Osteoblast integration of dental implant materials after challenge by sub-gingival pathogens: a co-culture study in vitro

Advanced co-culture model: Soft tissue cell and bacteria interactions at the transgingival dental implant interface

OBJECTIVES

To better simulate and understand the clinical situation in which tissue cells and bacteria compete for settlement on an implant surface, the aim was to develop an improved transgingival co-culture model.

METHODS

For this model human gingival fibroblasts (HGF) were seeded on different titanium surfaces in the presence of the early colonizer Streptococcus gordonii or mixed oral bacteria. Subsequently adhesion and viability of HGF cells was analyzed.

RESULTS

Simultaneous co-culture showed no decrease in the viability of HGF cells at early stages compared to the control group. However, a moderate impact on HGF viability (76 ± 23 %) was observed after 4 h of co-culture, which then significantly decreased after 5 h (21 ± 2 %) of co-cultivation, resulting in cell death and detachment from the surface. Further experiments including saliva pre-treatment of smooth and structured titanium surfaces with Streptococcus gordonii or mixed oral bacteria suggested a cell-protective property of saliva.

SIGNIFICANCE

Our study revealed that during simultaneous co-culture of cells and bacteria, which resembles the clinical situation the closest, the viability of gingival cells is considerably high in the early phase, suggesting that increasing initial cell adhesion rather than antibacterial functionality is a major goal and a relevant aspect in the development and testing of transgingival implant and abutment surface modifications.

Engineering Interfacial Environment of Epigallocatechin Gallate Coated Titanium for Next-Generation Bioactive Dental Implant Components

In view of endowing the surface of abutments, a component of titanium dental implant systems, with antioxidant and antimicrobial properties, a surface layer coated with epigallocatechin gallate (EGCg), a polyphenol belonging to the class of flavonoids, was built on titanium samples. To modulate interfacial properties, EGCg was linked either directly to the surface, or after populating the surface with terminally linked polyethyleneglycol (PEG) chains, Mw ~1600 Da. The underlying assumption is that fouling-resistant, highly hydrated PEG chains could reduce non-specific bioadhesion and magnify intrinsic EGCg properties. Treated surfaces were investigated by a panel of surface/interfacial sensitive techniques, to provide chemico-physical characterization of the surface layer and its interfacial environment. Results show: (i) successful EGCg coupling for both approaches; (ii) that both approaches endow the Ti surface with the same antioxidant properties; (iii) that PEG-EGCg coated surfaces are more hydrophilic and show a significantly higher (>50%) interaction force with water. Obtained results build up a rationale basis for evaluation of the merits of finely tuning interfacial properties of polyphenols coated surfaces in biological tests.

Reuse of healing abutments: Ethical, biological and professional training implications

Background

The aim was to estimate the prevalence of reuse of healing abutments, the methods used in disinfection and to analyze the reasons that lead to the reuse of these components by professionals who work in rehabilitation with dental implants.

Material and Methods

For this, an online data collection was carried out through a questionnaire developed in Google Forms. This questionnaire was applied to 284 specialists in implantology, randomized, of the 1,147 registered in the Regional Council of Dentistry of Rio Grande do Sul. The questionnaire was divided into three parts: the first containing the Free and Informed Consent Form; the second referring to the correspondents’ demographic data; and the third part with information on reuse, disinfection and sterilization routines used, risk perception and information from manufacturers. To estimate the prevalence in the reuse of healing abutments by implantologists, the frequency of responses was used.

Results

The results showed that almost all implantologists reuse healing abutments (98.1%). The main reasons for reuse were cost (71.2%) and practicality (26%). Regarding the limitations, 53.3% do not see limitations in its reuse, 20% associate it with increased roughness, 17.8% with the accumulation of organic matter and 8.9% with cross-infection as limitations for reuse. Already 95.3% did not receive any guidance from manufacturers on the reuse of these components. Enzymatic detergent and ultrasonic bath was the most used cleaning method (50.7%) followed by ultrasonic bath (23.3%). Autoclave was the method used for sterilization for all respondents.

