title: Synergistic effect of Er:YAG laser irradiation in combination with chlorhexidine on the viability of Enterococcus faecalis: an in vitro study.
abstract: OBJECTIVE
  This study aimed to examine the potential synergistic effect of laser and chlorhexidine (CHX) applications on the growth of Enterococcus faecalis.
  
  
  BACKGROUND
  CHX has been recommended for root canal irrigation because of its antibacterial properties. Er:YAG 2.94??m laser irradiation was shown to be beneficial in disinfecting infected root canals. Producing minimal side effects is the goal of any clinical procedure. One means of achieving this is via a synergistic effect caused by simultaneously introducing two applications with reduced dosages, with no compromise on their biological effect.
  
  
  METHODS
  Bacterial suspensions of E. faecalis supplemented with 0.01?0.0001% v/v CHX solutions were lased at energy levels between 300 and 500?mJ. Bacterial growth was continuously monitored for 18?h using a GENios apparatus.
  
  
  RESULTS
  Laser irradiation between 350 and 500?mJ delayed initiation of bacterial growth for 6?h. A concentration of 0.0001% CHX did not delay bacteria growth. However, a combination of 0.0001% CHX and laser irradiation had a synergistic effect on bacterial growth. A maximal inhibition period of bacterial growth was observed at energy levels of 500?mJ with 0.0001% CHX.
  
  
  CONCLUSIONS
  Laser combined with CHX has a synergistic effect in killing E. faecalis. A combined regimen of a low concentration of CHX with laser irradiation was found to be a potential means of inhibiting bacterial growth.
authors.affiliation: Dept of Endodontics, Hebrew University Hadassah School of Dental Medicine, Jerusalem, Israel. helft1@bezeqint.net
authors.forename: Sharonit
authors.initials: S
authors.lastname: Sahar-Helft
authors.forename: Iris
authors.initials: I
authors.lastname: Slutzky-Goldberg
authors.forename: Joshua
authors.initials: J
authors.lastname: Moshonov
authors.forename: Adam
authors.initials: A
authors.lastname: Stabholtz
authors.forename: Marcos
authors.initials: M
authors.lastname: Jacobovitz
authors.forename: Avshalom
authors.initials: A
authors.lastname: Tam
authors.forename: Doron
authors.initials: D
authors.lastname: Steinberg
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D002710:Chlorhexidine / Q000494:pharmacology*; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000528:radiation effects*; D053844:Lasers, Solid-State
chemical_list: D000891:Anti-Infective Agents, Local; D002710:Chlorhexidine