Role of anaerobic species in endodontic infection.

Many different bacterial species have been found in infected was obtained from each patient. Clinical signs and symptoms included pain, tenderness to percussion (TTP), purulent exudate, dental root canals [1]. The problem lies in deciding whether any individual species has clinical significance. Koch’s postulates were swelling, wet canal, periapical radiolucency, sinus formation, and swelling. The microbiological data and the clinical data were both historically used to show causal relationships between specific microbes and specific major diseases. Unfortunately, these postuentered into Quattro Pro spreadsheets (Borland International, Scotts Valley, CA) before statistical analysis was performed. lates cannot be demonstrated in the case of many diseases, which is why other approaches have been employed such as detecting SPSS/PC/ software (SPSS Inc., Chicago) was used to obtain correlations between patient clinical data and the presence of microrising titers of antibody during the course of illness or using germfree rats [2]. In the case of endodontic infection, research at the bial species with the Pearson x test or Fisher’s exact test, as appropriate. Statistical correlation of a species with a clinical sign University of Manchester and elsewhere has revealed that ú60 different microbial species have been isolated from endodontic or symptom does not actually prove a causal relationship. It is conceivable that pain could be caused by some unrecognized feainfections [1] , so we cannot demonstrate even the first of Koch’s postulates. ture that also encouraged selective growth of a specific organism. The fact that spurious correlations can be found if enough tests Various theories have been proposed to explain the source of microorganisms found to infect dental root canals. Pathways to are performed on any sets of data was taken into account. the pulp include exposure of accessory canals and apical foramina The statistical analyses highlighted interesting associations bein periodontal disease, exposure of dentine following caries, erotween individual clinical features and individual bacterial species. sion or cracking of enamel, restorative procedures, anachoresis Major associations between clinical features and individual bacte(blood-borne infection), and direct exposure of pulp. The presence rial species are shown in table 1. Certain organisms are clearly of some of these conditions would explain how only single species associated with particular signs or symptoms. It is of interest that might be present, as we have occasionally observed; the other ú50 species were not associated at all with individual clinical conditions explain why a complex flora will frequently be present. features. In periodontal disease, P. intermedia is the most comStatistics have been used in many studies to demonstrate that parmonly encountered Prevotella species, whereas P. melaninogenica ticular species are associated with particular oral diseases. Our is likely to be found in infected root canals. The presence of study tested the hypothesis that particular species can be associated Propionibacterium species in root canals that have previously been with individual signs or symptoms in endodontic infection. The treated may possibly indicate contamination during treatment. The study was not designed to determine the microorganism(s) responfinding that Prevotella species are associated with pain could be sible for the initial infection; that is a different question. In our study we examined 70 patients who had been referred to the University Dental Hospital because of difficulties experienced with endodontic management in the primary care situation. Table 1. Association between bacterial species and signs and symptoms in 70 patients with infected dental root canals. Therefore, all the pulp spaces sampled had established microflora related to pulpal or endodontic pathology. In the clinic, the inBacterial species Clinical feature P value fected tooth was isolated by the use of a clean (but not sterile) rubber dam that was swabbed with chlorhexidine. All reasonable Bacteroides species Purulent exudate .034 precautions were taken to minimize the chance of contamination Fusobacterium species Purulent exudate .011 of the root canal. Once the root canal had been exposed, microbial Fusobacterium necrophorum Purulent exudate .006 samples were taken immediately by paper point. The samples Prevotella species Pain .001 were rapidly obtained, then plated onto prereduced Fastidious Swelling .039 Anaerobe Agar (Lab M, Bury, UK) and, within 30 seconds, TTP .010 placed in an anaerobic transport bag (Generbag; bioMérieux, Wet canal .036 Prevotella loescheii Purulent exudate .018 Marcy l’Etoile, France) that provided an incompletely anaerobic Prevotella melaninogenica Pain .011 atmosphere. However, 5 minutes later, the plates were transferred TTP .021 to an anaerobic incubator (Don Whitley Scientific, Bradford, Eubacterium species Swelling .008 UK). The isolation and subsequent identification of the bacteria Wet canal .040 have been described elsewhere [1]. Eubacterium aerofaciens Swelling .035 Sixty-two different species were isolated during our study. A Peptostreptococcus species Pain .009 detailed history, including data on age, sex, and clinical features, Peptostreptococcus micros Pain .024 Swelling .039 Periapical radiolucency .026 Propionibacterium species Wet canal .019 Reprints or correspondence: Dr. D. B. Drucker, Microbiology Laboratory, Previous therapy* .022 Turner Dental School, University of Manchester, Higher Cambridge Street, Propionibacterium acnes Previous therapy* .011 Manchester M15 6FH, UK. NOTE. TTP Å tenderness to percussion. Clinical Infectious Diseases 1997;25(Suppl 2):S220–1 * Previous therapy refers to a completed course of treatment that was tempoq 1997 by The University of Chicago. All rights reserved. 1058–4838/97/2503–0041$03.00 rarily successful.