title: [Effect of different heat treatment on the bonding strength of porcelain and Co-Cr alloy].
abstract: OBJECTIVE
  To investigate and compare the effect of different heat treatment on the metal- ceramic bonding strength and the interfacial microstructure of the Co-Cr alloy.
  
  
  METHODS
  Thirty specimens were made according to ISO 9693,and then divided into 3 groups (n=10) through the measurements .Group A(degassed 60s):degassed and then maintained 60s in 980 degrees centigrade Group B(degassed 60s and preoxidation 60s): degassed and maintained 60s in 980 degrees centigrade, then were maintained continuously for 60s in 980 degrees centigrade after re-gassed,Group C(degassed 120s): degassed and maintained 120s in 980 degrees centigrade. The bonding strengths of the three groups were evaluated through three point bending test. Six specimens divided into 3 group were made in the same method to observe the metal-ceramic interface through scanning electronic microscope(SEM) and energy dispersive spectrum(EDS).The bonding strength data were analyzed using ANOVA and Bonferroni's test by SPSS13.0 software package.
  
  
  RESULTS
  The mean value of bonding strength was (39.03±2.70)MPa for group A, (34.43±2.36)MPa for group B, (31.65±1.49)MPa for group C, respectively. There were significant difference between every two groups (P<0.05). SEM demonstrated that the width of interfacial transition layer was 12.3-16.4μm in group A, 15.2-21.8μm in group B and 26.3-32.2μm in group C.
  
  
  CONCLUSIONS
  Higher metal-ceramic bonding strength for Co-Cr alloy will be formed under the situation of degassed,and maintained 60s in 980 degrees centigrade ; while extending degassed time, prolonging the heat maintained time and preoxidation after degassing will reduce metal-ceramic bonding strength.
authors.affiliation: Department of Stomatology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120 China. juankunliao@qq.com
authors.forename: Juan-kun
authors.initials: JK
authors.lastname: Liao
authors.forename: Jian-tao
authors.initials: JT
authors.lastname: Ye
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.forename: Cui-cui
authors.initials: CC
authors.lastname: Zhang
authors.forename: Xiao-shan
authors.initials: XS
authors.lastname: Wen
authors.forename: Yi-ping
authors.initials: YP
authors.lastname: Zhang
authors.forename: Bo-hua
authors.initials: BH
authors.lastname: Li
mesh_terms: D000497:Alloys; D002858:Chromium Alloys; D001840:Dental Bonding; D003776:Dental Porcelain; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys; D013499:Surface Properties
chemical_list: D000497:Alloys; D002858:Chromium Alloys; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain