Physico-chemical interactions in initial microbial adhesion and relevance for biofilm formation

Enhanced antimicrobial activity against oral bacteria Actinomyces viscous by cinnamaldehyde emulsion microencapsulated with cyclodextrin glycosyltransferase-catalyzed products

Actinomyces viscous (A. viscous) is well documented as a major cariogenic bacterium in the oral cavity and needs to be inhibited and removed timely. Essential oils (EOs) are recognized as secure antibacterial agents for treating oral diseases, but their volatility and insolubility limit their application. In this study, cinnamaldehyde was screened as the optimum EO for inhibiting the A. viscous growth by a micro-agar dilution method and microencapsulated by cyclodextrin glycosyltransferase (CGTase)-catalyzed products. The antibacterial effects against A. viscous were investigated and compared with the free cinnamaldehyde. Antibacterial diameter, antibacterial efficiency and stability, and time-kill curve results revealed that the cinnamaldehyde emulsion had better antibacterial properties. 1 MIC of the cinnamaldehyde emulsion had an inhibitory zone of 9.92 nm, a 100 % inhibition rate when acting for 2 min or 5 min, and still maintained the same inhibitory effect for 2 years. The extracellular environment showed more pH decrease, conductivity increase, and protein leakage, suggesting damage to the cell membrane. Microstructure and flow cytometric analysis further revealed that the CGTase-catalyzed products induced more changes in the A. viscous membrane integrity. Based on the results, CGTase-catalyzed products can be used as a potential substance for encapsulating EOs for treating oral bacteria.

Selective colonization of microplastics, wood and glass by antimicrobial-resistant and pathogenic bacteria

The Plastisphere is a novel niche whereby microbial communities attach to plastic debris, including microplastics. These communities can be distinct from those found in the surrounding environment or those attached to natural substrates and may serve as a reservoir of both pathogenic and antimicrobial-resistant (AMR) bacteria. Owing to the frequent omission of appropriate comparator particles (e.g. natural substrates) in previous studies, there is a lack of empirical evidence supporting the unique risks posed by microplastics in terms of enrichment and spread of AMR pathogens. This study investigated selective colonization by a sewage community on environmentally sampled microplastics with three different polymers, sources and morphologies, alongside natural substrate (wood), inert substrate (glass) and free-living/planktonic community controls. Culture and molecular methods (quantitative polymerase chain reaction (qPCR)) were used to ascertain phenotypic and genotypic AMR prevalence, respectively, and multiplex colony PCR was used to identify extra-intestinal pathogenic Escherichia coli (ExPECs). From this, polystyrene and wood particles were found to significantly enrich AMR bacteria, whereas sewage-sourced bio-beads significantly enriched ExPECs. Polystyrene and wood were the least smooth particles, and so the importance of particle roughness on AMR prevalence was then directly investigated by comparing the colonization of virgin vs artificially weathered polyethylene particles. Surface weathering did not have a significant effect on the AMR prevalence of colonized particles. Our results suggest that the colonization of plastic and non-plastic particles by AMR and pathogenic bacteria may be enhanced by substrate-specific traits.

Adhesion of Candida albicans on PTFE membranes used in guided bone regeneration

OBJECTIVES

Guided bone regeneration (GBR) is a core procedure used to regenerate bone defects. The aim of the study was to investigate the adherence of Candida albicans on six commercially available polytetrafluoroethylene (PTFE) membranes used in GBR procedures and the subsequent clinical consequences.

MATERIALS AND METHODS

Six commercially available PTFE membranes were tested. Two of the membranes had a textured surface and the other four a plane, nontextured one. C. albicans (ATCC 24433) was cultured for 24 h, and its cell surface hydrophobicity was assessed using a modified method. C. albicans adhesion to membrane discs was studied by scanning electron microscopy (SEM) and real-time polymerase chain reaction (PCR).

RESULTS

C. albicans was found to be hydrophobic (77.25%). SEM analysis showed that C. albicans adherence to all membranes examined was characterized by patchy, scattered, and small clustered patterns except for one nontextured membrane with a most rough surface in which a thick biofilm was observed. Real-time PCR quantification revealed significantly greater adhesion of C. albicans cells to PTFE membranes than the control membrane (p ≤ .001) with the membranes having a textured surface exhibiting the highest count of 2680 × 104 cells/ml compared to the count of 707 × 104 cells/mL on those with a nontextured one (p ≤ .001). One membrane with nontextured surface, but with most rough surface was found to exhibit the highest count of 3010 × 104 cells/ml (p ≤ .05).

CONCLUSION

The results of this study indicate that C. albicans adhesion on membranes' surfaces depends on the degree of surface roughness and/or on the presence of a texture. Textured PTFE membranes and/or membranes high roughness showed significantly more adhered C. albicans cells. These findings can impact the surgeon's choice of GBR membrane and postoperative maintenance.

Intraoral ageing of aligners and attachments: Adverse effects on clinical efficiency and release of biologically-active compounds

The clinical application of aligners is accompanied by the ageing of the polymer appliances and the attachments used, which may result in inefficiency in reaching the predicted range of tooth movement, and release of compounds and microplastics in the oral cavity as a result of the friction, wear and attrition of the aligner and composite attachment. The purpose of this review is to present the mechanism and effects of in vivo ageing; describe the hydrolytic degradation of aligners and enzymatic degradation of composite attachments; examine the ageing pattern of aligners in vivo, under actual clinical scenarios; and identify a link to the discrepancy between predicted and actual clinical outcome. Lastly, strategies to deal with three potentially critical issues associated with the use of aligners, namely the necessity of weekly renewal, the dissimilar mechanical properties of aligner and attachment resulting in wear and plastic deformation of the aligner, and the development of integuments and biofilms with microbial colonization of the appliance, are discussed.

