Effect of sodium hypochlorite gel on bacteria associated with periodontal disease.

OBJECTIVES: An adjunct in non-surgical periodontal therapy might be sodium hypochlorite (NaOCl)-based agents. The purpose of the present in vitro study was to get deeper knowledge on the influence of different parameters as time after mixing, pH, and chemical composition of an amino acid 0.475% NaOCl (AA-NaOCl) gel consisting of two components on its anti-biofilm activity. MATERIALS AND METHODS: Six-species biofilms were cultured for 5 days, before AA-NaOCl gel was applied. In the different series, the influence of the time after mixing of the two components before application, of the concentration of NaOCl in the gel mixture, of the pH of the gel mixture, and of an exchange of the amino acid component by hyaluronic acid (HA), was analyzed. RESULTS: Mixing time point experiments showed that the AA-NaOCl gel is capable of statistically significantly reducing colony-forming unit (cfu) counts up to 30 min after mixing, but only up to 20 min after mixing the reduction was more than 2 log10 cfu. The pH experiments indicate that a reduced pH results in a reduced activity of the NaOCl formulation. NaOCl concentrations in the formulation in the range from 0.475 to 0.2% provide adequate activity on biofilms. A HA/NaOCl gel was equally active against the biofilm as the AA-NaOCl gel. CONCLUSION: Mixing of the components should be made in a timeframe of 20 min before applications. An optimization of the composition of the NaOCl formulation might be possible and should be a topic in further in vitro studies. CLINICAL RELEVANCE: The AA-NaOCl gel formulation can be mixed up to 20 min before application. Further, the study indicates that the composition of the NaOCl gel formulation can be optimized.

In-vitro effects of novel periodontal scalers with a planar ultrasonic piezoelectric transducer on periodontal biofilm removal, dentine surface roughness, and periodontal ligament fibroblasts adhesion.

OBJECTIVES: To compare ultrasonic scaler prototypes based on a planar piezoelectric transducer with different working frequencies featuring a titanium (Ti-20, Ti-28, and Ti-40) or stainless steel (SS-28) instrument, with a commercially available scaler (com-29) in terms of biofilm removal and reformation, dentine surface roughness and adhesion of periodontal fibroblasts. MATERIALS AND METHODS: A periodontal multi-species biofilm was formed on specimens with dentine slices. Thereafter specimens were instrumented with scalers in a periodontal pocket model or left untreated (control). The remaining biofilms were quantified and allowed to reform on instrumented dentine slices. In addition, fibroblasts were seeded for attachment evaluation after 72 h of incubation. Dentine surface roughness was analyzed before and after instrumentation. RESULTS: All tested instruments reduced the colony-forming unit (cfu) counts by about 3 to 4 log10 and the biofilm quantity (each p < 0.01 vs. control), but with no statistically significant difference between the instrumented groups. After 24-hour biofilm reformation, no differences in cfu counts were observed between any groups, but the biofilm quantity was about 50% in all instrumented groups compared to the control. The attachment of fibroblasts on instrumented dentine was significantly higher than on untreated dentine (p < 0.05), with the exception of Ti-20. The dentine surface roughness was not affected by any instrumentation. CONCLUSIONS: The planar piezoelectric scaler prototypes are able to efficiently remove biofilm without dentine surface alterations, regardless of the operating frequency or instrument material. CLINICAL RELEVANCE: Ultrasonic scalers based on a planar piezoelectric transducer might be an alternative to currently available ultrasonic scalers.

Apelin Counteracts the Effects of Fusobacterium nucleatum on the Migration of Periodontal Ligament Cells In Vitro.

