Proteomic profile of the saliva and plasma protein layer adsorbed on Ti-Zr alloy: the effect of sandblasted and acid-etched surface treatment

Impact of citric acid and conventional denture cleansers on surface properties and antimicrobial performance of conventionally heat-processed acrylic resin: An in vitro study

STATEMENT OF PROBLEM

Effective decontamination of denture base acrylic resin is essential for biofilm removal but can compromise the integrity of the material. Citric acid has shown promise as a potent antimicrobial agent, though its effectiveness as a denture cleanser is unknown.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of citric acid on the surface properties and efficacy of biofilm removal on denture base acrylic resin compared with commonly used denture cleansers.

MATERIAL AND METHODS

A total of 130 conventional, heat-processed denture base acrylic resin disks were randomly allocated into 1 of 5 groups based on the decontamination solution applied: control 0.9% sodium chloride (NaCl), 0.1% sodium hypochlorite (SH), Periogard (chlorhexidine digluconate), effervescent denture cleansing tablets (Corega Tabs), and 10% citric acid (CA). Surface properties (roughness, hydrophilicity, microhardness, and color stability) were assessed at 3 time points: baseline (T0), after 5 minutes of exposure (T1), and after 1 week of exposure (T2) to the respective solution. A microcosm biofilm was formed on specimen surfaces to evaluate antimicrobial efficacy of the decontamination solution groups, through assessment of microbial viability, metabolic activity, biofilm dry weight, and morphology. A 2-way repeated measures ANOVA was performed for surface properties evaluations and for microbiological analysis, 1-way ANOVA was used (α=.05).

RESULTS

No significant differences in average surface roughness (Ra) were observed between T0, T1, and T2 across all groups (P>.05). CA significantly increased surface hydrophilicity at T2 (P<.001) compared with the other groups. No significant differences in ΔE00 were seen among the groups: all values near the 50% perceptibility threshold. Compared with the control group, all denture cleansers significantly reduced the viability of total microorganisms and Candida species, with no viable colonies detected after treatment (P<.001). However, CA demonstrated a robust antimicrobial effect, with a significant reduction in biofilm dry weight and metabolic activity (P<.001), suggesting superior biofilm disruption compared with the other groups.

CONCLUSIONS

Citric acid effectively increased hydrophilicity of conventional, heat-processed acrylic resin without negatively impacting surface roughness, microhardness, or color stability.

Microbiome modulation of implant-related infection by a novel miniaturized pulsed electromagnetic field device

Dental implant-related infections, which lack effective therapeutic strategies, are considered the primary cause for treatment failure. Pulsed electromagnetic field (PEMF) technology has been introduced as a safe and effective modality for enhancing biological responses. However, the PEMF effect on modulating microbial diversity has not been explored. Thus, we tested a miniaturized PEMF biomedical device as a healing component for dental implants. PEMF activation did not alter the chemical composition, surface roughness, wettability, and electrochemical performance. PEMF effectively controlled chronic in vitro polymicrobial microbial accumulation. The in vivo study where devices were inserted in the patients' oral cavities and 16S RNA sequencing analysis evidenced a fivefold or more reduction in 23 bacterial species for PEMF group and the absence of some species for this group, including pathogens associated with implant-related infections. PEMF altered bacterial interactions and promoted specific bacterial pathways. PEMF has emerged as an effective strategy for controlling implant-related infections.

Progress in Designing Therapeutic Antimicrobial Hydrogels Targeting Implant-associated Infections: Paving the Way for a Sustainable Platform Applied to Biomedical Devices

Implantable biomedical devices have found widespread use in restoring lost functions or structures within the human body, but they face a significant challenge from microbial-related infections, which often lead to implant failure. In this context, antimicrobial hydrogels emerge as a promising strategy for treating implant-associated infections owing to their tunable physicochemical properties. However, the literature lacks a comprehensive analysis of antimicrobial hydrogels, encompassing their development, mechanisms, and effect on implant-associated infections, mainly in light of existing in vitro, in vivo, and clinical evidence. Thus, this review addresses the strategies employed by existing studies to tailor hydrogel properties to meet the specific needs of each application. Furthermore, this comprehensive review critically appraises the development of antimicrobial hydrogels, with a particular focus on solving infections related to metallic orthopedic or dental implants. Then, preclinical and clinical studies centering on providing quantitative microbiological results associated with the application of antimicrobial hydrogels are systematically summarized. Overall, antimicrobial hydrogels benefit from the tunable properties of polymers and hold promise as an effective strategy for the local treatment of implant-associated infections. However, future clinical investigations, grounded on robust evidence from in vitro and preclinical studies, are required to explore and validate new antimicrobial hydrogels for clinical use.

