Article

Effects of low‐frequency ultrasound treatment of titanium surface roughness on osteoblast phenotype and maturation

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Abstract

Objective: Low-frequency ultrasound is widely used in the treatment of chronically infected wounds. To investigate its feasibility as a method for in situ restoration of metal implant surfaces in cases of peri-implantitis, we evaluated how low-frequency ultrasound affected surface properties of and response of human osteoblast-like MG63 cells to titanium (Ti). Material and methods: Three Ti surfaces [hydrophobic/smooth (pretreatment, PT); hydrophobic/rough (sandblasted/acid-etched, SLA); and hydrophilic/rough (SLA processed and stored hydrophilicity, mSLA)] were subjected to 25 kHz ultrasound for 10 min/cm(2) . Substrate roughness, chemical composition, and wettability were analyzed before and after ultrasound application. Osteoblastic maturation of cells on sonicated disks was compared to cells on untreated disks. Results: Ultrasound treatment altered the topography of all surfaces. Contact angles were reduced, and chemical compositions were altered by ultrasound on PT and SLA surfaces. Cell response to sonicated PT was comparable to untreated PT. Alkaline phosphatase was increased on sonicated SLA compared to untreated SLA, whereas DNA, osteocalcin, BMP2, osteoprotegerin, and VEGF-A were unchanged. Cells produced less osteocalcin and BMP2 on sonicated mSLA than on untreated mSLA, but no other parameters were affected. Conclusions: These results show that low-frequency ultrasound altered Ti surface properties. Osteoblasts were sensitive to the changes induced by ultrasound treatment. The data suggest that the effect is to delay differentiation, but it is unclear whether this delay will prevent osseointegration. These results suggest that low-frequency ultrasound may be useful for treating implant surfaces in situ leading to successful re-osseointegration of implants affected by peri-implantitis.

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... Ultrasonic treatment is used for surface modification in the medical industry. For example, in [60], the influence of ultrasound as a method for repairing the surfaces of metal titanium implants was studied. After treatment with ultrasound at a frequency of 25 kHz for 10 min, the topography of the specimens changed, with a decrease in the size of rough and wetting angles. ...
Article
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The ultrasonic treatment of metal products in liquid is used mainly to remove various kinds of contaminants from surfaces. The effects of ultrasound not only separate and remove contaminants, they also significantly impact the physical–mechanical and geometric properties of the surfaces of products if there is enough time for treatment. The aim of this study was to compare the dynamics of ultrasonic cavitation effects on the surface properties of 45 (ASTM M1044; DIN C45; GB 45) and 40Kh (AISI 5140; DIN 41Cr4; GB 40Cr) structural steels. During the study, changes in the structure, roughness, sub-roughness, and microhardness values of these materials were observed. The results showed significant changes in the considered characteristics. It was found that the process of cavitation erosion involves at least 3 stages. In the first stage, the geometric properties of the surface slightly change with the accumulation of internal stresses and an increase in microhardness. The second stage is characterized by structure refinement, increased roughness and sub-microroughness, and the development of surface erosion. In the third stage, when a certain limiting state is reached, there are no noticeable changes in the surface properties. The lengths of these stages and the quantitative characteristics of erosion for the considered materials differ significantly. It was found that the time required to reach the limiting state was longer for carbon steel than for alloy steel. The results can be used to improve the cleaning process, as well as to form the required surface properties of structural steels.
... While ultrasonic instrumentation is an uncomplicated measure for periodontal defects, for the treatment of peri-implantitis, one major problem exists concerning these devices: Since titanium alloys are rather soft materials, mechanical debridement with tips of hard materials like steel or titanium have been reported to change the elaborate surface topography of the pristine implant [11,12]. Such changes refer to surface characteristics like roughness and hydrophilic properties, which can negatively affect healing in terms of osseo-integration when a regenerative approach is considered [13,14] and may abet bacterial recolonization of formerly smooth surfaces [15]. Furthermore, the possible immunologic reaction to titanium particles, which are abraded from the implant by instrumentation and end up in the peri-implant tissues, is still a matter of scientific discussion [16]. ...
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Background To assess the changes of implant surfaces of different roughness after instrumentation with ultrasonic-driven scaler tips of different materials. Methods Experiments were performed on two moderately rough surfaces (I—Inicell® and II—SLA®), one surface without pre-treatment (III) and one smooth machined surface (IV). Scaler tips made of steel (A), PEEK (B), titanium (C), carbon (D) and resin (E) were used for instrumentation with a standardized pressure of 100 g for ten seconds and under continuous automatic motion. Each combination of scaler tip and implant surface was performed three times on 8 titanium discs. After instrumentation roughness was assessed by profilometry, morphological changes were assessed by scanning electron microscopy, and element distribution on the utmost surface by energy dispersive X-ray spectroscopy. Results The surface roughness of discs I and II were significantly reduced by instrumentation with all tips except E. For disc III and IV roughness was enhanced by tip A and C and, only for IV, by tip D. Instrumentation with tips B, D and E left extensive residuals on surface I, II and III. The element analysis of these deposits proved consistent with the elemental composition of the respective tip materials. Conclusion All ultrasonic instruments led to microscopic alterations of all types of implants surfaces assessed in the present study. The least change of implant surfaces might result from resin or carbon tips on machined surfaces.
... While ultrasonic instrumentation is an uncomplicated measure for periodontal defects, for the treatment of peri-implantitis however one major problem exists concerning these devices: Since titanium alloys are rather soft materials, mechanical debridement with tips of hard materials like steel or titanium have been reported to change the elaborate surface topography of the pristine implant [11,12]. Such changes refer to surface characteristics like roughness and hydrophilic properties, which can negatively affect healing in terms of osseo-integration when a regenerative approach is considered [13,14] and may abet bacterial recolonization of formerly smooth surfaces [15]. Furthermore, the possible immunologic reaction to titanium particles, which are abraded from the implant by instrumentation and end up in the peri-implant tissues, is still a matter of scienti c discussion [16]. ...
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Background To assess the changes of implant surfaces of different roughness after instrumentation with ultrasonic-driven scaler tips of different materials. Methods Experiments were performed on two moderately rough surfaces (I – Inicell® and II – SLA®), one surface without pre-treatment (III) and one smooth machined surface (IV). Scaler tips made of steel (A), PEEK (B), titanium (C), carbon (D) and resin (E) were used for instrumentation with a standardized pressure of 100 g for ten seconds and under continuous automatic motion. Each combination of scaler tip and implant surface was performed three times on 8 titanium discs. After instrumentation roughness was assessed by profilometry. Morphological changes were assessed by scanning electron microscopy, and element distribution on the utmost surface by energy dispersive X-ray spectroscopy. Results The surface roughness of discs I and II were significantly reduced by instrumentation with all tips except E. For disc III and IV roughness was enhanced by tip A and C and, only for IV, by tip D. Instrumentation with tips B, D and E left extensive residuals on surface I, II and III. The element analysis of these deposits proved consistent with the elemental composition of the respective tip materials. Conclusion Instrumentation by ultrasonic-driven tips changes implant surfaces of different roughness significantly. The least change of implant surfaces might result from resin or carbon tips on machined surfaces.
