title: Marginal quality in enamel and dentin after preparation and finishing with an Er:YAG laser.
abstract: OBJECTIVE
  To find the most appropriate Er:YAG laser parameters for an optimal marginal adaptation of Class V restorations in enamel and dentin.
  
  
  METHODS
  Six saucer-shaped mixed Class V cavities were prepared in each of the eight experimental groups with an Erbium:YAG hard laser (Opus Duo) on extracted human molars in near contact mode with a conical 800 microm sapphire tip under continuous water spray by using different pulse energy and pps (pulse per second) parameters. The cavities were restored under the simulation of dentin fluid with Clearfil SE Bond and Clearfil APX PLT composite applied in two layers and light-cured. Marginal adaptation in enamel and dentin was quantified before and after simultaneous thermal (5-50-5 degrees C, 2 minutes each) and mechanical (max. 49N; 1,200,000 cycles) stresses by using the replica technique in a SEM under x200 magnification.
  
  
  RESULTS
  With the exception of dentin margins before loading, significant differences for percentages of "continuous margin" and "enamel fractures" were detected before and after loading (P < 0.05, ANOVA, Student's t-test). A pulse energy of 100 mJ both on dentin and enamel was found optimal for finishing and smoothing the preparation margins after cavity preparation with 500 mJ or more.
authors.affiliation: Division of Cariology and Endodontology, School of Dentistry, University of Geneva, Rue Barthélemy-Menn 19, CH-1205 Geneva, Switzerland.
authors.forename: Carl
authors.initials: C
authors.lastname: Bader
authors.forename: Ivo
authors.initials: I
authors.lastname: Krejci
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000295:instrumentation*; D018772:Dental Marginal Adaptation; D003799:Dental Stress Analysis; D003804:Dentin / Q000648:ultrastructure; D003806:Dentin Permeability; D004871:Erbium; D006801:Humans; D007834:Lasers; D008963:Molar; D019279:Resin Cements
chemical_list: D003188:Composite Resins; D019279:Resin Cements; D004871:Erbium