalis” and “Surface Topography”. We excluded all reviews and or meta-analysis articles, articles not published in English, and articles with no surface characterization process or average surface roughness (Ra) value. A total of 26 selected publications were then included in this study. All research included showed the effect of topography on Porphyromonas gingivalis to various degrees. It was found that topography features such as size and shape affected Porphyromonas gingivalis adhesion to subperiosteal implant materials. In general, a smaller Ra value reduces Porphyromonas gingivalis regardless of the type of materials, with a threshold of 0.3 µm for titanium.

Hyaluronic Acid-Based Nanomaterials as a New Approach to the Treatment and Prevention of Bacterial Infections

Bacterial contamination of medical devices is a great concern for public health and an increasing risk for hospital-acquired infections. The ongoing increase in antibiotic-resistant bacterial strains highlights the urgent need to find new effective alternatives to antibiotics. Hyaluronic acid (HA) is a valuable polymer in biomedical applications, partly due to its bactericidal effects on different platforms such as contact lenses, cleaning solutions, wound dressings, cosmetic formulations, etc. Because the pure form of HA is rapidly hydrolyzed, nanotechnology-based approaches have been investigated to improve its clinical utility. Moreover, a combination of HA with other bactericidal molecules could improve the antibacterial effects on drug-resistant bacterial strains, and improve the management of hard-to-heal wound infections. This review summarizes the structure, production, and properties of HA, and its various platforms as a carrier in drug delivery. Herein, we discuss recent works on numerous types of HA-based nanoparticles to overcome the limitations of traditional antibiotics in the treatment of bacterial infections. Advances in the fabrication of controlled release of antimicrobial agents from HA-based nanosystems can allow the complete eradication of pathogenic microorganisms.

Three interfaces of the dental implant system and their clinical effects on hard and soft tissues

Anatomically, the human tooth has structures both embedded within and forming part of the exterior surface of the human body. When a tooth is lost, it is often replaced by a dental implant, to facilitate the chewing of food and for esthetic purposes. For successful substitution of the lost tooth, hard tissue should be integrated into the implant surface. The microtopography and chemistry of the implant surface have been explored with the aim of enhancing osseointegration. Additionally, clinical implant success is dependent on ensuring that a barrier, comprising strong gingival attachment to an abutment, does not allow the infiltration of oral bacteria into the bone-integrated surface. Epithelial and connective tissue cells respond to the abutment surface, depending on its surface characteristics and the materials from which it is made. In particular, the biomechanics of the implant-abutment connection structure (i.e., the biomechanics of the interface between implant and abutment surfaces, and the screw mechanics of the implant-abutment assembly) are critical for both the soft tissue seal and hard tissue integration. Herein, we discuss the clinical importance of these three interfaces: bone-implant, gingiva-abutment, and implant-abutment.

Bioactive coatings for dental implants: A review of alternative strategies to prevent peri-implantitis induced by anaerobic bacteria

Members of oral bacterial communities form biofilms not only on tooth surfaces but also on the surface of dental implants that replace natural teeth. Prolonged interaction of host cells with biofilm-forming anaerobes frequently elicits peri-implantitis, a destructive inflammatory disease accompanied by alveolar bone loss leading to implant failure. Here we wish to overview how the deposition of bioactive peptides to dental implant surfaces could potentially inhibit bacterial colonization and the development of peri-implantisis. One preventive strategy is based on natural antimicrobial peptides (AMPs) immobilized on titanium surfaces. AMPs are capable to destroy both Gram positive and Gram negative bacteria directly. An alternative strategy aims at coating implant surfaces - especially the transmucosal part - with peptides facilitating the attachment of gingival epithelial cells and connective tissue cells. These cells produce AMPs and may form a soft tissue seal that prevents oral bacteria from accessing the apical part of the osseointegrated implant. Because a wide variety of titanium-bound peptides were studied in vitro, we wish to concentrate on bioactive peptides of human origin and some of their derivatives. Furthermore, special attention will be given to peptides effective under in vivo test conditions.

In Vivo and In Vitro Analyses of Titanium-Hydroxyapatite Functionally Graded Material for Dental Implants

Purpose

The stress shielding effect caused due to the mechanical mismatch between the solid titanium and the surrounding bone tissue warrants the utilization of a mechanically and biologically compatible material such as the titanium-hydroxyapatite (Ti-HA) functionally graded material (FGM) for dental implants. This study is aimed at fabricating a Ti-HA FGM with superior mechanical and biological properties for dental implantation.