... The in vitro reprogramming from SCs of oral origin, which have differentiation potential, has been considered for potential use in personalized medicine [9]. Several studies have shown that lowfrequency ultrasound may be useful for treating implant titanium scaffolds in situ leading to successful ossseointegration of implants affected by peri-implantitis [106]. Published studies so far indicate the importance of in vitro testing and the efficiency of nanomaterials and biomaterials to promote iPSCs osteogenic differentiation before translation into the clinic. ...
Article
Progress of modern dentistry is accelerating at a spectacular speed in the scientific, technological and clinical are-as. Practical examples are the advancement in the digital field, which has guaranteed an average level of prosthetic practices for all patients, as well as other scientific developments, including research on stem cell biology. Given their plasticity, de-fined as the ability to differentiate into specific cell lineages with capacity of almost unlimited self-renewal and release of trophic/immunomodulatory factors, stem cells have gained significant scientific and commercial interest in the last 15 years. Stem cells that can be isolated from various tissues of the oral cavity have emerged as attractive sources for bone and dental regeneration, mainly due to their ease of accessibility. This review will present the current understanding on emerging con-ceptual and technological issues of the use of stem cells to treat bone and dental loss defects. In particular, we will focus on the clinical application of stem cells, either directly isolated from oral sources or in vitro reprogrammed from somatic cells [induced pluripotent stem cells. Research aimed at further unravelling stem cell plasticity will allow to identify optimal stem cell sources and characteristics, to develop novel regenerative tools in dentistry.
... Another potential contamination by Cl was from sonicated solution of low-frequency ultrasound (used to treat chronically infected wounds). The sonication solution from the ultrasound treatment was able to alter the Ti surface chemistry, depositing Cl as well as Ca, aluminium (Al), Si, Na and K on the implant surface [27]. ...
Article
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Contamination of titanium dental implants may lead to implant failure. There are two major types of contaminants: the inorganic and organic contaminants. The inorganic contaminants mostly consist of elements such as calcium, phosphorus, chlorine, sulphur, sodium, silicon, fluorine and some organic carbons. Whereas organic contaminants consist of hydrocarbon, carboxylates, salts of organic acids, nitrogen from ammonium and bacterial cells/byproducts. Contaminants can alter the surface energy, chemical purity, thickness and composition of the oxide layer, however, we lack clinical evidence that contaminations have any effect at all. However, surface cleanliness seems to be essential for implant osseointegration.These contaminants may cause dental implants to fail in its function to restore missing teeth and also cause a financial burden to the patient and the health care services to invest in decontamination methods. Therefore, it is important to discuss the aetiology of dental implant failures. In this narrative review, we discuss two major types of contaminants: the inorganic and organic contaminants including bacterial contaminants. This review also aims to discuss the potential effect of contamination on Ti dental implants.
... In eight out of 11 papers, the water contact angle measurements have not been performed [40-43, 45, 46, 48, 49]. We considered this parameter for study quality assessment because it reflects the hydrophilicity of titanium surfaces, which enhances the alkaline phosphatase expression of osteoblasts [61,62]. Three studies demonstrated a significant decrease in contact angle after bisphosphonate coating procedure [44,48,50], which might contribute to the improved osteoblasts differentiation. ...
Article
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Background: Bisphosphonate coating of dental implants is a promising tool for surface modification aiming to improve the osseointegration process and clinical outcome. The biological effects of bisphosphonates are thought to be mainly associated with osteoclasts inhibition, whereas their effects on osteoblast function are unclear. A potential of bisphosphonate coated surfaces to stimulate osteoblast differentiation was investigated by several in vitro studies with contradictory results. The purpose of this systematic review and meta-analysis was to evaluate the effect of bisphosphonate coated implant surfaces on alkaline phosphatase activity in osteoblasts. Methods: In vitro studies that assessed alkaline phosphatase activity in osteoblasts following cell culture on bisphosphonate coated titanium surfaces were searched in electronic databases PubMed/MEDLINE, Scopus and ISI Web of Science. Animal studies and clinical trials were excluded. The literature search was restricted to articles written in English and published up to August 2019. Publication bias was assessed by the construction of funnel plots. Results: Eleven studies met the inclusion criteria. Meta-analysis showed that coating of titanium surfaces with bisphosphonates increases alkaline phosphatase activity in osteoblasts after 3 days (n = 1), 7 (n = 7), 14 (n = 6) and 21 (n = 3) days. (7 days beta coefficient = 1.363, p-value = 0.001; 14 days beta coefficient = 1.325, p-value < 0.001; 21 days beta coefficient = 1.152, p-value = 0.159). Conclusions: The meta-analysis suggests that bisphosphonate coatings of titanium implant surfaces may have beneficial effects on osteogenic behaviour of osteoblasts grown on titanium surfaces in vitro. Further studies are required to assess to which extent bisphosphonates coating might improve osseointegration in clinical situations.
... In the clinical practice, a certain degree of toxicity can always be expected when antiseptics are used in the surgical treatment of peri-implantitis, alongside possible alterations of the physicochemical properties of implant surfaces [9]. Indeed, these alterations have been shown to affect osteoblastic differentiation of mesenchymal stem cells, osteoblast maturation, as well as the production of factors that regulate bone formation, influencing, thereby, the process of osseointegration [9,10]. As a result, it is important to evaluate the effects of antiseptic agents on titanium surface by detecting any change in the elemental composition. ...
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Several antiseptic agents have been proposed for the treatment of peri-implantitis as a complementary therapeutic strategy in addition to mechanical devices. The aim of this study was to compare six different antiseptics, as well as alternative formulations of the same chemical agent, with respect to their decontamination efficacy and impact on chemical properties of the implant surface. Titanium disks with a micro-rough surface, previously contaminated with Porphyromonas gingivalis and Streptococcus mutans biofilms, were treated for 2 min with different antiseptics (liquid sodium hypochlorite 5.25%, gel sodium hypochlorite 5.25%, liquid chlorhexidine 0.2%, gel chlorhexidine 1%, gel citric acid 40%, and gel orthophosphoric acid 37%) or sterile saline solution (control) and their antibacterial activity as well as their ability to remove biofilm were assessed by viable bacterial count and scanning electron microscopy, respectively. Spectroscopic analysis was also performed on non-contaminated disks after exposure to the antiseptics, in order to detect any change in the elemental composition of the titanium surface. All the antimicrobial formulations examined were effective against P. gingivalis and S. mutans biofilms. SEM analysis revealed however that liquid sodium hypochlorite 5.25% was more effective in dissolving biofilm residues. Spectroscopic analysis detected traces of the antiseptics, probably due to insufficient rinsing of the titanium surfaces. In conclusion, since gel formulations of these antiseptic agents possessed a similar antibacterial activity to the liquid formulations, these may be proposed as alternative treatments given their properties to avoid overflows and increase contact time without significant side effects on the bone.
