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

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.

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.

The effect of dental material type and masticatory forces on periodontitis-derived subgingival microbiomes

Restorative dental materials can frequently extend below the gingival margin, serving as a potential haven for microbial colonization, and altering the local oral microbiome to ignite infection. However, the contribution of dental materials on driving changes of the composition of the subgingival microbiome is under-investigated. This study evaluated the microbiome-modulating properties of three biomaterials, namely resin dental composites (COM), antimicrobial piezoelectric composites (BTO), and hydroxyapatite (HA), using an optimized in vitro subgingival microbiome model derived from patients with periodontal disease. Dental materials were subjected to static or cyclic loading (mastication forces) during biofilm growth. Microbiome composition was assessed by 16S rRNA gene sequencing. Dysbiosis was measured in terms of subgingival microbial dysbiosis index (SMDI). Biomaterials subjected to cyclic masticatory loads were associated with enhanced biofilm viability except on the antibacterial composite. Biomaterials held static were associated with increased biofilm biomass, especially on HA surfaces. Overall, the microbiome richness (Chao index) was similar for all the biomaterials and loading conditions. However, the microbiome diversity (Shannon index) for the HA beams was significantly different than both composites. In addition, beta diversity analysis revealed significant differences between composites and HA biomaterials, and between both loading conditions (static and cyclic). Under static conditions, microbiomes formed over HA surfaces resulted in increased dysbiosis compared to composites through the enrichment of periopathogens, including Porphyromonas gingivalis, Porphyromonas endodontalis, and Fretibacterium spp., and depletion of commensals such as Granulicatella and Streptococcus spp. Interestingly, cyclic loading reversed the dysbiosis of microbiomes formed over HA (depletion of periopathogenes) but increased the dysbiosis of microbiomes formed over composites (enrichment of Porphyromonas gingivalis and Fusobacterim nucleatum). Comparison of species formed on both composites (control and antibacterial) showed some differences. Commercial composites enriched Selenomonas spp. and depleted Campylobacter concisus. Piezoelectric composites effectively controlled the microbiome viability without significantly impacting the species abundance. Findings of this work open new understandings of the effects of different biomaterials on the modulation of oral biofilms and the relationship with oral subgingival infections.

Poly-3-hydroxybutyrate-silver nanoparticles membranes as advanced antibiofilm strategies for combatting peri-implantitis

Dental implant success is threatened by peri-implantitis, an inflammation leading to implant failure. Conventional treatments struggle with the intricate microbial and host factors involved. Antibacterial membranes, acting as barriers and delivering antimicrobials, may offer a promising solution. Thus, this study highlights the potential of developing antibacterial membranes of poly-3-hydroxybutyrate and silver nanoparticles (Ag Nps) to address peri-implantitis challenges, discussing design and efficacy against potential pathogens. Electrospun membranes composed of PHB microfibers and Ag Nps were synthesized in a blend of DMF/chloroform at three different concentrations. Various studies were conducted on the characterization and antimicrobial activity of the membranes. The synthesized Ag Nps ranged from 4 to 8 nm in size. Furthermore, Young's modulus decreased, reducing from 13.308 MPa in PHB membranes without Ag Nps to 0.983 MPa in PHB membranes containing higher concentrations of Ag Nps. This demonstrates that adding Ag Nps results in a less stiff membrane. An increase in elongation at break was noted with the rise in Ag Nps concentration, from 23.597 % in PHB membranes to 60.136 % in PHB membranes loaded with Ag Nps. The antibiotic and antibiofilm activity of the membranes were evaluated against Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus mutans, and Candida albicans. The results indicated that all PHB membranes containing Ag Nps exhibited potent antibacterial activity by inhibiting the growth of biofilms and planktonic bacteria. However, inhibition of C. albicans occurred only with the PHB-Ag Nps C membrane. These findings emphasize the versatility and potential of Ag Nps-incorporated membranes as a multifunctional approach for preventing and addressing microbial infections associated with peri-implantitis. The combination of antibacterial and antibiofilm properties in these membranes holds promise for improving the management and treatment of peri-implantitis-related complications.

