Comparing culture, real-time PCR and fluorescence resonance energy transfer technology for detection of Porphyromonas gingivalis in patients with or without peri-implant infections

Recent advances in nanomaterial-based biosensor for periodontitis detection

Periodontitis, a chronic inflammatory condition caused by bacteria, often causes gradual destruction of the components that support teeth, such as the alveolar bone, cementum, periodontal ligament, and gingiva. This ultimately results in teeth becoming loose and eventually falling out. Timely identification has a crucial role in preventing and controlling its progression. Clinical measures are used to diagnose periodontitis. However, now, there is a hunt for alternative diagnostic and monitoring methods due to the progress of technology. Various biomarkers have been assessed using multiple bodily fluids as sample sources. Furthermore, conventional periodontal categorization factors do not provide significant insights into the present disease activity, severity and amount of tissue damage, future development, and responsiveness to treatment. In recent times, there has been a growing utilization of nanoparticle (NP)-based detection strategies to create quick and efficient detection assays. Every single one of these platforms leverages the distinct characteristics of NPs to identify periodontitis. Plasmonic NPs include metal NPs, quantum dots (QDs), carbon base NPs, and nanozymes, exceptionally potent light absorbers and scatterers. These find application in labeling, surface-enhanced spectroscopy, and color-changing sensors. Fluorescent NPs function as photostable and sensitive instruments capable of labeling various biological targets. This article presents a comprehensive summary of the latest developments in the effective utilization of various NPs to detect periodontitis.

A method for Porphyromonas gingivalis based on recombinase polymerase amplification and lateral flow strip technology

OBJECTIVE

A practical visual detection method was established to detect Porphyromonas gingivalis (P. gingivalis) by employing a combination of recombinase polymerase amplification and lateral flow strips (RPA-LF) assay, designed for conducting point-of-care testing in clinical settings.

METHODS

Primers and probes targeting the P. gingivalis pepO gene were designed. The RPA-LF assay was established by optimising reaction temperature and time, determining the limit of detection (LOD). The specificity of the method was determined by assessing its cross-reactivity with deoxyribonucleic acid from 23 pathogenic bacteria. Finally, the clinical samples from healthy controls (n = 30) and individuals with periodontitis (n = 31) were analysed. The results were compared with those obtained using real-time polymerase chain reaction (PCR).

RESULTS

The optimal reaction temperature and time were 39 °C and 12 min. The method exhibited a LOD at 6.40 × 10-4 μg/mL and demonstrated high specificity and sensitivity during cross-reactivity assessment. The RPA-LF assay achieved a P. gingivalis detection rate of 84 % in individuals with periodontitis and 3 % in healthy controls. The results were consistent with those obtained through real-time PCR.

CONCLUSION

An RPA-LF assay was developed for detecting P. gingivalis, characterised by its high sensitivity, high specificity, simple operational procedure, and rapid reaction time.

Porphyromonas gingivalis outside the oral cavity

Porphyromonas gingivalis, a Gram-negative anaerobic bacillus present in periodontal disease, is considered one of the major pathogens in periodontitis. A literature search for English original studies, case series and review articles published up to December 2019 was performed using the MEDLINE, PubMed and GoogleScholar databases, with the search terms "Porphyromonas gingivalis" AND the potentially associated condition or systemic disease Abstracts and full text articles were used to make a review of published research literature on P. gingivalis outside the oral cavity. The main points of interest of this narrative review were: (i) a potential direct action of the bacterium and not the systemic effects of the inflammatory acute-phase response induced by the periodontitis, (ii) the presence of the bacterium (viable or not) in the organ, or (iii) the presence of its virulence factors. Virulence factors (gingipains, capsule, fimbriae, hemagglutinins, lipopolysaccharide, hemolysin, iron uptake transporters, toxic outer membrane blebs/vesicles, and DNA) associated with P. gingivalis can deregulate certain functions in humans, particularly host immune systems, and cause various local and systemic pathologies. The most recent studies linking P. gingivalis to systemic diseases were discussed, remembering particularly the molecular mechanisms involved in different infections, including cerebral, cardiovascular, pulmonary, bone, digestive and peri-natal infections. Recent involvement of P. gingivalis in neurological diseases has been demonstrated. P. gingivalis modulates cellular homeostasis and increases markers of inflammation. It is also a factor in the oxidative stress involved in beta-amyloid production.