... 2, 3 Attempts to improve the cell-surface interactions of titanium and zirconium surfaces have been investigated through modifications of the physical surface structure with some success. 4,5 These materials, however, continue to suffer from inappropriate bulk material properties. Polymeric implants provide the prospect of an isoelastic implant-tissue interface, significantly reducing the risk of stress shielding. ...
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Slow appositional growth of bone in vivo is a major problem associated with polyether ether ketone (PEEK) based orthopaedic implants. Early stage promotion of osteoblast activity, particularly bone nodule formation, would help to improve contact between PEEK implantable materials and the surrounding bone tissue. To improve interactions with bone cells, we explored here the use of plasma immersion ion implantation (PIII) treatment of PEEK to covalently immobilize biomolecules to the surface. In this study, a single step process was used to covalently immobilize tropoelastin on the surface of PIII modified PEEK through reactions with radicals generated by the treatment. Improved bioactivity was observed using the human osteoblast-like cell line, SAOS-2. Cells on surfaces that were PIII-treated or tropoelastin-coated exhibited improved attachment, spreading, proliferation, and bone nodule formation compared to cells on untreated samples. Surfaces that were both PIII-treated and tropoelastin-coated triggered the most favorable osteoblast-like responses. Surface treatment or tropoelastin coating did not alter alkaline phosphatase gene expression and activity of bound cells but did influence the expression of other bone markers including osteocalcin, osteonectin, and collagen I. We conclude that the surface modification of PEEK improves osteoblast interactions, particularly with respect to bone apposition, and enhances the orthopedic utility of PEEK.
... 71 Hence, clinical outcomes echo the uncertain impact high IT might have on peri-implant bone loss compared with low IT. Future research are currently investigating alternative strategies including the application of osseodensification protocols, 72 lasers, 73,74 or ultrasound tools [75][76][77][78] to enhance osseointegration. ...
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Despite the growing number of publications in the field of implant dentistry, there are limited studies to date investigating the biology and metabolism of bone healing around dental implants and their implications in peri-implant marginal bone loss. The aim of this review article is to provide a thorough understanding of the biological events taking place during osseointegration and the subsequent early and late phases of bone remodeling around dental implants. An update on the coupling mechanism occurring during bone resorption-bone remodeling is provided, focused on the relevance of the osteocytes, bone lining cells and immune cells during bone maintenance. An electronic and manual literature search was conducted by three independent reviewers in several databases, including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register databases for articles up to September 2016 with no language restriction. Local bone metabolism is subject to signals from systemic calcium-phosphate homeostasis and bone remodeling. Three areas of interest were reviewed due to recent reported compromises in bone healing including the putative effects of (1) cholesterol, (2) hyperlipidemia, and (3) low vitamin D intake. Moreover, the prominent influence of osteocytes and immune cells is discussed as being key regulators during dental implant osseointegration and maintenance. These cells are of crucial importance in the presence of biofilm accumulation and their associated byproducts that leads to hard and soft tissue breakdown; the so called peri-implantitis. Factors that could negatively impact osteoclastogenesis or osteal macrophage activation should be monitored in future research including implant placement/torque protocols, bone characteristics, as well as meticulous maintenance programs to favor osseointegration and future long-term stability and success of dental implants.
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Issues related to peri-implant disease were discussed. It was observed that the most common lesions that occur, i.e. peri-implant mucositis and peri-implantitis are caused by bacteria. While the lesion of peri-implant mucositis resides in the soft tissues, peri-implantitis also affects the supporting bone. Peri-implant mucositis occurs in about 80% of subjects (50% of sites) restored with implants, and peri-implantitis in between 28% and 56% of subjects (12–40% of sites). A number of risk indicators were identified including (i) poor oral hygiene, (ii) a history of periodontitis, (iii) diabetes and (iv) smoking. It was concluded that the treatment of peri-implant disease must include anti-infective measures. With respect to peri-implant mucositis, it appeared that non-surgical mechanical therapy caused the reduction in inflammation (bleeding on probing) but also that the adjunctive use of antimicrobial mouthrinses had a positive effect. It was agreed that the outcome of non-surgical treatment of peri-implantitis was unpredictable. The primary objective of surgical treatment in peri-implantitis is to get access to the implant surface for debridement and decontamination in order to achieve resolution of the inflammatory lesion. There was limited evidence that such treatment with the adjunctive use of systemic antibiotics could resolve a number of peri-implantitis lesions. There was no evidence that so-called regenerative procedures had additional beneficial effects on treatment outcome.
Article
Although it is established that peri-implantitis is a bacterially induced disease, little is known about the bacterial profile of peri-implant communities in health and disease. The purpose of the present investigation was to examine the microbial signatures of the peri-implant microbiome in health and disease. Subgingival and submucosal plaque samples were collected from forty subjects with periodontitis, peri-implantitis, periodontal and peri-implant health and analysed using 16S pyrosequencing. Peri-implant biofilms demonstrated significantly lower diversity than subgingival biofilms in both health and disease, however, several species, including previously unsuspected and unknown organisms, were unique to this niche. The predominant species in peri-implant communities belonged to the genera Butyrivibrio, Campylobacter, Eubacterium, Prevotella, Selenomonas, Streptococcus, Actinomyces, Leptotrichia, Propionibacterium, Peptococcus, Lactococcus and Treponema. Peri-implant disease was associated with lower levels of Prevotella and Leptotrichia and higher levels of Actinomyces, Peptococcus, Campylobacter, non-mutans Streptococcus, Butyrivibrio and Streptococcus mutans than healthy implants. These communities also demonstrated lower levels of Prevotella, non-mutans Streptococcus, Lactobacillus, Selenomonas, Leptotrichia, Actinomyces and higher levels of Peptococcus, Mycoplasma, Eubacterium, Campylobacter, Butyrivibrio, S. mutans and Treponema when compared to periodontitis-associated biofilms. The peri-implant microbiome differs significantly from the periodontal community in both health and disease. Peri-implantitis is a microbially heterogeneous infection with predominantly gram-negative species, and is less complex than periodontitis.
Article
Medical implants are prone to colonization by bacterial biofilms. Normally, surgery is required to replace the infected implant. One promising noninvasive modality is to destroy biofilms with high-intensity focused ultrasound. In our study, Pseudomonas aeruginosa biofilms were grown on implant-mimicking graphite disks in a flow chamber for 3 days prior to exposing them to ultrasound pulses. Exposure time at each treatment location was varied between 5, 15 and 30s. Burst period was varied between 1, 3, 6 and 12 milliseconds (ms). The pulses were 20 cycles in duration at 1.1 MHz from a spherically focused transducer (f/1, 63 mm focal length), creating peak compressional and rarefactional pressures at the graphite disk surface of 30 and 13 MPa, respectively. P. aeruginosa were tagged with green fluorescent protein, and killed cells were visualized using propidium iodide before determining the extent of biofilm destruction. The exposure-induced temperature rise was measured to be less than 0.2°C at the focus, namely the interface between graphite disk and water. Then, the temperature rise was measured at the focus between the graphite disk and a tissue-mimicking phantom to evaluate therapy safety. Two thresholds, of bacteria destruction increase and of complete bacteria removal, respectively, were identified to divide our eight exposure conditions. Results indicated that 30-s exposure and 6-ms pulse period were sufficient to destroy the biofilms. However, the 15-s exposure and 3-ms pulse period were viewed as optimum when considering exposure time, efficacy, and safety.
