Aggregation of Human Platelets by Tannerella Forsythia.

Context: Periodontitis is a persistent infection of the tissues surrounding the teeth characterized by inflamed microvasculature, and is associated with increased systemic platelet activation. Aims: The purpose of this study was to assess the in vitro platelet aggregating potential of the red-complex bacterium Tannerella forsythia. A second-related objective was to ascertain the in vitro effect of dual platelet inhibitors on T. forsythia-platelet interaction. Settings and Design: These ex vivo experiments were done in a basic science laboratory combining isolated human platelets with isolated bacterial cells. Methods: Dilutions of cells were counted by quantitative polymerase chain reaction. Aggregation was assayed in a platelet aggregometer after adding cells or sonic extracts to gel filtered platelets, some of which were preincubated with the dual platelet inhibitors aspirin plus clopidogrel. Results: Platelets aggregate in vitro when exposed to T. forsythia cells or sonic extracts and dilution results in increased lag times and decreased aggregation. Platelets preincubated with the combination of aspirin plus clopidogrel do not aggregate in response to T. forsythia. Conclusions: Within the limitations of this in vitro study, T. forsythia cells aggregate human platelets and the activity can be attenuated by diluting the cells and blocked by the combination of aspirin plus clopidogrel.

Mitigating saliva aerosol contamination in a dental school clinic.

BACKGROUND: Transmission of COVID-19 via salivary aerosol particles generated when using handpieces or ultrasonic scalers is a major concern during the COVID-19 pandemic. The aim of this study was to assess the spread of dental aerosols on patients and dental providers during aerosol-generating dental procedures. METHODS: This pilot study was conducted with one volunteer. A dental unit used at the dental school for general dental care was the site of the experiment. Before the study, three measurement meters (DustTrak 8534, PTrak 8525 and AeroTrak 9306) were used to measure the ambient distribution of particles in the ambient air surrounding the dental chair. The volunteer wore a bouffant, goggles, and shoe covers and was seated in the dental chair in supine position, and covered with a surgical drape. The dentist and dental assistant donned bouffant, goggles, face shields, N95 masks, surgical gowns and shoe covers. The simulation was conducted by using a high-speed handpiece with a diamond bur operating in the oral cavity for 6 min without touching the teeth. A new set of measurement was obtained while using an ultrasonic scaler to clean all teeth of the volunteer. For both aerosol generating procedures, the aerosol particles were measured with the use of saliva ejector (SE) and high-speed suction (HSS) followed a separate set of measurement with the additional use of an extra oral high-volume suction (HVS) unit that was placed close to the mouth to capture the aerosol in addition to SE and HSS. The distribution of the air particles, including the size and concentration of aerosols, was measured around the patient, dentist, dental assistant, 3 feet above the patient, and the floor. RESULTS: Four locations were identified with elevated aerosol levels compared to the baseline, including the chest of the dentist, the chest of patient, the chest of assistant and 3 feet above the patient. The use of additional extra oral high volume suction reduced aerosol to or below the baseline level. CONCLUSIONS: The increase of the level of aerosol with size less than 10 µm was minimal during dental procedures when using SE and HSS. Use of HVS further reduced aerosol levels below the ambient levels.

Antimicrobial activity of silver diamine fluoride on human periodontitis microbiota.

Silver diamine fluoride (SDF) has been used in management of dentinal hypersensitivity and dental caries. This in vitro study evaluated the antimicrobial effects of SDF on subgingival microorganisms from severe human periodontitis lesions. Subgingival biofilm specimens from 24 adults with severe periodontitis were mixed in vitro with 19% or 38% SDF or left untreated (n = 24 per group) and then inoculated on enriched Brucella blood agar with anaerobic incubation. Selected red- and orange-complex periodontal pathogens were phenotypically identified in the subgingival specimens, including Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Parvimonas micra, Campylobacter rectus, Fusobacterium nucleatum, and Streptococcus constellatus. Other microbial species recovered from SDF-treated specimens were identified using matrix-assisted laser desorption- ionization time-of-flight mass spectrometry. The SDF-treated specimens yielded significantly lower mean total viable counts and significantly lower mean total cultivable proportional levels of red- and orange-complex periodontal pathogens (0.5%-0.6%) than did untreated specimens (25.9%) (P < 0.001). The only red- and orange-complex species recovered from SDF-treated specimens were P micra (3 patients) and S constellatus (1 patient). The predominant cultivable isolates from SDF-treated specimens were Streptococcus oralis and other streptococci of relatively low periodontopathic and cariogenic potential. No statistically significant in vitro antimicrobial differences were found between 19% and 38% SDF against subgingival biofilm specimens. In this experiment, SDF exhibited substantial in vitro antimicrobial activity against putative periodontal pathogens from severe periodontitis lesions. The suppression of red- and orange-complex periodontal pathogens in subgingival biofilms by SDF treatment, along with the selection of SDF-resistant Streptococcus species that are associated with periodontal health, suggests a potential new therapeutic use for SDF in the management of human periodontal infections.

Bacteriostatic Effect of Simvastatin on Selected Oral Streptococci in Vitro.