The Effect of a Nature-Based Gel on Gingival Inflammation and the Proteomic Profile of Crevicular Fluid: A Randomized Clinical Trial

Evidence has shown the clear positive effects of nature-based products on biofilm control and improved gingival health. However, most studies have used in vitro models, have tested single natural components, or have not evaluated proteomic changes after treatment. This double-blind, parallel, randomized, and controlled clinical trial evaluated the benefits of a nature-based gel in controlling gingival inflammation and its effects on the proteomic gingival crevicular fluid (GCF) profile. Gingivitis patients were distributed into the following groups: (1) nature-based gel containing propolis, aloe vera, green tea, cranberry, and calendula (n = 10); (2) control-conventional toothpaste (n = 10). GCF was collected and evaluated by means of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). At 3 months, the groups showed similar clinical benefits (p < 0.05). A total of 480 proteins were identified across all groups. In a pooled comparison of both groups at both time points, exclusive proteins were identified in the nature-based gel (78) and the control (21) groups. The exclusive proteins identified for the toothpaste mainly acted in wound healing, and those for the nature-based gel mainly acted on immune system processes. The nature-based gel achieved similar clinical outcomes to conventional toothpaste. However, the nature-based gel markedly changed the proteomic profile of GCF after treatment, showing a profile associated with a host response.

Peri-implantitis: Knowledge and attitudes of implantology clinicians regarding the disease management: Peri-implantitis knowledge

OBJECTIVES

Since peri-implantitis is an increasing and prevalent concern in clinical practice and there is no consensus regarding the best therapeutic protocol, this study evaluated the knowledge and behaviours of dentists working in Implantology regarding implant-related infections modulating factors and therapeutic protocols used in the management of peri-implantitis.

METHODS

Cross-sectional study was conducted with 86 Brazilian Implantology clinicians. Data were collected using a structured and online questionnaire evaluating socioeconomic characteristics, education, work/clinical practice, knowledge and attitudes regarding the risk factors and management of peri-implantitis. The reliability of the questionnaire was evaluated by test-retest technique. The questionnaire was developed based on the last consensus on peri-implant diseases (2018) and the current evidence related to implant-related infections. Descriptive, bivariate and logistic regression analyses were conducted adopting a significance level of 5%.

RESULTS

In this study, 89.5% of included dentists reported that already treated patients with peri-implantitis. Approximately 80% of dentists use antibiotics and mouth rinses during the treatment, and surgical procedures seem the main choice to treat peri-implantitis (91.8%) by dentists. As a preventive approach, 94.2% of dentists reported that routinely assessed biofilm accumulation in the follow-up visits after implant placement. Logistic regression showed that the self-reported ability to treat peri-implantitis was statistically (p < 0.05) higher among dentists who reported abilities to diagnose the disease and use laser for peri-implantitis treatment.

CONCLUSION

Dentists working in Implantology have a good level of knowledge and behaviors in the management of peri-implantitis. However, the lack of consensus regarding the best treatment protocols may reflect dentist's behaviours because different treatment protocols have been used by evaluated clinicians.

Micro-arc driven porous ZrO2 coating for tailoring surface properties of titanium for dental implants application

Titanium (Ti) is an ideal material for dental implants due to its excellent properties. However, corrosion and mechanical wear lead to Ti ions and particles release, triggering inflammatory responses and bone resorption. To overcome these challenges, surface modification techniques are used, including micro-arc oxidation (MAO). MAO creates adherent, porous coatings on Ti implants with diverse chemical compositions. In this context, zirconia element stands out in its wear and corrosion properties associated with low friction and chemical stability. Therefore, we investigated the impact of adding zirconium oxide (ZrO2) to Ti surfaces through MAO, aiming for improved electrochemical and mechanical properties. Additionally, the antimicrobial and modulatory potentials, cytocompatibility, and proteomic profile of surfaces were investigated. Ti discs were divided into four groups: machined - control (cpTi), treated by MAO with 0.04 M KOH - control (KOH), and two experimental groups incorporating ZrO2 at concentrations of 0.04 M and 0.08 M, composing the KOH@Zr4 and KOH@Zr8 groups. KOH@Zr8 showed higher surface porosity and roughness, even distribution of zirconia, formation of crystalline phases like ZrTiO4, and hydrophilicity. ZrO2 groups showed better mechanical performance including higher hardness values, lower wear area and mass loss, and higher friction coefficient under tribological conditions. The formation of a more compact oxide layer was observed, which favors the electrochemical stability of ZrO2 surfaces. Besides not inducing greater biofilm formation, ZrO2 surfaces reduced the load of pathogenic bacteria evidenced by the DNA-DNA checkerboard analysis. ZrO2 surfaces were cytocompatible with pre-osteoblastic cells. The saliva proteomic profile, evaluated by liquid chromatography coupled with tandem mass spectrometry, was slightly changed by zirconia, with more proteins adsorbed. KOH@Zr8 group notably absorbed proteins crucial for implant biological responses, like albumin and fibronectin. Incorporating ZrO2 improved the mechanical and electrochemical behavior of Ti surfaces, as well as modulated biofilm composition and provided suitable biological responses.

