Necrotrophic growth of periodontopathogens is a novel virulence factor in oral biofilms

The oral use of antimicrobial agents embedded in toothpastes and mouth rinses results in an oral microbial massacre with high amounts of dead bacteria in close proximity to few surviving bacteria. It was hypothesized that this provides the surviving pathogenic bacteria a large amount of dead microbial biomass as a nutritional source for growth (necrotrophy). This study demonstrated the necrotrophic growth of periodontal pathogens in the presence of different dead oral species. In addition, the presence of dead bacteria resulted in an outgrowth of several periodontal pathogens in complex multispecies biofilms. Additionally, upon contact with dead oral bacteria, virulence genes of P. intermedia and P. gingivalis were up-regulated (necrovirulence). This resulted in a more pronounced epithelial cytotoxicity (necrotoxicity). These findings indicate that presence of dead bacteria induce necrotrophy, necrovirulence and necrotoxicity in several oral pathogens

Dysbiosis by neutralizing commensal mediated inhibition of pathobionts

Dysbiosis in the periodontal microbiota is associated with the development of periodontal diseases. Little is known about the initiation of dysbiosis. It was hypothesized that some commensal bacteria suppress the outgrowth of pathobionts by H2O2 production. However, serum and blood components released due to inflammation can neutralize this suppressive effect, leading to the initiation of dysbiosis. Agar plate, dual-species and multi-species ecology experiments showed that H2O2 production by commensal bacteria decreases pathobiont growth and colonization. Peroxidase and blood components neutralize this inhibitory effect primarily by an exogenous peroxidase activity without stimulating growth and biofilm formation of pathobionts directly. In multi-species environments, neutralization of H2O2 resulted in 2 to 3 log increases in pathobionts, a hallmark for dysbiosis. Our data show that in oral biofilms, commensal species suppress the amounts of pathobionts by H2O2 production. Inflammation can neutralize this effect and thereby initiates dysbiosis by allowing the outgrowth of pathobionts

Development of antiseptic adaptation and cross-adapatation in selected oral pathogens in vitro

There is evidence that pathogenic bacteria can adapt to antiseptics upon repeated exposure. More alarming is the concomitant increase in antibiotic resistance that has been described for some pathogens. Unfortunately, effects of adaptation and cross-adaptation are hardly known for oral pathogens, which are very frequently exposed to antiseptics. Therefore, this study aimed to determine the in vitro increase in minimum inhibitory concentrations (MICs) in oral pathogens after repeated exposure to chlorhexidine or cetylpyridinium chloride, to examine if (cross-)adaptation to antiseptics/antibiotics occurs, if (cross-)adaptation is reversible and what the potential underlying mechanisms are. When the pathogens were exposed to antiseptics, their MICs significantly increased. This increase was in general at least partially conserved after regrowth without antiseptics. Some of the adapted species also showed cross-adaptation, as shown by increased MICs of antibiotics and the other antiseptic. In most antiseptic-adapted bacteria, cell-surface hydrophobicity was increased and mass-spectrometry analysis revealed changes in expression of proteins involved in a wide range of functional domains. These in vitro data shows the adaptation and cross-adaptation of oral pathogens to antiseptics and antibiotics. This was related to changes in cell surface hydrophobicity and in expression of proteins involved in membrane transport, virulence, oxidative stress protection and metabolism

A dual-strain Lactobacilli reuteri probiotic improves the treatment of residual pockets: A randomized controlled clinical trial.

peer reviewedAIM: To examine the adjunctive effect of a Lactobacillus reuteri probiotic (ATCC PTA 5289 & DSM 17938) on the re-instrumentation of residual pockets. MATERIALS AND METHODS: This randomized, double-blind, placebo-controlled study included 39 previously non-surgically treated periodontitis patients. A re-instrumentation was carried out, and probiotic and/or placebo drops were applied according to the study protocoll. Patients afterwards received lozenges to use 2×/day for 12 weeks. Probing pocket depth (PPD), recession, bleeding on probing and plaque levels were analysed, next to the microbiological impact. RESULTS: No effects of the probiotic drops could be found. However, after 24 weeks, the overall PPD in the probiotic lozenges group (2.64 ± 0.33 mm) was significantly lower compared to the control lozenges (2.92 ± 0.42 mm). This difference was even more pronounced in moderate (4-6 mm) and deep (≥7 mm) pockets. In the probiotic lozenges group, there were also significantly more pockets converting from ≥4 mm at baseline to ≤3 mm at 24 weeks (67 ± 18% versus 54 ± 17%) and less sites in need for surgery (4 ± 4% versus 8 ± 6%). However, the probiotic products did not influence the microbiological counts of the periodontopathogens. CONCLUSION: The adjunctive consumption of L. reuteri lozenges after re-instrumentation improved the PPD reduction, without an impact on pocket colonization with periodontopathogens

Potential prebiotic substrates modulate composition, metabolism, virulence and inflammatory potential of an in vitro multi-species oral biofilm