Materials and Methods

We fabricated a Ti-HA FGM with different Ti volume fractions (VFs) using HA and Ti powders. Ti-HA was characterized by studying its mechanical properties. Cytotoxicity was examined using a Cell Counting Kit-8 assay and an LDH cell cytotoxicity assay. Scanning electron microscopy was performed on an XL30 environmental scanning electron microscope (ESEM). Alkaline phosphatase (ALP) and transforming growth factor (TGF-β1) expressions were quantitatively monitored using enzyme-linked immunosorbent assay (ELISA) kits. The expressions of TGF-β receptors and ALP genes were measured using real-time polymerase chain reaction. The Ti-HA FGM dental implants were placed in beagle dogs. Microcomputed tomography (CT) and hard tissue slices were performed to evaluate the bone-implant contact (BIC) and bone volume over total volume (BV/TV).

Results

The density and mechanical properties of the Ti-HA exhibited various graded distributions corresponding to VF. Based on the results of the Cell Counting Kit-8 (CCK-8) and lactate dehydrogenase (LDH) assays, the difference in cytotoxicity between the two groups was statistically nonsignificant (P = 0.11). The ALP and TGF-β1 levels were slightly upregulated. The transcript levels of ALP and TGF-βRI were higher in the Ti-HA groups than in the Ti group at 7 days, whereas the transcript levels of TGF-βRII exhibited no obvious increase. The BIC did not exhibit significant differences between the Ti and Ti-HA FGM groups (P = 0.0504). BV/TV showed the Ti-HA FGM group had better osteogenesis (P = 0.04).

Conclusion

Ti-HA FGM contributes to the osteogenesis of dental implants in vivo and in vitro.

Implant stability and survival rates of a hydrophilic versus a conventional sandblasted, acid-etched implant surface: Systematic review and meta-analysis

BACKGROUND

Modifying the implant surface via enhancing the wettability (hydrophilicity) improves osseointegration, reducing the healing period. In this study, the authors aimed to evaluate the stability and survival rates of implants with a hydrophilic surface compared with those with a sandblasted, acid-etched surface.

TYPES OF STUDIES REVIEWED

The included studies (randomized controlled trials) were identified through searches of PubMed, ScienceDirect, and Cochrane Library databases without date of publication restrictions. Quality assessment was performed using the Cochrane Collaboration tool. For primary outcome, confidence intervals were set at 95%; weighted means across the studies were calculated using a fixed-effects model or risk ratios and their 95% confidence intervals for secondary outcome.

RESULTS

The authors included 5 randomized controlled trials (246 dental implants) in the systematic review, which compared a hydrophilic with conventional sandblasted, acid-etched implant surface. The implant stability (primary outcome) was measured at baseline and 3, 6, and 8 weeks, and implant survival rates were measured as a secondary outcome. Overall, compared with the control groups, no clinically significant differences in implant stability or survival rates were identified for the hydrophilic surface groups.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The results did not show any clinically significant effect of a hydrophilic surface on improving implant stability or survival rates. However, these findings must be analyzed carefully owing to the limitations of this review, such as the small samples size and some differences among the included studies.

Modifications of Dental Implant Surfaces at the Micro- and Nano-Level for Enhanced Osseointegration

This review paper describes several recent modification methods for biocompatible titanium dental implant surfaces. The micro-roughened surfaces reviewed in the literature are sandblasted, large-grit, acid-etched, and anodically oxidized. These globally-used surfaces have been clinically investigated, showing survival rates higher than 95%. In the past, dental clinicians believed that eukaryotic cells for osteogenesis did not recognize the changes of the nanostructures of dental implant surfaces. However, research findings have recently shown that osteogenic cells respond to chemical and morphological changes at a nanoscale on the surfaces, including titanium dioxide nanotube arrangements, functional peptide coatings, fluoride treatments, calcium–phosphorus applications, and ultraviolet photofunctionalization. Some of the nano-level modifications have not yet been clinically evaluated. However, these modified dental implant surfaces at the nanoscale have shown excellent in vitro and in vivo results, and thus promising potential future clinical use.

Accentuated osseointegration in osteogenic nanofibrous coated titanium implants

Anchoring of endosseous implant through osseointegration continues to be an important clinical need. Here, we describe the development of superior endosseous implant demonstrating enhance osseointegration, achieved through surface modification via coating of osteogenic nanofibres. The randomized bio-composite osteogenic nanofibres incorporating polycaprolactone, gelatin, hydroxyapatite, dexamethasone, beta-glycerophosphate and ascorbic acid were electrospun on titanium implants mimicking bone extracellular matrix and subsequently induced osteogenesis by targeting undifferentiated mesenchymal stem cells present in the peri-implant niche to regenerate osseous tissue. In proof-of-concept experiment on rabbit study models (n = 6), micro-computed tomography (Micro-CT), histomorphometric analysis and biomechanical testing in relation to our novel osteogenic nanofibrous coated implants showed improved results when compared to uncoated controls. Further, no pathological changes were detected during gross examination and necropsy on peri-implant osseous tissues regenerated in response to such coated implants. The findings of the present study confirm that osteogenic nanofibrous coating significantly increases the magnitude of osteogenesis in the peri-implant zone and favours the dynamics of osseointegration.

