Salivary Microflora of Geriatric Edentulous Persons Wearing Dentures

Microbial signatures of oral dysbiosis, periodontitis and edentulism revealed by Gene Meter methodology

Conceptual models suggest that certain microorganisms (e.g., the "red" complex) are indicative of a specific disease state (e.g., periodontitis); however, recent studies have questioned the validity of these models. Here, the abundances of 500+ microbial species were determined in 16 patients with clinical signs of one of the following oral conditions: periodontitis, established caries, edentulism, and oral health. Our goal was to determine if the abundances of certain microorganisms reflect dysbiosis or a specific clinical condition that could be used as a 'signature' for dental research. Microbial abundances were determined by the analysis of 138,718 calibrated probes using Gene Meter methodology. Each 16S rRNA gene was targeted by an average of 194 unique probes (n=25nt). The calibration involved diluting pooled gene target samples, hybridizing each dilution to a DNA microarray, and fitting the probe intensities to adsorption models. The fit of the model to the experimental data was used to assess individual and aggregate probe behavior; good fits (R²>0.90) were retained for back-calculating microbial abundances from patient samples. The abundance of a gene was determined from the median of all calibrated individual probes or from the calibrated abundance of all aggregated probes. With the exception of genes with low abundances (<2 arbitrary units), the abundances determined by the different calibrations were highly correlated (r~1.0). Seventeen genera were classified as 'signatures of dysbiosis' because they had significantly higher abundances in patients with periodontitis and edentulism when contrasted with health. Similarly, 13 genera were classified as 'signatures of periodontitis', and 14 genera were classified as 'signatures of edentulism'. The signatures could be used, individually or in combination, to assess the clinical status of a patient (e.g., evaluating treatments such as antibiotic therapies). Comparisons of the same patient samples revealed high false negatives (45%) for next-generation-sequencing results and low false positives (7%) for Gene Meter results.

Detection and identification of non-Candida albicans species in human oral lichen planus

Candida species were detected and identified in samples from the buccal mucosa, dorsal surface of the tongue and supragingival plaque of subjects with oral lichen planus (OLP). The Candida in the samples were cultured on selection agars, and identified by sequence analyses of 18S, 5.8S and 25/28S rRNA. The isolation frequency of Candida was higher in subjects with OLP than in those with healthy oral mucosa. Non-C. albicans were only isolated from people with OLP. These results support the notion that subjects with OLP are more likely to have oral colonization with Candida, and that non-C. albicans are specifically present in subjects with this condition.

Endodontic Treatment of a Large Cyst-Like Periradicular Lesion Using a Combination of Antibiotic Drugs: A Case Report

This case report describes the endodontic treatment of a large cyst-like periradicular lesion using a combination of antibiotic drugs. A 15-yr-old boy with a large cyst-like lesion from the apices of his teeth 29 to 31. Conservative root canal treatment was performed (tooth #30). During treatment procedure, 2.5% sodium hypochlorite solution was used for irrigation and a combination of antibiotic drugs was used for the intracanal dressing. Periapical healing was observed 3-month after initial treatment and continued at the 7-month review.

Endodontic treatment of primary teeth using a combination of antibacterial drugs

AIM

To evaluate the clinical outcome of 'Lesion Sterilization and Tissue Repair' (LSTR) therapy for endodontic treatment of primary teeth.

METHODOLOGY

A mixture of metronidazole, ciprofloxacin, and minocycline (3Mix) in ointment (macrogol mixed with propylene glycol: MP) or in a root canal sealer was used to disinfect infected root canals of 56 patients aged 4-18 years. Out of a total of 87 primary teeth, 81 cases had physiologic root resorption. A total of 54 radiolucent periradicular lesions were present. The root canals were not prepared before or after disinfection. 3Mix medicament (3Mix-MP/3Mix-sealer) was placed at orifices of root canals or on the bottom of pulp chambers, and then sealed with glass-ionomer cement and further reinforced by a composite resin inlay prepared using a direct method and cemented with resin.

RESULTS

In all cases, clinical symptoms such as gingival swelling (52 cases), sinus tracts (22 cases), induced dull pain (3 cases), spontaneous dull pain (26 cases), and pain on biting (46 cases) disappeared after treatment, although in four cases clinical signs and symptoms were finally resolved only after retreatment using the same procedures. Thus, gingival abscesses and fistulae, if present, disappeared after a few days. Successor permanent teeth erupted without any disorders, or were found radiographically to be normal and in the process of eruption. All the cases were evaluated as successful. The mean function time of the primary teeth was 680 days (range: 68-2390 days), except for one case in which the successor permanent tooth was congenitally missing.

CONCLUSION

Primary teeth with periradicular lesions with or without physiologic root resorption were treated successfully by the LSTR endodontic therapy.