Washing- and Separation-Free Electrochemical Detection of Porphyromonas gingivalis in Saliva for Initial Diagnosis of Periodontitis

Indirect detection of Porphyromonas gingivalis in saliva, based on proteolytic cleavage by an Arg-specific gingipain (Arg-gingipain), has traditionally been used for simple, initial diagnosis of periodontitis. To accurately detect P. gingivalis using a point-of-care format, development of a simple biosensor that can measure the exact concentration of P. gingivalis is required. However, electrochemical detection in saliva is challenging due to the presence of various interfering electroactive species in different concentrations. Here, we report a washing- and separation-free electrochemical biosensor for sensitive detection of P. gingivalis in saliva. Glycine-proline-arginine conjugated with 4-aminophenol (AP) was used as an electrochemical substrate for a trypsin-like Arg-gingipain, and glycylglycine was used to increase the Arg-gingipain activity. The electrochemical signal of AP was increased using electrochemical-chemical (EC) redox cycling involving an electrode, AP, and tris(2-carboxyethyl)phosphine, and the electrochemical charge signal was corrected using the initial charge obtained before a 15 min incubation period. The EC redox cycling combined with the matrix-corrected signal facilitated a high and reproducible signal without requiring washing and separation steps. The proteolytic cleavage of the electrochemical substrate was specific to P. gingivalis. The calculated detection limit for P. gingivalis in artificial saliva was 5 × 10⁵ colony-forming units/mL, and the concentration of P. gingivalis in human saliva could be measured. The developed biosensor can be used as an initial diagnosis method to distinguish between healthy people and patients with periodontal diseases.

Elevated Baseline Salivary Protease Activity May Predict the Steadiness of Gingival Inflammation During Periodontal Healing: A 12-Week Follow-Up Study on Adults

Aim was to profile salivary total protease, Porphyromonas gingivalis gingipain, and neutrophil elastase activities in relation to the resolution of periodontal inflammation, salivary macrophage-derived chemokine (MDC), and macrophage inflammatory protein-1α concentrations. Nonsurgical periodontal treatment was performed in 24 periodontitis patients in a prospective interventional study design. Periodontal clinical parameters were recorded, and stimulated saliva samples were collected at baseline and 2, 6, and 12 weeks after treatment. Salivary total protease and gingipain activities were determined using fluorogenic substrates, elastase activity by chromogenic substrates, and cytokine concentrations by Luminex immunoassay. For statistical analyses, generalized linear mixed models for repeated measures were used. Salivary total protease activity elevated, while gingival inflammation and plaque accumulation decreased 2 and 6 weeks after periodontal therapy. Salivary MDC concentration was elevated 12 weeks after periodontal treatment. Patients with elevated protease activities at baseline in comparison to patients with low baseline total protease activities, had higher levels of gingival inflammation before and after periodontal treatment. In conclusion, elevations in salivary total protease activity seem to be part of periodontal healing at its early phases. Higher levels of salivary total protease activities before periodontal treatment may predict the severity and steadiness of unresolved gingival inflammation.

Salivary Total Protease Activity Based on a Broad-Spectrum Fluorescence Resonance Energy Transfer Approach to Monitor Induction and Resolution of Gingival Inflammation

OBJECTIVE

Salivary total protease and chitinase activities were measured by a broad-spectrum fluorescence resonance energy transfer approach as predictors of induction and resolution of gingival inflammation in healthy individuals by applying an experimental human gingivitis model.

METHODS

Dental biofilm accumulated (21 days, Induction Phase) by omitting oral hygiene practices followed by a 2-week Resolution Phase to restore gingival health in an experimental gingivitis study. Plaque accumulation, as assessed by the Turesky Modification of the Quigley-Hein Plaque Index (TQHPI), and gingival inflammation, assessed using the Modified Gingival Index (MGI), scores were recorded and unstimulated saliva was collected weekly. Saliva was analysed for total protein, albumin, total protease activity and chitinase activity (n = 18).

