Comparison of culture methods and multiplex PCR for the detection of periodontopathogenic bacteria in biofilm associated with severe forms of periodontitis.

Conventional culture methods and Multiplex PCR, both of which we have been used for a long time in our clinical microbiology laboratory, were compared for their ability to detect a selected panel of periodontopathic bacteria: Aggregatibacter actinomycetemcomitans, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia. Tests were performed in a single subgingival sample taken from a periodontal diseased site with a probing depth equal to or greater than 6mm. The results were compared site-by-site, taking into account the quality and the presence or absence of pathogens. 529 samples of subgingival plaque were analysed and the prevalence of the six species monitored varied in relation to the species itself and the method of detection. The most represented species is F. nucleatum, with a percentage of positive variability between 44.9% PCR and 46.5% culture test. Generally, the lowest prevalence was determined by culture test, with the exception of E. corrodens and F. nucleatum, which, unlike other bacteria, have been seen in higher percentages in culture with respect to PCR. For both methods, there was a good degree of accuracy in the determination of A. actinomycetemcomitans, C. rectus, E. corrodens, and P. gingivalis. It becomes weak for F. nucleatum and P. intermedia. Both culture and PCR techniques introduced many methodological problems when applied in oral microbiology, but the ideal technique for accurate detection of pathogens in subgingival plaque samples has yet to be developed.

Internal decontamination of dental implants: an in vivo randomized microbiologic 6-month trial on the effects of a chlorhexidine gel.

BACKGROUND: Microbial penetration inside an implant's internal cavity results in a bacterial reservoir that has been associated with an area of inflamed connective tissue facing the fixture-abutment junction. The aim of the present clinical trial was to evaluate the effectiveness of a 1% chlorhexidine gel on the internal bacterial contamination of implants with screw-retained abutments. METHODS: Thirty subjects (age range: 27.3 to 54.2 years) underwent single implant restoration. Three months after prosthodontic restoration, the modified sulcus bleeding index, modified plaque index, full-mouth plaque score, and full-mouth bleeding score were recorded. Microbiologic samples were also collected from the internal part of each fixture. Subjects were then divided into two equal groups: control and test groups (CG and TG, respectively). The CG had the abutment screwed and the crown cemented without any further intervention. Conversely, the TG had the internal part of the fixture filled with a 1% chlorhexidine gel before the abutment placement and screw tightening. Six months later, microbiologic and clinical procedures were repeated in both groups. Total bacterial count and multiplex polymerase chain analysis were performed to detect specific pathogens. RESULTS: Clinical parameters remained stable throughout the study. From baseline to the 6-month examination, the total bacterial counts underwent a significant reduction in the TG (P<0.05). Detection of the single pathogen species did not show any significant differences. However, periopathogens were detected more frequently in the CG. CONCLUSION: The application of a 1% chlorhexidine gel seemed to be an effective method to reduce bacterial colonization of the implant cavity over a 6-month period.

Diagnosis in periodontology: a further aid through microbiological tests.

Most of the current knowledge of the complex microbiology of oral biofilms, which initiates and maintains periodontal lesions, has been facilitated by the introduction of molecular techniques. Several studies exalt the high sensitivity and specificity of molecular tests in the detection and quantification of periodontal pathogens. Although they have large a diffusion, the old method of bacterial culture remains nowadays the gold standard when determining the utility of a new microbial test. Moreover, cultures have the important advantage of allowing an antibiotic sensitivity test and this is much more important during the treatment of patients with aggressive periodontitis.

Effectiveness of ultrasonic instruments in the therapy of severe periodontitis: a comparative clinical-microbiological assessment with curettes.

Patients with deep periodontal pockets were treated with either Vector System (TG) or manual instruments (CG). Clinical assessments by supragingival plaque (PL+), gingival index (GI), bleeding on probing (BOP), probing depth (PD), clinical attachment level (CAL) and subgingival plaque collection for microbiological analysis were made prior to and after treatment. Multiplex Polymerase Chain Reaction was used to determine the presence of Actinobacillus actinomycetemcomitans, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum, Prevotella intermedia, Porphyromonas gingivalis, Tannerella forsythensis and Treponema denticola. GI, PD, CAL and the number of BOP+ sites underwent a significant reduction over time in both groups. When compared to baseline, the pair-wise analyses showed significantly lower PD and CAL at 6 months in the CG and significant reductions in the GI, PD, CAL and a number of BOP+ sites at 3 and 6 months in the TG. For microbiological results, significant reductions were seen for C. rectus and R. gingivalis in the CG and for T. forsythensis, E. corrodens and T. denticola in the TG. The total bacterial count underwent a reduction in both groups. Both ultrasonic and manual debridement are equally effective in non-surgical periodontal therapy of severe periodontitis in terms of clinical and microbiological effects.