A novel multiplex fluorescent-labeling method for the visualization of mixed-species biofilms in vitro

In nature, bacteria usually exist as mixed-species biofilms, where they engage in a range of synergistic and antagonistic interactions that increase their resistance to environmental challenges. Biofilms are a major cause of persistent infections, and dispersal from initial foci can cause new infections at distal sites thus warranting further investigation. Studies of development and spatial interactions in mixed-species biofilms can be challenging due to difficulties in identifying the different bacterial species in situ. Here, we apply CellTrace dyes to studies of biofilm bacteria and present a novel application for multiplex labeling, allowing identification of different bacteria in mixed-species, in vitro biofilm models. Oral bacteria labeled with CellTrace dyes (far red, yellow, violet, and CFSE [green]) were used to create single- and mixed-species biofilms, which were analyzed with confocal spinning disk microscopy (CSDM). Biofilm supernatants were studied with flow cytometry (FC). Both Gram-positive and Gram-negative bacteria were well labeled and CSDM revealed biofilms with clear morphology and stable staining for up to 4 days. Analysis of CellTrace labeled cells in supernatants using FC showed differences in the biofilm dispersal between bacterial species. Multiplexing with different colored dyes allowed visualization of spatial relationships between bacteria in mixed-species biofilms and relative coverage by the different species was revealed through segmentation of the CSDM images. This novel application, thus, offers a powerful tool for studying structure and composition of mixed-species biofilms in vitro.IMPORTANCEAlthough most chronic infections are caused by mixed-species biofilms, much of our knowledge still comes from planktonic cultures of single bacterial species. Studies of formation and development of mixed-species biofilms are, therefore, required. This work describes a method applicable to labeling of bacteria for in vitro studies of biofilm structure and dispersal. Critically, labeled bacteria can be multiplexed for identification of different species in mixed-species biofilms using confocal spinning disk microscopy, facilitating investigation of biofilm development and spatial interactions under different environmental conditions. The study is an important step in increasing the tools available for such complex and challenging studies.

A review on antimicrobial strategies in mitigating biofilm-associated infections on medical implants

Biomedical implants are crucial in providing support and functionality to patients with missing or defective body parts. However, implants carry an inherent risk of bacterial infections that are biofilm-associated and lead to significant complications. These infections often result in implant failure, requiring replacement by surgical restoration. Given these complications, it is crucial to study the biofilm formation mechanism on various biomedical implants that will help prevent implant failures. Therefore, this comprehensive review explores various types of implants (e.g., dental implant, orthopedic implant, tracheal stent, breast implant, central venous catheter, cochlear implant, urinary catheter, intraocular lens, and heart valve) and medical devices (hemodialyzer and pacemaker) in use. In addition, the mechanism of biofilm formation on those implants, and their pathogenesis were discussed. Furthermore, this article critically reviews various approaches in combating implant-associated infections, with a special emphasis on novel non-antibiotic alternatives to mitigate biofilm infections.

Evaluation of surface roughness of differently manufactured denture base materials

STATEMENT OF PROBLEM

The popularity of computer-aided design and computer-aided manufacturing (CAD-CAM) dentures has led to the introduction of new denture materials and resins. However, studies on the surface characteristics of these materials and how they compare to dentures fabricated by more traditional methods are lacking.

PURPOSE

The purpose of this cross-sectional study was to determine whether the surface roughness (Ra) of denture base materials differed based on manufacturing technique.

MATERIAL AND METHODS

Disks of Ø10×2-mm (n=10) were fabricated using 6 different manufacturing techniques, including compression molding (Lucitone 199), injection molding (Ivocap High Impact), Computer Numerical Control (CNC) milling (Ivotion Base), and additive manufacturing on the Carbon M2 (Lucitone Digital Print), the SprintRay Pro55 S (Dentca Denture Base II), and the Envision One (Flexcera Base) systems. An automatic, noncontact laser confocal microscope (VK-X1000 Series; KEYENCE) was used to analyze the Ra surface roughness of each specimen at ×5 magnification. The images were imported into a multifile analyzer, horizontal and vertical roughness profiles were inserted into each scan, and Ra values were calculated and averaged by following the International Organization for Standardization (ISO) 4287 standard. A 1-way analysis of variance (ANOVA) was performed to compare the effect of manufacturing technique on surface roughness, followed by the Tukey multiple comparisons test (α=.05).

RESULTS

The additively manufactured Dentca Denture Base II (AM-DB) exhibited a statistically significantly higher Ra when compared with the other test groups (P<.001). The additively manufactured Flexcera Base (AM-FB) showed a higher Ra mean value when compared with injection molding (IM) (P=.036). No statistically significant difference in surface roughness was found among the other tested materials representing the different processing methods (P>.05).

CONCLUSIONS

The manufacturing method influences the Ra of denture base materials with varying results. The injection molding method resulted in the smoothest surface compared with additively manufactured and CNC-milled denture base materials.

Understanding the Predictive Potential of the Oral Microbiome in the Development and Progression of Early Childhood Caries

BACKGROUND

Early childhood caries (ECC) is the most common chronic disease in young children and a public health problem worldwide. It is characterized by the presence of atypical and fast progressive caries lesions. The aggressive form of ECC, severe early childhood caries (S-ECC), can lead to the destruction of the whole crown of most of the deciduous teeth and cause pain and sepsis, affecting the child's quality of life. Although the multifactorial etiology of ECC is known, including social, environmental, behavioral, and genetic determinants, there is a consensus that this disease is driven by an imbalance between the oral microbiome and host, or dysbiosis, mediated by high sugar consumption and poor oral hygiene. Knowledge of the microbiome in healthy and caries status is crucial for risk monitoring, prevention, and development of therapies to revert dysbiosis and restore oral health. Molecular biology tools, including next-generation sequencing methods and proteomic approaches, have led to the discovery of new species and microbial biomarkers that could reveal potential risk profiles for the development of ECC and new targets for anti-caries therapies. This narrative review summarized some general aspects of ECC, such as definition, epidemiology, and etiology, the influence of oral microbiota in the development and progression of ECC based on the current evidence from genomics, transcriptomic, proteomic, and metabolomic studies and the effect of antimicrobial intervention on oral microbiota associated with ECC.

CONCLUSION

The evaluation of genetic and proteomic markers represents a promising approach to predict the risk of ECC before its clinical manifestation and plan efficient therapeutic interventions for ECC in its initial stages, avoiding irreversible dental cavitation.

Efficiency of various biofilm carriers and microbial interactions with substrate in moving bed-biofilm reactor for environmental wastewater treatment

In a moving bed-biofilm reactor (MBBR), the fluidization efficiency, immobilization of microbial cells, and treatment efficiency are directly influenced by the shape and pores of biofilm carriers. Moreover, the efficacy of bioremediation mainly depends on their interaction interface with microbes and substrate. This review aims to comprehend the role of different carrier properties such as material shapes, pores, and surface area on bioremediation productivity. A porous biofilm carrier with surface ridges containing spherical pores sizes > 1 mm can be ideal for maximum efficacy. It provides diverse environments for cell cultures, develops uneven biofilms, and retains various cell sizes and biomass. Moreover, the thickness of biofilm and controlled scaling shows a significant impact on MBBR performance. Therefore, the effect of these parameters in MBBR is discussed detailed in this review, through which existing literature and technical strategies that focus on the surface area as the primary factor can be critically assessed.

