title: Screening of CO(2) laser (10.6 μm) parameters for prevention of enamel erosion.
abstract: OBJECTIVE
  The aim of this study was to screen CO(2) laser (10.6 μm) parameters to increase enamel resistance to a continuous-flow erosive challenge.
  
  
  BACKGROUND
  A new clinical CO(2) laser providing pulses of hundreds of microseconds, a range known to increase tooth acid-resistance, has been introduced in the market.
  
  
  METHODS
  Different laser parameters were tested in 12 groups (n=20) with varying fluences from 0.1 to 0.9 J/cm(2), pulse durations from 80 to 400 μs and repetition rates from 180 to 700 Hz. Non-lased samples (n=30) served as controls. All samples were eroded by exposure to hydrochloric acid (pH 2.6) under continuous acid flow (60 μL/min). Calcium and phosphate release into acid was monitored colorimetrically at 30 sec intervals up to 5 min and at 1 min intervals up to a total erosion time of 15 min. Scanning electron microscopic (SEM) analysis was performed in lased samples (n=3). Data were statistically analysed by one-way ANOVA (p<0.05) and Dunnett's post-hoc tests.
  
  
  RESULTS
  Calcium and phosphate release were significantly reduced by a maximum of 20% over time in samples irradiated with 0.4 J/cm(2) (200μs) at 450 Hz. Short-time reduction of calcium loss (≤1.5 min) could be also achieved by irradiation with 0.7 J/cm(2) (300μs) at 200 and 300 Hz. Both parameters revealed surface modification.
  
  
  CONCLUSIONS
  A set of CO(2) laser parameters was found that could significantly reduce enamel mineral loss (20%) under in vitro erosive conditions. However, as all parameters also caused surface cracking, they are not recommended for clinical use.
authors.affiliation: Department of Operative Dentistry, Periodontology and Preventive Dentistry, University Hospital, RWTH Aachen University, Aachen, Germany. mestevesoliveira@ukaachen.de
authors.forename: Marcella
authors.initials: M
authors.lastname: Esteves-Oliveira
authors.forename: Hao
authors.initials: H
authors.lastname: Yu
authors.forename: Carlos
authors.initials: C
authors.lastname: de Paula Eduardo
authors.forename: Jörg
authors.initials: J
authors.lastname: Meister
authors.forename: Friedrich
authors.initials: F
authors.lastname: Lampert
authors.forename: Thomas
authors.initials: T
authors.lastname: Attin
authors.forename: Annette
authors.initials: A
authors.lastname: Wiegand
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002130:Calcium Phosphates / Q000378:metabolism*; D002417:Cattle; D003743:Dental Enamel / Q000528:radiation effects*; D003747:Dental Enamel Solubility / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004869:Equipment Safety; D007180:Incisor; D054020:Lasers, Gas / Q000627:therapeutic use*; D028022:Low-Level Light Therapy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D012016:Reference Values; D012307:Risk Factors; D012494:Sampling Studies; D013997:Time Factors; D014072:Tooth Abrasion / Q000517:prevention & control; D014077:Tooth Erosion / Q000517:prevention & control*
chemical_list: D002130:Calcium Phosphates; C020243:calcium phosphate