RESULTS

The TQHPI and MGI scores, as well as total protease activity, increased until day 21. After re-establishment of oral hygiene, gingival inflammation levels returned to values similar to baseline (day 0). Levels of protease activity decreased significantly, but not to baseline values. Furthermore, 'fast' responders, who responded immediately to plaque, exhibited significantly higher proteolytic activity throughout the experimental course than 'slow' responders, who showed a lagged inflammatory response.

CONCLUSION

The results indicate that differential inflammatory responses encompass inherent variations in total salivary proteolytic activities, which could be further utilised in contemporary diagnostic, prognostic and treatment modalities for periodontal diseases.

Gingival tissue human beta-defensin levels in relation to infection and inflammation

AIM

To profile gingival tissue levels of human beta-defensin (hBD)-2 and hBD-3 in relation to gingival inflammation, Th17-related cytokine concentrations, Porphyromonas gingivalis counts, and gingipain and total protease activities.

MATERIALS AND METHODS

Gingival tissue and subgingival plaque samples were collected from 21 periodontitis patients including 48 periodontal pocket sites with marginal, mild, or moderate to severe inflammation. hBD levels were determined by immunodetection, P. gingivalis counts with real-time polymerase chain reaction, protease activities with fluorogenic substrates, and cytokine concentrations with Luminex technique. Data were statistically analysed using Kruskal-Wallis and Mann-Whitney U tests and Spearman correlation coefficients.

RESULTS

Subgingival plaque counts of P. gingivalis (p = .001) and gingipain activity (p < .001), as well as interleukin (IL)-1β (p = .012), IL-10 (p = .024), IL-17A (p = .002), IL-17F (p = .006), and IL-23 (p = .036) concentrations were elevated in severely inflamed sites, whereas no change was observed in hBD-2 and hBD-3 levels. Negative correlations were found between protease activity and hBD-2 (p = .033) and hBD-3(p = .003) levels.

CONCLUSIONS

Shift in gingival inflammation from marginal to mild stage is related to elevations in subgingival plaque P. gingivalis counts and gingipain activity, but not to tissue hBD levels. Negative correlations between hBDs and total protease activity suggest the degradation of these antimicrobial peptides in progressed inflammation.

On site visual detection of Porphyromonas gingivalis related periodontitis by using a magnetic-nanobead based assay for gingipains protease biomarkers

Porphyromonas gingivalis (P. gingivalis) is a pathogen causing periodontitis. A rapid assay is described for the diagnosis of periodontal infections related to P. gingivalis. The method is making use of gingipains, a group of P. gingivalis specific proteases as a detection biomarker. Magnetic-nanobeads were labeled with gingipain-specific peptide substrates and immobilized on a gold biosensing platform via gold-thiol linkage. As a result of this, the color of the gold layer turns black. Upon cleavage of the immobilized substrates by gingipains, the magnetic-nanobeads-peptide fragments were attracted by a magnet so that the golden surface color becomes visible again. This assay is highly sensitive and specific. It is capable of detecting as little as 49 CFU·mL^-1 of P. gingivalis within 30 s. Examination of periodontitis patients and healthy control saliva samples showed the potential of the assay. The simplicity and rapidity of the assay makes it an effective point-of-care device. Graphical abstract Schematic of the assay for the detection of P. gingivalis proteases as one of the promising biomarkers associated with periodontal diseases.

Detection of five potentially periodontal pathogenic bacteria in peri-implant disease: A comparison of PCR and real-time PCR

The aim of this study was to compare the microbial analysis methods of polymerase chain reaction (PCR) and real-time PCR (RT-PCR) in terms of detection of five selected potentially periodontal pathogenic bacteria in peri-implant disease. Therefore 45 samples of healthy, mucositis and peri-implantitis (n = 15 each) were assessed according to presence of the following bacteria using PCR (DNA-strip technology) and RT-PCR (fluorescent dye SYBR green-system): Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Treponema denticola (Td), Tanerella forsythia (Tf), and Fusobacterium nucleatum (Fn). There were no significant correlations between the bacterial and disease patterns, so the benefit of using microbiological tests for the diagnosis of peri-implant diseases is questionable. Correlations between the methods were highest for Tf (Kendall's Tau: 0.65, Spearman: 0.78), Fn (0.49, 0.61) and Td (0.49, 0.59). For Aa (0.38, 0.42) and Pg (0.04, 0.04), lower correlation values were detected. Accordingly, conventional semi-quantitative PCR seems to be sufficient for analyzing potentially periodontal pathogenic bacterial species.