An In Vitro Study on the Application of Silver-Doped Platelet-Rich Plasma in the Prevention of Post-Implant-Associated Infections

Implant therapy is a common treatment option in dentistry and orthopedics, but its application is often associated with an increased risk of microbial contamination of the implant surfaces that cause bone tissue impairment. This study aims to develop two silver-enriched platelet-rich plasma (PRP) multifunctional scaffolds active at the same time in preventing implant-associated infections and stimulating bone regeneration. Commercial silver lactate (L) and newly synthesized silver deoxycholate:β-Cyclodextrin (B), were studied in vitro. Initially, the antimicrobial activity of the two silver soluble forms and the PRP enriched with the two silver forms has been studied on microbial planktonic cells. At the same time, the biocompatibility of silver-enriched PRPs has been assessed by an MTT test on human primary osteoblasts (hOBs). Afterwards, an investigation was conducted to evaluate the activity of selected concentrations and forms of silver-enriched PRPs in inhibiting microbial biofilm formation and stimulating hOB differentiation. PRP-L (0.3 µg/mm2) and PRP-B (0.2 µg/mm2) counteract Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans planktonic cell growth and biofilm formation, preserving hOB viability without interfering with their differentiation capability. Overall, the results obtained suggest that L- and B-enriched PRPs represent a promising preventive strategy against biofilm-related implant infections and demonstrate a new silver formulation that, together with increasing fibrin binding protecting silver in truncated cone-shaped cyclic oligosaccharides, achieved comparable inhibitory results on prokaryotic cells at a lower concentration.

Oral Mycobiota: A Narrative Review

Numerous studies have proven the important role of the oral microbiota in health and disease. The dysfunctionality of the oral microbiota, known as dysbiosis, is incriminated in dental caries, periodontal disease, oral infectious diseases, oral cancer, and systemic disease. The lesser-known component of the oral microbiota, the mycobiota, is now assiduously investigated. Recent technological developments have helped foster the identification of new fungal species based on genomic research. Next-generation sequencing has expanded our knowledge about the diversity, architecture, and relationships of oral microorganisms within the oral cavity. The mycobiome structure and relationships with the bacteriome have been studied to identify a mycobiotic signature. This review aimed to emphasize the latest knowledge of the oral mycobiome.

Impact of multiscale surface topography characteristics on Candida albicans biofilm formation: From cell repellence to fungicidal activity

While there has been significant research conducted on bacterial colonization on implant materials, with a focus on developing surface modifications to prevent the formation of bacterial biofilms, the study of Candida albicans biofilms on implantable materials is still in its infancy, despite its growing relevance in implant-associated infections. C. albicans fungal infections represent a significant clinical concern due to their severity and associated high fatality rate. Pathogenic yeasts account for an increasing proportion of implant-associated infections, since Candida spp. readily form biofilms on medical and dental device surfaces. In addition, these biofilms are highly antifungal-resistant, making it crucial to explore alternative solutions for the prevention of Candida implant-associated infections. One promising approach is to modify the surface properties of the implant, such as the wettability and topography of these substrata, to prevent the initial Candida attachment to the surface. This review summarizes recent research on the effects of surface wettability, roughness, and architecture on Candida spp. attachment to implantable materials. The nanofabrication of material surfaces are highlighted as a potential method for the prevention of Candida spp. attachment and biofilm formation on medical implant materials. Understanding the mechanisms by which Candida spp. attach to surfaces will allow such surfaces to be designed such that the incidence and severity of Candida infections in patients can be significantly reduced. Most importantly, this approach could also substantially reduce the need to use antifungals for the prevention and treatment of these infections, thereby playing a crucial role in minimizing the possibility contributing to instances of antimicrobial resistance. STATEMENT OF SIGNIFICANCE: In this review we provide a systematic analysis of the role that surface characteristics, such as wettability, roughness, topography and architecture, play on the extent of C. albicans cells attachment that will occur on biomaterial surfaces. We show that exploiting bioinspired surfaces could significantly contribute to the prevention of antimicrobial resistance to antifungal and chemical-based preventive measures. By reducing the attachment and growth of C. albicans cells using surface structure approaches, we can decrease the need for antifungals, which are conventionally used to treat such infections.

Progress in the application of nanoparticles for the treatment of fungal infections: A review

The burden of fungal infections on human health is increasing worldwide. Aspergillus, Candida, and Cryptococcus are the top three human pathogenic fungi that are responsible for over 90% of infection-related deaths. Moreover, effective antifungal therapeutics are lacking, primarily due to host toxicity, pathogen resistance, and immunodeficiency. In recent years, nanomaterials have proved not only to be more efficient antifungal therapeutic agents but also to overcome resistance against fungal medication. This review will examine the limitations of standard antifungal therapy as well as focus on the development of nanomaterials.

