title: Disinfection of root canals using Er:YAG laser at different frequencies.
abstract: OBJECTIVE
  This study evaluated, in vitro, the degree of disinfection of the Er:YAG laser in root canals contaminated with Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans, for 28 days.
  
  
  METHODS
  Forty-six single-rooted human teeth were divided into five groups of eight teeth each; three teeth were used as negative controls and three as positive controls. After contamination, the root canals were prepared mechanically. Three groups were irradiated with Er:YAG laser at 100 mJ, varying the frequency (7, 10, and 16 Hz). Two groups were irrigated with 1.0% and 2.5% NaOCl solution. After treatment, two sterilized paper cones were placed in the root canals for 5 min. One cone was transferred to 2.0 mL of Letheen broth culture medium, incubated at 37 degrees C for 48 h, and then 0.1 mL of that solution was placed in 2.0 mL of brain heart infusion for 48 h to determine microbial growth. The other cone was transferred to a test pipette with peptone and water for serial dilution and spread in Müeller Hinton medium. After 24 h of incubation, the colony-forming units (CFUs) were counted.
  
  
  RESULTS
  There was a microbial reduction of 85.33% for the group irradiated with Er:YAG laser at 100 mJ/7 Hz, 74.58% at 100 mJ/10 Hz, and 89.50% at 100 mJ/16 Hz. For the groups irrigated with 1.0% and 2.5% NaOCl solution, 83.15% and 84.46% values of microbial reduction were obtained respectively.
  
  
  CONCLUSIONS
  All the groups showed statistically similar results (p > 0.05%). No method totally eliminated microorganisms.
authors.affiliation: Faculty of Dentistry, University of Ribeirão Preto, São Paulo, Brazil.
authors.forename: Márcia Saran
authors.initials: MS
authors.lastname: Vezzani
authors.forename: Rosimeire
authors.initials: R
authors.lastname: Pietro
authors.forename: Yara Teresinha
authors.initials: YT
authors.lastname: Silva-Sousa
authors.forename: Aldo
authors.initials: A
authors.lastname: Brugnera-Junior
authors.forename: Manoel Damião
authors.initials: MD
authors.lastname: Sousa-Neto
mesh_terms: D001412:Bacillus subtilis / Q000528:radiation effects; D002176:Candida albicans / Q000528:radiation effects; D003786:Dental Pulp Cavity; D004203:Disinfection / Q000379:methods*; D013293:Enterococcus faecalis / Q000528:radiation effects; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy; D011550:Pseudomonas aeruginosa / Q000528:radiation effects; D018915:Root Canal Preparation / Q000379:methods; D013211:Staphylococcus aureus / Q000528:radiation effects