title: Evaluation of shear bond strengths of gingiva-colored composite resin to porcelain, metal and zirconia substrates.
abstract: OBJECTIVE
  The purpose of this study is to evaluate and compare the shear bond strength of the gingiva-colored composite resin and the tooth-colored composite resin to porcelain, metal and zirconia.
  
  
  METHODS
  Sixty cylindrical specimens were fabricated and divided into the following 6 groups (Group 1-W: tooth-colored composite bonded to porcelain, Group 1-P: gingiva-colored composite bonded to porcelain, Group 2-W: tooth-colored composite bonded to base metal, Group 2-P: gingiva-colored composite bonded to base metal, Group 3-W: toothcolored composite bonded to zirconia, Group 3-P: gingiva-colored composite bonded to zirconia). The shear bond strength was measured with a universal testing machine after thermocycling and the failure mode was noted. All data were analyzed using the two-way analysis of variance test and the Bonferroni post-hoc test at a significance level of 0.05.
  
  
  RESULTS
  The mean shear bond strength values in MPa were 12.39, 13.42, 8.78, 7.98, 4.64 and 3.74 for Group 1-W, 1-P, 2-W, 2-P, 3-W and 3-P, respectively. The difference between the two kinds of composite resin was not significant. The shear bond strength of Group 1 was the highest and that of Group 3 was the lowest. The differences among Group 1, 2 and 3 were all significant (P<.05).
  
  
  CONCLUSIONS
  The shear bond strength of the gingiva-colored composite was not less than that of the tooth-colored composite. Thus, repairing or fabricating ceramic restorations using the gingiva-colored composite resin can be regarded as a practical method. Especially, the prognosis would be fine when applied on porcelain surfaces.
authors: Seoul Grace Dental Clinic, Seoul, Korea.
authors: Hong-Seok
authors: HS
authors: An
authors: Ji-Man
authors: JM
authors: Park
authors: Eun-Jin
authors: EJ
authors: Park