To better understand the link between periodontitis and metabolic diseases, our in vitro study aimed to assess the influence of the adipokine apelin and/or the periodontal pathogen Fusobacterium nucleatum on periodontal cells. Periodontal ligament (PDL) cells were exposed to F. nucleatum in the presence and absence of apelin. Scratch assays were used to analyze the in vitro wound healing and velocity of cell migration. To investigate if F. nucleatum and/or apelin have a regulatory effect on cell proliferation and apoptosis, proliferation and viability assays were performed as well as an analysis of caspase 9 expression. Both the in vitro wound closure and the cell migration rate were significantly reduced by F. nucleatum. Simultaneous incubation with apelin counteracted the adverse effects of F. nucleatum. The proliferation assay demonstrated that neither apelin nor F. nucleatum significantly affected PDL cell proliferation. Furthermore, neither apelin nor F. nucleatum was cytotoxic or affected apoptosis after 48 h. Apelin could play a modulatory role in the pathogenesis of periodontitis, as it was able to compensate for the inhibitory effects of the periodontal pathogen F. nucleatum on PDL cell migration in vitro.

Periodontal microbiology and microbial etiology of periodontal diseases: Historical concepts and contemporary perspectives.

This narrative review summarizes the collective knowledge on periodontal microbiology, through a historical timeline that highlights the European contribution in the global field. The etiological concepts on periodontal disease culminate to the ecological plaque hypothesis and its dysbiosis-centered interpretation. Reference is made to anerobic microbiology and to the discovery of select periodontal pathogens and their virulence factors, as well as to biofilms. The evolution of contemporary molecular methods and high-throughput platforms is highlighted in appreciating the breadth and depth of the periodontal microbiome. Finally clinical microbiology is brought into perspective with the contribution of different microbial species in periodontal diagnosis, the combination of microbial and host biomarkers for this purpose, and the use of antimicrobials in the treatment of the disease.

In vitro activity of hyaluronic acid and human serum on periodontal biofilm and periodontal ligament fibroblasts.

OBJECTIVES: A beneficial effect of cross-linked hyaluronic acid (cHA) on periodontal wound healing and regeneration has recently been demonstrated. The present in vitro study was designed to obtain deeper knowledge on the effect of cHA when applied in the gingival sulcus (serum-rich environment) during non-surgical periodontal therapy. MATERIALS AND METHODS: The influence of cHA, human serum (HS), and cHA/HS on (i) a 12-species biofilm formation, (ii) the adhesion of periodontal ligament fibroblasts (PDLF) to dentine surface, (iii) the expression and secretion of interleukin-8, and (iv) the expression of receptors of HA in PDLF and gingival fibroblasts (GF) were evaluated. RESULTS: At 4 h of biofilm formation, cHA and HS in combination (cHA/HS) slightly decreased the colony-forming unit counts in biofilm whereas the metabolic activity of biofilm was reduced in all test groups (cHA, HS, cHA/HS) vs. control. At 24 h, the quantity of biofilm was reduced in all test groups vs. untreated control. The test substances did not affect adhesion of PDLF to dentin. HS increased the expression of IL-8 by PDLF and GF which was partially downregulated by cHA. HS and/or cHA promoted the expression of the HA receptor RHAMM in GF but not in PDLF. CONCLUSIONS: In summary, the present data indicate that serum neither negatively affect the activity of cHA against periodontal biofilm nor had any unwanted influence on the activity of PDLF. CLINICAL RELEVANCE: These findings lend additional support for the positive effects of cHA on cells involved in periodontal wound healing, thus pointing to its potential use in non-surgical periodontal therapy.

Apelin Enhances the Effects of Fusobacterium nucleatum on Periodontal Ligament Cells In Vitro.

This study aimed to explore effects of Fusobacterium nucleatum with or without apelin on periodontal ligament (PDL) cells to better understand pathomechanistic links between periodontitis and obesity. First, the actions of F. nucleatum on COX2, CCL2, and MMP1 expressions were assessed. Subsequently, PDL cells were incubated with F. nucleatum in the presence and absence of apelin to study the modulatory effects of this adipokine on molecules related to inflammation and hard and soft tissue turnover. Regulation of apelin and its receptor (APJ) by F. nucleatum was also studied. F. nucleatum resulted in elevated COX2, CCL2, and MMP1 expressions in a dose- and time-dependent manner. Combination of F. nucleatum and apelin led to the highest (p < 0.05) expression levels of COX2, CCL2, CXCL8, TNF-α, and MMP1 at 48 h. The effects of F. nucleatum and/or apelin on CCL2 and MMP1 were MEK1/2- and partially NF-κB-dependent. The combined effects of F. nucleatum and apelin on CCL2 and MMP1 were also observed at protein level. Moreover, F. nucleatum downregulated (p < 0.05) the apelin and APJ expressions. In conclusion, obesity could contribute to periodontitis through apelin. The local production of apelin/APJ in PDL cells also suggests a role of these molecules in the pathogenesis of periodontitis.