A wear-resistant TiO2 nanoceramic coating on titanium implants for visible-light photocatalytic removal of organic residues

An effective treatment for peri-implantitis is to completely remove all the bacterial deposits from the contaminated implants, especially the organic residues, to regain biocompatibility and re-osseointegration, but none of the conventional decontamination treatments has achieve this goal. The photocatalytic activity of TiO₂ coating on titanium implants to degrade organic contaminants has attracted researchers' attention recently. But a pure TiO₂ coating only responses to harmful ultraviolet light. Additionally, the poor coating mechanical properties are unable to protect the coating integrity versus initial mechanical decontamination. To address these issues, a unique TiO₂ nanoceramic coating was fabricated on titanium substrates through an innovative plasma electrolytic oxidation (PEO) based procedure, which showed a disordered layer with oxygen vacancies on the outmost part. As a result, the coating could decompose methylene blue, rhodamine B, and pre-adsorbed lipopolysaccharide (LPS) under visible light. Additionally, the coating showed two-fold higher hardness than untreated titanium and excellent wear resistance against steel decontamination instruments, which could be attributed to the specific micro-structure, including the densely packed nanocrystals and good metallurgical combination. Moreover, the in vitro response of MG63 cells confirmed that the coating had comparable biocompatibility and osteoconductivity to untreated titanium substrates. This study provides a unique coating technique as well as a photocatalytic cleaning strategy to enhance decontamination of titanium dental implants, which will favour the development of peri-implantitis treatments. STATEMENT OF SIGNIFICANCE: The treatment of peri-implantitis is based on the complete removal of bacterial deposits, especially the organic residues, but conventional decontamination treatments are hard to achieve it. The photocatalytic activity of TiO₂ coating on titanium implants to degrade organic contaminants provides a promising strategy for deeper decontamination, but its nonactivation to visible light and poor mechanical properties have limited its application. To address these issues, a unique TiO₂ nanoceramic coating was fabricated on titanium substrates based on plasma electrolytic oxidation. The coating showed enhanced visible-light photocatalytic activity, excellent wear resistance and satisfied biocompatibility. Based on this functional coating, it is promising to develop a more efficient strategy for deep decontamination of implant surface, which will favour the development of peri-implantitis treatments.

Osteogenic Cell Behavior on Titanium Surfaces in Hard Tissue

It is challenging to remove dental implants once they have been inserted into the bone because it is hard to visualize the actual process of bone formation after implant installation, not to mention the cellular events that occur therein. During bone formation, contact osteogenesis occurs on roughened implant surfaces, while distance osteogenesis occurs on smooth implant surfaces. In the literature, there have been many in vitro model studies of bone formation on simulated dental implants using flattened titanium (Ti) discs; however, the purpose of this study was to identify the in vivo cell responses to the implant surfaces on actual, three-dimensional (3D) dental Ti implants and the surrounding bone in contact with such implants at the electron microscopic level using two different types of implant surfaces. In particular, the different parts of the implant structures were scrutinized. In this study, dental implants were installed in rabbit tibiae. The implants and bone were removed on day 10 and, subsequently, assessed using scanning electron microscopy (SEM), immunofluorescence microscopy (IF), transmission electron microscopy (TEM), focused ion-beam (FIB) system with Cs-corrected TEM (Cs-STEM), and confocal laser scanning microscopy (CLSM)-which were used to determine the implant surface characteristics and to identify the cells according to the different structural parts of the turned and roughened implants. The cell attachment pattern was revealed according to the different structural components of each implant surface and bone. Different cell responses to the implant surfaces and the surrounding bone were attained at an electron microscopic level in an in vivo model. These results shed light on cell behavioral patterns that occur during bone regeneration and could be a guide in the use of electron microscopy for 3D dental implants in an in vivo model.