Conclusions

The reuse of healing abutments is a practice adopted by implantologists in the state of Rio Grande do Sul, Brazil and most professionals do not observe limitations in this practice since these components are used repeatedly. Decontamination with enzymatic detergent and an ultrasonic bath is the most commonly used procedure associated with autoclave sterilization.

Key words:Abutment, reuse, decontamination, sterilization.

Fabrication and evaluation of antimicrobial biomimetic nanofibre coating for improved dental implant bio-seal: An in vitro study

BACKGROUND

A weak implant-soft tissue interface may lead to bacterial ingression, breakdown of underlying tissues, and eventually implant failure. This study proposes a surface modification technique of titanium alloy (Ti), using a nano-biopolymer scaffold to enhance soft tissue attachment in dental implants.

METHODS

Gelatin (20% w/v) embedded with 10±2 nm silver nanoparticles (AgNPs) was electrospun to form a Gelatin Electrospun Mat (GEM) scaffold, bonded to Ti alloy surface using chemical surface functionalization. Antimicrobial activity of AgNPs was tested against representative Gram-positive (S. aureus) and Gram-negative bacteria (E. coli) at 4, 24, and 48 hours (h) and after embedding in scaffold at 48 h. Cytotoxicity analysis (MTT assay) was carried out using the 3T3 mouse fibroblast cell line at 24 and 72 h for two groups: Control (unmodified Ti disc) and Experimental (GEM embedded with AgNPs); and further validated by scanning electron microscopy (SEM).

RESULTS

The AgNPs-embedded GEM showed good antimicrobial activity at 48 h, with the AgNPs showing complete (99.99%) inhibition of bacterial colony counts at 24 h and 48 h. Cell viability and proliferation over the GEM modified Ti discs were seen to be significantly increased (p < 0.05) at 72 h as compared to control. SEM images revealed intimate spreading of fibroblasts, with differentiated cell morphology and pseudopodial processes, indicative of enhanced fibroblastic adhesion, growth, and differentiation over the scaffold.

CONCLUSION

Results show good antifouling properties and biocompatibility of the fabricated coating, making it a promising strategy to reduce post-operative infections and peri-implant diseases in Ti dental implants. This article is protected by copyright. All rights reserved.

The effect of zirconia and titanium surfaces on biofilm formation and on host-derived immunological parameters

The aim of this study was to analyse the effect of zirconia and titanium surfaces on biofilm formation and host-derived parameters. Studies comparing zirconia and titanium surfaces were selected up to September 1, 2019. The outcome measures were surface roughness, contact angle, bacterial count, bacterial adherence, biofilm thickness, bacterial distribution, and specifically investigated biofilm and specific host-derived immunological parameters. Random-effects meta-analyses of in vitro and in vivo studies were conducted. A total of 39 studies were included for data extraction. In the systematic review data, 10 studies stated that zirconia accumulated less initial oral biofilm parameters, 16 investigations showed negligible inter-material differences, and only one study showed that zirconia attracted the most biofilm. However, in the meta-analysis, the bacterial coverage was found to be significantly superior for zirconia surfaces (P< 0.00001); the other outcome measures did not show any statistically significant differences between zirconia and titanium for the remaining parameters and the studies presented a substantial degree of heterogeneity. Overall, on the basis of the meta-analysis, the current data situation does not allow a clear preference for the use of zirconia or titanium.

Titanium Alloys for Dental Implants: A Review

The topic of titanium alloys for dental implants has been reviewed. The basis of the review was a search using PubMed, with the large number of references identified being reduced to a manageable number by concentrating on more recent articles and reports of biocompatibility and of implant durability. Implants made mainly from titanium have been used for the fabrication of dental implants since around 1981. The main alloys are so-called commercially pure titanium (cpTi) and Ti-6Al-4V, both of which give clinical success rates of up to 99% at 10 years. Both alloys are biocompatible in contact with bone and the gingival tissues, and are capable of undergoing osseointegration. Investigations of novel titanium alloys developed for orthopaedics show that they offer few advantages as dental implants. The main findings of this review are that the alloys cpTi and Ti-6Al-4V are highly satisfactory materials, and that there is little scope for improvement as far as dentistry is concerned. The conclusion is that these materials will continue to be used for dental implants well into the foreseeable future.