Colorimetric Assay for the Detection of Typical Biomarkers for Periodontitis Using a Magnetic Nanoparticle Biosensor

Periodontitis is a chronic disease which affects at least 10% of the population. If untreated, periodontitis can lead to teeth loss. Unfortunately, current diagnostic tests are limited in their sensitivity and specificity. In this study, a novel multiplex hand-held colorimetric diagnostic biosensor, using two typical inflammatory salivary biomarkers, Human Neutrophil Elastase (HNE) and Cathepsin-G, was constructed as proof of concept to potentially detect periodontitis. The biosensing method was based on the measurement of proteolytic activity using specific proteases probes. These probes consist of specific proteases substrates covalently bound to a magnetic bead from one end and to the gold sensor surface by the other end. When intact, this renders the golden sensor black. Upon proteolysis, the cleaved magnetic beads will be attracted by an external magnet revealing the golden color of the sensor surface observable by the naked eye. The biosensor was capable of specific and quantitative detection of HNE and Cathepsin-G in solution and in spiked saliva samples with a lower detection limit of 1 pg/mL and 100 fg/mL for HNE and Cathepsin-G, respectively. Examination of periodontitis patients' sample and a healthy control showed the potential of the multiplex biosensor to detect the presence of HNE and Cathepsin-G activity in situ. This approach is anticipated to be a useful biochip array amenable to low-cost point-of-care devices.

Microbiome of peri-implant infections: lessons from conventional, molecular and metagenomic analyses

Osseointegrated dental implants are now a well-established treatment option in the armament of restorative dentistry. These technologically advanced devices are designed to functionally and esthetically replace missing teeth. Despite the revolutionary advances that implants have incurred, they have also provided the oral cavity with new artificial surfaces prone to the formation of oral biofilms, similarly to the hard tissue surfaces of natural teeth. Biofilm formation on the implant surface can trigger the inflammatory destruction of the peri-implant tissue, in what is known as peri-implantitis. The mixed microbial flora of peri-implant infections resembles that of periodontal infections, with some notable differences. These are likely to expand with the ever increasing application of metagenomics and metatrascriptomics in the analysis of oral ecology. This review presents the wealth of knowledge we have gained from microbiological methods used in the characterization of peri-implant microflora and sheds light over potential new benefits, as well as limitations, of the new sequencing technology in our understanding of peri-implant disease pathogenesis.

Fractal analysis of ibuprofen effect on experimental dog peri-implantitis

INTRODUCTION

The aim of this study was to assess the correlation between the fractal analysis of gingival changes and systemic nitro-oxidative stress in a short-term low-dose ibuprofen (IBU) treatment at experimental peri-implantitis (PI).

MATERIALS AND METHODS

Six adult male mixed-breed dogs with PI were randomly treated for 2 weeks, 3 with IBU (5 mg/kg b.w.) and 3 with placebo. Clinical and radiological evaluation were performed. Gingival biopsies were assessed by light microscopy, transmission electron microscopy, and fractal analysis. Blood was collected to assay nitric oxide (NOx), total oxidative status (TOS), total antioxidant response (TAR), and oxidative stress index (OSI).

RESULTS

Specific gingival ultrastructural alterations, bone loss, and systemic nitro-oxidative stress were evident in PI-placebo animals. IBU caused significant clinical, microscopic, fractal dimensions (P < 0.01), NOx, TOS, and OSI improvements. IBU caused no important bone and TAR changes.

CONCLUSION

This study confirms that fractal analysis was a good method to assess the complex morphological changes and correlations with the nitro-oxidative stress in PI. Short-term low-dose IBU treatment consistently improved gingival status and reduced systemic nitro-oxidative stress.