Non-Invasive Physical Plasma Reduces the Inflammatory Response in Microbially Prestimulated Human Gingival Fibroblasts.

Non-invasive physical plasma (NIPP), an electrically conductive gas, is playing an increasingly important role in medicine due to its antimicrobial and regenerative properties. However, NIPP is not yet well established in dentistry, although it has promising potential, especially for periodontological applications. The aim of the present study was to investigate the effect of NIPP on a commercially available human gingival fibroblast (HGF) cell line and primary HGFs in the presence of periodontitis-associated bacteria. First, primary HGFs from eight patients were characterised by immunofluorescence, and cell numbers were examined by an automatic cell counter over 5 days. Then, HGFs that were preincubated with Fusobacterium nucleatum (F.n.) were treated with NIPP. Afterwards, the IL-6 and IL-8 levels in the cell supernatants were determined by ELISA. In HGFs, F.n. caused a significant increase in IL-6 and IL-8, and this F.n.-induced upregulation of both cytokines was counteracted by NIPP, suggesting a beneficial effect of physical plasma on periodontal cells in a microbial environment. The application of NIPP in periodontal therapy could therefore represent a novel and promising strategy and deserves further investigation.

Mammalian-like type II glutaminyl cyclases in Porphyromonas gingivalis and other oral pathogenic bacteria as targets for treatment of periodontitis.

The development of a targeted therapy would significantly improve the treatment of periodontitis and its associated diseases including Alzheimer's disease, rheumatoid arthritis, and cardiovascular diseases. Glutaminyl cyclases (QCs) from the oral pathogens Porphyromonas gingivalis, Tannerella forsythia, and Prevotella intermedia represent attractive target enzymes for small-molecule inhibitor development, as their action is likely to stabilize essential periplasmic and outer membrane proteins by N-terminal pyroglutamination. In contrast to other microbial QCs that utilize the so-called type I enzymes, these oral pathogens possess sequences corresponding to type II QCs, observed hitherto only in animals. However, whether differences between these bacteroidal QCs and animal QCs are sufficient to enable development of selective inhibitors is not clear. To learn more, we recombinantly expressed all three QCs. They exhibit comparable catalytic efficiencies and are inhibited by metal chelators. Crystal structures of the enzymes from P. gingivalis (PgQC) and T. forsythia (TfQC) reveal a tertiary structure composed of an eight-stranded ß-sheet surrounded by seven α-helices, typical of animal type II QCs. In each case, an active site Zn ion is tetrahedrally coordinated by conserved residues. Nevertheless, significant differences to mammalian enzymes are found around the active site of the bacteroidal enzymes. Application of a PgQC-selective inhibitor described here for the first time results in growth inhibition of two P. gingivalis clinical isolates in a dose-dependent manner. The insights gained by these studies will assist in the development of highly specific small-molecule bacteroidal QC inhibitors, paving the way for alternative therapies against periodontitis and associated diseases.

Mammalian-like type II glutaminyl cyclases in Porphyromonas gingivalis and other oral pathogenic bacteria as targets for treatment of periodontitis.