A Clue to the Existence of Bonding between Bone and Implant Surface: An In Vivo Study

We evaluated the shear bond strength of bone–implant contact, or osseointegration, in the rabbit tibia model, and compared the strength between grades 2 and 4 of commercially pure titanium (cp-Ti). A total of 13 grades 2 and 4 cp-Ti implants were used, which had an identical cylinder shape and surface topography. Field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and confocal laser microscopy were used for surface analysis. Four grades 2 and 4 cp-Ti implants were inserted into the rabbit tibiae with complete randomization. After six weeks of healing, the experimental animals were sacrificed and the implants were removed en bloc with the surrounding bone. The bone–implant interfaces were three-dimensionally imaged with micro-computed tomography. Using these images, the bone–implant contact area was measured. Counterclockwise rotation force was applied to the implants for the measurement of removal torque values. Shear bond strength was calculated from the measured bone–implant contact and removal torque data. The t-tests were used to compare the outcome measures between the groups, and statistical significance was evaluated at the 0.05 level. Surface analysis showed that grades 2 and 4 cp-Ti implants have similar topographic features. We found no significant difference in the three-dimensional bone–implant contact area between these two implants. However, grade 2 cp-Ti implants had a higher shear bond strength than grade 4 cp-Ti implants (p = 0.032). The surfaces of the grade 2 cp-Ti implants were similar to those of the grade 4 implants in terms of physical characteristics and the quantitative amount of attachment to the bone, whereas the grade 2 surfaces were stronger than the grade 4 surfaces in the bone–surface interaction, indicating osseointegration quality.

Bone-Healing Pattern on the Surface of Titanium Implants at Cortical and Marrow Compartments in Two Topographic Sites: an Experimental Study in Rabbits

This study evaluates the bone-healing patterns on the surface of titanium implants at the cortical and marrow compartments of bicortically-installed implants in the diaphysis and metaphysis of rabbit tibiae. In 27 New Zealand rabbits, two implants, one for each macro-design and with equal resorbable blasted media (RBM) implant surfaces, were randomly implanted in the diaphysis or metaphysis of each tibia. The flaps were sutured to allow submerged healing. The animals were sacrificed after two, four, or eight weeks, with nine weeks used for the period of healing. Ground sections were prepared and analyzed. No statistically significant differences were found between the two groups for newly formed bone in contact with the implant surface after two, four, and eight weeks of healing. Bone apposition in the marrow compartment was slightly higher in the diaphysis compared to metaphysis regions across healing stages. Despite the limitations of the present study, it can be concluded that new bone apposition was better than average in the cortical compartment as compared to the marrow compartments. Bone morphometry and density may affect bone apposition onto the implant surface. The apposition rates were slightly better at both the cortical and marrow compartments in diaphysis as compared to metaphysis sites. The new bone formation at the marrow compartment showed slightly better increasing values at diaphysis compared to metaphysis implantation sites.

Comparison of Osseointegration of Five Different Surfaced Titanium Implants

The topography, chemical features, surface charge, and hydrophilic nature of titanium implant surfaces are crucial factors for successful osseointegration. This study aimed to investigate the bone implant contact (BIC) ratio of titanium dental implants with different surface modification techniques using the rat femoral bone model. Sandblasted and acid washed (SL-AW), sandblasted (SL), resorbable blast material (RBM), microarc (MA), and sandblasted and microarc (SL-MA) surfaces were compared in this study. Forty male Sprague-Dawley rats were used in this study. The rats were divided into 5 equal groups (n = 8), and totally 40 implants were integrated into the right femoral bones of the rats. The rats were sacrificed 12 weeks after the surgical integration of the implants. The implant surface-bone tissue interaction was directly observed by a light microscope, and BIC ratios were measured after the nondecalcified histological procedures. Bone implant contact ratios were determined as follows: SL-AW: 59.26 ± 14.36%, SL: 66.01 ± 9.63%, RBM: 63.53 ± 11.23%, MA: 65.51 ± 10.3%, and SL-MA: 68.62 ± 6.6%. No statistically significant differences were found among the 5 different surfaced titanium implant groups (P > 0.05). Our results show that various implant surface modification techniques can provide favorable bone responses to the BIC of dental implants.

A review of nanostructured surfaces and materials for dental implants: surface coating, patterning and functionalization for improved performance

The emerging field of nanostructured implants has enormous scope in the areas of medical science and dental implants. Surface nanofeatures provide significant potential solutions to medical problems by the introduction of better biomaterials, improved implant design, and surface engineering techniques such as coating, patterning, functionalization and molecular grafting at the nanoscale. This review is of an interdisciplinary nature, addressing the history and development of dental implants and the emerging area of nanotechnology in dental implants. After a brief introduction to nanotechnology in dental implants and the main classes of dental implants, an overview of different types of nanomaterials (i.e. metals, metal oxides, ceramics, polymers and hydrides) used in dental implant together with their unique properties, the influence of elemental compositions, and surface morphologies and possible applications are presented from a chemical point of view. In the core of this review, the dental implant materials, physical and chemical fabrication techniques and the role of nanotechnology in achieving ideal dental implants have been discussed. Finally, the critical parameters in dental implant design and available data on the current dental implant surfaces that use nanotopography in clinical dentistry have been discussed.

