Salivary Microbial Dysbiosis Is Associated With Peri-Implantitis: A Case-Control Study in a Brazilian Population

Production and characterization of the lipopeptide with anti-adhesion for oral biofilm on the surface of titanium for dental implants

Titanium implants are subject to bacterial adhesion and peri-implantitis induction, and biosurfactants bring a new alternative to the fight against infections. This work aimed to produce and characterize the biosurfactant from Bacillus subtilis ATCC 19,659, its anti-adhesion and antimicrobial activity, and cell viability. Anti-adhesion studies were carried out against Streptococcus sanguinis, Staphylococcus aureus, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Proteus mirabilis as the minimum inhibitory concentration and the minimum bactericidal concentration. Cell viability was measured against osteoblast and fibroblast cells. The biosurfactant was classified as lipopeptide, with critical micelle concentration at 40 µg mL- 1, and made the titanium surface less hydrophobic. The anti-adhesion effect was observed for Staphylococcus aureus and Streptococcus sanguinis with 54% growth inhibition and presented a minimum inhibitory concentration of 15.7 µg mL- 1 for Streptococcus sanguinis and Aggregatibacter actinomycetemcomitans. The lipopeptide had no cytotoxic effect and demonstrated high potential application against bacterial biofilms.

Antimicrobial Activity of Methylene Blue Associated with Photodynamic Therapy: In Vitro Study in Multi-Species Oral Biofilm

The control of infectious diseases caused by biofilms is a continuing challenge for researchers due to the complexity of their microbial structures and therapeutic implications. Photodynamic therapy as an adjunctive anti-infective treatment has been described as a possible valid approach but has not been tested in polymicrobial biofilm models. This study evaluated the effect of photodynamic therapy in vitro with methylene blue (MB) 0.01% and red LEDs (λ = 660 nm, power density ≈ 330 mW/cm2, 2 mm distance from culture) on the metabolic activity and composition of a multispecies subgingival biofilm. Test Groups LED and MB + LED showed a more significant reduction in metabolic activity than the non-LED application group (~50 and 55%, respectively). Groups LED and MB equally affected (more than 80%) the total bacterial count in biofilms. No differences were noted in the bacterial biofilm composition between the groups. In vitro LED alone or the MB + LED combination reduced the metabolic activity of bacteria in polymicrobial biofilms and the total subgingival biofilm count.

Microbiological profile of peri-implantitis: Analyses of peri-implant microbiome

PURPOSE

To characterize the microbiome composition in peri-implant pocket of peri-implantitis and peri-implant sulcus controls using 16S rRNA gene sequencing.

MATERIALS AND METHODS

In this controlled clinical cross-sectional study, 23 subjects with control implants (n = 14) and diseased implants (peri-implantitis, n = 21) were included. The peri-implant pocket/sulcus was sampled and used to extract DNA and amplify the 16S rRNA gene using universal primers targeting the V3-V4 regions. The resulting 16S PCR amplicons were sequenced on Illumina MiSeq, and the sequences were processed using DADA2 and the Human Oral Microbiome Database (HOMD) as references. Alpha and Beta diversity, as well as core microbiome and differential abundance analyses, were performed using the MicrobiomeAnalyst workflow.

RESULTS

There were no significant differences in microbial diversity between control implants and implants with peri-implantitis (Shannon p = 0.82). Overall bacterial community structure assessed through beta diversity analysis was also not significantly different between the two groups (p = 0.18). However, high levels of Gram-negative bacteria were detected in peri-implant pockets compared to the control sulcus. Abundant species in peri-implantitis were Capnocytophaga leadbetteri, Treponema maltophilum, Peptostreptococcus, Neisseria, P. gingivalis, and Porphyromonas endodontali, Lactococcus lactis and Filifactor alocis (p < 0.05). Gram-positive bacteria such as Streptococcus salivaris, Prevotella melaninogenica, L. wadei, and Actinomyces spp. serve were more abundant in peri-implant control sulcus.

CONCLUSIONS

Peri-implant sulcus in control implants harbors predominantly Gram-positive bacteria, whereas pockets of implants with peri-implantitis harbor predominantly Gram-negative bacteria.

Colorimetric detection of oral bacteria using functionalized gold nanoparticles as a plasmonic biosensor array

Early detection of specific oral bacterial species would enable timely treatment and prevention of certain oral diseases. In this work, we investigated the sensitivity and specificity of functionalized gold nanoparticles for plasmonic sensing of oral bacteria. This approach is based on the aggregation of positively charged gold nanoparticles on the negatively charged bacteria surface and the corresponding localized surface plasmon resonance (LSPR) shift. Gold nanoparticles were synthesized in different sizes, shapes and functionalization. A biosensor array was developed consisting of spherical- and anisotropic-shaped (1-hexadecyl) trimethylammonium bromide (CTAB) and spherical mercaptoethylamine (MEA) gold nanoparticles. It was used to detect four oral bacterial species (Aggregatibacter actinomycetemcomitans, Actinomyces naeslundii, Porphyromonas gingivalis and Streptococcus oralis). The plasmonic response was measured and analysed using RGB and UV-vis absorbance values. Both methods successfully detected the individual bacterial species based on their unique responses to the biosensor array. We present an in-depth study relating the bacteria zeta potential and AuNP aggregation to plasmonic response. The sensitivity depends on multiple parameters, such as bacterial species and concentration as well as gold nanoparticle shape, concentration and functionalization.