The development of a targeted therapy would significantly improve the treatment of periodontitis and its associated diseases including Alzheimer Disease, rheumatoid arthritis, and cardiovascular diseases. Glutaminyl cyclases (QCs) from the oral pathogens Porphyromonas gingivalis, Tannerella forsythia and Prevotella intermedia represent attractive target enzymes for small-molecule inhibitor development, as their action is likely to stabilize essential periplasmic and outer membrane proteins by N-terminal pyroglutamination. In contrast to other microbial QCs that utilize so-called type I enzymes, these oral pathogens possess sequences corresponding to type II QCs, observed hitherto only in animals. However, whether differences between these bacteroidal QCs and animal QCs are sufficient to enable development of selective inhibitors is not clear. To learn more, we recombinantly expressed all three QCs. They exhibit comparable catalytic efficiencies and are inhibited by metal chelators. Crystal structures  of the enzymes from P. gingivalis (PgQC) and T. forsythia (TfQC) reveal a tertiary structure composed of an eight-stranded ß-sheet surrounded by seven α-helices, typical of animal type II QCs. In each case, an active site Zn ion is tetrahedrally coordinated by conserved residues. Nevertheless, significant differences to mammalian enzymes are found around the active site of the bacteroidal enzymes. Application of a PgQC-selective inhibitor described here for the first time results in growth inhibition of two P. gingivalis clinical isolates in a dose dependent manner. The insights gained by these studies will assist in the development of highly specific small-molecule bacteroidal QC inhibitors, paving the way for alternative therapies against periodontitis and associated diseases.

Periodontal microorganisms and Alzheimer disease - A causative relationship?

In the initiation or exacerbation of Alzheimer disease, the dissemination of oral microorganisms into the brain tissue or the low-level systemic inflammation have been speculated to play a role. However, the impact of oral microorganisms, such as Porphyromonas gingivalis, on the pathogenesis of Alzheimer disease and the potential causative relationship is still unclear. The present review has critically reviewed the literature by examining the following aspects: (a) the oral microbiome and the immune response in the elderly population, (b) human studies on the association between periodontal and gut microorganisms and Alzheimer disease, (c) animal and in vitro studies on microorganisms and Alzheimer disease, and (d) preventive and therapeutic approaches. Factors contributing to microbial dysbiosis seem to be aging, local inflammation, systemic diseases, wearing of dentures, living in nursing homes and no access to adequate oral hygiene measures. Porphyromonas gingivalis was detectable in post-mortem brain samples. Microbiome analyses of saliva samples or oral biofilms showed a decreased microbial diversity and a different composition in Alzheimer disease compared to cognitively healthy subjects. Many in-vitro and animal studies underline the potential of P gingivalis to induce Alzheimer disease-related alterations. In animal models, recurring applications of P gingivalis or its components increased pro-inflammatory mediators and ß-amyloid in the brain and deteriorated the animals' cognitive performance. Since periodontitis is the result of a disturbed microbial homoeostasis, an effect of periodontal therapy on the oral microbiome and host response related to cognitive parameters may be suggested and should be elucidated in further clinical trials.

Clinical, microbiological, and immunological effects of 3- or 7-day systemic antibiotics adjunctive to subgingival instrumentation in patients with aggressive (Stage III/IV Grade C) periodontitis: A randomized placebo-controlled clinical trial.

AIM: To evaluate the clinical non-inferiority of a 3-day protocol of systemic antibiotics adjunctive to subgingival instrumentation (SI) compared with a 7-day-protocol in patients with Stage III/IV Grade C periodontitis. MATERIALS AND METHODS: Fifty systemically healthy patients (32.7 ± 4.3 years) with aggressive periodontitis (AgP; Stage III/IV Grade C periodontitis) were treated by SI and adjunctive amoxicillin and metronidazole and were randomly assigned to Group A: (n = 25) 500 mg antibiotics (AB) 3 times a day for 3 days, followed by placebo 3 times a day for 4 days, or Group B: (n = 25) 500 mg AB 3 times a day for 7 days. Clinical, microbial, and immunological parameters were assessed at baseline, 3 months, and 6 months, and patient-related outcomes were assessed after 2 weeks. The primary outcome variable was the number of residual sites with pocket depth (PD) ≥6 mm at 6 months. RESULTS: For the primary outcome variable (the number of residual sites with PD ≥6 mm at 6 months), the null hypothesis was rejected and non-inferiority of the 3-day AB protocol compared with the 7-day AB protocol was demonstrated (the upper limits of the 95% confidence interval for intention to treat analysis: [-2.572; 1.050] and per protocol analysis: [-2.523; 1.318] were lower than the assumed margin of Δ = 3.1). Comparable clinical improvements were obtained for all parameters with both antibiotic protocols (p > .05). All investigated periodontopathogens and pro-inflammatory host-derived markers were statistically significantly reduced without differences between the treatments (p > .05). CONCLUSIONS: These findings indicate that in patients with AgP (Stage III/IV Grade C periodontitis), a 3-day systemic administration of amoxicillin and metronidazole adjunctive to SI may lead to non-inferior clinical outcomes after 6-months with fewer adverse events compared with a 7-day-protocol.