Clinical and microbiological effects of different restorative materials on the periodontal tissues adjacent to subgingival class V restorations.

OBJECTIVES: The relationship between subgingival dental restorations and periodontal health has been thoroughly investigated for many years. However, longitudinal data on the subgingival microflora features after the placement of well-finished subgingival restorations are still lacking. Therefore, this study compares the short-term clinical and microbiological features occurring in the gingiva after the completion of different subgingival restorations. MATERIAL AND METHODS: Sixteen systemically healthy subjects, 10 males and six females (ages: 31.7-45.8 years; mean age 39.3+/-5.1 years), who were non-smokers and were positive for the presence of three cervical abrasion/erosion defects to be restored in three different adjacent teeth were enrolled in this study. The cervical abrasion/erosion defects were each restored by using one of three different materials: amalgam, glass ionomer cement, or composite resin. Immediately before class V cavity preparations and restorations (baseline), clinical monitoring and subgingival plaque sampling were performed in the mid-buccal aspect of each experimental restored tooth and in one adjacent sound, non-treated, control tooth. These procedures were repeated every 4 months over the following 1 year. RESULTS: Throughout the study, the clinical parameters recorded did not change significantly in any of the experimental groups, and no differences were detected among them at each clinical session. Over this time, no significant changes in the composition of the subgingival microflora were observed in amalgam, glass ionomer cement, and control groups. Conversely, in the composite resin group, there was a significant increase in the total bacterial counts, and a significant (p<0.05) decrease in Gram-positive, aerobic bacteria, which was associated with a significant (p<0.05) increase in the Gram-negative, anaerobic microbiota. CONCLUSIONS: Over a 1-year observation period, amalgam, glass ionomer cement, and composite resin subgingival restorations do not significantly affect the clinical parameters recorded. However, composite resin restorations may have some negative effects on the quantity and quality of subgingival plaque.

Bacteriologic evaluation of the effect of Nd:YAG laser irradiation in experimental infected root canals.

The aim of this study was to evaluate the efficacy of the Pumped Diodium-Nd:YAG laser in sterilizing contaminated root canals. After hand instrumentation, 30 teeth were inoculated with Actinomyces naeslundii CH-12 and 30 teeth with Pseudomonas aeruginosa ATCC 27853 and incubated for 24 h. The teeth were divided into three subgroups: subgroup A received no treatment; subgroup B was irradiated with laser (5 Hz for 15 s or 10 Hz for 15 s); and subgroup C was irrigated with 5.25% NaOCl. The number of viable bacteria in each group was evaluated by using the surface-spread plate technique. The results indicated an average of 34.0% decrease in colony-forming units for A. naeslundii CH-12 and 15.7% for P. aeruginosa ATCC 27853 with the 5 Hz/15 s laser treatment, and for the 10 Hz laser frequency, a decrease of the 77.4% for A. naeslundii CH-12 and 85.8% for P. aeruginosa ATCC 27853. No bacteria were detected in the canals treated with 5.25% NaOCl. The results show an antibacterial effect of the Pumped Diodium Nd:YAG laser, depending on the radiation frequency. However, 5.25% NaOCl was more effective than either laser application.

Comparison of Etest, agar dilution, broth microdilution and disk diffusion methods for testing in vitro activity of levofloxacin against Staphylococcus spp. isolated from neutropenic cancer patients.

The susceptibility to levofloxacin of 194 consecutive staphylococcal (45 Staphylococcus aureus and 149 coagulase-negative staphylococci) isolates from neutropenic patients was determined by Etest and the results compared with those obtained using NCCLS-methods (broth microdilution, agar dilution and disk diffusion). Overall agreement at +/- 1log(2) dilution for Etest compared with broth microdilution and agar dilution was 99.0 and 83.5%, respectively. The Etest category agreement with broth microdilution and disk diffusion was 95.9 and 89.7%, respectively. Comparison of categories with Etest and agar dilution method gave only 67.0% absolute categorical agreement, with 29.9% minor errors and 10.7% major errors. No very major errors occurred by the four methods tested. Our results show that Etest is a valid alternative to the reference NCCLS-methods for monitoring the clinical usefulness of levofloxacin against staphylococci isolates from neutropenic patients.