Anti-adhesive and antibacterial properties of a proprietary denture cleanser

The antimicrobial efficacy and anti-adhesive attributes of a proprietary denture cleanser were evaluated. To determine cleanser antimicrobial efficacy, Streptococcus mutans was grown on denture acrylic strips which were then exposed to the cleanser. To evaluate anti-adhesive efficacy, the strips were treated with the cleanser and then placed in the Strep. mutans suspension. Following incubation, adhered bacteria were removed and enumerated by viable counting. Treated denture acrylic plates were also placed in a parallel-plate flow chamber and then exposed to Strep. oralis. Images of adhered bacteria were analysed to determine biofilm coverage. Biofilm removal force was quantified by increasing the flow rate between the acrylic plates. The cleanser exhibited a 100% kill against Strep. mutans adhered to the acrylic surface, and inhibited attachment of cells by 66%. The flow chamber study found that cleanser-treated denture acrylic allowed the formation of a multilayer biofilm which was easily removed by a slight increase in flow rate.

Differentiation of Veillonella atypica, Veillonella dispar and Veillonella parvula using restricted fragment-length polymorphism analysis of 16S rDNA amplified by polymerase chain reaction

Veillonella atypica, Veillonella dispar and Veillonella parvula cannot be reliably distinguished by conventional phenotypic tests, including the API ZYM test. In this study, restricted fragment-length polymorphism (RFLP) analysis of 16S rDNA amplified by polymerase chain reaction (PCR) was used to generate restriction profiles of the type strains of V. atypica, V. dispar and V. parvula and 20 Veillonella strains isolated from oral sites. 16S rRNA gene sequences from isolated genomic DNA samples were amplified by PCR. PCR products were purified and characterized by single digestion with 13 restriction endonucleases. Among them, Mn/I was found to discriminate the respective reference strains, and the clinical isolates were assigned to one of the three species on the basis of their restriction profiles by digestion with Mn/I. Thus, RFLP analysis of PCR-amplified 16S rDNA, using Mn/I, is a rapid and reliable method for the differentiation of V. atypica, V. dispar and V. parvula.

Sterilization of infected root-canal dentine by topical application of a mixture of ciprofloxacin, metronidazole and minocycline in situ

The aim of this study was to observe the potential of a mixture of ciprofloxacin, metronidazole and minocycline to kill bacteria in the deep layers of root canal dentine in situ. After the crowns of extracted teeth had been removed, the drug combination (0.5 mg of each drug), or sterile saline, as the control, was placed in the root canals which had been previously irrigated ultrasonically with G4M EDTA. The penetration and bactericidal efficacy were estimated by various procedures as follows. (1) A cell suspension of E. coli was placed into small cavities prepared parallel to the root canals on the cut planes of nine single-rooted teeth. The teeth were then entirely covered with blue inlay wax. At time 0, and at 5h, 24h and 48h after the drug combination had been applied, cells of E. coli were recovered from the cavities by washing the cavities several times with sterile saline solution, and were cultured on the surfaces of heart-infusion (HI) agar plates. Total colony-forming units were tuen counted. Bacterial recoveries decreased with time, and no bacteria were recovered 48 h after application of the drug combination, while bacteria survived in all cases with the controls, (2) After the drug combination or sterile saline had been placed into and sealed in the root canal with blue inlay wax, the teeth were placed into HI agar plates where cells of E. coli had been inoculated. After culturing, a clear zone caused by the inhibition of bacterial growth was observed around the teeth, but not in the control experiment. (3) After sampling infected root dentine of 12 freshly extracted teeth as positive controls, the drug combination (0.5 mg each) was placed in the root canals. No bacteria were recovered from the infected dentine of the root canal wall 24 h after application of the drug combination, except in one case in which a few bacteria were recovered. On the basis of these results, penetration through dentine and antibacterial efficacy of the drug combination can be expected against bacteria infecting the dentine of the root canal wall in situ when the drugs were placed in root canals which had been irrigated ultrasonically.

In-vitro antibacterial susceptibility of bacteria taken from infected root dentine to a mixture of ciprofloxacin, metronidazole and minocycline

The aim of this study was to clarify the antibacterial effect of a mixture of ciprofloxacin, metronidazole and minocycline, with and without the addition of rifampicin, on bacteria taken from infected dentine of root canal walls. The efficacy was also determined against bacteria of carious dentine and infected pulps which may the precursory bacteria of infected root dentine. This efficacy was estimated in vitro by measuring bacterial recovery on BHI-blood agar plates in the presence or absence of the drug combination. Bacteria ranging in number from 10(2) to 10(6) occurred in samples of infected root dentine (27 cases). However, none was recovered from the samples in the presence of the drug combination at concentrations of 25 micrograms ml-1 each. The respective drug alone (10, 25, 50 and 75 micrograms ml-1) substantially decreased the bacterial recovery, but could not kill all the bacteria. Bacteria taken from carious dentine (25 cases) and infected pulps (12 cases) were also sensitive to the drug combination. These results may indicate that the bactericidal efficacy of the drug combination is sufficiently potent to eradicate bacteria from the infected dentine of root canals.