Non-surgical mechanical therapy of peri-implantitis with or without repeated adjunctive diode laser application. A 6-month double-blinded randomized clinical trial.

OBJECTIVES: The objective of this study is to investigate the outcomes following non-surgical therapy of peri-implantitis (PI) with or without adjunctive diode laser application. MATERIALS AND METHODS: A double-blinded randomized controlled clinical trial was carried out in 25 subjects with 25 implants diagnosed with PI. Following curettage of granulation tissue, test implants (T) were treated with adjunctive application of a diode laser for 90 s (settings: 810 nm, 2.5 W, 50 Hz, 10 ms), while at control implants (C) non-activated adjunctive diode laser was applied. The entire treatment procedure was performed at days 0 (i.e., baseline), 7 and 14. The primary outcome measure was change in mean pocket probing depth (PPD). Clinical and microbiological outcomes, as well as host-derived inflammatory markers were evaluated at baseline, 3 and 6 months, while radiographic outcomes were assessed at baseline and at the 6-month follow-up. RESULTS: No statistically significant differences with respect to baseline patient characteristic were observed. After 6 months, both test and control implants yielded statistically significant PPD changes compared with baseline (T: 1.28 and C: 1.47 mm) but without statistically significant difference between groups (p = .381). No statistically significant changes in peri-implant marginal bone levels were detected (p = .936). No statistically significant differences between test and control implants were observed with respect to microbiological and host-derived parameters (p > .05). At the 6-month follow-up, treatment success was observed in 41.7% (n = 5) of test and 46.2% (n = 6) of control patients, respectively (p = .821). CONCLUSION: Repeated adjunctive application of diode laser in the non-surgical management of PI failed to provide significant benefits compared with mechanical instrumentation alone.

A novel in vitro periodontal pocket model to evaluate the effect of root surface instrumentation on biofilm-epithelial cell interactions.

OBJECTIVE: To develop a novel in vitro periodontal pocket model for evaluating the effect of two different root surface instrumentation modalities on biofilm-epithelial cell interactions. MATERIALS AND METHODS: An artificial periodontal pocket model was created using an impression material. Dentin discs were prepared and incubated for 3.5 days with a biofilm consisting of 12 bacterial strains. Then, the discs were inserted into the pocket model and instrumented for 10 s or 10 strokes either with ultrasonics (US) or hand instruments (HI). Subsequently, a glass slide coated with epithelial cells was placed in close vicinity to the discs. After incubation of the pocket model in a 5% CO2 atmosphere for 6 h, residual bacteria of the biofilm as well as bacteria adhering to or invaded into epithelial cells were determined using colony-forming unit (cfu) counts and real-time PCR. Further, as a parameter of the pro-inflammatory cell response, interleukin (IL)-8 expression was determined by ELISA. RESULTS: Compared to untreated control, HI reduced the cfu counts by 0.63 log10 (not significant) and US by 1.78 log10 (p = 0.005) with a significant difference between the treatment modalities favoring US (p = 0.048). By trend, lower detection levels of Tannerella forsythia were detected in the US group compared to HI. Concerning the interaction with epithelial cells, half of the control and the HI samples showed epithelial cells with attaching or invading bacteria, while US displayed bacteria only in two out of eight samples. In addition, US resulted in significantly lower IL-8 secretion by epithelial cells compared to the untreated control. Between HI and controls, no statistically significant difference in IL-8 secretion was found. CONCLUSION: This newly developed in vitro model revealed in terms of biofilm-epithelial cell interaction after root surface instrumentation that compared to hand curettes, ultrasonic instrumentation appeared to be more effective in removing bacterial biofilm and in decreasing the inflammatory response of epithelium to biofilm. CLINICAL RELEVANCE: Ultrasonic instrumentation might be more advantageous to reduce cellular inflammatory response than hand instruments.