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.

Cyclic strain of poly (methyl methacrylate) surfaces triggered the pathogenicity of Candida albicans

Candida albicans is an opportunistic yeast and the primary etiological factor in oral candidiasis and denture stomatitis. The pathogenesis of C. albicans could be triggered by several variables, including environmental, nutritional, and biomaterial surface cues. Specifically, biomaterial interactions are driven by different surface properties, including wettability, stiffness, and roughness. Dental biomaterials experience repetitive (cyclic) stresses from chewing and biomechanical movements. Pathogenic biofilms are formed over these biomaterial surfaces under cyclic strain. This study investigated the effect of the cyclic strain (deformation) of biomaterial surfaces on the virulence of Candida albicans. Candida biofilms were grown over Poly (methyl methacrylate) (PMMA) surfaces subjected to static (no strain) and cyclic strain with different levels (ε˜x=0.1 and 0.2%). To evaluate the biomaterial-biofilm interactions, the biofilm characteristics, yeast-to-hyphae transition, and the expression of virulent genes were measured. Results showed the biofilm biomass and metabolic activity to be significantly higher when Candida adhered to surfaces subjected to cyclic strain compared to static surfaces. Examination of the yeast-to-hyphae transition showed pseudo-hyphae cells (pathogenic) in cyclically strained biomaterial surfaces, whereas static surfaces showed spherical yeast cells (commensal). RNA sequencing was used to determine and compare the transcriptome profiles of cyclically strained and static surfaces. Genes and transcription factors associated with cell adhesion (CSH1, PGA10, and RBT5), biofilm formation (EFG1), and secretion of extracellular matrix (ECM) (CRH1, ADH5, GCA1, and GCA2) were significantly upregulated in the cyclically strained biomaterial surfaces compared to static ones. Genes and transcription factors associated with virulence (UME6 and HGC1) and the secretion of extracellular enzymes (LIP, PLB, and SAP families) were also significantly upregulated in the cyclically strained biomaterial surfaces compared to static. For the first time, this study reveals a biomaterial surface factor triggering the pathogenesis of Candida albicans, which is essential for understanding, controlling, and preventing oral infections. STATEMENT OF SIGNIFICANCE: Fungal infections produced by Candida albicans are a significant contributor to various health conditions. Candida becomes pathogenic when certain environmental conditions change, including temperature, pH, nutrients, and CO2 levels. In addition, surface properties, including wettability, stiffness, and roughness, drive the interactions between Candida and biomaterials. Clinically, Candida adheres to biomaterials that are under repetitive deformation due to body movements. In this work, we revealed that when Candida adhered to biomaterial surfaces subjected to repetitive deformation, the microorganism becomes pathogenic by increasing the formation of biofilms and the expression of virulent factors related to hyphae formation and secretion of enzymes. Findings from this work could aid the development of new strategies for treating fungal infections in medical devices or implanted biomaterials.

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.

Antimicrobial photodynamic therapy against oral biofilm: influencing factors, mechanisms, and combined actions with other strategies

Oral biofilms are a prominent cause of a wide variety of oral infectious diseases which are still considered as growing public health problems worldwide. Oral biofilms harbor specific virulence factors that would aggravate the infectious process and present resistance to some traditional therapies. Antimicrobial photodynamic therapy (aPDT) has been proposed as a potential approach to eliminate oral biofilms via in situ-generated reactive oxygen species. Although numerous types of research have investigated the effectiveness of aPDT, few review articles have listed the antimicrobial mechanisms of aPDT on oral biofilms and new methods to improve the efficiency of aPDT. The review aims to summarize the virulence factors of oral biofilms, the progress of aPDT in various oral biofilm elimination, the mechanism mediated by aPDT, and combinatorial approaches of aPDT with other traditional agents.

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.

