title: [Comparative study of microleakage by using different finished lines in selective laser melting metal crowns].
abstract: OBJECTIVE
  To evaluate microleakage of SLM Co -Cr alloy metal crown with two types finished line (chamfer and shoulder), compared with conventional fabrication of Co -Cr alloy metal crowns.
  
  
  METHODS
  Thirty healthy non-carious human molars were selected and randomly assigned to 3 groups, 10 in each. Teeth in group A and C received a chamfer finish line preparation, whereas teeth in group C received a shoulder finish line. Conventional Co -Cr alloy metal crowns were fabricated for group A when SLM metal crowns were made for group B and group C. Glass ionomer was applied for bonding. After 5000 thermocycles ranging from 5degrees centigrade to 55degrees centigrade,all the specimens were evaluated by dye penetration and then microleakage was examined under light microscope. The data were analyzed statistically with SPSS 20.0 software package.
  
  
  RESULTS
  Microleakage in group A was significantly higher than the other two groups, group B and group C showed no significant difference in microleakage while microleakage in group B was higher than that in group C.
  
  
  CONCLUSIONS
  Microleakage of SLM metal crowns was significantly less than that of conventional Co-Cr alloy metal crowns; chamfer finish line designs was recommended for SLM metal crowns in consideration of reducing microleakage and protecting tooth.
authors.affiliation: Shanghai Stomatological Hospital. Shanghai 200031, China. E-mail:458049611@qq.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Peng
authors.forename: Qun
authors.initials: Q
authors.lastname: Zhong
authors.forename: Xue-Ying
authors.initials: XY
authors.lastname: Wu
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Weng
mesh_terms: D000180:Acrylic Resins; D003442:Crowns; D003763:Dental Leakage; D018772:Dental Marginal Adaptation; D006801:Humans; D007834:Lasers; D008670:Metals; D008963:Molar; D012822:Silicon Dioxide
chemical_list: D000180:Acrylic Resins; D008670:Metals; C015897:glass ionomer; D012822:Silicon Dioxide