Prevention of Initial Bacterial Attachment by Osteopontin and Other Bioactive Milk Proteins

A considerable body of work has studied the involvement of osteopontin (OPN) in human physiology and pathology, but comparably little is known about the interaction of OPN with prokaryotic cells. Recently, bovine milk OPN has been proposed as a therapeutic agent to prevent the build-up of dental biofilms, which are responsible for the development of caries lesions. Bioactive milk proteins are among the most exciting resources for caries control, as they hamper bacterial attachment to teeth without affecting microbial homeostasis in the mouth. The present work investigated the ability of OPN to prevent the adhesion of three dental biofilm-forming bacteria to saliva-coated surfaces under shear-controlled flow conditions in comparison with the major milk proteins α-lactalbumin, β-lactoglobulin, αs1-casein, β-casein and κ-casein, as well as crude milk protein. OPN was the most effective single protein to reduce the adhesion of Actinomyces naeslundii, Lactobacillus paracasei subsp. paracasei and Streptococcus mitis. β-casein and crude milk protein also had a pronounced effect on all three species, which suggests binding to different microbial surface structures rather than the blocking of a specific bacterial adhesin. Bioactive milk proteins show potential to delay harmful biofilm formation on teeth and hence the onset of biofilm-related oral disease.

Modulation of Streptococcus mutans Adherence to Hydroxyapatite by Engineered Salivary Peptides

Since the modification of the proteinaceous components of the Acquired Enamel Pellicle (AEP) could influence the adhesion of Streptococcus mutans, the most cariogenic bacteria, to dental surfaces, we assessed if engineered salivary peptides would affect the adherence and modulate the bacterial proteome upon adherence. Single-component AEPs were formed onto hydroxyapatite (HAp) discs by incubating them with statherin, histatin-3, DR9, DR9-DR9, DR9-RR14, RR14, and parotid saliva. Then, the discs were inoculated with S. mutans UA159 and the bacteria were allowed to adhere for 2 h, 4 h, and 8 h (n = 12/treatment/time point). The number of bacteria adhered to the HAp discs was determined at each time point and analyzed by two-way ANOVA and Bonferroni tests. Cell-wall proteins were extracted from adhered, planktonic, and inoculum (baseline) bacteria and proteome profiles were obtained after a bottom-up proteomics approach. The number of adhered bacteria significantly increased over time, being the mean values obtained at 8 h, from highest to lowest, as follows: DR9-RR14 > statherin > RR14 = DR9-DR9 > DR9 = histatin3 > saliva (p < 0.05). Treatments modulated the bacterial proteome upon adherence. The findings suggested a potential use of our engineered peptide DR9-DR9 to control S. mutans biofilm development by reducing bacterial colonization.

Antibacterial Sonodynamic Therapy: Current Status and Future Perspectives

Multidrug-resistant bacteria have emerged in both community and hospital settings, partly due to the misuse of antibiotics. The inventory of viable antibiotics is rapidly declining, and efforts toward discovering newer antibiotics are not yielding the desired outcomes. Therefore, alternate antibacterial therapies based on physical mechanisms such as light and ultrasound are being explored. Sonodynamic therapy (SDT) is an emerging therapeutic approach that involves exposing target tissues to a nontoxic sensitizing chemical and low-intensity ultrasound. SDT can enable site-specific cytotoxicity by producing reactive oxygen species (ROS) in response to ultrasound, which can be harnessed for treating bacterial infections. This approach can potentially be used for both superficial and deep-seated microbial infections. The majority of the sonosensitizers reported are nonpolar, exhibiting limited bioavailability and a high clearance rate in the body. Therefore, targeted delivery agents such as nanoparticle composites, liposomes, and microbubbles are being investigated. This article reviews recent developments in antibacterial sonodynamic therapy, emphasizing biophysical and chemical mechanisms, novel delivery agents, ultrasound exposure and image guidance strategies, and the challenges in the pathway to clinical translation.

Extracellular Polymeric Substances (EPS) produced by Streptomyces sp. biofilms: Chemical composition and anticancer properties

The extracellular polymeric substances (EPS) have shown free radical scavenging and antitumor activity against both breast and colon cell lines. In this regard, actinobacteria have become an increasingly popular sources of EPS. Therefore, in this study four Streptomyces strains isolated from contaminated soil (M7, A5, A14 and MC1) were evaluated for determining its biofilm-forming capacity including under pesticide stress. In addition, chemical composition of EPS and its cytotoxic effects over 4T1 breast cancer cell and Caco-2 human tumor colon cells were evaluated. The results demonstrated that Streptomyces sp. A5 had the highest capability to develop biofilm more than other strains tested, even under pesticide stress. Moreover, this strain produced EPS with a total protein/total polysaccharide rate of 1.59 ± 0.05. On the other hand, cytotoxicity assays of EPS showed that Streptomyces sp. A5 display a higher toxic effect against 4T1 Breast cancer cells (96.2 ± 13.5 %), Caco-2 (73.9 ± 6.4 %) and low toxicity (29.9 % ± 9.1 %) against non-transformed intestinal cells (IEC-18). Data do not show cytotoxic effect relationship with biofilm-forming capabilities of strains, nor the chemical composition of EPS matrix. The gene that codes for polysaccharide deacetylase, parB-like and transRDD proteins, were identified. These results contribute to the knowledge about the variability of chemical composition and potential cytotoxic properties of EPS produced by Streptomyces biofilms. It proposes interesting future challenges for linking Streptomyces-based pesticide remediation technology with the development of new antitumor drugs.

The dentin pellicle - A neglected topic in dental research

OBJECTIVE

All soft and solid surfaces exposed to the oral cavity are covered by an acquired pellicle. While the pellicle adsorbed on enamel is well researched, only limited data are available on the dentin pellicle. The purpose of the present review is to summarize studies considering the composition, structure and properties of the dentin pellicle and compare them with the current state of research on enamel pellicle.

METHODS

The literature search was conducted using Medline database and Google Scholar, including checking reference lists of journal articles by handsearching. Thereby, 19 studies were included in the present review.

RESULTS AND CONCLUSION

The dentin pellicle has a similar ultrastructure to the enamel pellicle, which is up to 1 μm thick depending on pellicle formation time and localization in the oral cavity. In contrast, due to the lack of studies on the dentin pellicle regarding its composition and properties, a comparison to the enamel pellicle is difficult. So far, only one study showed anti-abrasive properties and data on anti-erosive properties were controversial. Despite becoming more and more clinically relevant due to the increasing frequency of dentin exposure, the dentin pellicle is largely unexplored. For further investigations it is not only necessary to standardize dentin specimens, but also to assess fundamental research on dentin itself, as its complex morphology and composition may have a crucial influence on pellicle formation. Furthermore, a more detailed knowledge of the dentin pellicle may also reveal target sites for modification in favor of its protective properties.

