title: The effect of water immersion on the shear bond strength between chairside reline and denture base acrylic resins.
abstract: OBJECTIVE
  The effect of water immersion on the shear bond strength (SBS) between 1 heat-polymerizing acrylic resin (Lucitone 550-L) and 4 autopolymerizing reline resins (Kooliner-K, New Truliner-N, Tokuso Rebase Fast-T, Ufi Gel Hard-U) was investigated. Specimens relined with resin L were also evaluated.
  
  
  METHODS
  One hundred sixty cylinders (20 x 20 mm) of L denture base resin were processed, and the reline resins were packed on the prepared bonding surfaces using a split-mold (3.5 x 5.0 mm). Shear tests (0.5 mm/min) were performed on the specimens (n = 8) after polymerization (control), and after immersion in water at 37 degrees C for 7, 90, and 180 days. All fractured surfaces were examined by scanning electron microscopy (SEM) to calculate the percentage of cohesive fracture (PCF). Shear data were analyzed with 2-way ANOVA and Tukey's test; Kruskall-Wallis test was used to analyze PCF data (alpha= 0.05).
  
  
  RESULTS
  After 90 days water immersion, an increase in the mean SBS was observed for U (11.13 to 16.53 MPa; p < 0.001) and T (9.08 to 13.24 MPa, p= 0.035), whereas resin L showed a decrease (21.74 MPa to 14.96 MPa; p < 0.001). The SBS of resins K (8.44 MPa) and N (7.98 MPa) remained unaffected. The mean PCF was lower than 32.6% for K, N, and T, and higher than 65.6% for U and L.
  
  
  CONCLUSIONS
  Long-term water immersion did not adversely affect the bond of materials K, N, T, and U and decreased the values of resin L. Materials L and U failed cohesively, and K, N, and T failed adhesively.
authors: Department of Dental Materials and Prosthodontics, Araquara Dental School, UNESP - São Paulo State University, Araraquara, São Paulo, Brazil.
authors: Andrea
authors: A
authors: Azevedo
authors: Ana Lucia
authors: AL
authors: Machado
authors: Eunice Teresinha
authors: ET
authors: Giampaolo
authors: Ana Claudia
authors: AC
authors: Pavarina
authors: Carlos Eduardo
authors: CE
authors: Vergani
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000268:Adhesiveness; D001840:Dental Bonding; D003819:Denture Bases; D003822:Denture Liners; D003823:Denture Rebasing; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry; D033081:Shear Strength; D012826:Silicone Elastomers / Q000737:chemistry; D013314:Stress, Mechanical; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D008689:Methacrylates; D011108:Polymers; D012826:Silicone Elastomers; C503430:Tokuso Rebase Fast; C483158:Ufi gel; D014867:Water; C103363:kooliner; C071514:truliner; C040291:Lucitone