Bacterial colonisation during regular daily use of a power-driven water flosser and risk for cross-contamination. Can it be prevented?

OBJECTIVE: To assess whether bacterial colonisation in a power-driven water flosser can be prevented. MATERIALS AND METHODS: Twenty-four patients undergoing supportive periodontal treatment used 2 power-driven water flossers [Sonicare AirFloss (SAF), AirFloss Ultra (SAFU)] for 12 weeks each as follows: (a) with bottled water (BW); (b) with BW and cleaning the device extra-orally twice per week with chlorhexidine gluconate or (c) essential-oil-based (EO) mouth-rinse; (d) with EO only. Water-jet samples were taken after 6 and 12 weeks with the used nozzle and after exchanging to a brand-new nozzle. After 12 weeks, all devices underwent an intensive cleaning procedure. Samples were analysed by PCR-based method for cariogenic and periodontal pathogens and culture for staphylococci, aerobe gram-negative bacteria, and Candida sp. RESULTS: Contamination of SAF/SAFU with Streptococcus mutans was found in > 95% of the samples; periodontal pathogens and aerobe gram-negative bacteria were detected in 19-56% of the samples, while Staphylococcus aureus and Candida sp. were identified only in few samples. Contamination rate was basically unaffected by time-point, device, or way of use. Further, exchanging the nozzle did not prevent transmission of a contaminated water-jet, but the intensive cleaning reduced most of the pathogens significantly, except of S. mutans. CONCLUSION: Neither a specific way of use nor exchanging the nozzle prevented bacterial colonisation and transmission of biofilm components via the water-jet of SAF/SAFU. CLINICAL RELEVANCE: Bacterial colonisation in a power-driven water flosser seems impossible to prevent; to restrict the risk of cross-contamination within a household, one device per person should be recommended.

Interaction of periodontitis and orthodontic tooth movement-an in vitro and in vivo study.

OBJECTIVES: The aim of this in vitro and in vivo study was to investigate the interaction of periodontitis and orthodontic tooth movement on interleukin (IL)-6 and C-X-C motif chemokine 2 (CXCL2). MATERIALS AND METHODS: The effect of periodontitis and/or orthodontic tooth movement (OTM) on alveolar bone and gingival IL-6 and CXCL2 expressions was studied in rats by histology and RT-PCR, respectively. The animals were assigned to four groups (control, periodontitis, OTM, and combination of periodontitis and OTM). The IL-6 and CXCL2 levels were also studied in human gingival biopsies from periodontally healthy and periodontitis subjects by RT-PCR and immunohistochemistry. Additionally, the synthesis of IL-6 and CXCL2 in response to the periodontopathogen Fusobacterium nucleatum and/or mechanical strain was studied in periodontal fibroblasts by RT-PCR and ELISA. RESULTS: Periodontitis caused an increase in gingival levels of IL-6 and CXCL2 in the animal model. Moreover, orthodontic tooth movement further enhanced the bacteria-induced periodontal destruction and gingival IL-6 gene expression. Elevated IL-6 and CXCL2 gingival levels were also found in human periodontitis. Furthermore, mechanical strain increased the stimulatory effect of F. nucleatum on IL-6 protein in vitro. CONCLUSIONS: Our study suggests that orthodontic tooth movement can enhance bacteria-induced periodontal inflammation and thus destruction and that IL-6 may play a pivotal role in this process. CLINICAL RELEVANCE: Orthodontic tooth movement should only be performed after periodontal therapy. In case of periodontitis relapse, orthodontic therapy should be suspended until the periodontal inflammation has been successfully treated and thus the periodontal disease is controlled again.

Effect of Bacterial Infection on Ghrelin Receptor Regulation in Periodontal Cells and Tissues.