Dental Biofilm and Saliva Microbiome and Its Interplay with Pediatric Allergies

Little is known about the interplay and contribution of oral microorganisms to allergic diseases, especially in children. The aim of the clinical study was to associate saliva and dental biofilm microbiome with allergic disease, in particular with allergic asthma. In a single-center study, allergic/asthmatic children (n = 15; AA-Chd; age 10.7 ± 2.9), atopic/allergic children (n = 16; AT/AL-Chd; 11.3 ± 2.9), and healthy controls (n = 15; CON-Chd; age 9.9 ± 2.2) were recruited. After removing adhering biofilms from teeth and collecting saliva, microbiome was analyzed by using a 16s-rRNA gene-based next-generation sequencing in these two mediums. Microbiome structure differed significantly between saliva and dental biofilms (β-diversity). Within the groups, the dental biofilm microbiome of AA-Chd and AT/AL-Chd showed a similar microbial fingerprint characterized by only a small number of taxa that were enriched or depleted (4) compared to the CON-Chd, while both diseased groups showed a stronger microbial shift compared to CON-Chd, revealing 14 taxa in AA-Chd and 15 taxa in AT/AL-Chd that were different. This could be the first note to the contribution of dental biofilm and its metabolic activity to allergic health or disease.

Oral biofilms revisited: A novel host tissue of bacteriological origin

The central theme of this volume of Periodontology 2000 is that the microbial dental plaque biofilm, specifically the subgingival dental plaque biofilm, mimics a human tissue in both structure and function. As a basis for this assertion we use the definition of a tissue as an aggregate of similar cells and cell products forming a defined structure with a specific function, in a multicellular organism. Accordingly, we propose that the dental plaque biofilm represents an acquired human tissue largely of bacterial origin that maintains the health of gingival tissue. Furthermore, we acknowledge that disease can be defined as a deviation from the normal structure or an interruption to the function of any body part, organ, or system, and that is manifested by a characteristic set of symptoms and signs whose etiology, pathology, and prognosis may be known or unknown. Therefore, in this volume we present the concept that periodontitis is a disruption of the normal function of the healthy subgingival plaque biofilm with concomitant disruption to its functional properties in relation to innate defense surveillance and tissue maintenance, leading to excessive, deregulated inflammation and tissue destruction.

Bacterial coaggregation in aquatic systems

The establishment of a sessile community is believed to occur in a sequence of steps where genetically distinct bacteria can become attached to partner cells via specific molecules, in a process known as coaggregation. The presence of bacteria with the ability to autoaggregate and coaggregate has been described for diverse aquatic systems, particularly freshwater, drinking water, wastewater, and marine water. In these aquatic systems, coaggregation already demonstrated a role in the development of complex multispecies sessile communities, including biofilms. While specific molecular aspects on coaggregation in aquatic systems remain to be understood, clear evidence exist on the impact of this mechanism in multispecies biofilm resilience and homeostasis. The identification of bridging bacteria among coaggregating consortia has potential to improve the performance of wastewater treatment plants and/or to contribute for the development of strategies to control undesirable biofilms. This study provides a comprehensive analysis on the occurrence and role of bacterial coaggregation in diverse aquatic systems. The potential of this mechanism in water-related biotechnology is further described, with particular emphasis on the role of bridging bacteria.

In vitro Biofilm Formation by Bioluminescent Bacteria Isolated from the Marine Fish Gut

The internal surface of the animal gastrointestinal tract is covered by microbial biofilms. They play an important role in the development and functioning of the host organism and protect it against pathogens. Microbial communities of gastrointestinal biofilms are less elucidated than luminal microbiota. Therefore, the studies of biofilm formation by gastrointestinal microorganisms are a topical issue. For the first time, we report the formation of a biofilm in vitro by the strains of bioluminescent bacteria isolated from the intestines of marine fish. These bacteria exhibit co-aggregation and tend to attach to solid surfaces. The attachment of cells is accompanied by appearance of the pili. Then, we observed the formation of microcolonies and the production of extracellular polymer substances (EPSs) connecting bacterial cells into an integrated system. The presence of acidic polysaccharides is shown in the EPS when using the ruthenium red staining. Acidic polysaccharides in this matrix is a biochemical evidence of microbial biofilms. On the fibers of the polymer matrix, these bacteria form the "mushroom body"-type structures. Matured biofilms exhibit a specific three-dimensional architecture with pores and channels formed by cells and EPS. We also demonstrated the formation of a biofilm by binary culture of the luminous enterobacterium Kosakonia cowanii and a Gram-positive Macrococcus sp. The data obtained help to understand the role of these bacteria in the intestines of fish. They lead to a new study in the field of investigation of the intestinal microbiome of fish.

Biological and Physiochemical Methods of Biofilm Adhesion Resistance Control of Medical-Context Surface

The formation of biofilms on medical-context surfaces gives the EPS embedded bacterial community protection and additional advantages that planktonic cells would not have such as increased antibiotic resistance and horizontal gene transfer. Bacterial cells tend to attach to a conditioning layer after overcoming possible electrical barriers and go through two phases of attachments: reversible and irreversible. In the first, bacterial attachment to the surface is reversible and occurs quickly whilst the latter is permanent and takes place over a longer period of time. Upon reaching a certain density in the bacterial community, quorum sensing causes phenotypical changes leading to a loss in motility and the production of EPS. This position paper seeks to address the problem of bacterial adhesion and biofilm formation for the medical surfaces by comparing inhabiting physicochemical interactions and biological mechanisms. Several physiochemical methodologies (e.g. ultrasonication, alternating magnetic field and chemical surface coating) and utilizing biological mechanisms (e.g. quorum quenching and EPS degrading enzymes) were suggested. The possible strategical applications of each category were suggested and evaluated to a balanced position to possibly eliminate the adhesion and formation of biofilms on medical-context surfaces.