Micro/nano hierarchical structured titanium treated by NH4OH/H2O2 for enhancing cell response

In this paper, two kinds of titanium surfaces with novel micro/nano hierarchical structures, namely Etched (E) surface and Sandblast and etched (SE) surface, were successfully fabricated by NH4OH and H2O2 mixture. And their cellular responses of MG63 were investigated compared with Sandblast and acid-etching (SLA) surface. Scanning electron microscope (SEM), Surface profiler, X-ray photoelectron spectroscopy (XPS), and Contact angle instrument were employed to assess the surface morphologies, roughness, chemistry and wettability respectively. Hierarchical structures with micro holes of 10-30 μm in diameter and nano pits of tens of nanometers in diameter formed on both E and SE surfaces. The size of micro holes is very close to osteoblast cell, which makes them wonderful beds for osteoblast. Moreover, these two kinds of surfaces possess similar roughness and superior hydrophilicity to SLA. Reactive oxygen species were detected on E and SE surface, and thus considerable antimicrobial performance and well fixation can be speculated on them. The cell experiments also demonstrated a boost in cell attachment, and that proliferation and osteogenic differentiation were achieved on them, especially on SE surface. The results indicate that the treatment of pure titanium with H2O2/NH4OH is an effective technique to improve the initial stability of implants and enhance the osseointegration, which may be a promising surface treatment to titanium implant.

Engineered Coatings for Titanium Implants To Present Ultralow Doses of BMP-7

The ongoing research to improve the clinical outcome of titanium implants has resulted in the implemetation of multiple approches to deliver osteogenic growth factors accelerating and sustaining osseointegration. Here we show the presentation of human bone morphogenetic protein 7 (BMP-7) adsorbed to titanium discs coated with poly(ethyl acrylate) (PEA). We have previously shown that PEA promotes fibronectin organization into nanonetworks exposing integrin- and growth-factor-binding domains, allowing a synergistic interaction at the integrin/growth factor receptor level. Here, titanium discs were coated with PEA and fibronectin and then decorated with ng/mL doses of BMP-7. Human mesenchymal stem cells were used to investigate cellular responses on these functionalized microenvironments. Cell adhesion, proliferation, and mineralization, as well as osteogenic markers expression (osteopontin and osteocalcin) revealed the ability of the system to be more potent in osteodifferentiation of the mesenchymal cells than combinations of titanium and BMP-7 in absence of PEA coatings. This work represents a novel strategy to improve the biological activity of titanium implants with BMP-7.

Bone Morphogenetic Protein Coating on Titanium Implant Surface: a Systematic Review

Objectives

The purpose of the study is to systematically review the osseointegration process improvement by bone morphogenetic protein coating on titanium implant surface.

Material and Methods

An electronic literature search was conducted through the MEDLINE (PubMed) and EMBASE databases. The search was restricted for articles published during the last 10 years from October 2006 to September 2016 and articles were limited to English language.

Results

A total of 41 articles were reviewed, and 8 of the most relevant articles that are suitable to the criteria were selected. Articles were analysed regarding concentration of bone morphogenetic protein (BMP), delivery systems, adverse reactions and the influence of the BMP on the bone and peri-implant surface in vivo. Finally, the present data included 340 implants and 236 models.

Conclusions

It’s clearly shown from most of the examined studies that bone morphogenetic protein increases bone regeneration. Further studies should be done in order to induce and sustain bone formation activity. Osteogenic agent should be gradually liberated and not rapidly released with priority to three-dimension reservoir (incorporated) titanium implant surface in order to avoid following severe side effects: inflammation, bleeding, haematoma, oedema, erythema, and graft failure.

Effects of alkaline treatment for fibroblastic adhesion on titanium

Background:

The surface energy of titanium (Ti) implants is very important when determining hydrophilicity or hydrophobicity, which is vital in osseointegration. The purpose of this study was to determine how Ti plates with an alkaline treatment (NaOH) affect the adhesion and proliferation of human periodontal ligament fibroblasts (HPLF).

