DIAGNOdent laser fluorescence assessment of endodontic infection.

INTRODUCTION: Real-time assessment of the microbial status of the root canal system would be useful in clinical endodontic practice for determining endpoints of biomechanical treatment. This laboratory study used an existing laser fluorescence device, the DIAGNOdent (KaVo, Biberach, Germany), in a proof-of-concept study. METHODS: Visible laser red light (wavelength 655 nm) was used to elicit fluorescence emissions in the near-infrared range from infected and uninfected root canals. A prototype sapphire tip designed for periodontal assessment was used to analyze the pulp chamber and coronal third of the root canal system in extracted teeth. The fluorescence properties of bacterial cultures, monospecies biofilms in root canals, pulpal soft tissues, and sound dentin were also evaluated, together with 50 extracted teeth with known endodontic pathology. RESULTS: Sound dentin and healthy pulpal soft tissue gave an average fluorescence reading of 5 (on a scale of 100), whereas biofilms of Enterococcus faecalis and Streptococcus mutans established in root canals showed a progressive increase in fluorescence over time. Fluorescence readings reduced to the "healthy" threshold reading of 5 when root canals were endodontically treated, and the experimentally created bacterial biofilms were removed completely. High fluorescence readings were recorded in the root canals and pulp chambers of extracted teeth with radiographic evidence of periapical pathology and scanning electron microscopy evidence of bacterial infection. CONCLUSIONS: The use of the DIAGNOdent fluorescence approach for the assessment of the status of the pulp chamber and root canal system holds promise for clinical application; once more, flexible tips can be developed for gaining greater penetration into middle and apical thirds of the root canal.

Assessment of intraradicular bacterial composition by terminal restriction fragment length polymorphism analysis.

BACKGROUND: The aim of the study was to assess the bacterial community structures associated with endodontic infections using terminal restriction fragment length polymorphism (T-RFLP), and to investigate the correlation of whole community profiles with the manifestation of particular clinical features. METHODS: Intraradicular samples were collected from 34 subjects and classified into three study groups based on the observed clinical symptoms: acute (n = 16), sub-acute (n = 8), and asymptomatic (n = 10). Genomic DNA was extracted from each sample, submitted to polymerase chain reaction using a fluorescently labeled 16S ribosomal DNA forward primer, and digested with two tetrameric endonucleases (HhaI and MspI). The terminal restriction fragments (T-RFs) were subsequently discriminated in an automated DNA sequencer, and the results were filtered using a statistics-based criterion. RESULTS: Totals of 138 (HhaI) and 145 (MspI) unique T-RFs were detected (means 13.1 and 11.9) and there was high inter-subject variability in the bacterial assemblages. Odds-ratio analysis unveiled the existence of higher order groups of positively associated T-RFs, restating the concept that intricate ecological relationships may take place in the root canal space. A significantly greater T-RF prevalence was detected in acute cases, suggesting a straight correlation between species richness and spontaneous pain. CONCLUSION: Overall, no T-RFLP profile representing a specific bacterial consortium could be associated with the manifestation of symptoms of endodontic origin.

Assessment of periradicular microbiota by DNA-DNA hybridization.

In the present study the "checkerboard" DNA-DNA hybridization technique was used to identify bacteria in periapical endodontic lesions of asymptomatic teeth. Thirty-four patients with root-filled teeth and apical periodontitis were divided into two groups, each containing 17 patients. In Group 1, a marginal incision was performed during surgery to expose the lesion, and in Group 2, a submarginal incision was applied. The gingiva and mucosa were swabbed with an 0.2% chlorhexidine gluconate solution prior to surgery. Bacterial DNA was identified in all samples from the two groups using 40 different whole genomic probes. The mean number (+/- SD) of species detected was 33.7 +/- 3.3 in Group 1 and 21.3 +/- 6.3 in Group 2 (P < 0.001). The majority of the probe-detected bacteria were present in more lesions from Group 1 than from Group 2. The differences were most notable for Campylobacter gracilis, Porphyromonas endodontalis, Propionibacterium acnes, Capnocytophaga gingivalis, Fusobacterium nucleatum ssp. nucleatum, Fusobacterium nucleatum ssp. polymorphum, Prevotella intermedia, Treponema denticola, Streptococcus constellatus and Actinomyces naeslundii I. Bacterial species such as Actinobacillus actinomycetemcomitans and Bacteroides forsythus were detected in more than 60% of the lesions from both groups. Also, P. endodontalis was abundant in periapical tissue. The data supported the idea that following a marginal incision, bacteria from the periodontal pocket might reach the underlying tissues by surgeon-released bacteremia. The study provided solid evidence that bacteria invade the periapical tissue of asymptomatic teeth with apical periodontitis. The detection of much more bacteria with the "checkerboard" DNA-DNA hybridization method than has previously been recovered by anaerobic culture indicated that the endodontic (and periodontal) microfloras should be redefined using molecular methods.