The influence of organic load on the antimicrobial activity of different concentrations of NaOCl and chlorhexidine in vitro.
OBJECTIVE
To evaluate bacterial growth after contact with sodium hypochlorite (NaOCl; 1 and 5%) and chlorhexidine (CHX; 0.12, 0.5 and 1%) in vitro with or without the addition of organic material (bovine serum albumin (BSA) 0.5%).


METHODS
Bacterial samples (American Type Culture Collection (ATCC)) of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Porphyromonas gingivalis and Fusobacterium nucleatum were kept in contact with each irrigating solution for varying intervals of time: immediately (t0), 5 min (t5), 15 min (t15) and 30 min (t30). Each test was repeated 10 times. In half of the specimens, 0.5% BSA was added as organic material in an attempt to simulate the organic tissue present in the root canal system. Bacterial growth under appropriate condition of incubation was evaluated and compared for each microorganism at all time intervals.


RESULTS
A 0.12% CHX solution did not eliminate E. faecalis at any time interval. One percent CHX eliminated all strains, as did both NaOCl concentrations. BSA did not interfere substantially with the antimicrobial activity of any of the irrigating solutions.


CONCLUSIONS
Under the condition of this study, a 0.12% CHX solution was ineffective at killing E. faecalis.
Sassone
L M
LM
Proclin Department, School of Dentistry, Rio de Janeiro State University, Rio de Janeiro, Brazil. lsassone@montreal.com.br
Fidel
R
R
Fidel
S
S
Vieira
M
M
Hirata
R
R
D000891:Anti-Infective Agents, Local / Q000008:administration & dosage*; D001421:Bacteria, Anaerobic / Q000187:drug effects*; D002710:Chlorhexidine / Q000008:administration & dosage*; D015169:Colony Count, Microbial; D003470:Culture Media / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D008826:Microbial Sensitivity Tests; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D012710:Serum Albumin, Bovine / Q000378:metabolism; D012973:Sodium Hypochlorite / Q000008:administration & dosage*
D000891:Anti-Infective Agents, Local; D003470:Culture Media; D012388:Root Canal Irrigants; D012710:Serum Albumin, Bovine; D012973:Sodium Hypochlorite; D002710:Chlorhexidine