Learned and unlearned concepts in periodontal diagnostics: a 50-year perspective

In the past 50 years, conceptual changes in the field of periodontal diagnostics have paralleled those associated with a better scientific understanding of the full spectrum of processes that affect periodontal health and disease. Fifty years ago, concepts regarding the diagnosis of periodontal diseases followed the classical pathology paradigm. It was believed that the two basic forms of destructive periodontal disease were chronic inflammatory periodontitis and 'periodontosis'- a degenerative condition. In the subsequent 25 years it was shown that periodontosis was an infection. By 1987, major new concepts regarding the diagnosis and pathogenesis of periodontitis included: (i) all cases of untreated gingivitis do not inevitably progress to periodontitis; (ii) progression of untreated periodontitis is often episodic; (iii) some sites with untreated periodontitis do not progress; (iv) a rather small population of specific bacteria ('periodontal pathogens') appear to be the main etiologic agents of chronic inflammatory periodontitis; and (v) tissue damage in periodontitis is primarily caused by inflammatory and immunologic host responses to infecting agents. The concepts that were in place by 1987 are still largely intact in 2012. However, in the decades to come, it is likely that new information on the human microbiome will change our current concepts concerning the prevention, diagnosis and treatment of periodontal diseases.

Bacterial proteases: targets for diagnostics and therapy

Proteases are essential for the proliferation and growth of bacteria, and are also known to contribute to bacterial virulence. This makes them interesting candidates as diagnostic and therapeutic targets for infectious diseases. In this review, the authors discuss the most recent developments and potential applications for bacterial proteases in the diagnosis and treatment of bacterial infections. Current and future bacterial protease targets are described and their limitations outlined.

Antibiotic resistance in human peri-implantitis microbiota

OBJECTIVES

Because antimicrobial therapy is often employed in the treatment of infectious dental implant complications, this study determined the occurrence of in vitro antibiotic resistance among putative peri-implantitis bacterial pathogens.

METHODS

Submucosal biofilm specimens were cultured from 160 dental implants with peri-implantitis in 120 adults, with isolated putative pathogens identified to species level, and tested in vitro for susceptibility to 4 mg/l of doxycycline, 8 mg/l of amoxicillin, 16 mg/l of metronidazole, and 4 mg/l of clindamycin. Findings for amoxicillin and metronidazole were combined post-hoc to identify peri-implantitis species resistant to both antibiotics. Gram-negative enteric rods/pseudomonads were subjected to ciprofloxacin disk diffusion testing.

RESULTS

One or more cultivable submucosal bacterial pathogens, most often Prevotella intermedia/nigrescens or Streptococcus constellatus, were resistant in vitro to clindamycin, amoxicillin, doxycycline, or metronidazole in 46.7%, 39.2%, 25%, and 21.7% of the peri-implantitis subjects, respectively. Only 6.7% subjects revealed submucosal test species resistant in vitro to both amoxicillin and metronidazole, which were either S. constellatus (one subject) or ciprofloxacin-susceptible strains of gram-negative enteric rods/pseudomonads (seven subjects). Overall, 71.7% of the 120 peri-implantitis subjects exhibited submucosal bacterial pathogens resistant in vitro to one or more of the tested antibiotics.

CONCLUSIONS

Peri-implantitis patients frequently yielded submucosal bacterial pathogens resistant in vitro to individual therapeutic concentrations of clindamycin, amoxicillin, doxycycline, or metronidazole, but only rarely to both amoxicillin and metronidazole. Due to the wide variation in observed drug resistance patterns, antibiotic susceptibility testing of cultivable submucosal bacterial pathogens may aid in the selection of antimicrobial therapy for peri-implantitis patients.

Electrical stimuli improve osteogenic differentiation mediated by aniline pentamer and PLGA nanocomposites

Electrical stimulation may improve the proliferation of animal cells. In the present study, osteoblasts were cultured on electroactive aniline pentamer (AP)/poly(lactic-co-glycolic acid) (PLGA) copolymer composites, on which electric pulse was imposed. The combination of polymer and electric pulse enhanced the osteogenic differentiation of the osteoblasts, characterized by the upregulated expression of bone morphogenetic protein (BMP)-2, collagen I and osteonectin and the phosphorylation of Samd4, in contrast to polymer or electrical pulse alone. This action occurred in a polymer content-dependent manner. Therefore, the action of the electric pulse, assisted by the electroactive polymer implant, may be promising in the expedition of injured bone repair.