Microbial culture and checkerboard DNA-DNA hybridization assessment of bacteria in root canals of primary teeth pre- and post-endodontic therapy with a calcium hydroxide/chlorhexidine paste

• Published in: International journal of paediatric dentistry Vol. 21; no. 5; pp. 353 - 360
• Main Authors: ITO, IZABEL YOKO, JUNIOR, FUMIO MATOBA, PAULA-SILVA, FRANCISCO WANDERLEY GARCIA, Da SILVA, LÉA ASSED BEZERRA, LEONARDO, MÁRIO ROBERTO, NELSON-FILHO, PAULO
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2011
• Subjects: aerobic microorganisms; Anaerobic microorganisms; Analysis of Variance; Antimicrobial agents; Bacteria; Bacteria, Aerobic - drug effects; Bacteria, Anaerobic - drug effects; Bacteroides; Bacteroides - drug effects; Calcium hydroxide; Calcium Hydroxide - pharmacology; Cell culture; Chi-Square Distribution; Child; Child, Preschool; Chlorhexidine; Chlorhexidine - pharmacology; Colony Count, Microbial; Colony-forming cells; Contamination; Dental Pulp Cavity - microbiology; Dental Pulp Necrosis - microbiology; Dental Pulp Necrosis - therapy; Dentistry; Deoxyribonucleic acid; DNA; DNA, Bacterial - analysis; Dressings; Female; Gram-Negative Bacteria - drug effects; Humans; Hybridization; Infection; Male; Nucleic Acid Hybridization; Periapical Periodontitis - microbiology; Periapical Periodontitis - therapy; Periodontitis; Probes; Root Canal Irrigants - pharmacology; Root Canal Preparation - methods; root canals; Soil testing; Statistics, Nonparametric; Streptococcus; Streptococcus - drug effects; Teeth; Tooth, Deciduous - microbiology
• ISSN: 0960-7439; 1365-263X
• DOI: 10.1111/j.1365-263X.2011.01131.x

International Journal of Paediatric Dentistry 2011 Aim.  To investigate the root canal microbiota of primary teeth with apical periodontitis and the in vivo antimicrobial effects of a calcium hydroxide/chlorhexidine paste used as root canal dressing. Design.  Baseline samples were collected from 30 root canals of primary teeth with apical periodontitis. Then, the root canals were filled with a calcium hydroxide paste containing 1% chlorhexidine for 14 days and the second bacteriologic samples were taken prior to root canal filling. Samples were submitted to microbiologic culture procedure to detect root canal bacteria and processed for checkerboard DNA–DNA hybridization. Results.  Baseline microbial culture revealed high prevalence and cfu number of anaerobic, black‐pigmented bacteroides, Streptococcus, and aerobic microorganisms. Following root canal dressing, the overall number of cfu was dramatically diminished compared to initial contamination (P <0.05), although prevalence did not change (P > 0.05). Of 35 probes used for checkerboard DNA–DNA hybridization, 31 (88.57%) were present at baseline, and following root canal dressing, the number of positive probes reduced to 13 (37.14%). Similarly, the number of bacterial cells diminished folowing application of calcium hydroxide/chlorhexidine root canal dressing (P = 0.006). Conclusion.  Apical periodontitis is caused by a polymicrobial infection, and a calcium hydroxide/chlorhexidine paste is effective in reducing the number of bacteria inside root canals when applied as a root canal dressing.