Hydrodynamics and surface properties influence biofilm proliferation

A biofilm is an interface-associated colloidal dispersion of bacterial cells and excreted polymers in which microorganisms find protection from their environment. Successful colonization of a surface by a bacterial community is typically a detriment to human health and property. Insight into the biofilm life-cycle provides clues on how their proliferation can be suppressed. In this review, we follow a cell through the cycle of attachment, growth, and departure from a colony. Among the abundance of factors that guide the three phases, we focus on hydrodynamics and stratum properties due to the synergistic effect such properties have on bacteria rejection and removal. Cell motion, whether facilitated by the environment via medium flow or self-actuated by use of an appendage, drastically improves the survivability of a bacterium. Once in the vicinity of a stratum, a single cell is exposed to near-surface interactions, such as van der Waals, electrostatic and specific interactions, similarly to any other colloidal particle. The success of the attachment and the potential for detachment is heavily influenced by surface properties such as material type and topography. The growth of the colony is similarly guided by mainstream flow and the convective transport throughout the biofilm. Beyond the growth phase, hydrodynamic traction forces on a biofilm can elicit strongly non-linear viscoelastic responses from the biofilm soft matter. As the colony exhausts the means of survival at a particular location, a set of trigger signals activates mechanisms of bacterial release, a life-cycle phase also facilitated by fluid flow. A review of biofilm-relevant hydrodynamics and startum properties provides insight into future research avenues.

A study of bacteria adhesion and microbial corrosion on different stainless steels in environment containing Desulfovibrio vulgaris

Stainless steel is an important material used in many applications due to its mechanical strength and corrosion-resistant properties. The high corrosion resistance of stainless steel is provided by the passive film. Different stainless steels have different alloy elements and surface properties which could have a significant influence on bacterial attachment to the surface and thus might result in different microbial corrosion behaviours. In this study, the effect of adhesion of sulfate-reducing bacteria (SRB) on corrosion behaviour in artificial seawater on different stainless steels was investigated. Stainless steel materials used were SS 410, SS 420, SS 316 and DSS 2205 and pure chromium. The contact angle was measured to study the effect of surface properties of materials. Adhesion was measured by counting cells attached to the surface of materials. The corrosion behaviour of the materials was measured by electrochemical testing including measuring open circuit potential, electrochemical impedance spectroscopy and potentiodynamic behaviour. The long-term corrosion behaviour of each material was studied after six months of exposure by measuring weight loss and surface analysis with scanning electron microscope with energy-dispersive X-ray analysis. Hydrophobicity had a strong effect on bacterial attachment. Alloying elements e.g. nickel also had shown its ability to attract bacteria to adhere on the surface. However, the corrosion rate of different materials is determined not only by bacterial attachment but also by the stability of the passive film which is determined by the alloying elements, such as Mo and Cr. Chromium showed high resistance to corrosion, possibly due to toxicity on bacterial attachment. The nature of bacterial attachment and corrosion behaviour of the materials are discussed.

The penetration effect of HMME-mediated low-frequency and low-intensity ultrasound against the Staphylococcus aureus bacterial biofilm

Background

The purpose of this study was to observe the effect of hematoporphyrin monomethyl ether (HMME)-mediated low-frequency and low-intensity ultrasound on mature and stable Staphylococcus aureus (S. aureus) biofilms under different ultrasound parameters.

Methods

The biofilm was formed after 48-h culture with stable concentration of bacterial solution. Different types of ultrasound and time were applied to the biofilm, and the ultrasonic type and time of our experiments were determined when the biofilm was not damaged. The penetration effects of low-frequency and low-intensity ultrasound were decided by the amount of HMME that penetrated into the biofilm which was determined by fluorescence spectrometry.

Results

The destruction of biofilms by pulse waveform was the strongest. Sinusoidal low-frequency and low-intensity ultrasound can enhance the biofilm permeability. For a period of time after the ultrasound was applied, the biofilm permeability increased, however, changes faded away over time.

Conclusions

Low-frequency and low-intensity sinusoidal ultrasound significantly increased the permeability of the biofilms, which was positively correlated with the time and the intensity of ultrasound. Simultaneous action of ultrasound and HMME was the most effective way to increase the permeability of the biofilms.

Effects of Experimental Agents Containing Tannic Acid or Chitosan on the Bacterial Biofilm Formation in Situ

Chitosan and tannic acid are known for their antibacterial properties. In the present in-situ study, their antibacterial and anti-adherent effects on biofilm formation on enamel were investigated. Six subjects carried upper jaw splints with bovine enamel specimens, allowing in-situ biofilm formation. During the two-day trial, subjects rinsed with experimental solutions that contained either chitosan, tannic acid (pH = 2.5), tannic acid (pH = 7) or hydrochloric acid. Water served as the negative and chlorhexidine as the positive control. Rinsing occurred four or five times following two different rinsing protocols to investigate both the immediate and long-lasting effects. After 48 h of intraoral exposure, the dental plaque was stained with LIVE/DEAD^® BacLight, and fluorescence micrographs were evaluated by using the software ImageJ. The results were verified by scanning electron microscopy. Rinsing with chitosan resulted in little immediate antibacterial and anti-adherent effects but failed to show any long-lasting effect, while rinsing with tannic acid resulted in strong immediate and long-lasting effects. Except for a slightly lower antibacterial effect, the neutral solution of tannic acid was as good as the acidic solution. Hydrochloric acid showed neither an antibacterial nor an anti-adherent effect on dental biofilm formation. Experimental solutions containing tannic acid are promising anti-biofilm agents, irrespective of the pH values of the solutions. Chitosan, on the other hand, was not able to prevent biofilm formation.

Materials Sealing Preventing Biofilm Formation in Implant/Abutment Joints: Which Is the Most Effective? A Systematic Review and Meta-Analysis

The purpose of this systematic review was to evaluate the literature available for materials exhibiting the best efficacy in preventing biofilm formation in the interior of implants. We searched PubMed/MEDLINE, Scopus, and Cochrane databases. This review is registered with the PROSPERO database and followed the suitability of the PRISMA protocol. The initial search resulted in 326 articles from the databases. After they were read, 8 articles remained, and the inclusion and exclusion criteria were applied. Six of these 8 articles were classified as in vitro and 2 were classified as in situ. The regions of the implants evaluated ranged from the interface of the pieces to the occlusal upper access of the abutment. The implant connections evaluated the Morse taper, external connection, and internal connection. Meta-analysis of the quantitative data was performed at a significance level of .05. Cotton exhibited poor control of infiltration, even in combination with other materials. Isolated gutta-percha (GP) and polytetrafluoroethylene (PTFE) tape with composite resin (CR) or GP performed better as physical barriers. The best results for chemical barriers were observed by the application of 1% chlorhexidine gluconate (CG) gel, thymol varnish, and the deposition of Ag films onto the surface. The applied meta-analysis did not show a significant difference in comparison between the different types of implant connections (P > .05). The application of CG and thymol varnish antimicrobials was effective in preventing biofilm formation and easy clinical execution; these could be used in combination with CR, GP, and PTFE.