Effects of Candidalysin Derived from Candida albicans on the Expression of Pro-Inflammatory Mediators in Human Gingival Fibroblasts

Candida albicans (Ca) is frequently detected in the peri-implant sulcus with peri-implantitis, a major postoperative complication after oral implant therapy. However, the involvement of Ca in the pathogenesis of peri-implantitis remains unclear. In this study, we aimed to clarify Ca prevalence in the peri-implant sulcus and investigated the effects of candidalysin (Clys), a toxin produced by Ca, on human gingival fibroblasts (HGFs). Peri-implant crevicular fluid (PICF) was cultured using CHROMagar and Ca colonization rate and colony numbers were calculated. The levels of interleukin (IL)-1β and soluble IL-6 receptor (sIL-6R) in PICF were quantified by enzyme-linked immunosorbent assay (ELISA). Pro-inflammatory mediator production and intracellular signaling pathway (MAPK) activation in HGFs were measured by ELISA and Western blotting, respectively. The Ca colonization rate and the average number of colonies in the peri-implantitis group tended to be higher than those in the healthy group. IL-1β and sIL-6R levels in the PICF were significantly higher in the peri-implantitis group than in the healthy group. Clys significantly induced IL-6 and pro-matrix metalloproteinase (MMP)-1 productions in HGFs, and co-stimulation with Clys and sIL-6R increased IL-6, pro-MMP-1, and IL-8 production levels in HGFs compared with Clys stimulation alone. These findings suggest that Clys from Ca plays a role in the pathogenesis of peri-implantitis by inducing pro-inflammatory mediators.

Short-term influence of antimicrobial photodynamic therapy as an adjuvant to mechanical debridement in reducing soft-tissue inflammation and subgingival yeasts colonization in patients with peri-implant mucositis

OBJECTIVE

The objective of this short-term follow-up study was to evaluate the influence of antimicrobial photodynamic therapy (aPDT) as an adjuvant to mechanical debridement (MD) in reducing soft-tissue inflammation and subgingival yeasts colonization (SYC) in patients with peri‑implant mucositis (PiM).

METHODS

Individuals diagnosed with PiM were included. Demographic data was collected using a questionnaire. Peri-implant plaque index (PI), bleeding index (BI), probing depth (PD), crestal bone levels and SYC were measured at baseline. Therapeutically, these individuals were divided into test and control groups. In the control-group patients underwent MD and in the test-group patients underwent MD with adjunct single session of aPDT. Clinical peri‑implant parameters and SYC were reassessed after 12-weeks. Correlation between age, gender and duration of implants with SYC and clinical peri‑implant status was assessed using logistic regression models. P < 0.05 was selected as an indicator of statistical significance.

RESULTS

The test and control-groups comprised of 24 and 23 individuals, respectively. In the test and control groups, toothbrushing twice daily was reported by 7 (29.2%) and 5 (21.7%) individuals, respectively. None of the individuals had ever used a dental floss. At baseline, there was no difference in peri‑implant PI, BI, PD and CBL in the test and control groups. At follow-up, peri‑implant PI (P < 0.01), BI (P < 0.01) and PD (P < 0.01) were significantly higher in the control compared with the test-group. At baseline, SYC in the test and control groups were 1865.3 ± 403.4 CFU/ml and 1963.7 ± 512.4 CFU/ml, respectively. At 90 days' follow-up, SYC in the test and control groups were 1472 ± 202.7 and 1538.4 ± 331.7 CFU/ml, respectively. There was no significant difference in SYC in both groups when baseline values were compared with 90 days' follow-up.

CONCLUSION

One session of aPDT after MC with adjunct aPDT is effective in reducing soft tissue inflammation but not SYC in patients with PiM.

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 [...].

Inhibitory effect of ficin on Candida albicans biofilm formation and pre-formed biofilms

BACKGROUND

To investigate the effect of ficin, a type of proteases, on Candida albicans (C. albicans) biofilm, including forming and pre-formed biofilms.

METHODS

Crystal violet tests together with colony forming unit (CFU) counts were used to detect fungal biofilm biomass. Live/dead staining of biofilms observed by confocal laser scanning microscopy was used to monitor fungal activity. Finally, gene expression of C. albicans within biofilms was assessed by qRT-PCR.

RESULTS

According to our results, biofilm biomass was dramatically reduced by ficin in both biofilm formation and pre-formed biofilms, as revealed by the crystal violet assay and CFU count (p < 0.05). Fungal activity in biofilm formation and pre-formed biofilms was not significantly influenced by ficin according to live/dead staining. Fungal polymorphism and biofilm associated gene expression were influenced by ficin, especially in groups with prominent antibiofilm effects.

CONCLUSIONS

In summary, ficin effectively inhibited C. albicans biofilm formation and detached its preformed biofilm, and it might be used to treat C. albicans biofilm associated problems.