title: Scanning electron microscopy (SEM) and optical microscopy: effects of Er:YAG and Nd:YAG lasers on apical seals after apicoectomy and retrofill.
abstract: OBJECTIVE
  This study evaluated the dentinal and marginal permeability of the cut surface after apicoectomy, treatment and retrocavity preparation with Er:YAG and Nd:YAG lasers. Furthermore, scanning electron microscopy (SEM) analysed the morphological alteration of dentin caused by laser irradiation through an optical fiber.
  
  
  BACKGROUND
  Numerous studies have shown the beneficial effects of laser treatment upon sealing dental apex, avoiding the changes of organic fluids, microorganisms and their by-products between the root canal system and periapex.
  
  
  METHODS
  Twenty-four extracted and endodontically treated teeth were divided into three groups: GI, apices were resected with Er:YAG laser (350 mJ; 4 Hz) treatment of cut dentinal surface and retrocavity were lased with this same laser (120 mJ; 4 Hz; bur 2051) using the optical fiber 50/10; GII, apicoectomy was performed similar to GI, however the cut dentinal surface was treated with Nd:YAG laser through optical fiber, as well as the retrocavity preparation (100 mJ; 15 Hz; 1.5 W); and GIII (control group), high speed burs were used.
  
  
  RESULTS
  Analysis of methylene blue dye penetration into dentin demonstrated that the specimens of the groups irradiated with laser showed to have lower infiltration indices than the control group. These results were compatible with structural and morphological injuries, evidenced by SEM.
  
  
  CONCLUSIONS
  Under the conditions of the present study, apicoectomy using Er:YAG laser, followed by dentinal surface irradiation and retrocavity preparation with Nd:YAG laser, showed to be an alternative clinical tool able to reduce the dentinal permeability.
authors.affiliation: Mestrado Profissionalizante Lasers em Odontologia, IPEN/FOUSP, Brazil.
authors.forename: R G
authors.initials: RG
authors.lastname: Oliveira
authors.forename: S
authors.initials: S
authors.lastname: Gouw-Soares
authors.forename: S L
authors.initials: SL
authors.lastname: Baldochi
authors.forename: C P
authors.initials: CP
authors.lastname: Eduardo
mesh_terms: D006801:Humans; D007834:Lasers; D008855:Microscopy, Electron, Scanning; D014070:Tooth / Q000528:radiation effects*