Dental Plaque Removal by Ultrasonic Toothbrushes

With the variety of toothbrushes on the market, the question arises, which toothbrush is best suited to maintain oral health? This thematic review focuses first on plaque formation mechanisms and then on the plaque removal effectiveness of ultrasonic toothbrushes and their potential in preventing oral diseases like periodontitis, gingivitis, and caries. We overviewed the physical effects that occurred during brushing and tried to address the question of whether ultrasonic toothbrushes effectively reduced the microbial burden by increasing the hydrodynamic forces. The results of published studies show that electric toothbrushes, which combine ultrasonic and sonic (or acoustic and mechanic) actions, may have the most promising effect on good oral health. Existing ultrasonic/sonic toothbrush models do not significantly differ regarding the removal of dental biofilm and the reduction of gingival inflammation compared with other electrically powered toothbrushes, whereas the manual toothbrushes show a lower effectiveness.

The antimicrobial and cytotoxic effects of a copper-loaded zinc oxide phosphate cement

Objectives

Evidence about modifications of dental luting materials to minimize biological failure at the “marginal gap” between teeth and fixed prosthodontics is scarce. We compared a copper-modified (Co-ZOP) and a conventional zinc oxide phosphate cement (ZOP) in terms of antimicrobial and cytotoxic potentials in vitro and in vivo.

Materials and methods

Specimens of ZOP and Co-ZOP were characterized by the mean arithmetic roughness (Ra) and surface free energy (SFE). Powder components were examined using scanning electron microscopy (SEM). Energy-dispersive X-ray spectroscopy (EDX) showed elemental material compositions. In vitro microbial adhesion was shown using SEM, luminescence, and fluorescence assays. CCK-8 assays of mouse fibroblasts (L929) and human gingival fibroblasts (GF-1) were performed after 6, 24, and 48 h of specimen incubation. In vivo, ZOP and Co-ZOP specimens were applied intraorally for 12 h; biofilm accumulation was shown using SEM.

Results

Ra of ZOP and Co-ZOP showed no significant differences; SFE was significantly higher for Co-ZOP. EDX exhibited minor copper radiation for Co-ZOP, none for ZOP. In vitro fungal adhesion to Co-ZOP was significantly higher than to ZOP; in vitro streptococcal adhesion, cytotoxicity, and in vivo biofilm formation were not significantly different.

Conclusions

Co-ZOP showed low surface allocations of copper with no improved antimicrobial properties compared with conventional ZOP in vitro or in vivo.

Clinical relevance

Antimicrobial effects and low cytotoxicity of biomaterials are important for the clinical outcome. Based on our in vitro and in vivo results, no clinical recommendation can be given for the tested Co-ZOP.

Análise da “1a Recomendação Brasileira para o Gerenciamento do Biofilme em Feridas Crônicas e Complexas”

Objetivos: Analisar criticamente a “1ª Recomendação brasileira para o gerenciamento de biofilme em feridas crônicas e complexas”. Método: Realizou-se revisão da literatura atual às informações nele contidas. Resultados: Observou-se que a publicação carece de metodologia compatível com o título, existem lacunas nas recomendações quanto à classificação das evidências e com ausência de fundamentação a partir de importantes consensos internacionais para o tratamento das feridas complexas com suspeita de biofilme, publicados nos últimos três anos. Conclusão: Conclui-se que o manuscrito não deve ser usado como guia de recomendações clínicas, mas como revisão bibliográfica sobre o tema.

Analysis of “1st Brazilian Recommendation for Biofilm Management in Chronic and Complex Wounds”

Objectives: Analyze critically the “1st Brazilian Recommendation for Biofilm Management in Chronic and Complex Wounds” (from Portuguese, “1a Recomendação Brasileira para o Gerenciamento de Biofilme em Feridas Crônicas e Complexas”). Method: Reviewing information contained in said document according to current literature. Results: The publication was showed to lack methodology compatible with its title; gaps in the recommendations were perceived regarding evidence classification, as well as an absence of grounding from important international consensus, published in the last three years, about treatment of complex wounds with suspected biofilm. Conclusion: The document was concluded to be inadequate for use as a clinical guideline, being considered only a bibliographic review about the theme.

From the Titanic and other shipwrecks to biofilm prevention: The interesting role of polyphenol-protein complexes in biofilm inhibition

Bacteria attach themselves either reversibly or irreversibly onto practically any surface in aqueous and other environments in order to reproduce, while generating extracellular polymeric substances (EPS) as a supportive structure for biofilm formation. Surfaces with a potential to prevent cellular attachment and aggregation (biofilm) would be extremely useful in environmental, biotechnological, medical and industrial applications. The scientific community is currently focusing on the design of micro- and nano-scale textured surfaces with antibacterial and/or antifouling properties (e.g., filtration membranes). Several serum and tissue proteins promote bacterial adhesion (for example, albumin, fibronectin and fibrinogen), whereas polyphenols form complexes with proteins which change their structural, functional and nutritional properties. For example, tannic acid, a compound composed of polygalloyl glucoses or polygalloyl quinic acid esters and several galloyl moieties, inhibits the growth of many bacterial strains. The present review is based on different nautical archaeology research data, and asks a simple but as yet unanswered question: What is the chemistry that prevents leather biodegradation by environmental bacteria and/or formation of biofilms? Future research should answer these questions, which are highly important for biofilm prevention.

Changes in Cellular Elasticities and Conformational Properties of Bacterial Surface Biopolymers of Multidrug-Resistant Escherichia coli (MDR-E. coli) Strains in Response to Ampicillin

The roles of the thicknesses and grafting densities of the surface biopolymers of four multi-drug resistant (MDR) Escherichia coli bacterial strains that varied in their biofilm formation in controlling cellular elasticities after exposure to ampicillin were investigated using atomic force microscopy. Exposure to ampicillin was carried out at minimum inhibitory concentrations for different duration times. Our results indicated that the four strains resisted ampicillin through variable mechanisms. Strain A5 did not change its cellular properties upon exposure to ampicillin and as such resisted ampicillin through dormancy. Strain H5 increased its biopolymer brush thickness, adhesion and biofilm formation and kept its roughness, surface area and cell elasticity unchanged upon exposure to ampicillin. As such, this strain likely limits the diffusion of ampicillin by forming strong biofilms. At three hours’ exposure to ampicillin, strains D4 and A9 increased their roughness, surface areas, biofilm formation, and brush thicknesses and decreased their elasticities. Therefore, at short exposure times to ampicillin, these strains resisted ampicillin through forming strong biofilms that impede ampicillin diffusion. At eight hours’ exposure to ampicillin, strains D4 and A9 collapsed their biopolymers, increased their apparent grafting densities and increased their cellular elasticities. Therefore, at long exposure times to ampicillin, cells utilized their higher rigidity to reduce the diffusion of ampicillin into the cells. The findings of this study clearly point to the potential of using the nanoscale characterization of MDR bacterial properties as a means to monitor cell modifications that enhance “phenotypic antibiotic resistance”.

