title: The efficacy of laser-assisted in-office bleaching and home bleaching on sound and demineralized enamel.
abstract: OBJECTIVE
  This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel.
  
  
  METHODS
  The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups.
  
  
  RESULTS
  There were significant differences in the color change between T2 and T3 (ΔE T2-T3) and T2 and T4 (ΔE T2-T4) stages among the study groups (p<0.05). Pairwise comparison by Duncan test revealed that both ΔET2-T3 and ΔET2-T4 were significantly greater in demineralized teeth submitted to laser-assisted in-office bleaching (group 1) as compared to the other groups (P< 0.05).
  
  
  CONCLUSIONS
  Laser-assisted in-office bleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth.
authors.affiliation: Dental Research Center, Department of Orthodontics, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Ahrari
authors.affiliation: Dental Research Center, Department of Operative dentistry, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Akbari
authors.affiliation: Postgraduate Dental Student, Department of Periodontics, School of Dentistry, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Sakineh
authors.initials: S
authors.lastname: Mohammadpour
authors.affiliation: Dental Materials Research Center, Department of Endodontics, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Forghani
keywords: Diode; In office bleaching; Tooth color; demineralized enamel; home bleaching; laser-spectrophotometry; white spot lesion