Co-culture of induced pluripotent stem cells with cardiomyocytes is sufficient to promote their differentiation into cardiomyocytes

Various types of stem cells and non-stem cells have been shown to differentiate or transdifferentiate into cardiomyocytes by way of co-culture with appropriate inducer cells. However, there is a limited demonstration of a co-culture induction system utilizing stem cell-derived cardiomyocytes as a stimulatory source for cardiac reprogramming (of stem cells or otherwise). In this study, we utilized an inductive co-culture method to show that previously differentiated induced pluripotent stem (iPS) cell-derived cardiomyocytes (iCMs), when co-cultivated with iPS cells, constituted a sufficient stimulatory system to induce cardiac differentiation. To enable tracking of both cell populations, we utilized GFP-labeled iPS cells and non-labeled iCMs pre-differentiated using inhibitors of GSK and Wnt signaling. Successful differentiation was assessed by the exhibition of spontaneous self-contractions, structural organization of α-actinin labeled sarcomeres, and expression of cardiac specific markers cTnT and α-actinin. We found that iCM-iPS cell-cell contact was essential for inductive differentiation, and this required overlaying already adherent iPS cells with iCMs. Importantly, this process was achieved without the exogenous addition of pathway inhibitors and morphogens, suggesting that 'older' iCMs serve as an adequate stimulatory source capable of recapitulating the necessary culture environment for cardiac differentiation.

Strategies to Prevent Biofilm Infections on Biomaterials: Effect of Novel Naturally-Derived Biofilm Inhibitors on a Competitive Colonization Model of Titanium by Staphylococcus aureus and SaOS-2 Cells

Biofilm-mediated infection is a major cause of bone prosthesis failure. The lack of molecules able to act in biofilms has driven research aimed at identifying new anti-biofilm agents via chemical screens. However, to be able to accommodate a large number of compounds, the testing conditions of these screenings end up being typically far from the clinical scenario. In this study, we assess the potential applicability of three previously discovered anti-biofilm compounds to be part of implanted medical devices by testing them on in vitro systems that more closely resemble the clinical scenario. To that end, we used a competition model based on the co-culture of SaOS-2 mammalian cells and Staphylococcus aureus (collection and clinical strains) on a titanium surface, as well as titanium pre-conditioned with high serum protein concentration. Additionally, we studied whether these compounds enhance the previously proven protective effect of pre-incubating titanium with SaOS-2 cells. Out of the three, DHA1 was the one with the highest potential, showing a preventive effect on bacterial adherence in all tested conditions, making it the most promising agent for incorporation into bone implants. This study emphasizes and demonstrates the importance of using meaningful experimental models, where potential antimicrobials ought to be tested for the protection of biomaterials in translational applications.

Real-Time Imaging of Bacteria/Osteoblast Dynamic Coculture on Bone Implant Material in an in Vitro Postoperative Contamination Model

Biomedical implants are an important part of evolving modern medicine but have a potential drawback in the form of postoperative pathogenic infection. Accordingly, the "race for surface" combat between invasive bacteria and host cells determines the fate of implants. Hence, proper in vitro systems are required to assess effective strategies to avoid infection. In this study, we developed a real time observation model, mimicking postoperative contamination, designed to follow E. coli proliferation on a titanium surface occupied by human osteoblastic progenitor cells (STRO). This model allowed us to monitor E. coli invasion of human cells on titanium surfaces coated and uncoated with fibronectin. We showed that the surface colonization of bacteria is significantly enhanced on fibronectin coated surfaces irrespective of whether areas were uncovered or covered with human cells. We further revealed that bacterial colonization of the titanium surfaces is enhanced in coculture with STRO cells. Finally, this coculture system provides a comprehensive system to describe in vitro and in situ bacterial and human cells and their localization but also to target biological mechanisms involved in adhesion as well as in interactions with surfaces, thanks to fluorescent labeling. This system is thus an efficient method for studies related to the design and function of new biomaterials.

