Effectiveness of ozone against endodontopathogenic microorganisms in a root canal biofilm model.
OBJECTIVE
To assess the antimicrobial efficacy of aqueous (1.25-20 microg mL(-1)) and gaseous ozone (1-53 g m(-3)) as an alternative antiseptic against endodontic pathogens in suspension and a biofilm model.


METHODS
Enterococcus faecalis, Candida albicans, Peptostreptococcus micros and Pseudomonas aeruginosa were grown in planctonic culture or in mono-species biofilms in root canals for 3 weeks. Cultures were exposed to ozone, sodium hypochlorite (NaOCl; 5.25%, 2.25%), chlorhexidine digluconate (CHX; 2%), hydrogen peroxide (H(2)O(2); 3%) and phosphate buffered saline (control) for 1 min and the remaining colony forming units counted. Ozone gas was applied to the biofilms in two experimental settings, resembling canal areas either difficult (setting 1) or easy (setting 2) to reach. Time-course experiments up to 10 min were included. To compare the tested samples, data were analysed by one-way anova.


RESULTS
Concentrations of gaseous ozone down to 1 g m(-3) almost and aqueous ozone down to 5 microg mL(-1) completely eliminated the suspended microorganisms as did NaOCl and CHX. Hydrogen peroxide and lower aqueous ozone concentrations were less effective. Aqueous and gaseous ozone were dose- and strain-dependently effective against the biofilm microorganisms. Total elimination was achieved by high-concentrated ozone gas (setting 2) and by NaOCl after 1 min or a lower gas concentration (4 g m(-3)) after at least 2.5 min. High-concentrated aqueous ozone (20 microg mL(-1)) and CHX almost completely eliminated the biofilm cells, whilst H(2)O(2) was less effective.


CONCLUSIONS
High-concentrated gaseous and aqueous ozone was dose-, strain- and time-dependently effective against the tested microorganisms in suspension and the biofilm test model.
Huth
K C
KC
Department of Restorative Dentistry & Periodontology, Ludwig-Maximilians University, Munich, Germany. khuth@dent.med.uni-muenchen.de
Quirling
M
M
Maier
S
S
Kamereck
K
K
Alkhayer
M
M
Paschos
E
E
Welsch
U
U
Miethke
T
T
Brand
K
K
Hickel
R
R
D000891:Anti-Infective Agents, Local / Q000008:administration & dosage / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002021:Buffers; D002176:Candida albicans / Q000187:drug effects; D002710:Chlorhexidine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D015169:Colony Count, Microbial; D003786:Dental Pulp Cavity / Q000382:microbiology*; D004305:Dose-Response Relationship, Drug; D013293:Enterococcus faecalis / Q000187:drug effects; D005740:Gases; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000494:pharmacology; D016877:Oxidants / Q000008:administration & dosage / Q000494:pharmacology; D010083:Oxidants, Photochemical / Q000008:administration & dosage / Q000494:pharmacology*; D010126:Ozone / Q000008:administration & dosage / Q000494:pharmacology*; D010462:Peptostreptococcus / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D012388:Root Canal Irrigants / Q000008:administration & dosage / Q000494:pharmacology*; D012973:Sodium Hypochlorite / Q000008:administration & dosage / Q000494:pharmacology; D012996:Solutions; D013997:Time Factors
D000891:Anti-Infective Agents, Local; D002021:Buffers; D005740:Gases; D016877:Oxidants; D010083:Oxidants, Photochemical; D012388:Root Canal Irrigants; D012996:Solutions; D010126:Ozone; D006861:Hydrogen Peroxide; D012973:Sodium Hypochlorite; C010882:chlorhexidine gluconate; D002710:Chlorhexidine