title: Decontamination of root canals with the gallium-aluminum-arsenide laser: an in vitro study.
abstract: OBJECTIVE
  In this in vitro study, we investigated the bactericidal effects on root canals of 810-nm diode laser irradiation, alone or combined with sodium hypochlorite and citric acid irrigation.
  
  
  METHODS
  One hundred sixteen single-rooted human teeth extracted for periodontal reasons were randomly divided into four experimental groups. The canal of each tooth was prepared with a conventional step-back technique and a pure culture of vancomycin-resistant Enterococcus faecalis grown in brain heart infusion broth was used to contaminate the root canal. The specimens were incubated at 37 degrees C for 15 d in a test tube filled with agar, adding fresh bacterial suspension every 48 h, and sent them for microbiological analysis and bacterial count. Subsequently they were divided into four groups: in group A, 29 teeth were irrigated with 2 mL of 10% citric acid solution; in group B, 29 teeth were irrigated with 2 mL 5.25% sodium hypochlorite (NaOCl) solution; in group C, 29 teeth were irradiated with 810-nm laser energy via a 200-microm optic fiber at 2.5 W power in pulsed mode (10 msec on and 10 msec off) for 5 sec; and in group D, 29 teeth were irrigated with NaOCl, irradiated with the laser, then irrigated with citric acid, and irradiated with the laser, followed again by NaOCl irrigation and laser irradiation. All the samples were again sent for microbiological analysis and bacterial count.
  
  
  RESULTS
  Group A had a bactericidal effect of 0.041 log mean CFU, that of group B was 3.381 log mean CFU, and that of group C was 1.459 log mean CFU, whereas group D showed the best results, with a bactericidal effect of 7.178 log mean CFU.
  
  
  CONCLUSIONS
  The use of NaOCl, citric acid, and diode laser energy together have a synergistic effect, increasing treatment efficacy and leading to significantly better decontamination of the root canal.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biofisiche Medich Odontostomatologiche, Biostatistics Section, University of Genoa, Genoa. stefano.benedicenti@tiscali.it
authors.forename: S
authors.initials: S
authors.lastname: Benedicenti
authors.forename: C
authors.initials: C
authors.lastname: Cassanelli
authors.forename: A
authors.initials: A
authors.lastname: Signore
authors.forename: G
authors.initials: G
authors.lastname: Ravera
authors.forename: F
authors.initials: F
authors.lastname: Angiero
mesh_terms: D019343:Citric Acid / Q000008:administration & dosage; D003666:Decontamination; D003786:Dental Pulp Cavity / Q000382:microbiology* / Q000528:radiation effects*; D006801:Humans; D066298:In Vitro Techniques; D054023:Lasers, Semiconductor; D011897:Random Allocation; D012973:Sodium Hypochlorite / Q000008:administration & dosage; D012996:Solutions / Q000008:administration & dosage
chemical_list: D012996:Solutions; D019343:Citric Acid; D012973:Sodium Hypochlorite