Materials and Methods:

In vitro experimental study was carried out. Type 1 commercially pure Ti plates were analyzed with atomic force microscopy to evaluate surface roughness. The plates were treated ultrasonically with NaOH at 5 M (pH 13.7) for 45 s. HPLF previously established from periodontal tissue was inoculated on the treated Ti plates. The adhered and proliferated viable cell numbers were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method for 60 min and 24 h, respectively. The data were analyzed using Kruskal–Wallis tests and multiple comparisons of the Mann–Whitney U-test,P value was fixed at 0.05.

Results:

The mean roughness values equaled 0.04 μm with an almost flat surface and some grooves. The alkaline treatment of Ti plates caused significantly (P < 0.05) more pronounced HPLF adhesion and proliferation compared to untreated Ti plates.

Conclusion:

The treatment of Ti plates with NaOH enhances cell adhesion and the proliferation of HPLF cells. Clinically, the alkaline treatment of Ti-based implants could be an option to improve and accelerate osseointegration.

Influence of Implant Surfaces on Osseointegration: A Histomorphometric and Implant Stability Study in Rabbits

The aim of this study was to evaluate the stability and osseointegration of implant with different wettability using resonance frequency analysis (RFA) and histomorphometric analysis (bone implant contact, BIC; and bone area fraction occupied, BAFO) after 2 and 4 weeks in rabbit tibiae. Thirty-two Morse taper implants (length 7 mm, diameter 3.5 mm) were divided according to surface characteristics (n=8): Neo, sandblasted and dual acid-etched; and Aq, sandblasted followed by dual acid-etched and maintained in an isotonic solution of 0.9% sodium chloride. Sixteen New Zealand rabbits were used. Two implants of each group were installed in the right and left tibiae according to the experimental periods. The RFA (Ostell(r)) was obtained immediately and after the sacrifice (2 and 4 weeks). The bone/implant blocks were processed for histomorphometric analysis. Data were analyzed using two-way ANOVA followed by Tukey's test and Pearson's correlation for ISQ, BIC and BAFO parameters (p=0.05). No significant effect of implant, period of evaluation or interaction between implant and period of evaluation was found for BIC and BAFO values (p>0.05). Only period of evaluation had significant effect for RFA values at 4 weeks (p=0.001), and at 2 weeks (p<0.001). RFA values were significantly higher at the final period of evaluation compared with those obtained at early periods. There was a significant correlation between BIC values and BAFO values (p=0.009). Both implant surfaces, Aq and Neo, were able to produce similar implant bone integration when normal cortical bone instrumentation was performed.

Modification of a SLA titanium surface with calcium-containing nanosheets and its effects on osteoblast behavior

The aim of this study was to present a procedure to prepare a calcium-containing nanosheets-modified sandblasted and acid etched (SLA) titanium surface and explore its effects on osteoblast behavior.

Occurrence of Progressive Bone Loss Around Anodized Surface Implants and Resorbable Blasting Media Implants: A Retrospective Cohort Study

BACKGROUND

This study evaluates occurrence of progressive bone loss (PBL) around implants with different implant surfaces.

METHODS

Retrospective examination of 2,517 implants was performed in 903 patients, including 1,147 anodized-surface implants in 454 patients and 1,370 resorbable blasting media (RBM)-surface implants in 449 patients, which were placed from January 2006 to December 2010. Through regular check-up radiographs and records, presence of PBL (up to >50% of fixture length) was investigated. Implant removal for any reason was regarded a failure.

RESULTS

In total, 2,186 implants (979 anodized implants and 1,207 RBM implants) in 793 patients were included in this study. PBL was more frequently observed among anodized implants (n = 36 in 21 patients; 4%) than among RBM implants (n = 19 in 14 patients; 2%), and this difference was statistically significant (P <0.001). Occurrence of PBL was significantly influenced by surface modification and implant diameter (odds ratio [OR] of anodized surface = 4.40, 95% confidence interval [CI] = 1.78 to 10.89, P = 0.001; OR of wide implants = 9.62, 95% CI = 1.13 to 81.68, P = 0.038; determined by mixed-effects logistic regression analysis with random patient effect). However, total survival rate was significantly influenced by implant diameter and not by surface modification (P = 0.019), although effect of implant diameter was observed to be significant on anodized implants (P = 0.030).

CONCLUSION

Implant surface modification and implant diameter are significantly associated with occurrence of PBL.

Electrochemical Cathodic Polarization, a Simplified Method That Can Modified and Increase the Biological Activity of Titanium Surfaces: A Systematic Review

Background

The cathodic polarization seems to be an electrochemical method capable of modifying and coat biomolecules on titanium surfaces, improving the surface activity and promoting better biological responses.

Objective

The aim of the systematic review is to assess the scientific literature to evaluate the cellular response produced by treatment of titanium surfaces by applying the cathodic polarization technique.