Article
Endochondral bone formation is regulated by systemically and locally acting growth factors. A role for vascular endothelial growth factor (VEGF) in this process has recently been proposed, because inactivation of VEGF inhibits endochondral bone formation via inhibition of angiogenesis. Despite the known effect of VEGF as specific endothelial growth factor, its effects on osteoblast differentiation have not been studied. We, therefore, examined the expression of VEGF-A, -B, -C, and -D and their receptors in a model of osteoblast differentiation using the mouse preosteoblast-like cell line KS483. Early in differentiation, KS483 cells express low levels VEGF-A, -B, and -D messenger RNA, whereas during mineralization, KS483 cells express high levels. In addition, expression of the VEGF receptors, VEGFR1, VEGFR2, and VEGF165R/neuropilin, coincided with expression of their ligands, being maximally expressed during mineralization. VEGF-A production during osteoblast differentiation was stimulated by insulin-like growth factor I that enhances osteoblast differentiation and was inhibited by PTH-related peptide that inhibits osteoblast differentiation. Furthermore, continuous treatment of KS483 cells with recombinant human VEGF-A stimulated nodule formation. Although treatment of KS483 cells with soluble FLT1, an agent that blocks binding of VEGF-A and -B to VEGFR1, did not inhibit nodule formation, this observation does not exclude involvement of VEGFR2 in the regulation of osteoblast differentiation. As it is known that VEGF-A, -C, and -D can act through activation of VEGFR2, other isoforms might compensate for VEGF-A loss. The expression pattern of VEGFs and their receptors shown here suggests that VEGFs play an important role in the regulation of bone remodeling by attracting endothelial cells and osteoclasts and by stimulating osteoblast differentiation.
Article
Peri-implant bone formation depends on the ability of mesenchymal cells to colonize the implant surface and differentiate into osteoblasts. Human mesenchymal stem cells (HMSCs) undergo osteoblastic differentiation on microstructured titanium (Ti) surfaces in the absence of exogenous factors, but the mechanisms are unknown. Wnt proteins are associated with an osteoblast phenotype, but how Wnt signaling regulates HMSC differentiation on microstructured Ti surfaces is not known. HMSCs were cultured on tissue culture polystyrene or Ti (PT [Sa = 0.33 μm, θ = 96°], SLA [Sa = 2.5 μm, θ = 132°], modSLA [hydrophilic-SLA]). Expression of calcium-dependent Wnt ligand WNT5A increased and canonical Wnt pathway ligands decreased on microstructured Ti in a time-dependent manner. Treatment of HMSCs with canonical ligand Wnt3a preserved the mesenchymal phenotype on smooth surfaces. Treatment with Wnt5a increased osteoblastic differentiation. Expression of integrins ITGA1, ITGA2, and ITGAV increased over time and correlated with increased WNT5A expression. Treatment of HMSCs with Wnt5a, but not Wnt3a, increased integrin expression. Regulation of integrin expression due to surface roughness and energy was ablated in WNT5A-knockdown HMSCs. This indicates that surface properties regulate stem cell fate and induce osteoblast differentiation via the Wnt calcium-dependent pathway. Wnt5a enhances osteogenesis through a positive feedback with integrins and local factor regulation, particularly though BMP signaling.
Article
The aim of this study was to analyse the influence of the microtopography and hydrophilicity of titanium (Ti) substrates on initial oral biofilm formation. Nine bacterial species belonging to the normal oral microbiota, including: Aggregatibacter actinomycetemcomitans, Actinomyces israelii, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum, Parvimonas micra, Porphyromonas gingivalis, Prevotella intermedia, and Streptococcus sanguinis were tested on Ti surfaces: pretreatment (PT [R(a) <0.2 μm]), acid-etched (A [R(a) <0.8 μm]), A modified to be hydrophilic (modA), sand-blasted/acid-etched (SLA [R(a) =4 μm]), and hydrophilic SLA (modSLA). Disks were incubated for 24 h in anaerobic conditions using a normal culture medium (CM) or human saliva (HS). The total counts of bacteria and the proportion of each bacterial species were analysed by checkerboard DNA-DNA hybridization. Higher counts of bacteria were observed on all surfaces incubated with CM compared with the samples incubated with HS. PT, SLA, and modSLA exhibited higher numbers of attached bacteria in CM, whereas SLA and modSLA had a significant increase in bacterial adhesion in HS. The proportion of the species in the initial biofilms was also influenced by the surface properties and the media used: SLA and modSLA increased the proportion of species like A. actinomycetemcomitans and S. sanguinis in both media, while the adhesion of A. israelii and P. gingivalis on the same surfaces was affected in the presence of saliva. The initial biofilm formation and composition were affected by the microtopography and hydrophilicity of the surface and by the media used.
Article
To describe the microbiota associated with peri-implant disease, with a specific emphasis on the differential diagnosis of the condition. The potentially relevant literature was preliminarily assessed via scoping searches to find the most appropriate search terms and the most efficient Boolean search algorithm. We identified 29 reports on subjects with osseointegrated implants, with a pathological condition compatible with the definition of "peri-implant disease", and reporting microbiological data from samples taken in affected sites. In most studies bacterial samples were obtained by methods that destroy the three-dimensional structure of the biofilm. The samples therefore describe mixtures of bacteria from unspecified districts of biofilm associated with peri-implant diseases. Analyses of such samples with various methods indicate that peri-implant disease maybe viewed as a mixed anaerobic infection. In most cases the composition of the flora is similar to the subgingival flora of chronic periodontitis that is dominated by Gram-negative bacteria. Peri-implant infections may occasionally be linked to a different microbiota, including high numbers of peptostreptococci or staphylococci. Beneficial effects of mechanical and chemical interventions to disrupt the peri-implant biofilm demonstrate that microorganisms are involved in the disease process, even if they may not always be the origin of the condition.
Article
Titanium (Ti) osseointegration is critical for the success of dental and orthopedic implants. Previous studies have shown that surface roughness at the micro- and submicro-scales promotes osseointegration by enhancing osteoblast differentiation and local factor production. Only relatively recently have the effects of nanoscale roughness on cell response been considered. The aim of the present study was to develop a simple and scalable surface modification treatment that introduces nanoscale features to the surfaces of Ti substrates without greatly affecting other surface features, and to determine the effects of such superimposed nano-features on the differentiation and local factor production of osteoblasts. A simple oxidation treatment was developed for generating controlled nanoscale topographies on Ti surfaces, while retaining the starting micro-/submicro-scale roughness. Such nano-modified surfaces also possessed similar elemental compositions, and exhibited similar contact angles, as the original surfaces, but possessed a different surface crystal structure. MG63 cells were seeded on machined (PT), nano-modified PT (NMPT), sandblasted/acid-etched (SLA), and nano-modified SLA (NMSLA) Ti disks. The results suggested that the introduction of such nanoscale structures in combination with micro-/submicro-scale roughness improves osteoblast differentiation and local factor production, which, in turn, indicates the potential for improved implant osseointegration in vivo.