Network meta-analysis of survival rate and complications in implant-supported single crowns with different abutment materials

OBJECTIVES

To compare the survival rate of abutments, marginal bone loss and peri-implant soft tissue discoloration among implant-supported single crowns with different abutment materials.

DATA

Randomized controlled trials (RCTs), controlled clinical trials, and cohort studies of implant-supported single crowns with different dental abutment materials.

SOURCES

A systematic search was conducted by an electronic search in 6 databases without restrictions on September 16, 2018, complemented by a manual search. "Grey" literatures were also searched.

STUDY SELECTION

Of 3417 studies initially retrieved, thirteen were eligible for inclusion. After studies selected and data extraction, pair-wise and network meta-analyses were performed to analyze the survival rate of the abutment, the marginal bone loss and the soft tissue discoloration. The risk of bias was assessed based on the Cochrane guidelines, Newcastle-Ottawa scale, and funnel plots. Statistical heterogeneity, inconsistencies, and cumulative ranking were also evaluated.

RESULTS

Fourteen RCTs and nine non-RCTs were included. No significant differences was detected among titanium (Ti), zirconia (Zr), gold (Au), and alumina (Al) abutments in terms of survival rate (excluding Al < Ti (P < 0.05), marginal bone loss (excluding Zr  < Ti (P < 0.05) and Au  > Zr (P < 0.05)), or discoloration of peri-implant soft tissue. Additionally, Ti abutment had the highest cumulative ranking of survival rate (97.9%); Al abutment had the lowest marginal bone loss (81.4%) and Zr abutment had the least discoloration of peri-implant soft tissue (84.8%).

CONCLUSIONS

Ti abutment has a comparable survival rate with Zr, but better than Al. In addition, Zr abutment has a better effect in maintaining the marginal bone level, compared with Au and Ti. However, there was no difference in the discoloration of peri-implant soft tissue among Au, Ti, and Zr abutment.

CLINICAL SIGNIFICANCE

Based on the results of our network meta-analysis, Zr might be a recommended abutment material considering the clinical efficacy of implant-supported single crowns.

Safety and efficacy of a novel, gradually anodized dental implant surface: A study in Yucatan mini pigs

BACKGROUND

A newly developed dental implant system combining advancements in surface chemistry, topography, nanostructure, color, and surface energy aims to address biological challenges and expand clinical applications.

PURPOSE

To assess the short- and long-term safety and efficacy of a novel, gradually anodized dental implant surface/anodized abutment.

MATERIALS AND METHODS

Twenty-four Yucatan mini pigs (20-24 months old) received two dental implants in each jaw quadrant. Each site was randomized to receive either a commercially available anodized implant/machined abutment or a gradually anodized implant/anodized abutment with a protective layer. Animals were euthanized at 3, 6, and 13 weeks. Microcomputed tomography and histological analyses were performed.

RESULTS

No significant histological differences in inflammation scores, epithelium length, bone-to-implant contact, or bone density were observed between groups for any healing time. Mucosal height was significantly higher at 3 weeks for controls (Δ = 0.2 mm); no differences were observed at 6 and 13 weeks. No significant differences in radiographic bone volume, bone-to-implant contact, trabecular thickness, and crestal bone levels were observed, irrespective of healing time. Trabecular spacing was borderline significant at 3 weeks in favor of the test implant sites; no differences were observed at 6 weeks. No significant differences were observed between experimental groups at 13 weeks.

CONCLUSIONS

The new implant system yielded results comparable to a commercially available predicate device.

Biological characterization of surface-treated dental implant materials in contact with mammalian host and bacterial cells: titanium versus zirconia

Early-colonizing oral bacterial adhesion and mammal cell proliferation were similar on surface-treated titanium and zirconia.

