title: Nd:YAG laser influence on microleakage of class V composite restoration.
abstract: OBJECTIVE
  The purpose of this research was to evaluate the influence of the Nd:YAG laser on microleakage of class V composite restorations.
  
  
  BACKGROUND
  There has been very little research that concerns microleakage resulting from the use of lasers and restorative materials.
  
  
  METHODS
  Thirty-six cavities were prepared and divided into three groups (n = 12) as follows: Group 1, control; Group 2, Nd:YAG laser irradiation before adhesive technique; Group 3, Nd:YAG laser irradiation after adhesive technique. Nd:YAG laser parameters were 320 micro m of fiberoptics; energy/pulse of 40 mJ of energy/pulse; repetition rate of 15 Hz; power of 0.6 W; pulsed and non-contact, 1 mm from the surface; 30 sec in scanning mode; energy density was 49,76 J/cm(2). Cavities were restored with microhybrid composite. After polishing, thermocycling and impermeabilization procedures were performed and specimens were submitted to a microleakage test, with complete immersion in aqueous solution of 50% silver nitrate for 8 h, in the total absence of light. After washing and drying, teeth were embedded to facilitate buccal-lingual vertical sectioning. Microleakage was revealed by light.
  
  
  RESULTS
  We used the Kruskal-Wallis test at a 5% level of confidence and observed no statistically significant difference among the tested groups.
  
  
  CONCLUSIONS
  It was possible to conclude that Nd:YAG laser does not influence marginal microleakage on composite restorations, independent of the moment the laser had been used.
mesh_terms: D000134:Acid Etching, Dental; D003188:Composite Resins / Q000528:radiation effects* / Q000627:therapeutic use; D003737:Dental Cavity Preparation / Q000379:methods*; D003763:Dental Leakage / Q000517:prevention & control*; D003793:Dental Restoration, Permanent; D006801:Humans; D053685:Laser Therapy
chemical_list: D003188:Composite Resins