Article
The removal of adherent biofilms was assessed using ultrasonic waves in a non-contact mode. In in vitro experiments, Streptococcus mutans (S. mutans) biofilms were exposed to ultrasonic waves at various frequencies (280 kHz, 1 MHz, or 2 MHz), duty ratios (0-90%), and exposure times (1-3 minutes), and the optimal conditions for biofilm removal were identified. Furthermore, the effect of adding a contrast medium, such as micro bubbles (Sonazoid), was examined. The spatial distribution and architecture of S. mutans biofilms before and after ultrasonic wave exposure were examined via scanning electron microscopy. The biofilm removal effect was also examined in in vivo experiments, using a custom-made oral cleaning device. When a 280 kHz probe was used, the biofilm-removing effect increased significantly compared to 1 and 2 MHz probes; more than 80% of the adherent biofilm was removed with a duty cycle of 50-90% and a 3 minutes exposure time. The maximum biofilm-removing effect was observed with a duty cycle of 80%. Furthermore, the addition of micro bubbles enhanced this biofilm-removing effect. In in vivo experiments, moderate biofilm removal was observed when a 280 kHz probe was used for 5 minutes. This study demonstrated that ultrasonic wave exposure in a non-contact mode effectively removed adherent biofilms composed of S. mutans in vitro.
Article
This review was undertaken to address the similarities and dissimilarities between the two disease entities of periodontitis and peri-implantitis. The overall analysis of the literature on the etiology and pathogenesis of periodontitis and peri-implantitis provided an impression that these two diseases have more similarities than differences. First, the initiation of the two diseases is dependent on the presence of a biofilm containing pathogens. While the microbiota associated with periodontitis is rich in gram-negative bacteria, a similar composition has been identified in peri-implant diseases. However, increasing evidence suggests that S. aureus may be an important pathogen in the initiation of some cases of peri-implantitis. Further research into the role of this gram-positive facultative coccus, and other putative pathogens, in the development of peri-implantitis is indicated. While the initial host response to the bacterial challenge in peri-implant mucositis appears to be identical to that encountered in gingivitis, persistent biofilm accumulation may elicit a more pronounced inflammatory response in peri-implant mucosal tissues than in the dentogingival unit. This may be a result of structural differences (such as vascularity and fibroblast-to-collagen ratios). When periodontitis and peri-implantitis were produced experimentally by applying plaque-retaining ligatures, the progression of mucositis to peri-implantitis followed a very similar sequence of events as the development of gingivitis to periodontitis. However, some of the peri-implantitis lesions appeared to have periods of rapid progression, in which the infective lesion reached the alveolar bone marrow. It is therefore reasonable to assume that peri-implantitis in humans may also display periods of accelerated destruction that are more pronounced than that observed in cases of chronic periodontitis. From a clinical point of view the identified and confirmed risk factors for periodontitis may be considered as identical to those for peri-implantitis. In addition, patients susceptible to periodontitis appear to be more susceptible to peri-implantitis than patients without a history of periodontitis. As both periodontitis and peri-implantitis are opportunistic infections, their therapy must be antiinfective in nature. The same clinical principles apply to debridement of the lesions and the maintenance of an infection-free oral cavity. However, in daily practice, such principles may occasionally be difficult to apply in peri-implantitis treatment. Owing to implant surface characteristics and limited access to the microbial habitats, surgical access may be required more frequently, and at an earlier stage, in periimplantitis treatment than in periodontal therapy. In conclusion, it is evident that periodontitis and peri-implantitis are not fundamentally different from the perspectives of etiology, pathogenesis, risk assessment, diagnosis and therapy. Nevertheless, some difference in the host response to these two infections may explain the occasional rapid progression of peri-implantitis lesions. Consequently, a diagnosed peri-implantitis should be treated without delay.
Article
Preventing wound infection and the development of resistant bacteria are important concerns in wound management. To determine if noncontact, nonthermal, low-frequency ultrasound therapy is effective in controlling wound bacterial colony counts, a series of four related experiments was conducted. First, ultrasound penetration in both wounded and intact skin was assessed in vitro. Compared to sham, noncontact ultrasound penetrated farther into both wounded (3 mm to 3.5 mm versus 0.35 mm to 0.50 mm) and intact (2.0 mm to 2.5 mm versus 0.05 mm to 0.07 mm, respectively) pig skin. Second, using an in vitro model to stain and count live/dead bacteria, 0% of sham treated and 33% of Pseudomonas aeruginosa, 40% of Escherichia coli and 27% of Enterococcus faecalis were dead after one ultrasound application. Minimal effects on methicillin-resistant Staphylococcus aureus and S. aureus were observed. Third, using an in vivo model, after 1 week, while differences between different bacterial species were observed, overall bacterial quantity decreased with ultrasound treatment (from 7.2 +/- 0.79 to 6.7 +/- 0.91 colony forming units per gram of tissue [CFU/g]) and silver antimicrobial dressings (from 7.2 +/- 0.79 to 5.7 +/- 0.6 CFU/g) but increased to 8.6 +/- 0.15 CFU/g for sham and 8.6 +/- 0.06 CFU/g for water-moistened gauze. Fourth, 11 patients (average age 60 years) with pressure ulcers containing bacterial counts >10(5) CFU/g of tissue received 2 weeks of noncontact ultrasound therapy. The quantities of seven bacterial organisms were reduced substantially from baseline to 2 weeks post treatment. None of the wounds exhibited signs of a clinical infection during the treatment period and no adverse events were observed. Taken together, these four studies indicate that noncontact ultrasound can be used to reduce bacterial quantity. Controlled clinical studies are warranted to ascertain the efficacy of this treatment and to further elucidate its effects on various Gram-negative and Gram-positive bacteria.
Article
The aim of the current review was to describe the prevalence of peri-implant diseases including peri-implant mucositis and peri-implantitis. A MEDLINE search (PubMed) until December 2007 was conducted and different keywords related to the prevalence of peri-implant diseases were used. Cross-sectional and longitudinal studies including > or =50 implant-treated subjects exhibiting a function time of > or =5 years were considered. The current review revealed that only a few studies provided data on the prevalence of peri-implant diseases. Cross-sectional studies on implant-treated subjects are rare and data from only two study samples were available. Peri-implant mucositis occurred in approximately 80% of the subjects and in 50% of the implants. Peri-implantitis was found in 28% and > or =56% of subjects and in 12% and 43% of implant sites.
Article
Nineteen human tumors, mostly of sarcomatous nature, were cultured in vitro. Three cell lines were isolated and further characterized: MG-57 derived from a giant cell tumor, MG-63 derived from an osteosarcoma and MG-72 derived from a xanthohistiocytoma. The cell lines varied in morphology and growth pattern. An abnormal karyotype with marker chromosomes was present in Mg-63 and MG-72. None of the cell lines spontaneously produced detectable C-type virus particles. Stimulation with IUDR and dexamethasone also failed to induce detectable particle release.