Enhanced antibacterial activity and superior biocompatibility of cobalt-deposited titanium discs for possible use in implant dentistry

The clinical success of implants depends on rapid osseointegration, and new materials are being developed considering the increasing demand. Considering cobalt (Co) antibacterial characteristics, we developed Co-deposited titanium (Ti) using direct current (DC) sputtering and investigated it as a new material for implant dentistry. The material was characterized using atomic absorption spectroscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The material's surface topography, roughness, surface wettability, and hardness were also analyzed. The Co thin film (Ti-Co15) showed excellent antibacterial effects against microbes implicated in peri-implantitis. Furthermore, Ti-Co15 was compatible and favored the attachment and spreading of MG-63 cells. The alkaline phosphatase and calcium mineralization activities of MG-63 cells cultured on Ti-Co15 remained unaltered compared to Ti. These data correlated well with the time-dependent expression of ALP, RUNX-2, and BMP-2 genes involved in osteogenesis. The results demonstrate that Co-deposited Ti could be a promising material in implant dentistry.

In-vitro polymicrobial oral biofilm model represents clinical microbial profile and disease progression during implant-related infections

AIM

Clinically relevant in-vitro biofilm models are essential and valuable tools for mechanistically dissecting the etiopathogenesis of infectious diseases and test new antimicrobial therapies. Thus, the aim of this study was to develop and test a clinically relevant in-vitro oral polymicrobial biofilm model that mimics implant-related infections in terms of microbial profile.

METHODS AND RESULTS

For this purpose, 24-well plate system was used to model oral biofilms, using three different microbial inoculums to grow in-vitro biofilms: (1) human saliva from periodontally healthy patients; (2) saliva as in inoculum 1 + Porphyromonas gingivalis strain; and (3) supra and subgingival biofilm collected from peri-implant sites of patients diagnosed with peri-implantitis. Biofilms were grown to represent the dynamic transition from an aerobic to anaerobic community profile. Subsequently, biofilms were collected after each phase and evaluated for microbiological composition, microbial counts, biofilm biomass, structure, and susceptibility to chlorhexidine (CHX). Results showed higher live cell count (P < .05) for biofilms developed from patients' biofilm inoculum, but biomass volume, dry weight, and microbiological composition were similar among groups (P > .05). Interestingly, according to the checkerboard DNA-DNA hybridization results, the biofilm developed from stimulated human saliva exhibited a microbial composition more similar to the clinical subgingival biofilm of patients with peri-implantitis, with proportions of the main pathogens closer to those found in the disease. In addition, biofilm developed using saliva as inoculum was shown to be susceptible to CHX with significant reduction in bacteria compared with biofilms without exposure to CHX (P < .05).

CONCLUSION

The findings suggested that the in-vitro polymicrobial biofilm developed from human saliva as inoculum is a suitable model and clinically relevant tool for mimicking the microbial composition of implant-related infections.

Oral microbial colonization on titanium and polyetheretherketone dental implant healing abutments: An in vitro and in vivo study

STATEMENT OF PROBLEM

Although polyetheretherketone (PEEK) implant healing abutments have become popular because of their esthetic, mechanical, and chemical properties, studies analyzing oral polymicrobial adhesion to PEEK abutments are lacking.

PURPOSE

The purpose of this in vitro and in vivo study was to evaluate oral microbial adhesion and colonization on titanium (Ti) and PEEK healing abutments.

MATERIAL AND METHODS

Ti (N=35) and PEEK substrates (N=35) were evaluated in vitro in terms of the initial adhesion (1 hour) or biofilm accumulation (48 hours) of Candida albicans and a polymicrobial inoculum using stimulated human saliva to mimic a diverse oral microbiome. Surface decontamination ability was evaluated after 24 hours of in vitro biofilm formation after exposure to an erbium-doped yttrium aluminum garnet (Er:YAG) laser. Conventional and flowable composite resin veneering on PEEK was also tested for microbial adhesion. In addition, an in vivo model with 3 healthy volunteers was conducted by using a palatal appliance containing the tested materials (3 or 4 specimens of each material per appliance) for 2 days to evaluate the effect of substrate on the microbial profile. Biofilms were evaluated by live cell counts and scanning electron microscopy images, and the microbial profile by Checkerboard deoxyribonucleic acid (DNA)-DNA hybridization. The t test and Mann-Whitney test were used to compare the groups (α=.05).

