title: The influence of a novel in-office tooth whitening procedure using an Er,Cr:YSGG laser on enamel surface morphology.
abstract: OBJECTIVE
  The purpose of this in vitro study was to evaluate the influence of a novel in-office tooth whitening procedure using Er,Cr:YSGG laser radiation on bovine enamel.
  
  
  METHODS
  Forty-eight enamel specimens were prepared from bovine canines and divided into four groups: Group 1 specimens (control) received no whitening treatment; Group 2 received whitening treatment with an at-home whitening agent (22% carbamide peroxide) for 7 days; Group 3 received whitening treatment with a novel in-office whitening agent (35% H(2)O(2)); Group 4 received the same in-office whitening therapy with Group 3 using Er,Cr:YSGG laser in order to accelerate the whitening procedure. The specimens were stored for 10 days after the whitening treatment in artificial saliva. Vickers hardness was determined using a microhardness tester and surface roughness was evaluated using a VSI microscope. Three specimens of each experimental group were examined under SEM and the mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post-hoc test, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05).
  
  
  RESULTS
  The surface microhardness of the enamel was reduced after the in-office whitening treatments (P< 0.05), but not influenced after the at-home whitening treatment (P> 0.05). Moreover, the surface roughness was not significantly changed after tooth whitening. EDS analysis did not show alterations in the enamel mineral composition, while SEM observations indicated changes in the surface morphology, especially after in-office tooth whitening (P< 0.05).
  
  
  CONCLUSIONS
  The laser-assisted whitening treatment with Er,Cr:YSGG laser did not affect the alterations in enamel surface compared with the conventional in-office whitening technique.
authors.affiliation: Research Associate, Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Dionysopoulos
authors.affiliation: Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Strakas
authors.affiliation: Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Koliniotou-Koumpia
mesh_terms: D000818:Animals; D002417:Cattle; D003743:Dental Enamel / Q000473:pathology / Q000528:radiation effects*; D053844:Lasers, Solid-State / Q000009:adverse effects*; D011897:Random Allocation; D014073:Tooth Bleaching / Q000379:methods*
keywords: laser assisted whitening; mineral composition; surface microhardness; surface morphology; surface roughness; whitening agent