title: Comparison of ozone gas and sodium hypochlorite/chlorhexidine two-visit disinfection protocols in treating apical periodontitis: a randomized controlled clinical trial.
abstract: OBJECTIVE
  In this single-blinded, prospective, randomized, controlled clinical trial, the effectiveness of an ozone gas or NaOCl/CHX disinfection protocol was compared within the root canal treatment of apical periodontitis.
  
  
  METHODS
  Sixty permanent teeth were randomly allocated to one technique. The clinical/radiographic assessment criteria included clinical symptoms, periapical index (PAI), and size of the apical lesion. In both groups, the root canal was mechanically cleaned and irrigated with NaCl and EDTA. Ozone gas (32 g m-3) or NaOCl (3 %) was applied followed by a 1-week inter-appointment dressing (Ca(OH)2). As final disinfection, ozone gas (ozone group) or CHX 2 % (NaOCl group) was applied. Microbial samples were taken after preparing the access cavity, after chemo-mechanical treatment and after inter-appointment dressing by sterile paper points. Microbial identification was performed by mass spectroscopy (MALDI-TOF-MS) and 16S-rRNA gene sequencing. The treated teeth were blindly re-evaluated after 6/12 months. Success rates, the decrease in PAI, the size of apical lesions and bacterial reduction were compared between groups (Fischer's exact test, Mann-Whitney U test).
  
  
  RESULTS
  There were no significant differences between the success rates (ozone group: 96.2/95.5 % after 6/12 months; NaOCl group: 95.5/95.2 % after 6/12 months). The differences in the decreases in PAI values and apical lesion sizes were also insignificant after 6 and 12 months. The bacterial reduction showed no significant differences between groups after chemo-mechanical treatment and after inter-appointment dressing. The most commonly found bacterial genera were Streptococcus spp., Parvimonas spp. and Prevotella spp.
  
  
  CONCLUSIONS
  The here used ozone gas and NaOCl/CHX protocols showed no difference in bacterial reduction in the sampled areas of the root canals.
  
  
  CONCLUSIONS
  Within the limitations of the study, ozone gas seems to be a possible alternative disinfection agent within the root canal treatment of apical periodontitis.
authors.affiliation: Department of Restorative Dentistry, Periodontology & Paedodontics, Ludwig Maximilians University, Goethestrasse 70, 80336, Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Kist
authors.affiliation: Department of Restorative Dentistry, Periodontology & Paedodontics, Ludwig Maximilians University, Goethestrasse 70, 80336, Munich, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Kollmuss
authors.affiliation: Max-von-Pettenkofer Institute for Hygiene and Clinical Microbiology, Ludwig Maximilians University, Munich, Germany.
authors.forename: Jette
authors.initials: J
authors.lastname: Jung
authors.affiliation: Max-von-Pettenkofer Institute for Hygiene and Clinical Microbiology, Ludwig Maximilians University, Munich, Germany.
authors.forename: Sören
authors.initials: S
authors.lastname: Schubert
authors.affiliation: Department of Restorative Dentistry, Periodontology & Paedodontics, Ludwig Maximilians University, Goethestrasse 70, 80336, Munich, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Hickel
authors.affiliation: Department of Restorative Dentistry, Periodontology & Paedodontics, Ludwig Maximilians University, Goethestrasse 70, 80336, Munich, Germany. khuth@dent.med.uni-muenchen.de.
authors.forename: Karin Christine
authors.initials: KC
authors.lastname: Huth
mesh_terms: D000891:Anti-Infective Agents, Local / Q000627:therapeutic use*; D002710:Chlorhexidine / Q000627:therapeutic use*; D004202:Disinfectants / Q000627:therapeutic use*; D004203:Disinfection / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010126:Ozone / Q000627:therapeutic use*; D010485:Periapical Periodontitis / Q000382:microbiology* / Q000628:therapy*; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D012390:Root Canal Therapy; D016037:Single-Blind Method; D012973:Sodium Hypochlorite / Q000627:therapeutic use*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D016896:Treatment Outcome
chemical_list: D000891:Anti-Infective Agents, Local; D004202:Disinfectants; D010126:Ozone; D012973:Sodium Hypochlorite; D002710:Chlorhexidine
keywords: Apical periodontitis; Disinfection; Endodontics; Ozone; RCT; Sodium hypochlorite