Molecular identification and quantification of bacteria from endodontic infections using real-time polymerase chain reaction.
BACKGROUND
It was the aim of the present study to evaluate root canal samples for the presence and numbers of specific species as well as for total bacterial load in teeth with chronic apical periodontitis using quantitative real-time polymerase chain reaction (PCR).


METHODS
Forty adult patients with one radiographically documented periapical lesion were included. Twenty teeth presented with primary infections and 20 with secondary infections, requiring retreatment. After removal of necrotic pulp tissue or root canal filling, a first bacterial sample was obtained. Following chemo-mechanical root canal preparation a second sample was taken and a third sample was obtained after 14 days of intracanal dressing with calcium hydroxide. Analysis by real-time PCR enabled the quantification of total bacterial counts and of nine selected species.


RESULTS
Root canals with primary infections harbored significantly more bacteria (by total bacterial count) than teeth with secondary infections (P < 0.05). Mean total bacterial count in the retreatment group was 2.1 x 10(6) and was significantly reduced following root canal preparation (3.6 x 10(4)) and intracanal dressing (1.4 x 10(5)). Corresponding values for primary infections were: 4.6 x 10(7), 3.6 x 10(4), and 6.9 x 10(4). The numbers of the selected bacteria and their detection frequency were also significantly reduced.


CONCLUSIONS
Root canals with primary infections contained a higher bacterial load. Chemo-mechanical root canal preparation reduced bacterial counts by at least 95%.
Blome
B
B
Department of Operative Dentistry and Periodontology, University of Bonn, Bonn, Germany. BennyBlome@gmx.net
Braun
A
A
Sobarzo
V
V
Jepsen
S
S
D000328:Adult; D000368:Aged; D001439:Bacteroides / Q000145:classification; D002126:Calcium Hydroxide / Q000627:therapeutic use; D002710:Chlorhexidine / Q000627:therapeutic use; D015169:Colony Count, Microbial; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003788:Dental Pulp Diseases / Q000382:microbiology* / Q000628:therapy; D003790:Dental Pulp Necrosis / Q000382:microbiology / Q000628:therapy; D005260:Female; D005500:Follow-Up Studies; D016967:Fusobacterium nucleatum / Q000145:classification; D006090:Gram-Negative Bacteria / Q000145:classification*; D006094:Gram-Positive Bacteria / Q000145:classification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010462:Peptostreptococcus / Q000145:classification; D010485:Periapical Periodontitis / Q000382:microbiology / Q000628:therapy; D016133:Polymerase Chain Reaction / Q000379:methods*; D045202:Porphyromonas endodontalis / Q000145:classification; D019233:Retreatment; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000379:methods; D012390:Root Canal Therapy; D012973:Sodium Hypochlorite / Q000627:therapeutic use
D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite; D002126:Calcium Hydroxide; D002710:Chlorhexidine