Clinical antimicrobial efficacy of NiTi rotary instrumentation with NaOCl irrigation, final rinse with chlorhexidine and interappointment medication: a molecular study.
OBJECTIVE
To evaluate clinically the antibacterial effects of root canal treatment procedures using molecular microbiology analyses.


METHODS
Samples were taken from 14 necrotic root canals of teeth with apical periodontitis before (S1) and after instrumentation with NaOCl irrigation (S2), a final rinse with chlorhexidine (CHX) (S3) and then one-week interappointment medication with calcium hydroxide/CHX paste (S4). The parameters examined included the following: incidence of positive broad-range PCR results for bacterial presence; impact on bacterial community structures evaluated by PCR-Denaturing Gradient Gel Electrophoresis (DGGE); quantitative bacterial reduction determined by real-time PCR; and identification of bacterial persisters by cloning and sequencing. Data from the different tests were subjected to statistical analyses and diversity indicator calculations.


RESULTS
All S1 samples were positive for bacteria in all tests. Treatment procedures promoted a decrease in microbial diversity and significantly reduced the incidence of positive results and the bacterial counts (P < 0.05). In general, each subsequent treatment step improved disinfection. No specific taxon or community pattern was associated with post-treatment samples.


CONCLUSIONS
Supplementary steps consisting of a final rinse with CHX followed by calcium hydroxide interappointment medication promoted further decrease in the bacterial bioburden to levels significantly below those achieved by the chemomechanical procedures alone. Because the long-term outcome of root canal treatment is dependent upon maximal bacterial reduction, the present results are of clinical relevance.
Institute of Microbiology Prof. Paulo de Góes, Federal University of Rio de Janeiro, Brazil.
S S M
SS
Paiva
J F
JF
Siqueira
I N
IN
Rôças
F L
FL
Carmo
D C A
DC
Leite
D C
DC
Ferreira
C T C
CT
Rachid
A S
AS
Rosado
D000891:Anti-Infective Agents, Local / Q000627:therapeutic use*; D058491:Bacterial Load / Q000187:drug effects; D044822:Biodiversity; D002126:Calcium Hydroxide / Q000627:therapeutic use*; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D058645:Denaturing Gradient Gel Electrophoresis; D003722:Dental Alloys / Q000737:chemistry; D003782:Dental Pulp / Q000382:microbiology; D003786:Dental Pulp Cavity / Q000382:microbiology; D003790:Dental Pulp Necrosis / Q000382:microbiology / Q000628:therapy; D004203:Disinfection / Q000379:methods*; D004492:Edetic Acid / Q000627:therapeutic use; D006090:Gram-Negative Bacteria / Q000145:classification / Q000235:genetics; D006094:Gram-Positive Bacteria / Q000145:classification / Q000235:genetics; D006801:Humans; D059013:Microbial Consortia / Q000187:drug effects; D008967:Molecular Biology; D009532:Nickel / Q000737:chemistry; D010485:Periapical Periodontitis / Q000382:microbiology / Q000628:therapy; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D012388:Root Canal Irrigants / Q000627:therapeutic use*; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D017423:Sequence Analysis, RNA; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000627:therapeutic use*; D014025:Titanium / Q000737:chemistry
D000891:Anti-Infective Agents, Local; D003722:Dental Alloys; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012388:Root Canal Irrigants; C040654:titanium nickelide; D009532:Nickel; D004492:Edetic Acid; D014025:Titanium; D012973:Sodium Hypochlorite; C010882:chlorhexidine gluconate; D002126:Calcium Hydroxide; D002710:Chlorhexidine