RESULTS

PEEK and Ti materials showed similar fungal adhesion (P>.05). Although the PEEK surface limited the initial in vitro polymicrobial adhesion (approximately 2 times less) compared with Ti (P=.040), after 48 hours of biofilm accumulation, the microbial load was statistically similar (P=.209). Er:YAG laser decontamination was more effective on PEEK than on Ti surfaces, reducing approximately 11 times more microbial accumulation (P=.019). Both composite resins tested showed similar microbial adhesion (1 hour). In vivo, the PEEK material showed reduced levels of 6 bacterial species (P<.05), including the putative pathogen Treponema denticola.

CONCLUSIONS

Although PEEK and Ti had similar bacterial and fungus biofilm attachment and accumulation, PEEK promoted a host-compatible microbial profile with a significantly reduced T. denticola load.

Effect of Surface Modifications on Surface Roughness of Ti6Al4V Alloy Manufactured by 3D Printing, Casting, and Wrought

This work aimed to comprehensively evaluate the influence of different surface modifications on the surface roughness of Ti6Al4V alloys produced by selective laser melting (SLM), casting and wrought. The Ti6Al4V surface was treated using blasting with Al₂O₃ (70-100 µm) and ZrO₂ (50-130 µm) particles, acid etching with 0.017 mol/dm³ hydrofluoric acids (HF) for 120 s, and a combination of blasting and acid etching (SLA). It was found that the optimization of the surface roughness of Ti6Al4V parts produced by SLM differs significantly from those produced by casting or wrought processes. Experimental results showed that Ti6Al4V alloys produced by SLM and blasting with Al₂O₃ followed by HF etching had a higher surface roughness (Ra = 2.043 µm, Rz = 11.742 µm), whereas cast and wrought Ti6Al4V components had surface roughness values of (Ra = 1.466, Rz = 9.428 m) and (Ra = 0.940, Rz = 7.963 m), respectively. For Ti6Al4V parts blasted with ZrO₂ and then etched by HF, the wrought Ti6Al4V parts exhibited higher surface roughness (Ra = 1.631 µm, Rz = 10.953 µm) than the SLM Ti6Al4V parts (Ra = 1.336 µm, Rz = 10.353 µm) and the cast Ti6Al4V parts (Ra = 1.075 µm, Rz = 8.904 µm).

Biomaterial engineering surface to control polymicrobial dental implant-related infections: focusing on disease modulating factors and coatings development

INTRODUCTION

Peri-implantitis is the leading cause of dental implant loss and is initiated by a polymicrobial dysbiotic biofilm formation on the implant surface. The destruction of peri-implant tissue by the host immune response and the low effectiveness of surgical or non-surgical treatments highlight the need for new strategies to prevent, modulate and/or eliminate biofilm formation on the implant surface. Currently, several surface modifications have been proposed using biomolecules, ions, antimicrobial agents, and topography alterations.

AREAS COVERED

Initially, this review provides an overview of the etiopathogenesis and host- and material-dependent modulating factors of peri-implant disease. In addition, a critical discussion about the antimicrobial surface modification mechanisms and techniques employed to modify the titanium implant material is provided. Finally, we also considered the future perspectives on the development of antimicrobial surfaces to narrow the bridge between idea and product and favor the clinical application possibility.

EXPERT OPINION

Antimicrobial surface modifications have demonstrated effective results; however, there is no consensus about the best modification strategy and in-depth information on the safety and longevity of the antimicrobial effect. Modified surfaces display recurring challenges such as short-term effectiveness, the burst release of drugs, cytotoxicity, and lack of reusability. Stimulus-responsive surfaces seem to be a promising strategy for a controlled and precise antimicrobial effect, and future research should focus on this technology and study it from models that better mimic clinical conditions.