The effect of bacterial infection on the expression of growth hormone secretagogue receptor (GHS-R) was investigated in periodontal cells and tissues, and the actions of ghrelin were evaluated. GHS-R was assessed in periodontal tissues of rats with and without periodontitis. Human gingival fibroblasts (HGFs) were exposed to Fusobacterium nucleatum in the presence and absence of ghrelin. GHS-R expression was determined by real-time PCR and immunocytochemistry. Furthermore, wound healing, cell viability, proliferation, and migration were evaluated. GHS-R expression was significantly higher at periodontitis sites as compared to healthy sites in rat tissues. F. nucleatum significantly increased the GHS-R expression and protein level in HGFs. Moreover, ghrelin significantly abrogated the stimulatory effects of F. nucleatum on CCL2 and IL-6 expressions in HGFs and did not affect cell viability and proliferation significantly. Ghrelin stimulated while F. nucleatum decreased wound closure, probably due to reduced cell migration. Our results show original evidence that bacterial infection upregulates GHS-R in rat periodontal tissues and HGFs. Moreover, our study shows that ghrelin inhibited the proinflammatory actions of F. nucleatum on HGFs without interfering with cell viability and proliferation, suggesting that ghrelin and its receptor may act as a protective molecule during bacterial infection on periodontal cells.

Triggering NETosis via protease-activated receptor (PAR)-2 signaling as a mechanism of hijacking neutrophils function for pathogen benefits.

Neutrophil-derived networks of DNA-composed extracellular fibers covered with antimicrobial molecules, referred to as neutrophil extracellular traps (NETs), are recognized as a physiological microbicidal mechanism of innate immunity. The formation of NETs is also classified as a model of a cell death called NETosis. Despite intensive research on the NETs formation in response to pathogens, the role of specific bacteria-derived virulence factors in this process, although postulated, is still poorly understood. The aim of our study was to determine the role of gingipains, cysteine proteases responsible for the virulence of P. gingivalis, on the NETosis process induced by this major periodontopathogen. We showed that NETosis triggered by P. gingivalis is gingipain dependent since in the stark contrast to the wild-type strain (W83) the gingipain-null mutant strain only slightly induced the NETs formation. Furthermore, the direct effect of proteases on NETosis was documented using purified gingipains. Notably, the induction of NETosis was dependent on the catalytic activity of gingipains, since proteolytically inactive forms of enzymes showed reduced ability to trigger the NETs formation. Mechanistically, gingipain-induced NETosis was dependent on proteolytic activation of protease-activated receptor-2 (PAR-2). Intriguingly, both P. gingivalis and purified Arg-specific gingipains (Rgp) induced NETs that not only lacked bactericidal activity but instead stimulated the growth of bacteria species otherwise susceptible to killing in NETs. This protection was executed by proteolysis of bactericidal components of NETs. Taken together, gingipains play a dual role in NETosis: they are the potent direct inducers of NETs formation but in the same time, their activity prevents P. gingivalis entrapment and subsequent killing. This may explain a paradox that despite the massive accumulation of neutrophils and NETs formation in periodontal pockets periodontal pathogens and associated pathobionts thrive in this environment.

Microbial and host-derived biomarker changes during ligature-induced and spontaneous peri-implantitis in the Beagle dog.

OBJECTIVE: To evaluate microbial and host-derived biomarker changes during experimental peri-implantitis in the Beagle dog. BACKGROUND: Limited data exist on the microbial and biomarker changes during progressive bone loss as result of experimental peri-implantitis. METHODS: In total, 36 implants (ndogs  = 6) were assessed over 3 episodes of ligature-induced peri-implantitis followed by a period of spontaneous progression. Implants with hybrid (H) and completely rough (R) surface designs were used. Clinical and radiographic parameters were recorded at 4 timepoints. Peri-implant sulcus fluid was collected from the buccal and lingual aspects of the implants. The presence of 7 bacterial species and 2 host-derived biomarkers was assessed during the study period. RESULTS: Total bacterial counts were significantly correlated with marginal bone loss (MBL) (r = .21; P = .009). Further, Phorphyromonas gulae (Pg) and Tannerella forsythia (Tf) were commonly correlated with MBL, suppuration (SUP) and the sulcular bleeding index scores (mSBI) (P < .05). Other bacteria were further correlated with SUP, mSBI, and MBL. While the analyzed bacteria dropped, Prevotella intermedia (Pi) further increased during the spontaneous progressive phase (P < .05). Total bacterial load did not differ significantly between H and R implants. Host-derived IL-10 was undetected along the study period. IL-1ß positively correlated with probing pocket depth (r = .18; P = .03). During spontaneous progression, H implants displayed statistically significant lower levels of IL-1ß (P = .003). CONCLUSION: Experimental peri-implantitis is associated with an increase in bacterial counts. While Pg and Tf are associated with ligature-induced disease progression, Pi augmented its load during the spontaneous progressive phase. IL-1ß is associated with pocket probing depth and influenced by implant surface characteristics during the spontaneous progression phase.