A Comparison of Bacterial Adhesion and Biofilm Formation on Commonly Used Orthopaedic Metal Implant Materials: An In vitro Study

BACKGROUND

Bacterial adherence and biofilm formation on the surface of biomaterials can often lead to implant-related infections, which may vary depending on the species of microorganisms, type of biomaterial used, and physical characteristics of implant surfaces. However, there are limited studies specifically comparing biofilm formation between commonly used metallic orthopaedic implant materials and different bacterial strains. This in vitro study is to evaluate the ability of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa to adhere to and to form biofilms on the surface of five orthopaedic biomaterials, viz., cobalt and chromium, highly cross-linked polyethylene, stainless steel, trabecular metal, and titanium alloy.

MATERIALS AND METHODS

Bacterial adherence and bacterial biofilm-formation assays were performed by culturing S. aureus ATCC 29213, S. epidermidis ATCC 35984, E. coli ATCC 35218, K. pneumoniae ATCC 700603, and P. aeruginosa ATCC 27853 for 48 h on five different biomaterials. Quantitative bacterial adherence and biofilm formation were analyzed with a scanning electron microscope.

RESULTS

The highest level of adherence was observed on highly cross-linked polyethylene, followed by titanium, stainless steel, and trabecular metal, with the lowest occurring on the cobalt-chromium alloy. Among the bacterial strains tested, the ability for high adherence was observed with S. epidermidis and K. pneumoniae followed by P. aeruginosa and E. coli, whereas S. aureus showed the least adherence.

CONCLUSION

Cobalt-chromium was observed to have the lowest proclivity towards bacterial adherence compared to the other biomaterials tested. However, bacterial adhesion occurred with all the materials. Hence, it is necessary to further evaluate newer biomaterials that are resistant to bacterial adherence.

In Vitro Comparison of the Efficacy of Peri-Implantitis Treatments on the Removal and Recolonization of Streptococcus gordonii Biofilm on Titanium Disks

Objective: To compare the efficacy of four commonly used clinical procedures in removing Streptococcus gordonii biofilms from titanium disks, and the recolonization of the treated surfaces. Background: Successful peri-implantitis treatment depends on the removal of the dental biofilm. Biofilm that forms after implant debridement may threaten the success of the treatment and the long-term stability of the implants. Methods:S. gordonii biofilms were grown on titanium disks for 48 h and removed using a plastic curette, air-abrasive device (Perio-Flow®), titanium brush (TiBrush®), or implantoplasty. The remaining biofilm and the recolonization of the treated disks were observed using scanning electron microscopy and quantified after staining with crystal violet. Surface roughness (Ra and Rz) was measured using a profilometer. Results:S. gordonii biofilm biomass was reduced after treatment with Perio-Flow®, TiBrush®, and implantoplasty (all p < 0.05), but not plastic curette (p > 0.05), compared to the control group. Recolonization of S. gordonii after treatment was lowest after Perio-Flow®, TiBrush®, and implantoplasty (all p < 0.05 vs. control), but there was no difference between the plastic curette and the control group (p > 0.05). Ra and Rz values ranged from 1–6 µm to 1–2 µm and did not differ statistically between the control, plastic curette, Perio-Flow, and TiBrush groups. However, the implantoplasty group showed a Ra value below 1 µm (p < 0.01, ANOVA, Tukey). Conclusions: Perio-Flow^®, TiBrush^®, and implantoplasty were more effective than the plastic curette at removing the S. gordonii biofilm and preventing recolonization. These results should influence the surgical management of peri-implantitis.

Candida Interactions with the Oral Bacterial Microbiota

The human oral cavity is normally colonized by a wide range of microorganisms, including bacteria, fungi, Archaea, viruses, and protozoa. Within the different oral microenvironments these organisms are often found as part of highly organized microbial communities termed biofilms, which display consortial behavior. Formation and maintenance of these biofilms are highly dependent on the direct interactions between the different members of the microbiota, as well as on the released factors that influence the surrounding microbial populations. These complex biofilm dynamics influence oral health and disease. In the latest years there has been an increased recognition of the important role that interkingdom interactions, in particular those between fungi and bacteria, play within the oral cavity. Candida spp., and in particular C. albicans, are among the most important fungi colonizing the oral cavity of humans and have been found to participate in these complex microbial oral biofilms. C. albicans has been reported to interact with individual members of the oral bacterial microbiota, leading to either synergistic or antagonistic relationships. In this review we describe some of the better characterized interactions between Candida spp. and oral bacteria.

Surface roughness implant-retained mandibular bar and ball joint overdentures and adherence of microorganisms

Objective:

The aim of this study is to assess the surface roughness of the implant-retained mandibular bar overdenture (BOD) and the implant-retained mandibular ball joint overdenture (BJOD) in jaw and its relation with the adhesion of molds and yeasts and mesophyll aerobe, in time 30 and 180 days in mouth.

Materials and Methods:

Five-systems titanium bar CARES^® and synOcta^® Straumann^® Dental Implant System, Holding AG Inc., Basel, Switzerland (BOD), and five-systems joint ball Klockner^® Implant System; Soadco Inc., Escaldes-Engordany; Andorra (BJOD), were used in two parallel groups of five participants, in an essay to simple blind person. To 30 and 180 days, the overdentures were withdrawn and evaluated the Ra: ųm. SJ-301^® Mitutoyo Corporation Inc., Kanagawa, Japan, and the adhesion of microorganisms (colony-forming unit/ml).

Results:

The results were as follows: the R_a: Um (30^th and 180^th): BOD, 0.965–1.351; BJOD, 1.325–2.384. Adhesion: Molds and yeasts, BOD, 2.6 × 10² and 4.6 × 10³; BJOD, 3.0 × 10² and 5.3 × 10⁴. Adhesion: Mesophyll aerobe, BOD, 3.8 × 10⁶ and 5.8 × 10⁶; BJOD, 4.3 × 10⁶ and 7.1 × 10⁷.

Conclusions:

At 30 days (P = 0.489), there were no differences in BOD and BJOD for adhesion of molds and yeasts and mesophyll aerobe between both overdentures. At 180 days (P = 0.723), there were differences in the adhesion of mold and yeast and mesophyll aerobe, being greater in BJOD.

In vitro evaluation of microbial adhesion on the different surface roughness of acrylic resin specific for ocular prosthesis

OBJECTIVE

The purpose of this study was to evaluate the influence of surface roughness in biofilm formation of four microorganisms (Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecalis, and Candida albicans) on acrylic resin surface of ocular prostheses.