Underestimated microbial infection of resorbable membranes on guided regeneration

Barrier membranes are critical in creating tissuecompartmentalization for guided tissue (GTR) and bone regeneration (GBR) therapies. More recently, resorbable membranes have been widely used for tissue and bone regeneration due to their improved properties and the dispensable re-entry surgery for membrane removal. However, in cases with membrane exposure, this may lead to microbial contamination that will compromise the integrity of the membrane, surrounding tissue, and bone regeneration, resulting in treatment failure. Although the microbial infection can negatively influence the clinical outcomes of regenerative therapy, such as GBR and GTR, there is a lack of clinical investigations in this field, especially concerning the microbial colonization of different types of membranes. Importantly, a deeper understanding of the mechanisms of biofilm growth and composition and pathogenesis on exposed membranes is still missing, explaining the mechanisms by which bone regeneration is reduced during membrane exposure. This scoping review comprehensively screened and discussed the current in vivo evidence and possible new perspectives on the microbial contamination of resorbable membranes. Results from eligible in vivo studies suggested that different bacterial species colonized exposed membranes according to their composition (collagen, expanded polytetrafluoroethylene (non-resorbable), and polylactic acid), but in all cases, it negatively affected the attachment level and amount of bone gain. However, limited models and techniques have evaluated the newly developed materials, and evidence is scarce. Finally, new approaches to enhance the antimicrobial effect should consider changing the membrane surface or incorporating long-term released antimicrobials in an effort to achieve better clinical success.

Effect of Processing Methods of Human Saliva on the Proteomic Profile and Protein-Mediated Biological Processes

The use of saliva as a protein source prior to microbiological and biological assays requires previous processing. However, the effect of these processing methods on the proteomic profile of saliva has not been tested. Stimulated human saliva was collected from eight healthy volunteers. Non-processed saliva was compared with 0.22 μm filtered, 0.45 μm filtered, and pasteurized saliva, by liquid chromatography-mass spectrometry. Data are available via ProteomeXchange with identifier PXD039248. The effect of processed saliva on microbial adhesion was tested using bacterial and fungus species and in biological cell behavior using HaCaT immortalized human keratinocytes. Two hundred and seventy-eight proteins were identified in non-processed saliva, of which 54 proteins (≈19%) were exclusive. Saliva processing reduced identified proteins to 222 (≈80%) for the 0.22 μm group, 219 (≈79%) for the 0.45 μm group, and 201 (≈72%) for the pasteurized saliva, compared to non-processed saliva. The proteomic profile showed similar molecular functions and biological processes. The different saliva processing methods did not alter microbial adhesion (ANOVA, p > 0.05). Interestingly, pasteurized saliva reduced keratinocyte cell viability. Saliva processing methods tested reduced the proteomic profile diversity of saliva but maintained similar molecular functions and biological processes, not interfering with microbial adhesion and cell viability, except for pasteurization, which reduced cell viability.

Proteomic profile of in situ acquired pellicle on tooth and restorative material surfaces

OBJECTIVES

To evaluate and compare the proteomic profile of acquired pellicle on smooth bovine tooth and tooth-coloured restorative materials, including resin composite (RC), glass ionomer cement (GIC), and casein phosphopeptide-amorphous calcium phosphate modified GIC (CPP-ACP GIC).

METHODS

Two-hour in situ pellicles on tooth/materials specimens mounted in oral appliances worn by ten healthy adults were investigated. Pellicle proteins and corresponding unstimulated whole saliva were quantitatively analysed through liquid chromatography-tandem mass spectrometry.

RESULTS

Significantly higher amounts of protein were adsorbed onto tooth surface than restorative materials tested (4.11 ± 0.69 vs. 2.54 ± 0.38/2.98 ± 0.80/3.01 ± 0.37 µg, RC/GIC/CPP-ACP GIC). From the ten participants, 1,444 (487-1,086/person), 1,454 (645-1,051/person), 1,731 (454-1,475/person), or 1,597 (423-1,261/person) pellicle proteins were detected at least once on bovine tooth, RC, GIC, or CPP-ACP GIC, respectively, and with 1,072 (304-793/person) salivary proteins identified. Comparative quantification revealed minor differences between tooth and restorative materials pellicle profiles. High inter-individual variations in pellicle protein composition were demonstrated. Compared to the salivary protein profile, 214/57 proteins showed significantly increased/decreased abundance in pellicle formed on at least one substrate (fold change > 3.325/fold change < 0.301). Gene Ontology enrichment analysis showed some pellicle proteins detected with increased affinity to tooth/material surface were identified as being related to "calcium-dependent protein binding" or "cell-cell adhesion mediator activity".

CONCLUSION

Similar protein quantity and composition was observed in 2 h in situ pellicles formed on different smooth restorative material surfaces. The proteomic profile of pellicles appeared distinct from that of the corresponding unstimulated whole saliva.

CLINICAL SIGNIFICANCE

Host backgrounds appeared more influential on the proteomic profile of the in situ acquired pellicle than the underlying substrate characteristics among systemically and orally healthy adults. Pellicle proteins preferentially adsorbed on tooth/materials were putatively associated with calcium ion homeostasis or host-microbiota interaction.