Data, Sources, and Selection

The literature search was performed in several databases including PubMed, Web of Science, Scopus, Science Direct, Scielo and EBSCO Host, until June 2016, with no limits used. Eligibility criteria were used and quality assessment was performed following slightly modified ARRIVE and SYRCLE guidelines for cellular studies and animal research.

Results

Thirteen studies accomplished the inclusion criteria and were considered in the review. The quality of reporting studies in animal models was low and for the in vitro studies it was high. The in vitro and in vivo results reported that the use of cathodic polarization promoted hydride surfaces, effective deposition, and adhesion of the coated biomolecules. In the experimental groups that used the electrochemical method, cellular viability, proliferation, adhesion, differentiation, or bone growth were better or comparable with the control groups.

Conclusions

The use of the cathodic polarization method to modify titanium surfaces seems to be an interesting method that could produce active layers and consequently enhance cellular response, in vitro and in vivo animal model studies.

Surface Tension Drives the Orientation of Crystals at the Air-Water Interface

The fabrication of oriented crystalline thin films is essential for a range of applications ranging from semiconductors to optical components, sensors, and catalysis. Here we show by depositing micrometric crystal particles on a liquid interface from an aerosol phase that the surface tension of the liquid alone can drive the crystallographic orientation of initially randomly oriented particles. The X-ray diffraction patterns of the particles at the interface are identical to those of a monocrystalline sample cleaved along the {104} (CaCO3) or {111} (CaF2) face. We show how this orientation effect can be used to produce thin coatings of oriented crystals on a solid substrate. These results also have important implications for our understanding of heterogeneous crystal growth beneath amphiphile monolayers and for 2D self-assembly processes at the air-liquid interface.

Chemical and Topographic Analysis of Eight commercially Available Dental Implants

BACKGROUND

Surface characterization of dental implants allows us to better understand the effects of the implant on the host biological response. In this study, we analyzed and compared these characteristics among implants commercially available in South Africa.

MATERIALS AND METHODS

Eight implants from different manufacturers were chosen for analysis (Touareg, ICE, (R)Evolutions, Uniti, AnyRidge, MIS, Ivory-QSI, Southern), using scanning electron microscopy (SEM), interferometry, and energy dispersive X-ray spectroscopy to study the surface chemical composition and morphology.

RESULTS

The results indicate that variations in manufacturer processes result in implant surfaces that are distinctly different from one another. Most implants presented a moderately rough surface with sandblasted-only implant surfaces having a lower mean value of Sa when compared with sandblasted and acid-etched surfaces. Carbon contamination was detected on all the implants and that of aluminum on five implant surfaces. Ca and P were detected on the surface of Touareg implants, indicating the manufacturer's attempt to enhance osseointegration.

CONCLUSION

The surface of the implants showed a range of chemical, physical properties, and surface topographies.

CLINICAL SIGNIFICANCE

The results indicate that implant surface treatment is not standardized. This may have clinical implications. Further clinical research is required.

Titanium Surface Priming with Phase-Transited Lysozyme to Establish a Silver Nanoparticle-Loaded Chitosan/Hyaluronic Acid Antibacterial Multilayer via Layer-by-Layer Self-Assembly

Objectives

The formation of biofilm around implants, which is induced by immediate bacterial colonization after installation, is the primary cause of post-operation infection. Initial surface modification is usually required to incorporate antibacterial agents on titanium (Ti) surfaces to inhibit biofilm formation. However, simple and effective priming methods are still lacking for the development of an initial functional layer as a base for subsequent coatings on titanium surfaces. The purpose of our work was to establish a novel initial layer on Ti surfaces using phase-transited lysozyme (PTL), on which multilayer coatings can incorporate silver nanoparticles (AgNP) using chitosan (CS) and hyaluronic acid (HA) via a layer-by-layer (LbL) self-assembly technique.

Methods

In this study, the surfaces of Ti substrates were primed by dipping into a mixture of lysozyme and tris(2-carboxyethyl)phosphine (TCEP) to obtain PTL-functionalized Ti substrates. The subsequent alternating coatings of HA and chitosan loaded with AgNP onto the precursor layer of PTL were carried out via LbL self-assembly to construct multilayer coatings on Ti substrates.

Results

The results of SEM and XPS indicated that the necklace-like PTL and self-assembled multilayer were successfully immobilized on the Ti substrates. The multilayer coatings loaded with AgNP can kill planktonic and adherent bacteria to 100% during the first 4 days. The antibacterial efficacy of the samples against planktonic and adherent bacteria achieved 65%-90% after 14 days. The sustained release of Ag over 14 days can prevent bacterial invasion until mucosa healing. Although the AgNP-containing structure showed some cytotoxicity, the toxicity can be reduced by controlling the Ag release rate and concentration.