Article
Photomicrographs of the surfaces of recently extracted teeth stained with erythrosin dye were obtained. The stained surfaces were treated with an ultrasonic scaler using two different types of scaling tips driven by the same instrument operated at a medium power setting. Small areas of stained plaque removal occurred when the stationary scaling tip was operated without water cooling. Additional areas of removal were observed where a water coolant was present, which were larger than those produced by the non-water cooled tip. These additional areas were influenced by the type of scaling tip used, it's orientation to the tooth surface and it's displacement amplitude. Cavitational activity in the cooling water supply of the ultrasonic scaler is able to remove dental plaque from tooth surfaces and may be a useful adjunct to the mechanical action of the instrument.
Article
In an experimental group of 40 rats, the ultrasonic cleaner proved safe and effective in reducing the bacterial count of infected full-thickness burn wounds, with a markedly improved mortality rate and degree of healing.
Article
Osteoblasts in vitro undergo a developmental sequence of growth and differentiation characterized by a stage-specific expression of cell growth and bone-related genes. Our studies show that contributions to development of the osteoblast phenotype include: (1) the down-regulation of proliferation, (2) biosynthesis and organization of type 1 collagen extracellular matrix, and (3) mineralization of this matrix. Hormones and growth factors added to isolated osteoblasts during the initial proliferation period can dramatically alter the subsequent program of developmental stages of differentiation. Studies are presented that demonstrate alterations in gene expression in response to: (1) transforming growth factor beta (TGF beta 1), that prevents differentiation of the cells and their ability to form bony tissue-like nodules; (2) glucocorticoids, which induce and accelerate development of the bone-cell phenotype; and (3) the active metabolite of vitamin D, 1,25(OH)2D3, which results in both inhibitory and stimulatory effects of the hormone on growth and differentiation--effects that are dependent upon the differentiated state of the osteoblast. Thus, in the presence of these physiological mediators of bone-cell phenotype development, many of the growth and differentiation relationships operative in osteoblasts are modified or abrogated, precluding expression of the structural and functional properties of mature bone cells and tissue. These findings have significant implications for use of hormones or growth factors in the treatment of disorders where bone is involved.
Article
The hypothesis that teeth act as reservoirs of micro-organisms for the colonization of oral implants has recently been stated several times. The present study aimed at examining, in partially edentulous patients with severe periodontitis, whether pockets around teeth and implants harbored a comparable micro-flora. In 6 patients (3 with refractory periodontitis and 3 with advanced chronic adult periodontitis), plaque samples were taken from a deep and shallow pocket around both teeth and implants for differential phase contrast microscopy and DNA probe analysis. The results showed important differences in the sub-gingival flora between the 2 disease groups, as well as between deep and shallow pockets, around both implants and teeth. On the other hand, when pockets around teeth and implants with equal depths were compared a striking similarity was observed in the microbial composition. These observations confirm the hypothesis that pockets around teeth act as a reservoir and highlight the importance of periodontal health when oral implants are planned.
Article
The discovery of S. aureus small colony variants as persistent and intracellular has provided new insight into the understanding of pathogenesis associated with staphylococcal diseases. Survival advantages are afforded to SCVs on the basis of their ability to hide within host cells, which provide protection from the immune system and some antibiotics. In addition, because most clinical SCVs are defective in electron transport, their uptake of positively charged antimicrobial substances is reduced. The atypical clinical microbiologic characteristics make identification and susceptibility testing difficult. SCVs have been recovered from patients with unusually persistent infections, particularly those patients with long disease-free intervals, and from patients who are chronically exposed to aminoglycosides and TMP-SMZ, suggesting that these clinical situations are those in which SCVs should be suspected and the clinical laboratory should carefully search for them.
Article
The purpose of this report was to compare the distribution of periodontal pathogens recovered from failing implants and teeth with adult and recurrent forms of periodontitis. A total of 41 consecutive microbial samples from patients with failing implants (IMP) were received at the Microbiology Testing Laboratory (MTL) of the University of Pennsylvania over a 2-year period. Paired control samples were selected from samples received concurrently by MTL from 41 patients with a diagnosis of adult periodontitis (AP) and 41 with a diagnosis of recurrent or refractory periodontitis (RP). Patients' mean ages for the 3 categories were 59, 47, and 53 years, respectively. Samples were collected with paper points or scalers and shipped in prereduced medium by express mail to the laboratory where they were processed within 48 hours from the time of collection. Culture was used for detection of A. actinomycetemcomitans, C. rectus, P. intermedia/nigrescens, E. corrodens, P. micros, Capnocytophaga and Fusobacterium sp., enteric Gram-negative rods, Enterococcus and Staphylococcus sp., and yeast. P. gingivalis and B. forsythus were detected by indirect immunofluorescence. Morphotypes were enumerated by dark-field microscopy. The most frequently detected microorganisms from IMP were B. forsythus (59%), spirochetes (54%), Fusobacterium (41%), P. micros (39%), and P. gingivalis (27%). Recovery levels (mean +/- SD) were 1+/-1, 4+/-5, 4+/-5, 9+/-11, 1+/-2, respectively. The most frequently detected organisms for AP were B. forsythus (83%), Fusobacterium (80%), spirochetes (79%), P. gingivalis (59%), P. micros (51%), and E. corrodens (37%), at levels 2+/-2, 5+/-4, 9+/-6, 4+/-5, and 6+/-7, respectively. Corresponding data for RP were B. forsythus (85%), Fusobacterium (83%), P. gingivalis (60%), spirochetes (59%), C. rectus (56%), and P. micros (56%), at levels of 3+/-2, 8+/-8, 4+/-4, 2+/-2, 1+/-1, and 9+/-10, respectively. These results indicate that the detection frequency and levels of recovery of some periodontal pathogens in failing implants are significantly different from that of teeth with periodontitis; however, the detection frequency and levels of recovery are similar in teeth affected by adult and refractory (recurrent) forms of periodontitis.