The "Race for the Surface" experimentally studied: In vitro assessment of Staphylococcus spp. adhesion and preosteoblastic cells integration to doped Ti-6Al-4V alloys

OBJECTIVE

Implant-related infection is a devastating complication in orthopedic surgery. Aiming to minimize this problem, many material modifications have been developed. Here we report a study of a surface modification of Ti-6 Al-4 V alloy using a methodology that enables the study of interactions between bacteria and the material in the presence of eukaryotic cells.

METHODS

We mixed different concentrations of collection or clinical strains of staphylococci isolated from implant-related infections with preosteoblastic cells using a previously published methodology, analyzing the minimal concentration of bacteria able to colonize the surface of the material through image analysis. Ti-6 Al-4 V alloy was modified by anodization to obtain two F-doped nanostructured surfaces that have been previously described to have antibacterial properties.

RESULTS

Our results show similar bacterial adhesion results to nanoporous and nanotubular F-doped surfaces. The presence of preosteoblastic cells increases the adherence of all bacterial strains to both structures. No effect of the surface on eukaryotic cells adherence was detected.

CONCLUSION

To our knowledge, this is the first time that anin vitro study emulating the race for the surface evaluates and compares the osseointegration and antibacterial properties between two nanostructured- modified titanium alloy surfaces. Clinical strains show different behavior from collection ones in bacterial adherence. The presence of cells increased bacterial adherence. NP and NT surface modifications didn´t show significant differences in bacterial adhesion and preosteoblastic cells integration.

Automated noninvasive epithelial cell counting in phase contrast microscopy images with automated parameter selection

Cell counting is commonly used to determine proliferation rates in cell cultures and for adherent cells it is often a ‘destructive’ process requiring disruption of the cell monolayer resulting in the inability to follow cell growth longitudinally. This process is time consuming and utilises significant resource. In this study a relatively inexpensive, rapid and widely applicable phase contrast microscopy‐based technique has been developed that emulates the contrast changes taking place when bright field microscope images of epithelial cell cultures are defocused. Processing of the resulting images produces an image that can be segmented using a global threshold; the number of cells is then deduced from the number of segmented regions and these cell counts can be used to generate growth curves. The parameters of this method were tuned using the discrete mereotopological relations between ground truth and processed images. Cell count accuracy was improved using linear discriminant analysis to identify spurious noise regions for removal.

The proposed cell counting technique was validated by comparing the results with a manual count of cells in images, and subsequently applied to generate growth curves for oral keratinocyte cultures supplemented with a range of concentrations of foetal calf serum. The approach developed has broad applicability and utility for researchers with standard laboratory imaging equipment.

Comparative adsorption profiles of basal lamina proteome and gingival cells onto dental and titanium surfaces

Titanium (Ti) dental implants are susceptible to bacterial infections and failure due to lack of proper epithelial seal. Epithelial cells establish a strong epithelial seal around natural teeth by the deposition of basal lamina (BL) proteins that adsorb on the tooth surface. This seal can even be re-established onto cementum or dentin following injury or periodontal therapy. However, it is unclear how tooth surfaces promote this cell attachment and protein adsorption. Understanding the interactions between BL proteins and epithelial cells with dentin and Ti will facilitate the development of implant surfaces that promote the formation of an epithelial seal and improve the success of periodontal therapy and wound healing on natural teeth. To study these interactions, we used a surface proteomic approach to decipher the adsorption profile of BL proteins onto Ti and dentin, and correlated these adsorption profiles with in vitro interactions of human gingival fibroblasts and epithelial cells. Results showed that dentin adsorbed higher amounts of key BL proteins, particularly laminin and nidogen-1, and promoted more favorable interactions with epithelial cells than Ti. Next, dentin specimens were deproteinized or partially demineralized to determine if its mineral or protein component was responsible for BL adsorption and cell attachment. Deproteinized (mineral-rich) and partially demineralized (protein-rich) dentin specimens revealed BL proteins (i.e. laminin and nidogen-1) and epithelial cells interact preferentially with dentinal proteins rather than dentin mineral. These findings suggest that, unlike Ti, dentin and, in particular, dentinal proteins have a selective affinity to BL proteins that enhance epithelial cell attachment.

