title: Composite-to-composite microtensile bond strength in the repair of a microfilled hybrid resin: effect of surface treatment and oxygen inhibition.
abstract: OBJECTIVE
  To compare the 24-h microtensile bond strength of a microfilled hybrid composite to the same material after mechanical and/or chemical treatment and assess the effect of oxygen inhibition on the composite-composite bond.
  
  
  METHODS
  Forty composite cylinders of Gradia Direct Anterior (GC) were prepared and stored 24 h prior to the following surface treatments: 50-microm aluminum oxide air abrasion and 37% phosphoric acid etching (group 1); hydrochloric acid and 6.9% hydrofluoric acid etching (group 2); diamond bur roughening and 37% phosphoric acid etching (group 3); diamond bur roughening (group 4). In all groups, Prime & Bond NT (Dentsply De Trey) was applied and light cured in air or under a nitrogen atmosphere, prior to layering a buildup of the repairing resin composite. Microtensile bond strength measurements were performed. Data were statistically analyzed with two-way ANOVA and Tukey's test (alpha = 0.05).
  
  
  RESULTS
  The curing atmosphere did not significantly influence the interfacial strength (p < 0.05). Surface treatment significantly affected the composite-composite bond (p > 0.05). Air abrasion, regardless of curing atmosphere, resulted in the strongest bond (p < 0.05). The other treatments were comparable.
  
  
  CONCLUSIONS
  Air abrasion and the application of a bonding agent offer satisfactory bond strengths for composite repair. The oxygen inhibition layer on a light-cured adhesive is not crucial to the success of the 24-h composite-composite bond.
authors: Department of Dental Materials and Restorative Dentistry, University of Siena, Policlinico "Le Scotte" Viale Bracci, Siena, Italy.
authors: Federica
authors: F
authors: Papacchini
authors: Susanna
authors: S
authors: Dall'Oca
authors: Nicoletta
authors: N
authors: Chieffi
authors: Cecilia
authors: C
authors: Goracci
authors: Fernanda Tranchesi
authors: FT
authors: Sadek
authors: Byoung I
authors: BI
authors: Suh
authors: Franklin R
authors: FR
authors: Tay
authors: Marco
authors: M
authors: Ferrari
mesh_terms: D000134:Acid Etching, Dental; D020906:Air Abrasion, Dental; D000537:Aluminum Oxide / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D017269:Dental Prosthesis Repair; D018130:Diamond / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D010756:Phosphoric Acids / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D003188:Composite Resins; C470230:Gradia; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D018130:Diamond; C030242:phosphoric acid; D000537:Aluminum Oxide; D009584:Nitrogen; D010100:Oxygen