Evaluation of root canal bacteria and their antimicrobial susceptibility in teeth with necrotic pulp

Abstract

This study aimed to evaluate the microbiota of necrotic pulp in teeth without carious lesions where the crown and root were intact and to test the sensitivity of this microbiota to antibiotics in order to improve treatment. The necrotic pulp was sampled from 26 single-rooted teeth in intact pulp chambers. A total of 84 strains were isolated. The number of species isolated per tooth varied from 2 to 8, with a strong component (81%) of anaerobic bacteria. The most commonly represented species were Bacteroides gracilis, Propionibacterium acnes, Fusobacterium nucleatum, Prevotella buccae and Eubacterium lentum. The sensitivity of these organisms to amoxicillin, amoxicillin combined with clavulanate and tetracycline was evaluated by Etest on 38 isolates. For all strains tested, the minimum inhibitory concentration values obtained were low and substantially below effective serum concentrations for these antibiotics. These data enable us to devise suitable treatments for acute development of apical lesions and to prevent dissemination of this source of infection to the rest of the host.

Invasion of Dentinal Tubules by Oral Bacteria

“…However, while the components of the root canal microflora are well-established, it is interesting that no single bacterial species has been indicted as the major pulp and periapical pathogen in chronic asymptomatic conditions. P. gingivalis , which is strongly implicated in destructive adult periodontal disease (Socransky and Haffajee, 1992;Lamont and Jenkinson, 1998), is recovered in low numbers from asymptomatic chronic root canal infections (Sundqvist, 1994;Le Goff et al, 1997). However, numbers of Porphyromonasand Prevotellaspecies increase dramatically when there are signs and symptoms of acute periapical infection (Haapasalo, 1989;Sundqvist et al , 1989;Hashioka et al , 1992).…”

“…However, many infections of the pulp occur as a result of supra-or subgingival bacteria penetrating exposed dentin, enamel-dentin cracks, and around restorations (Pashley, 1990;Peters et al , 1995;Love, 1996a) and then invading dentinal tubules. Almost all bacteria recovered from the root canal systems of teeth with intact crowns belong to the oral microflora (Wittgow and Sabiston, 1975;Sundqvist, 1976;Le Goff et al , 1997). The concept that bacteria can gain access to the pulp system viathe blood stream has not been proven.…”

“…Commonly, between 2 and 8 bacterial species are recovered from infected root canals, with F. nucleatum, P. intermedia , and streptococci being often present (Sundqvist, 1994;Le Goff et al, 1997) (Table 3). A series of studies on the dynamics of experimental root canal infections of monkey teeth has shown that facultative anaerobic bacteria, mainly streptococci, are the first colonizers of the root canal, but that by 6 months, obligate anaerobes dominate the microflora.…”

Coinvasion of Dentinal Tubules by Porphyromonas gingivalis and Streptococcus gordonii Depends upon Binding Specificity of Streptococcal Antigen I/II Adhesin

“…After longer periods of infection (for example, 6 months or so), facultatively anaerobic bacteria become progressively outnumbered by obligate anaerobes (12,13). These are the predominant organisms in chronic infections and include species of Fusobacterium, Peptostreptococcus, Prevotella, and Porphyromonas (28,41,42). Attempts have been made to correlate the presence of certain bacterial species with clinical symptoms.…”

Morphological Assessment and Cleaning Capacity of a Reciprocating System in Root Canals of Deciduous Teeth

“…Farm. LTDA, São Paulo, Brazil); then initial collection was performed with a sterile number 15 paper cone (Dentsply Maillefer, Petrópolis, RJ, Brazil) for 1 minute; followed by instrumentation with the WaveOne system using the Small Brazil) for 1 minute and then diluted, before three 25 ul aliquots were seeded onto blood agar plates using the micropipette technique [12]. After seeding, the cultures were incubated in anaerobiosis at 37°C for 5 days in an atmosphere of 85% N2, 10% CO2 and 5% H2, created using the sachet system.…”