STATEMENT OF SIGNIFICANCE

It is remains unclear why natural teeth, unlike titanium dental implants, promote the formation of an epithelial seal that protects them against the external environment. This study used a surface screening approach to analyze the adsorption of proteins produced by epithelial tissues onto tooth-dentin and titanium surfaces, and correlate it with the behaviour of cells. This study shows that tooth-dentin, in particular its proteins, has a higher selective affinity to certain adhesion proteins, and subsequently allows more favourable interactions with epithelial cells than titanium. This knowledge could help in developing new approaches for re-establishing and maintaining the epithelial seal around teeth, and could pave the way for developing implants with surfaces that allow the formation of a true epithelial seal.

Construction of three-dimensional net-like polyelectrolyte multilayered nanostructures onto titanium substrates for combined antibacterial and antioxidant applications

Fabrication of nanofibers and a bacteria-triggered antibiotic-releasing coating to modify titanium substrates for antibacterial and antioxidant applications.

Dicationic Imidazolium-Based Ionic Liquid Coatings on Zirconia Surfaces: Physico-Chemical and Biological Characterization

In the present work, dicationic imidazolium-based ionic liquids (ILs) were investigated as multi-functional coatings on a zirconia (ZrO₂) surface to prevent biofilm formation and enhance the wear performance of zirconia while maintaining the material’s compatibility with host cells. ILs containing phenylalanine and methionine were synthesized and deposited on zirconia. Intermolecular interactions driving IL deposition on zirconia were studied using X-ray photoelectron spectroscopy (XPS). Anti-biofilm activity and cell compatibility were evaluated in vitro after one and seven days, and wear performance was tested using a pin-on-disk apparatus. ILs were observed to form strong hydrogen bonds with zirconia. IL containing phenylalanine formed a stable film on the surface after one and seven days in phosphate-buffered saline (PBS) and artificial saliva and showed excellent anti-biofilm properties against Streptococcussalivarius and Streptococcussanguinis. Compatibility with gingival fibroblasts and pre-osteoblasts was maintained, and conditions for growth and differentiation were preserved. A significantly lower coefficient of friction and wear volume loss were observed for IL-coated surfaces as compared to non-coated substrates. Overall, zirconia is an emerging alternative to titanium in dental implants systems, and this study provides additional evidence of the materials’ behavior and IL coatings as a potential surface treatment technology for improvement of its properties.

Surface characterization of titanium implant healing abutments before and after placement

BACKGROUND

Implant healing abutments (IHA) have a vital role in soft tissue healing after implant placement. Although there is thorough investigation on the implant surface, little is known about the effects potentially damaging oral conditions impose on healing abutments.

PURPOSE

To characterize the surface of titanium healing abutments before and after clinical placement to understand the effects of the oral environment and time on the device surface.

MATERIALS AND METHODS

Ten regular Straumann IHA were subjected to characterization pre and postplacement to elucidate the effects of the oral environment on device surfaces. Changes in surface crystallinity, morphology, and elemental composition were monitored with Raman spectroscopy, scanning electron microscopy, optical microscopy, and x-ray photoelectron spectroscopy, respectively. In addition, corrosion rate and polarization resistance were obtained to assess electrochemical device stability after placement.

RESULTS

Control analysis indicated the titanium oxide of IHAs was thicker than natural commercially pure titanium and had the structure of crystalline anatase. After removal, the abutments possessed large amounts of biological debris, visible scratches, and discoloration sparsely on the surface. Spectroscopic analysis revealed the titanium oxide on the surface of IHAs was structurally unchanged, with crystalline titanium dioxide still present on the surface. Electrochemical results revealed that implanted healing abutments possessed a significantly higher corrosion rate than controls (change in corrosion rate = 2.34 ± 0.58 nm/year).

CONCLUSIONS

Healing abutments were stable in the oral environment due to the chemical stability of the oxide, and were likely subjected to abrasions from unintentional loading and oral hygiene techniques.

