title: A method to investigate the shrinkage stress developed by resin-composites bonded to a single flat surface.
abstract: OBJECTIVE
  To purpose a method for predicting the shrinkage stress development in the adhesive layer of resin-composite cylinders that shrink bonded to a single flat surface, by measuring the deflection of a glass coverslip caused by the shrinkage of the bonded cylinders. The correlation between the volume of the bonded resin-composite and the stress-peak was also investigated.
  
  
  METHODS
  A glass coverslip deflection caused by the shrinkage of a bonded resin-composite cylinder (diameter: d=8 mm, 4 mm, or 2 mm, height: h=4 mm, 2 mm, 1 mm, or 0.5 mm) was measured, and the same set-up was simulated by finite element analysis (3D-FEA). Stresses generated in the adhesive layer were plotted versus two geometric variables of the resin-composite cylinder (C-Factor and volume) to verify the existence of correlations between them and stresses.
  
  
  RESULTS
  The FEA models were validated. A significant correlation (p<0.01, Pearson's test) between the stress-peak and the coverslip deflection when the resin-composites were grouped by diameter was found for diameters of 2 and 4 mm. The stress-peak of the whole set of data showed a logarithmic correlation with the bonded resin-composite volume (p<0.001, Pearson's test), but did not correlate with the C-Factor.
  
  
  CONCLUSIONS
  The described method should be considered for standardizing the stress generated by the shrinkage of resin-composite blocks bonded to a single flat surface.
authors.affiliation: Department of Dental Materials, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Lucas V S
authors.initials: LV
authors.lastname: Pabis
authors.forename: Tathy A
authors.initials: TA
authors.lastname: Xavier
authors.forename: Ecinele F
authors.initials: EF
authors.lastname: Rosa
authors.forename: Flávia P
authors.initials: FP
authors.lastname: Rodrigues
authors.forename: Josete B C
authors.initials: JB
authors.lastname: Meira
authors.forename: Raul G
authors.initials: RG
authors.lastname: Lima
authors.forename: Leonardo E
authors.initials: LE
authors.lastname: Rodrigues Filho
authors.forename: Rafael Y
authors.initials: RY
authors.lastname: Ballester
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003799:Dental Stress Analysis / Q000379:methods*; D020342:Finite Element Analysis; D005898:Glass; D008422:Materials Testing; D058105:Polymerization; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003188:Composite Resins