MATERIALS AND METHODS

Acrylic resin samples were divided into six groups according to polishing: Group 1200S (1200 grit + silica solution); Group 1200; Group 800; Group 400; Group 120 and Group unpolished. Surface roughness was measured using a profilometer and surface images obtained with atomic force microscopy. Microbial growth was evaluated after 4, 24, and 48 hours of incubation by counting colony-forming units.

STATISTICAL ANALYSIS USED

For roughness, it was performed 1-way ANOVA and parametric Tukey test α5% (P ≤ 0.05). For CFU data found, it was applied Kruskal-Wallis and Mann-Whitney tests.

RESULTS

Group 120 and 400 presented the highest roughness values. For S. epidermidis and S. aureus, Group 1200S presented the lowest values of microbial growth. For E. faecalis at 4 hour, microbial growth was not observed. C. albicans did not adhere to the acrylic resin. Except for Group 1200S, different surface roughnesses did not statistically interfere with microbial adhesion and growth on acrylic surfaces of ocular prostheses.

CONCLUSIONS

The roughness did not interfere with the microbial adhesion of the microorganisms evaluated. The use of silica decreases significantly microbial growth.

Microbial Biofilms and Chronic Wounds

Background is provided on biofilms, including their formation, tolerance mechanisms, structure, and morphology within the context of chronic wounds. The features of biofilms in chronic wounds are discussed in detail, as is the impact of biofilm on wound chronicity. Difficulties associated with the use of standard susceptibility tests (minimum inhibitory concentrations or MICs) to determine appropriate treatment regimens for, or develop new treatments for use in, chronic wounds are discussed, with alternate test methods specific to biofilms being recommended. Animal models appropriate for evaluating biofilm treatments are also described. Current and potential future therapies for treatment of biofilm-containing chronic wounds, including probiotic therapy, virulence attenuation, biofilm phenotype expression attenuation, immune response suppression, and aggressive debridement combined with antimicrobial dressings, are described.

Biosurfactants: promising bioactive molecules for oral-related health applications

Biosurfactants are naturally produced molecules that demonstrate potentially useful properties such as the ability to reduce surface tensions between different phases. Besides having similar properties to their artificial chemical counterparts, they are regarded as environmental friendly, biodegradable and less toxic, which make them desirable candidates for downstream applications. The structure-activity-related properties of the biosurfactants which are directly correlated with potency of the biosurfactants as antimicrobial agents, the ability of the biosurfactants to alter surface energies and their ability to increase bioavailability are particularly what attract researchers to exploit their potential use in the oral-related health applications. Current research into biosurfactant indicates significant future potential for use in cosmetic and therapeutic oral hygiene product formulations and related medical device treatments.

Subnanometric Roughness Affects the Deposition and Mobile Adhesion of Escherichia coli on Silanized Glass Surfaces

We investigate the deposition and transient adhesion of Escherichia coli on alkyl and fluoroalkyl silanized glass surfaces of different carbon chain lengths. The rate at which bacteria deposit onto these surfaces decreases as the shear stress is increased from 3 to 67 mPa, but trends in the deposition rate across all surfaces cannot be predicted from extended DLVO calculations of the interaction potential. As the surface root-mean-square (rms) roughness increases, the deposition rate increases and the percentage of motile tethered cells decreases. Furthermore, on surfaces of root-mean-square roughness of less than 0.2 nm, bacteria exhibit mobile adhesion, for which surface-associated cells linearly translate distances greater than approximately 1.5 times their average body length along the flow direction. E. coli bacteria with and without flagella exhibit mobile adhesion, indicating that this behavior is not driven by these appendages. Cells that express fimbriae do not exhibit mobile adhesion. These results suggest that even subnanoscale roughness can influence the deposition and transient adhesion of bacteria and imply that strategies to reduce frictional interactions by making cells or surfaces smoother may help to control the initial fouling of surfaces by E. coli bacteria.

Influence of Physicochemical Aspects of Substratum Nanosurface on Bacterial Attachment for Bone Implant Applications

Biofilm formation on implant materials is responsible for periprosthetic infections. Bacterial attachment is important as the first stage in biofilm formation. It is meaningful to understand the influence of nanostructured surface on bacterial attachment. This review discusses the influence of physicochemical aspects of substratum nanosurface on bacterial attachment.

The Oral Microbiota

The oral microbiota represents an important part of the human microbiota, and includes several hundred to several thousand diverse species. It is a normal part of the oral cavity and has an important function to protect against colonization of extrinsic bacteria which could affect systemic health. On the other hand, the most common oral diseases caries, gingivitis and periodontitis are based on microorganisms. While (medical) research focused on the planktonic phase of bacteria over the last 100 years, it is nowadays generally known, that oral microorganisms are organised as biofilms. On any non-shedding surfaces of the oral cavity dental plaque starts to form, which meets all criteria for a microbial biofilm and is subject to the so-called succession. When the sensitive ecosystem turns out of balance - either by overload or weak immune system - it becomes a challenge for local or systemic health. Therefore, the most common strategy and the golden standard for the prevention of caries, gingivitis and periodontitis is the mechanical removal of this biofilms from teeth, restorations or dental prosthesis by regular toothbrushing.

Oral Streptococci Biofilm Formation on Different Implant Surface Topographies

The establishment of the subgingival microbiota is dependent on successive colonization of the implant surface by bacterial species. Different implant surface topographies could influence the bacterial adsorption and therefore jeopardize the implant survival. This study evaluated the biofilm formation capacity of five oral streptococci species on two titanium surface topographies. In vitro biofilm formation was induced on 30 titanium discs divided in two groups: sandblasted acid-etched (SAE- n = 15) and as-machined (M- n = 15) surface. The specimens were immersed in sterilized whole human unstimulated saliva and then in fresh bacterial culture with five oral streptococci species: Streptococcus sanguinis, Streptococcus salivarius, Streptococcus mutans, Streptococcus sobrinus, and Streptococcus cricetus. The specimens were fixed and stained and the adsorbed dye was measured. Surface characterization was performed by atomic force and scanning electron microscopy. Surface and microbiologic data were analyzed by Student's t-test and two-way ANOVA, respectively (P < 0.05). S. cricetus, S. mutans, and S. sobrinus exhibited higher biofilm formation and no differences were observed between surfaces analyzed within each species (P > 0.05). S. sanguinis exhibited similar behavior to form biofilm on both implant surface topographies, while S. salivarius showed the lowest ability to form biofilm. It was concluded that biofilm formation on titanium surfaces depends on surface topography and species involved.