Clinical outcomes following periodontal surgery and root surface decontamination by erythritol-based air polishing. A randomized, controlled, clinical pilot study.

AIM: To evaluate the outcomes following surgical periodontal treatment and root surface decontamination by means of air polishing using an erythritol powder or conventional mechanical root debridement. MATERIAL AND METHODS: Thirty systemically healthy patients (44.38 ± 8.2 years old, 11 smokers, 19 women) diagnosed with periodontitis stages III-IV were included. Each patient, with one single-rooted tooth, with one probing pocket depth (PD) ≥ 6 mm associated with horizontal bone loss, was treated by means of simplified papilla preservation flap (SPPF) and randomized to either test treatment (careful removal of the calculus with the tip of a blade, air polishing of the root surfaces with erythritol) or to the control group (scaling and root planing with hand curettes, ultrasonic instruments). PD, clinical attachment (CAL), bone sounding (BS), and radiographic bone level (BL) were evaluated at baseline and 12 months postsurgically. RESULTS: Twenty-seven patients completed the 12-month follow-up (test: n = 14, control: n = 13). In both groups, statistically significant improvements were obtained (p < 0.05, mean CAL gain/PD reduction: test, 2.50 ± 1.60 mm/3.00 ± 0.96 mm; control, 2.85 ± 1.21 mm/3.38 ± 1.12 mm). No statistically significant differences were observed between the groups for any of the investigated parameters (p < 0.05). CONCLUSION: Within their limits, the present results indicate that the use of air polishing with an erythritol powder during periodontal surgery may represent a valuable minimally invasive adjunct following calculus removal by means of hand and ultrasonic instruments or a valuable alternative to these, for root surfaces without calculus. CLINICAL RELEVANCE: The use of air polishing with an erythritol powder during periodontal surgery appears to represent a valuable minimally invasive adjunct following calculus removal by means of hand and ultrasonic instruments or a valuable alternative to these, for root surfaces without calculus.

Effect of scaling on the invasion of oral microorganisms into dentinal tubules including the response of pulpal cells-an in vitro study.

OBJECTIVES: To investigate how scaling affects the penetration of microorganisms into dentinal tubules, how pulpal cells seeded into the pulp cavity respond to bacterial challenge, and how penetration and inflammatory response may depend on the bacterial composition. MATERIALS AND METHODS: Root canals of 102 extracted human teeth underwent shaping and cleaning. Half of the teeth were subjected to scaling and root planing, the other half remained untreated. Teeth were exposed to either Streptococcus gordonii and Actinomyces oris or S. gordonii and Porphyromonas gingivalis for 10 weeks. Bacterial invasion was assessed in a depth of 1 mm to the root surface. Human pulpal cells were seeded into the cavities to assess the expression of interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and matrix metalloproteinase-3 (MMP-3) by real-time polymerase chain reaction and immunoassay. RESULTS: The percentage of teeth with bacteria detected in dentine was higher when teeth received scaling than when they were untreated: 66.6% versus 44.4% when exposed to A. oris/S. gordonii, and 50% versus 25% when exposed to P. gingivalis/S. gordonii (p = 0.043). Scaling had no impact on IL-8 and MMP-3 expression in pulpal cells. P. gingivalis/S. gordonii caused higher levels of IL-8, MCP-1, and MMP-3 than A. oris/S. gordonii (p = 0.003, p = 0.011, p = 0.037). CONCLUSION: Scaling supports the penetration of bacteria into the dentine of extracted human teeth. P. gingivalis may affect the immune response in pulpal cells. CLINICAL RELEVANCE: Root surface debridement with hand instruments may facilitate bacterial penetration. Other kinds of mechanical instrumentation in this experimental setting should be investigated.