title: Tensile bond strength of resin composite repair in vitro using different surface preparation conditionings to an aged CAD/CAM resin nanoceramic.
abstract: OBJECTIVE
  This study was conducted in order to assess the pretreatment method (air abrasion, both wet and dry, and Al2O3 grinder), the conditioning method (comprised of different adhesive systems), the repair resin composite (low and high modulus of elasticity), the contamination of CoJet air-abraded surfaces with water, and the effect phosphoric acid on the macrotensile bond strength (TBS) to aged CAD/CAM resin nanoceramic (RNC).
  
  
  METHODS
  Aged RNC substrates (LAVA Ultimate, 3M ESPE; N = 900; 10,000 cycles, 5 °C/55 °C) were air-abraded (CoJet 3M ESPE) with and without water contamination or treated with an Al2O3 grinder (Cimara, Voco). Immediately after pretreatment, half of the specimens were additionally cleaned with phosphoric acid, while the rest were only rinsed with water. Four intermediate agents (Futurabond U/VOCO, Scotchbond Universal/3M ESPE, One Coat Bond/Coltène Whaledent, visio.link/bredent) were selected for conditioning the surface, while no conditioned specimens acted as control groups. Specimens were thereafter repaired using two direct resin composites (Arabesk Top and GrandioSo, VOCO), stored for 24 h at 37 °C in H2O, and thermally aged for 10,000 cycles (5 °C/55 °C; n = 15/subgroup). TBS and failure types were determined and evaluated with four- and one-way ANOVA and χ (2) test (p < 0.05).
  
  
  RESULTS
  The highest influence on TBS was exerted by the conditioning method (partial eta-squared (η P (2)) = 0.273, p < 0.05), followed by the resin composite repair (η P (2) = 0.07, p < 0.05) and the surface pretreatment method (η P (2) = 0.032, p < 0.05), while an acid contamination after surface pretreatment was insignificant (p = 0.154).
  
  
  CONCLUSIONS
  Air abrasion produced superior TBS compared to grinding of the surface with Al2O3 prior to repair. The tested universal adhesives proved to be effective intermediate agents for repairing aged CAD/CAM RNC, while visio.link and Scotchbond Universal performed slightly better than Futurabond U.
  
  
  CONCLUSIONS
  Phosphoric acid or water contamination of the air-abraded surface does not affect the repair bond strength.
authors.affiliation: Department of Prosthodontics, Dental School, Ludwig-Maximilians University, Goethestrasse 70, 80336, Munich, Germany, bogna.stawarczyk@med.uni-muenchen.de.
authors.forename: Bogna
authors.initials: B
authors.lastname: Stawarczyk
authors.forename: Andreas
authors.initials: A
authors.lastname: Krawczuk
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Ilie
mesh_terms: D002516:Ceramics; D003188:Composite Resins; D066298:In Vitro Techniques; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D003188:Composite Resins