The race for the optimal antimicrobial surface: perspectives and challenges related to plasma electrolytic oxidation coating for titanium-based implants

Plasma electrolytic oxidation (PEO) is a low-cost, structurally reliable, and environmentally friendly surface modification method for orthopedic and dental implants. This technique is successful for the formation of porous, corrosion-resistant, and bioactive coatings, besides introducing antimicrobial compounds easily. Given the increase in implant-related infections, antimicrobial PEO-treated surfaces have been widely proposed to surmount this public health concern. This review comprehensively discusses antimicrobial implant surfaces currently produced by PEO in terms of their in vitro and in vivo microbiological and biological properties. We present a critical [part I] and evidence-based [part II] review about the plethora of antimicrobial PEO-treated surfaces. The mechanism of microbial accumulation on implanted devices and the principles of PEO technology to ensure antimicrobial functionalization by one- or multi-step processes are outlined. Our systematic literature search showed that particular focus has been placed on the metallic and semi-metallic elements incorporated into PEO surfaces to facilitate antimicrobial properties, which are often dose-dependent, without leading to cytotoxicity in vitro. Meanwhile, there are concerns over the biocompatibility of PEO and its long-term antimicrobial effects in animal models. We clearly highlight the importance of using clinically relevant infection models and in vivo long-term assessments to guarantee the rational design of antimicrobial PEO-treated surfaces to identify the 'finish line' in the race for antimicrobial implant surfaces.

Oral Microorganisms and Biofilms: New Insights to Defeat the Main Etiologic Factor of Oral Diseases

The oral cavity presents a highly diverse community of microorganisms due to the unique environmental conditions for microbial adhesion and growth [...].

Do the progression of experimentally induced gingivitis and peri-implant mucositis present common features? A systematic review of clinical human studies

This systematic review evaluated the features of the progression of experimentally induced gingivitis and peri-implant mucositis in humans. Included were studies that evaluated clinical, immunological, or microbiological responses between experimentally induced gingivitis and peri-implant mucositis in periodontally healthy patients. A total of 887 articles were initially identified, but only 12 were included in the final analysis. Implants accumulate less biofilm and suffer the most heterogeneous alterations in the microbiota, in the abstinence of oral hygiene, compared with the tooth. Interestingly, although dental implants presented less biofilm accumulation, the peri-implant mucosa showed a more exacerbated clinical response than the gingival tissue. The risk of bias of the selected studies was moderate to low, with one study presenting serious risk. The progression events of peri-implant mucositis were similar to those of experimental gingivitis but led to a different host response. This review was registered in the PROSPERO database CRD420201 123360.

Bacterial-derived extracellular polysaccharides reduce antimicrobial susceptibility on biotic and abiotic surfaces

OBJECTIVE

Extracellular biofilm matrix plays a role in reducing bacterial susceptibility against antimicrobials. Since the surface where biofilm is growing modulates microbial accumulation and bacterial-derived exopolysaccharides (EPS) synthesis, this study compared the role of EPS to reduce antimicrobial susceptibility on biotic (dental surface) and abiotic (titanium (Ti) material) surfaces and the effect of remaining matrix-enriched biofilms to promote bacterial recolonization.

DESIGN

48 h Streptococcus mutans UA159 strain biofilms were grown on enamel and Ti surfaces. The medium was supplemented with 1% sucrose, substrate for EPS synthesis, or with 0.5% glucose + 0.5% fructose as control. Chlorhexidine (CHX) 0.2% was used for antimicrobial treatment. Biofilms were collected and the following analyses were considered: viable bacterial counts, biofilm pH, EPS content, and biofilm structure by scanning electron microscopy and confocal laser scanning microscopy (CLSM). Substrate surfaces were analyzed by 3D laser scanning confocal microscope.

RESULTS

Enamel surface showed a higher amount of EPS content (p < 0.05), which may be explained by the higher bacterial biomass compared to Ti material. EPS content reduced bacterial susceptibility against antimicrobial treatments for both substrates, compared to EPS control (p < 0.05). However, sucrose-treated cells presented the same magnitude of reduction for Ti or enamel. Interestingly, matrix-enriched biofilms favored bacterial recolonization for both substrates.

CONCLUSION

The surface where the biofilm is growing modulates the amount of EPS synthesized and matrix content plays a key role in reducing antimicrobial susceptibility and promoting bacterial recolonization.

