title: Ablation of composite resins using Er:YAG laser--comparison with enamel and dentin.
abstract: OBJECTIVE
  The purpose of this work is to investigate comparative ablation rate between composite resins and dental hard tissues (enamel and dentin) after Er:YAG laser irradiation to verify possible development of an ultra-conservative dentistry to with minimum effect for the teeth tissue.
  
  
  METHODS
  We have used 11 extracted or exfoliated primary anterior and posterior teeth and six extracted permanent molar teeth. Three different types of composite resin were chosen (microfiller, hybrid, and condensable) in terms of chemical and structural composition. Composite tablets and the teeth were irradiated with a Er:YAG laser at different laser beam energy level per pulse (100, 200, 300, and 400 mJ). Diameter and depth of each resulted microcavity were measured and the material removed volumes were calculated. The resulted values were plotted and fitted to allow a comparative observation of the material removed as a function of energy level per pulse.
  
  
  RESULTS
  While the idea of ultra-conservative dentistry seems to apply well for enamel of primary and permanent teeth, at the present stage it does not apply well for primary or permanent dentin. For dentin, the composition and content of water makes the Er:YAG laser ablation equal or superior in rate compared with the three used resins.
  
  
  CONCLUSIONS
  This work presents of a comparative study of Er:YAG laser ablation, allowing to analyze the possible selective ablation between composite resin placed and cured and dental hard tissues, with the goal to propose a new clinical technique: differential ablation for composite resin restorations using Er:YAG laser.
authors.affiliation: Instituto de Física de São Carlos, USP, Av. Trabalhador Sancarlense, 400, São Carlos, SP, Brazil. lizarelli@if.sc.usp.br
authors.forename: Rosane de F Z
authors.initials: Rde F
authors.lastname: Lizarelli
authors.forename: Lilian T
authors.initials: LT
authors.lastname: Moriyama
authors.forename: Vanderlei S
authors.initials: VS
authors.lastname: Bagnato
mesh_terms: D000180:Acrylic Resins / Q000528:radiation effects*; D003188:Composite Resins / Q000528:radiation effects*; D003737:Dental Cavity Preparation / Q000379:methods / Q000639:trends; D003743:Dental Enamel / Q000528:radiation effects*; D003804:Dentin / Q000528:radiation effects*; D006801:Humans; D053685:Laser Therapy / Q000295:instrumentation*; D011140:Polyurethanes / Q000528:radiation effects*; D014070:Tooth / Q000601:surgery*
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes