title: Enamel caries initiation and progression after argon laser irradiation: in vitro argon laser systems comparison.
abstract: OBJECTIVE
  The purpose of this in vitro laboratory study was to determine the effect of low-fluence argon laser (AL) irradiation delivered from two different argon laser systems on enamel caries-like lesion initiation and progression.
  
  
  BACKGROUND
  Previous in vitro investigations and a recent in vivo pilot study have shown that AL irradiation of enamel provided a protective effect against in vitro and in vivo cariogenic challenges.
  
  
  METHODS
  Twenty extracted human molars were selected, and 10 teeth were assigned to the HGM argon laser group and 10 were assigned to the LaserMed argon laser group. The exposed buccal windows of sound enamel were exposed to low-fluence irradiation, while the lingual windows of enamel were not exposed to laser irradiation and served as the no-treatment (control) group. Enamel caries-like lesions were created using an acidified gel. Two longitudinal sections were taken per sample (n = 20 lesions per group) and evaluated by polarized light microscopy for body of the lesion depths after lesion initiation (8 weeks) and progression (12 weeks) periods.
  
  
  RESULTS
  After lesion initiation and progression, the body of lesion depths were similar for both argon-irradiated groups (p > 0.05). With the no-treatment (control) group, there were significant increases in lesion depth with a 61-78% increase for the lesion initiation period and a 50-69% increase for the lesion progression period when compared with the argon laser-treated groups.
  
  
  CONCLUSIONS
  Argon laser irradiation provides a certain degree of protection against in vitro enamel caries initiation and progression. Resistance to a continuous caries challenge was similar with either argon laser delivery systems (HGM and LaserMed). Argon laser irradiation may prove to be beneficial in reducing the caries susceptibility of sound enamel and white spot lesions in the clinical environment.
authors.affiliation: Department of Community and Preventive Dentistry, Creighton University, School of Dentistry, Omaha, Nebraska, USA. ghwester@Creighton.edu
authors.forename: Gary H
authors.initials: GH
authors.lastname: Westerman
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Flaitz
authors.forename: G Lynn
authors.initials: GL
authors.lastname: Powell
authors.forename: M John
authors.initials: MJ
authors.lastname: Hicks
mesh_terms: D001128:Argon; D003731:Dental Caries / Q000473:pathology / Q000517:prevention & control*; D003733:Dental Caries Susceptibility / Q000528:radiation effects; D003743:Dental Enamel / Q000473:pathology / Q000528:radiation effects*; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy; D007834:Lasers
chemical_list: D001128:Argon