Superhydrophilic Nanotextured Surfaces for Dental Implants: Influence of Early Saliva Contamination and Wet Storage

Hydrophilic and nanotextured surfaces for dental implants have been reported as relevant properties for early osseointegration. However, these surface characteristics are quite sensitive to oral interactions. Therefore, this pilot study aimed to investigate the superficial alterations caused on hydrophilic nanotubular surfaces after early human saliva interaction. Titanium disks were treated using an anodization protocol followed by reactive plasma application in order to achieve nanotopography and hydrophilicity, additionally; surfaces were stored in normal atmospheric oxygen or wet conditioning. Following, samples were interacted with saliva for 10 min and analyzed regarding physical–chemical properties and cellular viability. Saliva interaction did not show any significant influence on morphological characteristics, roughness measurements and chemical composition; however, hydrophilicity was statistically altered compromising this feature when the samples were stored in common air. Cellular viability tested with pre-osteoblasts cell line (MC3T3-E1) reduced significantly at 48 h on the samples without wet storage after saliva contamination. The applied wet-storage methodology appears to be effective in maintaining properties such as hydrophilicity during saliva interaction. In conclusion, saliva contamination might impair important properties of hydrophilic nanotubular surfaces when not stored in wet conditions, suggesting the need of saliva-controlled sites for oral application of hydrophilic surfaces and/or the use of modified-package methods associated with their wet storage.

Polymicrobial biofilms related to dental implant diseases: unravelling the critical role of extracellular biofilm matrix

Biofilms are complex tri-dimensional structures that encase microbial cells in an extracellular matrix comprising self-produced polymeric substances. The matrix rich in extracellular polymeric substance (EPS) contributes to the unique features of biofilm lifestyle and structure, enhancing microbial accretion, biofilm virulence, and antimicrobial resistance. The role of the EPS matrix of biofilms growing on biotic surfaces, especially dental surfaces, is largely unravelled. To date, there is a lack of a broad overview of existing literature concerning the relationship between the EPS matrix and the dental implant environment and its role in implant-related infections. Here, we discuss recent advances in the critical role of the EPS matrix on biofilm growth and virulence on the dental implant surface and its effect on the etiopathogenesis and progression of implant-related infections. Similar to other biofilms associated with human diseases/conditions, EPS-enriched biofilms on implant surfaces promote microbial accumulation, microbiological shift, cross-kingdom interaction, antimicrobial resistance, biofilm virulence, and, consequently, peri-implant tissue damage. But intriguingly, the protagonism of EPS role on implant-related infections and the development of matrix-target therapeutic strategies has been neglected. Finally, we highlight the need for more in-depth analyses of polymicrobial interactions within EPS matrix and EPS-targeting technologies' rationale for disrupting the complex biofilm microenvironment with more outstanding translation to implant applications in the near future.

Surface Modification Techniques to Produce Micro/Nano-scale Topographies on Ti-Based Implant Surfaces for Improved Osseointegration

Titanium and titanium alloys are used as artificial bone substitutes due to the good mechanical properties and biocompatibility, and are widely applied in the treatment of bone defects in clinic. However, Pure titanium has stress shielding effect on bone, and the effect of titanium-based materials on promoting bone healing is not significant. To solve this problem, several studies have proposed that the surface of titanium-based implants can be modified to generate micro or nano structures and improve mechanical properties, which will have positive effects on bone healing. This article reviews the application and characteristics of several titanium processing methods, and explores the effects of different technologies on the surface characteristics, mechanical properties, cell behavior and osseointegration. The future research prospects in this field and the characteristics of ideal titanium-based implants are proposed.

Cross-kingdom microbial interactions in dental implant-related infections: is Candida albicans a new villain?

Candida albicans, an oral fungal opportunistic pathogen, has shown the ability to colonize implant surfaces and has been frequently isolated from biofilms associated with dental implant-related infections, possibly due to its synergistic interactions with certain oral bacteria. Moreover, evidence suggests that this cross-kingdom interaction on implant can encourage bacterial growth, leading to increased fungal virulence and mucosal damage. However, the role of Candida in implant-related infections has been overlooked and not widely explored or even considered by most microbiological analyses and therapeutic approaches. Thus, we summarized the scientific evidence regarding the ability of C. albicans to colonize implant surfaces, interact in implant-related polymicrobial biofilms, and its possible role in peri-implant infections as far as biologic plausibility. Next, a systematic review of preclinical and clinical studies was conducted to identify the relevance and the gap in the existing literature regarding the role of C. albicans in the pathogenesis of peri-implant infections.

