title: Near-IR image-guided laser ablation of demineralization on tooth occlusal surfaces.
abstract: BACKGROUND
  Studies have shown that reflectance images at near-IR wavelengths coincident with higher water absorption are well-suited for image-guided laser ablation of carious lesions since the contrast between sound and demineralized enamel is extremely high and interference from stains is minimized. The objective of this study was to demonstrate that near-IR reflectance images taken at a wavelength range of 1,500-1,700 nm can be used to guide a 9.3 μm CO(2) laser for the selective ablation of early demineralization on tooth occlusal surfaces.
  
  
  METHODS
  The occlusal surfaces of ten sound human molars were used in this in vitro study. Shallow simulated caries lesions with random patterns and varying depth and position were produced on tooth occlusal surfaces. Sequential near-IR reflectance images at 1,500-1,700 nm were used to guide the laser for the selective removal of the demineralized enamel. Digital microscopy and polarization sensitive optical coherence tomography (PS-OCT) were used to assess selectivity.
  
  
  RESULTS
  Images taken before and after lesion removal suggest that the demineralized areas were removed with high selectivity. Although the estimated volume of tissue ablated was typically higher than the initial lesion volume measured with PS-OCT, the volume of enamel removed by the laser correlated well with the initial lesion volume.
  
  
  CONCLUSIONS
  Sequential near-IR reflectance images at 1,500-1,700 nm can be used to guide a 9.3 μm CO(2) laser for the selective ablation of early demineralization on tooth occlusal surfaces.
authors.affiliation: Department of Preventive and Restorative Dental Science, University of California, San Francisco, California, 94143-0758.
authors.forename: Henry
authors.initials: H
authors.lastname: Tom
authors.affiliation: Department of Preventive and Restorative Dental Science, University of California, San Francisco, California, 94143-0758.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Chan
authors.affiliation: Department of Preventive and Restorative Dental Science, University of California, San Francisco, California, 94143-0758.
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Darling
authors.affiliation: Department of Preventive and Restorative Dental Science, University of California, San Francisco, California, 94143-0758.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fried
mesh_terms: D003766:Dental Occlusion; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000379:methods*; D019265:Spectroscopy, Near-Infrared; D025321:Surgery, Computer-Assisted; D017001:Tooth Demineralization / Q000601:surgery*
keywords: carbon dioxide laser; image-guided ablation; near-IR imaging; optical coherence tomography; selective laser ablation