CONTEXT AND OBJECTIVE: Simvastatin is a widely used cholesterol-lowering drug, which has been found to have a number of pleiotropic effects. The aim of this study was to evaluate the antimicrobial effectiveness of simvastatin against selected oral streptococci as determined by the minimum inhibitory concentration (MIC). METHODS: Streptococcus mutans, Streptococcus sanguis, Streptococcus anginosus, and Streptococcus salivarius were the test microorganisms. The serial dilution method was used to determine the MIC of simvastatin against these organisms. The MIC was defined as the lowest concentration of simvastatin that completely inhibited growth of the test organisms. RESULTS: The data indicate that simvastatin inhibits the growth of the test organisms, with MIC's ranging from 7.8 to 15.6 µg/ml. CONCLUSIONS: Simvastatin has MIC's against the selected bacteria that compare favorably with reported values for topical agents such as essential oil, chlorhexidine gluconate, and triclosan. The levels of simvastatin required to inhibit bacterial growth of oral bacteria exceed the reported levels of the drug found in plasma or crevicular fluid of patients who are treated with this cholesterol-lowering drug. However, clinical studies are warranted to investigate the potential use of simvastatin as a novel antiplaque agent that could be used in local drug delivery to the oral cavity of those patients who are prescribed this cholesterol-lowering drug.

Systematic review of the in vitro effects of statins on oral and perioral microorganisms.

Statins are medications administered orally and are widely used for lowering the blood cholesterol level. The aim of this study was to investigate the effects of orally administered statins on microorganisms infecting oral and perioral tissues. We performed a systematic review of published studies of the in vitro antimicrobial effects of statins on bacteria, viruses, and fungi, and searched PubMed, Web of Science, Cochrane Central, and Google scholar. Studies show that most statins exhibit antimicrobial effects against various oral microorganisms. Simvastatin is most effective against the periodontal pathogens Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, and against most dental plaque bacteria, including Streptococcus mutans. Statins also exhibit antiviral properties against human cytomegalovirus, hepatitis B virus, and hepatitis C virus, and have antifungal properties against Candida albicans, Aspergillus fumigatus, and Zygomycetes spp. There were notable differences in the minimum inhibitory concentrations (MICs) between different studies, which may be attributed to differences in study design. Further studies are warranted to ascertain if statins can be solubilized so that patients, who have been prescribed statins for cardiovascular diseases, can use the medication as a swish and swallow, giving patients the added benefit of the antimicrobial action topically in the mouth against infectious oral diseases.

Centipeda periodontii in human periodontitis.

This study assessed the subgingival occurrence of the flagellated, Gram-negative, anaerobic rod Centipeda periodontii in chronic periodontitis and periodontal health/gingivitis with species-specific nucleic acid probes, and evaluated the in vitro resistance of subgingival isolates to therapeutic levels of amoxicillin, metronidazole, and doxycycline. Subgingival plaque biofilm specimens from 307 adults with chronic periodontitis, and 48 adults with periodontal health/localized gingivitis, were evaluated with digoxigenin-labeled, whole-chromosomal, DNA probes to C. periodontii ATCC 35019 possessing a 10(4) cell detection threshold. Fifty-two C. periodontii subgingival culture isolates were assessed on antibiotic-supplemented enriched Brucella blood agar for in vitro resistance to either amoxicillin at 2 µg/ml, metronidazole at 4 µg/ml, or doxycycline at 2 µg/ml. A significantly greater subgingival occurrence of C. periodontii was found in chronic periodontitis subjects as compared to individuals with periodontal health/gingivitis (13.4 vs. 0 %, P < 0.003), although high subgingival counts of the organism (≥ 10(6) cells) were rarely detected (1.3 % of chronic periodontitis subjects). In vitro resistance was not found to amoxicillin or metronidazole, and to doxycycline in only 2 (3.9 %) of the 52 C. periodontii clinical isolates studied. These findings indicate that C. periodontii is not a major constituent of the subgingival microbiome in chronic periodontitis or periodontal health/gingivitis. The potential contribution of C. periodontii to periodontal breakdown in the few chronic periodontitis subjects who yielded high subgingival levels of the organism remains to be delineated. C. periodontii clinical isolates were susceptible in vitro to therapeutic concentrations of three antibiotics frequently used in treatment of human periodontitis.

Effect of acetylsalicylic acid on aggregation of human platelets by Porphyromonas gingivalis.

This study investigated the effect of in vivo low-dose acetylsalicylic acid (ASA, aspirin) on human platelet aggregation induced in vitro by Porphyromonas gingivalis cells. Blood was collected from volunteers (n = 20), half of whom ingested 81 mg of aspirin 24 hours before donating blood. Low-dose aspirin inhibited P. gingivalis cell-induced platelet aggregation and produced an inverse correlation of inhibition to number of cells. At the higher concentration of cells used in this in vitro assay, aspirin inhibition was significant (P = 0.001); however, partial platelet activation was observed. The significance of partial platelet activation is discussed in this article, as is the relevance of platelet aggregation to the putative link between inflammatory periodontal disease and cardiovascular disease.

Primary, secondary and tertiary treatment of dental caries: a 20-year case report.

BACKGROUND: This case report follows the 20-year clinical treatment of a patient at high risk of developing dental caries. The author describes the treatment of the primary and permanent dentitions. CASE DESCRIPTION: The author describes the use of primary, secondary and tertiary measures to treat caries in a high-risk patient. He emphasizes the need for long-term care to monitor disease activity and describes the use of in-office tests for estimating Streptococcus mutans levels. This case illustrates the episodic nature of the caries process in which caries activity is related to risk factors, and the treatment regimen varies from tooth to tooth. CONCLUSION AND CLINICAL IMPLICATIONS: This case report documents the use of the medical paradigm in the treatment of dental caries, as well as the surgical paradigm as an important component of treatment.