The Impact of Early Saliva Interaction on Dental Implants and Biomaterials for Oral Regeneration: An Overview

The presence of saliva in the oral environment is relevant for several essential health processes. However, the noncontrolled early saliva interaction with biomaterials manufactured for oral rehabilitation may generate alterations in the superficial properties causing negative biological outcomes. Therefore, the present review aimed to provide a compilation of all possible physical-chemical-biological changes caused by the early saliva interaction in dental implants and materials for oral regeneration. Dental implants, bone substitutes and membranes in dentistry possess different properties focused on improving the healing process when in contact with oral tissues. The early saliva interaction was shown to impair some positive features present in biomaterials related to quick cellular adhesion and proliferation, such as surface hydrophilicity, cellular viability and antibacterial properties. Moreover, biomaterials that interacted with contaminated saliva containing specific bacteria demonstrated favorable conditions for increased bacterial metabolism. Additionally, the quantity of investigations associating biomaterials with early saliva interaction is still scarce in the current literature and requires clarification to prevent clinical failures. Therefore, clinically, controlling saliva exposure to sites involving the application of biomaterials must be prioritized in order to reduce impairment in important biomaterial properties developed for rapid healing.

Emerging titanium surface modifications: The war against polymicrobial infections on dental implants

Abstract Dental implants made of titanium (Ti) material is recognized as the leading treatment option for edentulous patients’ rehabilitation, showing a high success rate and clinical longevity. However, dental implant surface acts as a platform for microbial adhesion and accumulation once exposed to the oral cavity. Biofilm formation on implant surfaces has been considered the main etiologic factor to induce inflammatory diseases, known as peri-implant mucositis and peri-implantitis; the latter being recognized as the key reason for late dental implant failure. Different factors, such as biofilm matrix production, source of carbohydrate exposure, and cross-kingdom interactions, have encouraged increased microbial accumulation on dental implants, leading to a microbiological community shift from a healthy to a pathogenic state, increasing inflammation and favoring tissue damage. These factors combined with the spatial organization of biofilms, reduced antimicrobial susceptibility, complex microbiological composition, and the irregular topography of implants hamper biofilm control and microbial killing. In spite of the well-known etiology, there is still no consensus regarding the best clinical protocol to control microbial accumulation on dental implant surfaces and treat peri-implant disease. In this sense, different coatings and Ti surface treatments have been proposed in order to reduce microbial loads and control polymicrobial infections on implantable devices. Therefore, this critical review aims to discuss the current evidence on biofilm accumulation on dental implants and central factors related to the pathogenesis process of implant-related infections. Moreover, the potential surface modifications with anti-biofilm properties for dental implant devices is discussed to shed light on further promising strategies to control peri-implantitis.

Titanium and Protein Adsorption: An Overview of Mechanisms and Effects of Surface Features

Titanium and its alloys, specially Ti6Al4V, are among the most employed materials in orthopedic and dental implants. Cells response and osseointegration of implant devices are strongly dependent on the body-biomaterial interface zone. This interface is mainly defined by proteins: They adsorb immediately after implantation from blood and biological fluids, forming a layer on implant surfaces. Therefore, it is of utmost importance to understand which features of biomaterials surfaces influence formation of the protein layer and how to guide it. In this paper, relevant literature of the last 15 years about protein adsorption on titanium-based materials is reviewed. How the surface characteristics affect protein adsorption is investigated, aiming to provide an as comprehensive a picture as possible of adsorption mechanisms and type of chemical bonding with the surface, as well as of the characterization techniques effectively applied to model and real implant surfaces. Surface free energy, charge, microroughness, and hydroxylation degree have been found to be the main surface parameters to affect the amount of adsorbed proteins. On the other hand, the conformation of adsorbed proteins is mainly dictated by the protein structure, surface topography at the nano-scale, and exposed functional groups. Protein adsorption on titanium surfaces still needs further clarification, in particular concerning adsorption from complex protein solutions. In addition, characterization techniques to investigate and compare the different aspects of protein adsorption on different surfaces (in terms of roughness and chemistry) shall be developed.

Targeting implant-associated infections: titanium surface loaded with antimicrobial

Implant devices have = proven a successful treatment modality in reconstructive surgeries. However, increasing rates of peri-implant diseases demand further examination of their pathogenesis. Polymicrobial biofilm formation on titanium surfaces has been considered the main risk factor for inflammatory processes on tissues surrounding implant devices, which often lead to implant failure. To overcome microbial accumulation on titanium surfaces biofilm targeting strategies have been developed to modify the surface and incorporate antimicrobial coatings. Because antibiotics are widely used to treat polymicrobial infections, these agents have recently started to be incorporated on titanium surface. This review discusses the biofilm formation on titanium dental implants and key factors to be considered in therapeutic and preventative strategies. Moreover, a systematic review was conducted on coatings developed for titanium surfaces using different antibiotics. This review will also shed light on potential alternative strategies aiming to reduce microbial loads and control polymicrobial infection on implanted devices.