Background: Modulation of the commensal oral microbiota constitutes a promising preventive/therapeutic approach in oral healthcare. The use of prebiotics for maintaining/restoring the health-associated homeostasis of the oral microbiota has become an important research topic. Aims: This study hypothesised that in vitro 14-species oral biofilms can be modulated by (in)direct stimulation of beneficial/commensal bacteria with new potential prebiotic substrates tested at 1 M and 1%((w/v)), resulting in more host-compatible biofilms with fewer pathogens, decreased virulence and less inflammatory potential. Methods: Established biofilms were repeatedly rinsed with N-acetyl-D-glucosamine, alpha-D-lactose, D-(+)-trehalose or D-(+)-raffinose at 1 M or 1%((w/v)). Biofilm composition, metabolic profile, virulence and inflammatory potential were eventually determined. Results: Repeated rinsing caused a shift towards a more health-associated microbiological composition, an altered metabolic profile, often downregulated virulence gene expression and decreased the inflammatory potential on oral keratinocytes. At 1 M, the substrates had pronounced effects on all biofilm aspects, whereas at 1%((w/v)) they had a pronounced effect on virulence gene expression and a limited effect on inflammatory potential. Conclusion: Overall, this study identified four new potential prebiotic substrates that exhibit different modulatory effects at two different concentrations that cause in vitro multi-species oral biofilms to become more host-compatible

Usefulness of a new malodour-compound detection portable device in oral malodour diagnosis.

peer reviewedA new device (BB Checker) able to detect malodour compounds has recently been made available. This retrospective analysis aimed at evaluating the usefulness of this device as adjunct tool for the diagnosis of oral malodour. Data from 100 consecutive volunteers with bad breath complaints attending their first consultation at a halitosis clinic were analysed. In addition to the standard protocol (organoleptic ratings from mouth and nose air, and from tongue coating when present; OralChroma and Halimeter measurements from mouth air; and intra-oral examinations), oral, exhaled and nasal air samples were examined with the BB Checker. We could not establish a correlation between the BB Checker values and the organoleptic scores, or the sulfur-compound levels determined by the OralChroma or the Halimeter (R 0.05). The overall sensitivity and specificity of the new device did not exceed the 50%. The correlations between the organoleptic scores and the OralChroma and the Halimeter measurements were good and in line with previous reports (R between 0.56 and 0.73). Our results do not favour the use of the BB Checker as adjunct tool in the diagnosis of oral malodour

The role of Solobacterium moorei in oral malodour.

peer reviewedThis study aims to analyze the correlation between Solobacterium moorei (S. moorei), both on the tongue and in saliva, and several oral malodour- and clinical parameters. Data from 193 patients visiting a halitosis clinic were used for analysis. A questionnaire assessed their general health, allergies, medication, smoking habits and oral hygiene. Following halitosis parameters were recorded: organoleptic score (OLS) (0-5), total concentration of volatile sulfur compounds (VSC) (Halimeter), individual concentrations of VSC (Oral Chroma), tongue coating (MTCI, WTCI and mWTCI), salivary parameters (flow rate and pH), oral hygiene, tonsil health and periodontal health. In all subjects, microbiological samples were collected from the tongue coating and from the saliva, and a quantitative polymerase chain reaction was performed to detect S. moorei. A significant correlation could be established between S. moorei, from both tongue and saliva, and several breath parameters (OLS, H2S, CH3SH, (CH3)2S and total VSCs), tongue coating indices and periodontal indices (gingivitis, periodontitis and oral hygiene). This study suggests a strong association between the presence of S. moorei and oral malodour (s54747)

Advances in the aetiology of periodontitis. Group A consensus report of the 5th European Workshop in Periodontology

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Dental cone beam computed tomography: justification for use in planning oral implant placement

Intra-oral and panoramic radiographs are most frequently used in oral health care. Yet, the inherent nature of jaws and teeth renders three-dimensional diagnosis essential, especially in relation to oral surgery. Nowadays, this can be accomplished by dental cone beam computed tomography, which provides high-quality images at low radiation doses and low costs. Nonetheless, the effective dose ranges of cone beam computed tomography machines may easily vary from 10 to 1000 μSv, this being equivalent to two to 200 panoramic radiographs, even for similar presurgical indications. Moreover, the diagnostic image quality varies massively among available machines and parameter settings. Apart from the radiodiagnostic possibilities, dental cone beam computed tomography may offer a vast therapeutic potential, including opportunities for surgical guidance and further prosthetic rehabilitation via computer-aided design/computer-aided manufacturing solutions. These additional options may definitely explain part of the success of cone beam computed tomography for oral implant placement. In conclusion, dental cone beam computed tomography imaging could be justified for oral implant-related diagnosis, planning and transfer to surgical and further prosthetic treatment, but guidelines for justification and cone beam computed tomography optimization remain mandatory.status: publishe

Letter to the editor: RE: Optimized platelet-rich fibrin with the low-speed concept: Growth factor release, biocompatibility, and cellular response

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