Article
In this study we assessed whether osteogenic cells respond in a differential manner to changes in surface roughness depending on their maturation state. Previous studies using MG63 osteoblast-like cells, hypothesized to be at a relatively immature maturation state, showed that proliferation was inhibited and differentiation (osteocalcin production) was stimulated by culture on titanium (Ti) surfaces of increasing roughness. This effect was further enhanced by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. In the present study, we examined the response of three additional cell lines at three different maturation states: fetal rat calvarial (FRC) cells (a mixture of multipotent mesenchymal cells, osteoprogenitor cells, and early committed osteoblasts), OCT-1 cells (well-differentiated secretory osteoblast-like cells isolated from calvaria), and MLO-Y4 cells (osteocyte-like cells). Both OCT-1 and MLO-Y4 cells were derived from transgenic mice transformed with the SV40 large T-antigen driven by the osteocalcin promoter. Cells were cultured on Ti disks with three different average surface roughnesses (Ra): PT, 0.5 microm; SLA, 4.1 microm; and TPS, 4.9 microm. When cultures reached confluence on plastic, vehicle or 10(-7) M or 10(-8) M 1,25(OH)2D3 was added for 24 h to all of the cultures. At harvest, cell number, alkaline phosphatase-specific activity, and production of osteocalcin, transforming growth factor beta1 (TGF-beta1) and prostaglandin E2 (PGE2) were measured. Cell behavior was sensitive to surface roughness and depended on the maturation state of the cell line. Fetal rat calvarial (FRC) cell number and alkaline phosphatase-specific activity were decreased, whereas production of osteocalcin, TGF-beta1, and PGE2 were increased with increasing surface roughness. Addition of 1,25(OH)2D3 to the cultures further augmented the effect of roughness for all parameters in a dose-dependent manner; only TGF-beta1 production on plastic and PT was unaffected by 1,25(OH)2D3. OCT-1 cell number and alkaline phosphatase (SLA > TPS) were decreased and production of PGE2, osteocalcin, and TGF-beta1 were increased on SLA and TPS. Response to 1,25(OH)2D3 varied with the parameter being measured. Addition of the hormone to the cultures had no effect on cell number or TGF-beta1 production on any surface, while alkaline phosphatase was stimulated on SLA and TPS; osteocalcin production was increased on all Ti surfaces but not on plastic; and PGE2 was decreased on plastic and PT, but unaffected on SLA and TPS. In MLO-Y4 cultures, cell number was decreased on SLA and TPS; alkaline phosphatase was unaffected by increasing surface roughness; and production of osteocalcin, TGF-beta1, and PGE2 were increased on SLA and TPS. Although 1,25(OH)2D3 had no effect on cell number, alkaline phosphatase, or production of TGF-beta1 or PGE2 on any surface, the production of osteocalcin was stimulated by 1,25(OH)2D3 on SLA and TPS. These results indicate that surface roughness promotes osteogenic differentiation of less mature cells, enhancing their responsiveness to 1,25(OH)2D3. As cells become more mature, they exhibit a reduced sensitivity to their substrate but even the terminally differentiated osteocyte is affected by changes in surface roughness.
Article
The aim of the present study was to characterise microbiota and inflammatory host response around implants and teeth in patients with peri-implantitis. We included 17 partly edentulous patients with a total of 98 implants, of which 45 showed marginal bone loss of more than three fixture threads after the first year of loading. Nineteen subjects with stable marginal tissue conditions served as controls. Oral hygiene, gingival inflammation, and probing pocket depth were evaluated clinically at teeth and implants. Microbiological and crevicular fluid samples were collected from five categories of sites: 1) implants with peri-implantitis (PI), 2) stable implants (SI) in patients with both stable and peri-implantitis implants, 3) control implants (CI) in patients with stable implants alone, 4) teeth in patients (TP) and 5) controls (TC). Crevicular fluid from teeth and implants was analysed for elastase activity, lactoferrin and IL-1 beta concentrations. Elastase activity was higher at PI than at CI in controls. Lactoferrin concentration was higher at PI than at SI in patients with peri-implantitis. Higher levels of both lactoferrin and elastase activity were found at PI than at teeth in patients. The concentrations of IL-1 beta were about the same in the various sites. Microbiological DNA-probe analysis revealed a putative periodontal microflora at teeth and implants in patients and controls. Patients with peri-implantitis harboured high levels of periodontal pathogens, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus and Treponema denticola. These findings indicate a site-specific inflammation rather than a patient-associated specific host response.
Article
Titanium (Ti) is used for implantable devices because of its biocompatible oxide surface layer. TiO2 surfaces that have a complex microtopography increase bone-to-implant contact and removal torque forces in vivo and induce osteoblast differentiation in vitro. Studies examining osteoblast response to controlled surface chemistries indicate that hydrophilic surfaces are osteogenic, but TiO2 surfaces produced until now exhibit low surface energy because of adsorbed hydrocarbons and carbonates from the ambient atmosphere or roughness induced hydrophobicity. Novel hydroxylated/hydrated Ti surfaces were used to retain high surface energy of TiO2. Osteoblasts grown on this modified surface exhibited a more differentiated phenotype characterized by increased alkaline phosphatase activity and osteocalcin and generated an osteogenic microenvironment through higher production of PGE2 and TGF-beta1. Moreover, 1alpha,25OH2D3 increased these effects in a manner that was synergistic with high surface energy. This suggests that increased bone formation observed on modified Ti surfaces in vivo is due in part to stimulatory effects of high surface energy on osteoblasts.
Article
Periodic wound debridement promotes healing in chronic wounds. Low-frequency ultrasonic debridement (LFUD) is a promising adjunct to wound care, which offers relatively painless debridement and bacterial biofilm destruction. We performed LFUD on 17 patients over 8 months, with a minimum follow-up of 3 months. Nine of the wounds (53%) healed primarily or with the aid of a skin graft. Six additional patients (35%) experienced a wound-size reduction of at least 50%. The remaining 2 patients (12%), one with sickle cell anemia and one with a venous stasis ulcer, had reductions in wound area of 20%-30%. None of the patients required initiation of antibiotic treatment after starting LFUD. LFUD has had an early favorable experience in our institution. Further randomized clinical studies are required to better define the mechanism of action and the patient populations most appropriate for this modality.
Article
Direct observations of the surfaces of orthopaedic prostheses that have failed and of bone affected by osteomyelitis with and without the presence of a prosthesis have shown that the bacteria that cause these infections live in well-developed biofilms. The cells within these matrix-enclosed surface-associated communities are protected from host defenses and antibiotics, and clinical experience has shown that they must be removed physically before the infection can be resolved. The biofilm etiology of these diseases demands new diagnostic methods because biofilm cells typically do not grow on agar plates when recovered by scraping or swabbing. I will recommend new molecular and immunologic diagnostic methods that have been useful in other biofilm infections. These diseases progress through quiescent periods that alternate with acute exacerbations, and clinicians must realize that antibiotic therapy can control the acute phases but cannot resolve the basic biofilm nidus of the infection. Now that it has been realized that these orthopaedic infections are caused by relatively common biofilm-forming bacterial pathogens, new technologies that deliver very high concentrations of antibiotics locally and "on demand" and novel molecular "mimics" that block the signals that control biofilm formation need to be examined.
Article
Roughness-induced hydrophobicity, well-known from natural plant surfaces and intensively studied toward superhydrophobic surfaces, has currently been identified on microstructured titanium implant surfaces. Studies indicate that microstructuring by sandblasting and acid etching (SLA) enhances the osteogenic properties of titanium. The undesired initial hydrophobicity, however, presumably decelerates primary interactions with the aqueous biosystem. To improve the initial wettability and to retain SLA microstructure, a novel surface modification was tested. This modification differs from SLA by its preparation after acid etching, which was done under protective gas conditions following liquid instead of dry storage. We hypothesized that this modification should have increased wettability due to the prevention of contaminations that occurs during air contact. The main outcome of dynamic wettability measurements was that the novel modification shows increased surface free energy (SFE) and increased hydrophilicity with initial water contact angles of 0 degrees compared to 139.9 degrees for SLA. This hydrophilization was kept even after any drying. Reduced hydrocarbon contaminations were identified to play a possible role in altered surface thermodynamics. Such surfaces aim to retain the hydrophilicity and natural high surface energy of the Ti dioxide surface until surgical implants' insertion and are compared in this in vitro study with structural surface variants of titanium to compare roughness and chemically induced wettability.