Natural and bioinspired nanostructured bactericidal surfaces

Bacterial antibiotic resistance is becoming more widespread due to excessive use of antibiotics in healthcare and agriculture. At the same time the development of new antibiotics has effectively ground to a hold. Chemical modifications of material surfaces have poor long-term performance in preventing bacterial build-up and hence approaches for realising bactericidal action through physical surface topography have become increasingly important in recent years. The complex nature of the bacteria cell wall interactions with nanostructured surfaces represents many challenges while the design of nanostructured bactericidal surfaces is considered. Here we present a brief overview of the bactericidal behaviour of naturally occurring and bio-inspired nanostructured surfaces against different bacteria through the physico-mechanical rupture of the cell wall. Many parameters affect this process including the size, shape, density, rigidity/flexibility and surface chemistry of the surface nanotextures as well as factors such as bacteria specificity (e.g. gram positive and gram negative) and motility. Different fabrication methods for such bactericidal nanostructured surfaces are summarised.

Does tantalum exhibit any intrinsic antimicrobial or antibiofilm properties?

Aims

Tantalum (Ta) trabecular metal components are increasingly used to reconstruct major bone defects in revision arthroplasty surgery. It is known that some metals such as silver have antibacterial properties. Recent reports have raised the question regarding whether Ta components are protective against infection in revision surgery. This laboratory study aimed to establish whether Ta has intrinsic antibacterial properties against planktonic bacteria, or the ability to inhibit biofilm formation.

Materials and Methods

Equal-sized pieces of Ta and titanium (Ti) acetabular components were sterilised and incubated with a low dose inoculum of either Staphylococcus (S.) aureus or S. epidermidis for 24 hours. After serial dilution, colony forming units (cfu) were quantified on Mueller-Hinton agar plates. In order to establish whether biofilms formed to a greater extent on one material than the other, these Ta and Ti pieces were then washed twice, sonicated and washed again to remove loosely adhered planktonic bacteria. They were then re-incubated for 24 hours prior to quantifying the number of cfu. All experiments were performed in triplicate.

Results

More than 1x108 cfu/ml were observed in both the Ta and Ti experiments. After washing and sonication, more than 2x107 cfu/ml were observed for both Ta and Ti groups. The results were the same for both S. aureus and S. epidermidis.

Conclusion

Compared with Ti controls, Ta did not demonstrate any intrinsic antibacterial activity or ability to inhibit biofilm formation. Hence, intrinsic antimicrobial properties of Ta do not account for the previously observed reduction in the frequency of subsequent infections when Ta was used in revision procedures. Cite this article: Bone Joint J 2017;99-B:1153–6.

Influence of Laser-Microtextured Surface Collar on Marginal Bone Loss and Peri-Implant Soft Tissue Response: A Systematic Review and Meta-Analysis

BACKGROUND

A laser-microtextured surface (LMS) dental implant collar appears to promote a more tooth-like gingival collagen fiber attachment, which may help to stabilize peri-implant tissues. The purpose of this systematic review is to assess the clinical effect of an LMS versus non-LMS collar on crestal bone level and peri-implant soft tissue response.

METHODS

Electronic and manual literature searches were performed by two independent reviewers for articles written in English up to December 2016. Studies were included if they were human clinical trials with the purpose of evaluating the impact of an LMS collar on peri-implant hard and soft tissues. Cumulative marginal bone loss (MBL), probing depth (PD), and survival rate (SR) with 95% confidence intervals (CIs) were calculated to show the performance of LMS implant collars. MBL, PD, and SR data were analyzed with a random effects model to compare the influence of LMS collars with non-LMS collars (e.g., roughened surface and machined surface).

