title: [Effect of thermal cycling on the composite- composite repair bond strength].
abstract: OBJECTIVE
  To evaluate the effect of aging of the composite and the adhesive interface on composite-composite repair bond strength.
  
  
  METHODS
  Methacrylate-based composite resin (Clearfil AP-X, composite A) and silorane-based composite resin (Filtek P90, composite B) and their corresponding adhesive, Clearfil SE Bond (adhesive a) and Filtek P90 System Adhesive (adhesive b), were selected in this study. Twenty-four substrates were prepared from composite A or B separately and divided into three groups, each group had 8 substrates: group one, new composites were adhered to the substrates with the use of adhesive a or b, followed by cutting the blocks into sticks; group two, new composites were adhered to the substrates using adhesive a or b, followed by cutting into sticks and thermal cycling; group three, substrates were thermocycled, then polished and adhered new composites using adhesive a or b, followed by cutting into sticks. Each group had 8 combinations of substrate(A, B)-adhesive(a, b)-repair composite (A, B). Fifteen sticks without flaws in each combination of 3 groups were selected utilizing stereomicroscope. The data were analyzed by independent samples t test.
  
  
  RESULTS
  In group two, the microtensile strength(MS) of combinations using adhesive a and composite A or B to repair [A-a-A: (45.0 ± 3.2) MPa, B-a-A: (41.7 ± 3.3) MPa, A-a-B: (28.6 ± 3.9) MPa, B-a-B: (47.7 ± 6.6) MPa], and using adhesive b and composite A to repair [A-b-A: (44.2 ± 4.7) MPa, B-b-A: (38.0 ± 3.2) MPa] decreased significantly compared with corresponding combinations in group 1[A-a-A: (70.7 ± 5.5) MPa, B-a-A: (60.3 ± 5.1) MPa, A-a-B: (44.2 ± 1.6) MPa, B-a-B: (54.1 ± 3.2) MPa, A-b-A: (65.6 ± 7.2) MPa, B-b-A: (59.1 ± 4.1) MPa] (P<0.05). However, there was no significant difference between the MS of combinations using adhesive b and composite B to repair in group one and the MS of combinations in group two (P>0.05). The MS of all combinations in group three decreased significantly (P<0.05).
  
  
  CONCLUSIONS
  Aging of the composite and the adhesive interface might affect the composite-composite repair bond strength.
authors.affiliation: Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Lin
authors.affiliation: Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing 100081, China; Email: kqlinyue@bjmu.edu.cn.
authors.forename: Lin
authors.initials: L
authors.lastname: Yue
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000379:methods*; D006358:Hot Temperature; D006801:Humans; D008689:Methacrylates / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry*; D062047:Silorane Resins / Q000737:chemistry; D013718:Tensile Strength
chemical_list: C112828:Clearfil AP-X; C438313:Clearfil SE Bond; D003188:Composite Resins; D003738:Dental Cements; D008689:Methacrylates; D019279:Resin Cements; D062047:Silorane Resins; C544925:filtek P90; C555513:silorane composite resin