Microbiological Aspects of Naturally Occurring Primary Endodontic Infections in Dogs

Abstract

Dental fractures are common in dogs, but data on microbiology of naturally occurring primary endodontic infections, and their relation to clinical and radiographic signs, are lacking. Samples were obtained from root canals of 32 periodontally healthy fractured teeth under aseptic conditions and immediately cultured for aerobic and anaerobic bacteria. Cultures were further identified by matrix-assisted laser desorption/ionization, time of flight technology. Sixty-one bacteria (30 bacterial species) were isolated from root canals; 54% were Gram-negative bacteria, 53% were facultative anaerobic, and 42% were anaerobic bacteria. Number of bacterial species in the root canals declined with the duration of fractures over 12 months. No statistically significant association was found between the number of bacterial species involved in the root canal infection and any of the clinical or radiographic signs of endodontic disease. Naturally occurring primary endodontic infections in dogs appear to be polymicrobial and involve only a selected number of opportunistic pathogen species.

Endodontic Microbiome of Fractured Non-vital Teeth in Dogs Determined by 16S rRNA Gene Sequencing

“…This is most likely a result of the endodontic environment favoring specific genera (11). Bacteriodetes/ Bacteroides have been reported as one of the most frequently identified phyla/genera in the pulp cavities of teeth in dogs affected by primary endodontic infection (8, 10), but the other findings of the present study mostly differ from previously published data on endodontic microbiota in dogs. The observed difference may be a sequel of case selection.…”

“…Duration of pulp exposure most likely influences the endodontic microbiome. A decline in number of bacterial species with longer pulp exposure times was observed in one previous veterinary clinical study (10), while data from human literature show higher number and diversity of endodontic bacteria associated with the severity and acuteness of the endodontic disease (4, 18). Furthermore, the veterinary study (identifying Pasteurella, Bacteroides , and Propionibacterium as the most frequently isolated genera from the exposed pulp cavities) included both vital and non-vital fractured teeth (10).…”

“…A decline in number of bacterial species with longer pulp exposure times was observed in one previous veterinary clinical study (10), while data from human literature show higher number and diversity of endodontic bacteria associated with the severity and acuteness of the endodontic disease (4, 18). Furthermore, the veterinary study (identifying Pasteurella, Bacteroides , and Propionibacterium as the most frequently isolated genera from the exposed pulp cavities) included both vital and non-vital fractured teeth (10). Finally, all previously published veterinary studies were performed using culture-based methods of bacterial identification (8–10), possibly missing some difficult-to-culture microorganisms (11, 20, 21).…”

“…One sample (endodontic sample) was collected from the pulp cavity by inserting a 60 mm sterile endodontic paper point ranging between ISO #15 and #25, via the pulp exposure site all the way to the apical third while avoiding contact with any external dental or oral mucosal surface. Following previously reported protocols in similar veterinary studies, no dental dam was used (8, 10). Once inside the canal, the paper point was left in place for approximately 15 s prior to removal.…”

“…The oral cavity and the gingival sulcus harbor highly diverse microbiota that can act as a source of microorganisms that can infect the compromised endodontic system (2–5). Primary endodontic infections are polymicrobial in nature and well-documented in humans (4, 6, 7), but much less so in dogs (8–10). Moreover, data obtained to date in veterinary dentistry stem from culture-based microbiological studies, which are known to underestimate the diversity of microbiota associated with endodontic disease in humans (4, 6, 7).…”