title: Effect of different adhesive strategies on microtensile bond strength of computer aided design/computer aided manufacturing blocks bonded to dentin.
abstract: BACKGROUND
  The aim of this study was to determine the microtensile bond strength (μTBS) of ceramic and composite computer aided design-computer aided manufacturing (CAD-CAM) blocks bonded to dentin using different adhesive strategies.
  
  
  METHODS
  In this in vitro study, 30 crowns of sound freshly extracted human molars were sectioned horizontally 3 mm above the cementoenamel junction to produce flat dentin surfaces. Ceramic and composite CAD/CAM blocks, size 14, were sectioned into slices of 3 mm thick. Before bonding, CAD/CAM block surfaces were treated according to the manufacturer's instructions. Groups were created based on the adhesive strategy used: Group 1 (GI) - conventional resin cement + total-etch adhesive system, Group 2 (GII) - conventional resin cement + self-etch adhesive system, and Group 3 (GIII) - self-adhesive resin cement with no adhesive. Bonded specimens were stored in 100% humidity for 24h at 37΀C, and then sectioned with a slow-speed diamond saw to obtain 1 mm × 1 mm × 6 mm microsticks. Microtensile testing was then conducted using a microtensile tester. μTBS values were expressed in MPa and analyzed by one-way ANOVA with post hoc (Tukey) test at the 5% significance level.
  
  
  RESULTS
  Mean values and standard deviations of μTBS (MPa) were 17.68 (±2.71) for GI/ceramic; 17.62 (±3.99) for GI/composite; 13.61 (±6.92) for GII/composite; 12.22 (±4.24) for GII/ceramic; 7.47 (±2.29) for GIII/composite; and 6.48 (±3.10) for GIII/ceramic; ANOVA indicated significant differences among the adhesive modality and block interaction (P < 0.05), and no significant differences among blocks only, except between GI and GII/ceramic. Bond strength of GIII was consistently lower (P < 0.05) than GI and GII groups, regardless the block used.
  
  
  CONCLUSIONS
  Cementation of CAD/CAM restorations, either composite or ceramic, can be significantly affected by different adhesive strategies used.
authors.affiliation: Department of Comprehensive Care, School of Dental Medicine, Case Western Reserve University, Ohio 44106, USA.
authors.forename: Renato
authors.initials: R
authors.lastname: Roperto
authors.affiliation: Department of Comprehensive Care, School of Dental Medicine, Case Western Reserve University, Ohio 44106, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Akkus
authors.affiliation: Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, 10900 Euclid Avenue, Ohio 44106, USA.
authors.forename: Ozan
authors.initials: O
authors.lastname: Akkus
authors.affiliation: Department of Comprehensive Care, School of Dental Medicine, Case Western Reserve University, Ohio 44106, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Lang
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, University of Sao Paulo (FORP-USP), Ribeirao Preto, SP, 14024-070, Brazil.
authors.forename: Manoel Damiao
authors.initials: MD
authors.lastname: Sousa-Neto
authors.affiliation: Department of Comprehensive Care, School of Dental Medicine, Case Western Reserve University, Ohio 44106, USA.
authors.forename: Sorin
authors.initials: S
authors.lastname: Teich
authors.affiliation: Department of Comprehensive Care, School of Dental Medicine, Case Western Reserve University, Ohio 44106, USA.
authors.forename: Thiago Soares
authors.initials: TS
authors.lastname: Porto
keywords: Adhesion; ceramic; composite resin; computer aided design/computer aided manufacturing