RESULTS

Fifteen human clinical studies (three randomized controlled trials, six cohort studies, and six case series) with 772 implants met the inclusion criteria. For the overall data, the weighted mean MBL was 0.72 mm (95% CI: 0.59 to 0.85 mm), PD was 1.81 mm (95% CI: 1.13 to 2.49 mm), and SR was 0.97 (95% CI: 0.95 to 0.98). MBL around an LMS collar was significantly less than around machined-surface collars (weighted mean difference [WMD]: -0.77; 95% CI: -1.01 to -0.52; I2 = 95.2%; P <0.001). PD in the LMS group was significantly shallower than in the machined-surface group (WMD: -1.34; 95% CI: -1.62 to -1.05; I2 = 81.4%; P <0.001). However, no statistically significant difference was detected for MBL between the LMS and roughened-surface groups (WMD: -0.04; 95% CI: -0.16 to 0.08; I2 = 0.0%; P = 0.75). No statistically significant difference was found for SR between the LMS and non-LMS groups (risk ratio: 1.01; 95% CI: 0.97 to 1.04; I2 = 0.0%; P = 0.91).

CONCLUSIONS

Meta-analysis showed that an LMS collar can reduce the amount of MBL and PD compared with a machined-surface collar. Due to high heterogeneity between the included studies, results should be interpreted cautiously.

Evaluation of bacterial adherence of clinical isolates of Staphylococcus sp. using a competitive model: An in vitro approach to the "race for the surface" theory

Objectives

Implant-related infection is one of the most devastating complications in orthopaedic surgery. Many surface and/or material modifications have been developed in order to minimise this problem; however, most of the in vitro studies did not evaluate bacterial adhesion in the presence of eukaryotic cells, as stated by the ‘race for the surface’ theory. Moreover, the adherence of numerous clinical strains with different initial concentrations has not been studied.

Methods

We describe a method for the study of bacterial adherence in the presence of preosteoblastic cells. For this purpose we mixed different concentrations of bacterial cells from collection and clinical strains of staphylococci isolated from implant-related infections with preosteoblastic cells, and analysed the minimal concentration of bacteria able to colonise the surface of the material with image analysis.

Results

Our results show that clinical strains adhere to the material surface at lower concentrations than collection strains. A destructive effect of bacteria on preosteoblastic cells was also detected, especially with higher concentrations of bacteria.

Conclusions

The method described herein can be used to evaluate the effect of surface modifications on bacterial adherence more accurately than conventional monoculture studies. Clinical strains behave differently than collection strains with respect to bacterial adherence.

Cite this article: M. Martinez-Perez, C. Perez-Jorge, D. Lozano, S. Portal-Nuñez, R. Perez-Tanoira, A. Conde, M. A. Arenas, J. M. Hernandez-Lopez, J. J. de Damborenea, E. Gomez-Barrena, P. Esbrit, J. Esteban. Evaluation of bacterial adherence of clinical isolates of Staphylococcus sp. using a competitive model: An in vitro approach to the “race for the surface” theory. Bone Joint Res 2017;6:315–322. DOI: 10.1302/2046-3758.65.BJR-2016-0226.R2.

Competitive colonization of prosthetic surfaces by staphylococcus aureus and human cells

Implantation of a biomaterial provides an adhesion substratum both to host cell integration and to contaminating bacteria. We studied simultaneous competitive adhesion of Staphylococcus aureus in serial 1:10 dilutions of 10⁸ colony forming units (CFU)/mL and human osteogenic sarcoma (SaOS-2) or primary osteoblast (hOB) cells, both 1x10⁵ cells/mL, to the surfaces of titanium, polydimethylsiloxane and polystyrene. The bacterial adherence and human cell proliferation, cytotoxicity and production of reactive oxygen species (ROS) were studied using fluorometric (fluorescent microscopy and flow cytometry) and colorimetric methods (MTT, LDH and crystal violet). The bacterial cell viability was also evaluated using the drop plate method. The presence of bacteria resulted in reduced adherence of human cells to the surface of the biomaterials, increased production of ROS, and into increased apoptosis. On the other hand, the presence of either type of human cells was associated with a reduction of bacterial colonization of the biomaterial with Staphylococcus aureus. These results suggest that increasing colonization of the biomaterial surface in vitro by one negatively affects colonization by the other. Host cell integration to an implant surface reduces bacterial contamination, which opens novel opportunities for the design of infection-resistant biomaterials in current implantology and future regenerative medicine. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 62-72, 2017.