Saliva biofilm-derived outer membrane vesicles regulate biofilm formation and immune response of oral epithelial cells on titanium surfaces

OBJECTIVES

While the significant roles of outer membrane vesicles (OMVs) from individual oral bacterial species in bacterial-host interactions are known, the involvement of saliva biofilm-derived OMVs in peri-implant disease pathogenesis remains unclear. This study aimed to investigate the effect of saliva biofilm-derived OMVs on regulating saliva biofilm formation and modulating the immune response of the epithelial cells on titanium surfaces.

MATERIALS AND METHODS

Saliva derived biofilms were cultured on tissue culture plates (TCP) for 4 days using pooled saliva from four healthy donors. OMVs secreted from the TCP bound biofilm (referred to as OMVs or healthy saliva biofilm OMVs) were enriched using the size-exclusion chromatography method. We then evaluated the effects of these OMVs on the viability, metabolic activity, and the presence of oral pathogens in saliva biofilm grown on titanium discs for 24 h and 72 h. Furthermore, the impact of OMVs on the mRNA expression and inflammatory cytokines [interleukin (IL)-6, IL-1α, and monocyte chemoattractant protein-1 (MCP-1)] in human oral epithelial cells (OKF6/TERT-2) was investigated using RT-qPCR and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

Healthy saliva biofilm OMVs improved the biomass and activity of saliva biofilm cultured on the titanium surfaces, with inhibited Porphyromonas gingivalis and Fusobacterium nucleatum, and enhanced Streptococcus mutans expression. Additionally, OMVs increased pro-inflammatory cytokine IL-6 mRNA and IL-6 cytokine expression in human oral epithelial cells. However, IL-1α and MCP-1 cytokines were inhibited 24-hour post-incubation with OMVs.

CONCLUSION

Healthy saliva biofilm derived OMVs regulate the activity and pathogen composition of biofilms formed on titanium, while modulating the secretion of pro-inflammation factors of oral epithelial cells grown on titanium surfaces.

CLINICAL RELEVANCE

Healthy saliva biofilm OMVs may regulate the early biofilm formation on abutment surfaces and modulate epithelial cell immune response, which may alter the peri-implant niche and participate in the pathogenesis of peri-implant disease.

Microbiological profile of peri-implantitis: Analyses of microbiome within dental implants

PURPOSE

To characterize the microbiome composition within dental implants of peri-implantitis subjects and healthy controls using 16S rRNA gene sequencing.

MATERIALS AND METHODS

Twenty-three subjects with healthy (n = 11 implants) and diseased (peri-implantitis, n = 21) implants were included in this controlled clinical cross-sectional study. Samples were obtained from internal surfaces of dental implants using sterile paper points for microbiological analysis. DNA was extracted, and the16S rRNA gene was amplified using universal primers targeting the V3-V4 regions. The resulting 16S polymerize chain reaction amplicons were sequenced on Illumina MiSeq, and the sequences were processed using DADA2 and the Human Oral Microbiome Database (HOMD) as references. Alpha and Beta diversity, as well as core microbiome and differential abundance analyses were then performed using the MicrobiomeAnalyst workflow.

RESULTS

A significant increase in microbial diversity was observed in the internal implant surface of healthy implants compared with the internal surfaces of peri-implantitis (Shannon p = 0.02). Bacterial community structure was significantly different among groups (p = 0.012). High levels of Gram-positive bacteria were detected inside implants with peri-implantitis compared to healthy implants, especially Enterococci.

CONCLUSIONS

There is a shift in bacterial diversity inside implants with peri-implantitis from the healthy control. The microbial colonization within that space might contribute to the etiology of peri-implant disease.

The Microbiome of Peri-Implantitis: A Systematic Review of Next-Generation Sequencing Studies

(1) Introduction: Current evidence shows that mechanical debridement augmented with systemic and topical antibiotics may be beneficial for the treatment of peri-implantitis. The microbial profile of peri-implantitis plays a key role in identifying the most suitable antibiotics to be used for the treatment and prevention of peri-implantitis. This systematic review aimed to summarize and critically analyze the methodology and findings of studies which have utilized sequencing techniques to elucidate the microbial profiles of peri-implantitis. (2) Results: Fusobacterium, Treponema, and Porphyromonas sp. are associated with peri-implantitis. Veillonella sp. are associated with healthy implant sites and exhibit a reduced prevalence in deeper pockets and with greater severity of disease progression. Streptococcus sp. have been identified both in diseased and healthy sites. Neisseria sp. have been associated with healthy implants and negatively correlate with the probing depth. Methanogens and AAGPRs were also detected in peri-implantitis sites. (3) Methods: The study was registered with the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42023459266). The PRISMA criteria were used to select articles retrieved from a systematic search of the Scopus, Cochrane, and Medline databases until 1 August 2023. Title and abstract screening was followed by a full-text review of the included articles. Thirty-two articles were included in the final qualitative analysis. (4) Conclusions: A distinct microbial profile could not be identified from studies employing sequencing techniques to identify the microbiome. Further studies are needed with more standardization to allow a comparison of findings. A universal clinical parameter for the diagnosis of peri-implantitis should be implemented in all future studies to minimize confounding factors. The subject pool should also be more diverse and larger to compensate for individual differences, and perhaps a distinct microbial profile can be seen with a larger sample size.