Conclusions

The PTL priming method provides a promising strategy for fabricating long-term antibacterial multilayer coatings on titanium surfaces via the LbL self-assembly technique, which is effective in preventing implant-associated infections in the early stage.

Nanoscale surface modification by anodic oxidation increased bone ingrowth and reduced fibrous tissue in the porous coating of titanium-alloy femoral hip arthroplasty implants

Hip arthroplasty femoral stems coated with Ti6Al4V beads were treated by anodic oxidation in H₃ PO₄ for enhanced bioactivity and were studied in a 6-month canine model to determine the effects of the treated surface on the ingrowth of bone and soft tissues. The area fractions of bone, marrow, and fibrous tissue in the porous coating of seven treated and seven untreated control implants were determined using histomorphological techniques. The area fraction of bone within the porous coating was greater for anodic oxide treated (23.6 ± 8.3%) compared to control implants (l2.7 ± 4.7%) (p = 0.013), and there was less fibrous tissue in the treated implants (18.0 ± 9.5%) compared to the controls (33.1 ± 7.9%) (p = 0.006). XPS, XRD, TEM, and SEM analyses of the treated implants revealed a 400 nm-thick titanium oxide layer of low crystallinity with an undulating surface, populated with more than 25 nm-size pores per square micrometer. There was no detectable increase in serum titanium or in generation of particulates locally compared to the control implants. Micro and nanoscale surface modification by anodic oxidation increased bone ingrowth and reduced fibrous tissue, which may extend the longevity of fixation, limiting pathways for particle migration, and impeding the progression of osteolysis and aseptic loosening of arthroplasty components. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 283-290, 2017.

Adhesion and spreading of osteoblast-like cells on surfaces coated with laminin-derived bioactive core peptides

Functional peptides are attractive as novel therapeutic reagents because their amino acid sequences are flexible in adopting and mimicking the local functional features of proteins. These peptides are of low molecular weight, synthetically versatile and inexpensive to produce, suggesting that they can be used as drug targeting, potent, stable and bioavailable agents. A short bioactive peptide is expected to be more beneficial in regenerative medicine than an entire protein because of the lower antigenicity of short amino acid sequences. We detected core peptides from human laminin that are involved in adhesion and spreading, which are the first steps of various cells including osteogenic cells, in becoming functional. In this experiment, we detected adhesion and spreading of osteoblast-like cells seeded on the core peptide-coated surface. These in vitro data are related to the research article, entitled “Identification of a bioactive core sequence from human laminin and its applicability to tissue engineering” (Yeo et al., 2015) [1].

Effects of a micro/nano rough strontium-loaded surface on osseointegration

We developed a hierarchical hybrid micro/nanorough strontium-loaded Ti (MNT-Sr) surface fabricated through hydrofluoric acid etching followed by magnetron sputtering and evaluated the effects of this surface on osseointegration. Samples with a smooth Ti (ST) surface, micro Ti (MT) surface treated with hydrofluoric acid etching, and strontium-loaded nano Ti (NT-Sr) surface treated with SrTiO₃ target deposited via magnetron sputtering technique were investigated in parallel for comparison. The results showed that MNT-Sr surfaces were prepared successfully and with high interface bonding strength. Moreover, slow Sr release could be detected when the MNT-Sr and NT-Sr samples were immersed in phosphate-buffered saline. In in vitro experiments, the MNT-Sr surface significantly improved the proliferation and differentiation of osteoblasts compared with the other three groups. Twelve weeks after the four different surface implants were inserted into the distal femurs of 40 rats, the bone–implant contact in the ST, MT, NT-Sr, and MNT-Sr groups were 39.70%±6.00%, 57.60%±7.79%, 46.10%±5.51%, and 70.38%±8.61%, respectively. In terms of the mineral apposition ratio, the MNT-Sr group increased by 129%, 58%, and 25% compared with the values of the ST, MT, and NT-Sr groups, respectively. Moreover, the maximal pullout force in the MNT-Sr group was 1.12-, 0.31-, and 0.69-fold higher than the values of the ST, MT, and NT-Sr groups, respectively. These results suggested that the MNT-Sr surface has a synergistic effect of hierarchical micro/nano-topography and strontium for enhanced osseointegration, and it may be a promising option for clinical use. Compared with the MT surface, the NT-Sr surface significantly improved the differentiation of osteoblasts in vitro. In the in vivo animal experiment, the MT surface significantly enhanced the bone-implant contact and maximal pullout force than the NT-Sr surface.