Article
Objectives: Studies showing that osteoblasts exhibit a more differentiated phenotype on rough titanium (Ti) surfaces and osteoclast-resorbed bone surfaces used materials characterized by average peak to valley distance (Ra). Other surface features impacting the cells include distance between peaks, curvature of the valleys, and relative distribution of flat and smooth regions. We used novel Ti surfaces prepared by electrochemical micromachining as models to examine specific contributions of individual design features to osteoblast response. Results show that micron-scale topography modulates cell number, cell morphology and prostaglandin E2 (PGE2). In the presence of the appropriate microtopography, submicron-scale rugosity modulates differentiation and transforming growth factor-beta1 (TGF-beta1) levels. In this study, we examined the role of different types of submicron-scale structures. Material and methods: Thirty micrometer diameter craters on Ti disks were produced by photolithography resulting in an electropolished smooth surface, and arranged so that inside crater area vs. outside flat area was 6 (30/6). Submicron-scale structures were superposed by acid etching and porous anodization. Ra's were 700, 400, 60 nm on acid-etched, porous anodized and smooth 30/6 surfaces, respectively. Results: MG63 osteoblast-like cells were sensitive to submicron-scale architecture. Cell morphology on anodized surfaces was similar to morphology on smooth surfaces, whereas on etched surfaces, cells had a more elongated differentiated shape. Cell number was greatest on smooth surfaces > anodized > etched. Osteocalcin and PGE2 were affected in a reverse manner. Active TGF-beta1 was greatest on etched 30/6 surfaces > anodized > smooth; latent TGF-beta1 was elevated on all rough surfaces. Conclusions: These results support our previous observations that submicron-scale structures modulate osteoblastic phenotype and show that the physical properties of the submicron-scale structures are important variables in determining osteoblast response to substrate topography.
Article
Background: From an ecological viewpoint, the oral cavity, in fact the oro-pharynx, is an 'open growth system'. It undergoes an uninterrupted introduction and removal of both microorganisms and nutrients. In order to survive within the oro-pharyngeal area, bacteria need to adhere either to the soft or hard tissues in order to resist shear forces. The fast turn-over of the oral lining epithelia (shedding 3 x/day) is an efficient defence mechanism as it prevents the accumulation of large masses of microorganisms. Teeth, dentures, or endosseous implants, however, providing non-shedding surfaces, allow the formation of thick biofilms. In general, the established biofilm maintains an equilibrium with the host. An uncontrolled accumulation and/or metabolism of bacteria on the hard surfaces forms, however, the primary cause of dental caries, gingivitis, periodontitis, peri-implantitis, and stomatitis. Objectives: This systematic review aimed to evaluate critically the impact of surface characteristics (free energy, roughness, chemistry) on the de novo biofilm formation, especially in the supragingival and to a lesser extent in the subgingival areas. Methods: An electronic Medline search (from 1966 until July 2005) was conducted applying the following search items: 'biofilm formation and dental/oral implants/surface characteristics', 'surface characteristics and implants', 'biofilm formation and oral', 'plaque/biofilm and roughness', 'plaque/biofilm and surface free energy', and 'plaque formation and implants'. Only clinical studies within the oro-pharyngeal area were included. Results: From a series of split-mouth studies, it could be concluded that both an increase in surface roughness above the R(a) threshold of 0.2 microm and/or of the surface-free energy facilitates biofilm formation on restorative materials. When both surface characteristics interact with each other, surface roughness was found to be predominant. The biofilm formation is also influenced by the type (chemical composition) of biomaterial or the type of coating. Direct comparisons in biofilm formation on different transmucosal implant surfaces are scars. Conclusions: Extrapolation of data from studies on different restorative materials seems to indicate that transmucosal implant surfaces with a higher surface roughness/surface free energy facilitate biofilm formation.
Article
Biofilm formation on oral implants can cause inflammation of peri-implant tissues, which endangers the long-term success of osseointegrated implants. It has been reported previously that implants revealing signs of peri-implantitis contain subgingival microbiota similar to those of natural teeth with periodontitis. The purpose of the first part of this study was an atraumatic, quantitative investigation of biofilm formation on oral implant abutments; the objective of the second part was to investigate whether Haemophilus actinomycetemcomitans and Porphyromonas gingivalis were present in the crevicular fluid around oral implants. Biofilm formation on 14 healing abutments, inserted for 14 days in 10 patients, was analysed quantitatively by use of secondary-electron and Rutherford-backscattering-detection methods. A 16S rRNA-based polymerase chain reaction detection method was used to detect the presence of H. actinomycetemcomitans and P. gingivalis in the crevicular fluid. For this investigation, samples of sulcus fluid were collected with sterile paper points at four measurement points per abutment. The difference between biofilm coverage of supragingival surfaces (17.5 +/- 18.3%) and subgingival surfaces (0.8 +/- 1.0%) was statistically significant (P < 0.05). By use of universal primers, bacteria were found in all the samples taken, although the two periodontal pathogens were not found in any of the samples. The absence of periodontal pathogens from the sulcus fluid during initial bacterial colonization, despite massive supragingival biofilm formation, substantiates the assumption that cellular adherence of peri-implant tissue by means of hemidesmosoma, actin filaments and microvilli reduces the risk of formation of anaerobic subgingival pockets.
Article
To assess the impact of different implant systems on the clinical conditions and the microbiota at implants, and whether the presence of bacteria at tooth sites was predictive of the presence at implant sites. Subjects with either AstraTech or Brånemark in function for 7 years were enrolled. Sub-gingival bacterial samples at tooth and implant sites were collected with sterile endodontic paper points, and analyzed by the checkerboard DNA-DNA hybridization method (40 species). Fifty-four subjects, 27 supplied with AstraTech (n=132 implants) and 27 with Brånemark (n=102) implants, were studied. Test tooth sites had significantly less evidence of bleeding on probing (P<0.001) and presence of plaque (P<0.001) than implant test sites. Implant sites presented with deeper probing pocket depth than tooth sites (mean difference: 1.1 mm, standard error of differences: 0.08, 95% confidence intervals (CI): 0.9-1.3, P<0.001). Tannerella forsythia (P<0.05), Capnocytophaga sputigena (P<0.05), Actinomyces israelii (P<0.05) and Lactobacillus acidophilus (P<0.05) were found at higher levels at tooth surfaces. No differences in bacterial load for any species were found between the two implant systems. The odds of being present/absent at tooth and implants sites were only significant for Staphylococcus aureus [odds ratio (OR): 5.2 : 1, 95% CI: 1.4-18.9, P<0.01]. After 7 years in function, implants presented with deeper probing depths than teeth. S. aureus was commonly present at both teeth and implants sites. S. aureus at tooth sites was predictive of also being present at implant sites.
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