title: Shear bond strength fatigue limit of rest seats made with dental restoratives.
abstract: OBJECTIVE
  This study compared the shear bond strength (SBS) to enamel of rest seats made with a glass-ionomer cement (Fuji IX GP Fast), a resin-modified glass-ionomer cement (Fuji II LC), and a composite resin (Z100 MP) under monotonic and cyclic loading.
  
  
  METHODS
  Rest seats were built up onto the lingual surfaces of 80 intact human mandibular incisors. Specimens (n = 10) were stored in distilled water at 37 degrees C for 30 days and subjected to shear forces in a universal testing machine (0.5 mm/min) until fracture. The SBS values were calculated (MPa) using the bonding area (9.62 mm2) delimited by adhesive tags. A staircase approach was used to determine the SBS fatigue limit of each material. Specimens were submitted to either 10,000 cycles (5 Hz) or until specimen fracture. A minimum of 15 specimens was tested for each material. Scanning electron microscopy was used to examine the mode of failure. Data were statistically analyzed with one-way ANOVA and Tukey HSD tests (alpha = 0.05).
  
  
  RESULTS
  Z100 MP yielded higher (p < 0.05) SBS (12.25 MPa) than Fuji IX GP Fast (7.21 MPa). No differences were found between Fuji II LC (10.29 MPa) and the other two materials (p > 0.05). Fuji II LC (6.54 MPa) and Z100 MP (6.26 MPa) had a similar SBS limit. Fuji IX GP Fast promoted the lowest (p < 0.05) SBS fatigue limit (2.33 MPa). All samples showed cohesive failure patterns.
  
  
  CONCLUSIONS
  Fatigue testing can provide a better means of estimating the performance of rest seats made with dental restoratives.
authors.affiliation: Department of Prosthodontics, Sacred Heart University, Bauru, Brazil.
authors.forename: José Fernando Scarelli
authors.initials: JF
authors.lastname: Lopes
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Vergani
authors.forename: Eunice Teresinha
authors.initials: ET
authors.lastname: Giampaolo
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Pavarina
authors.forename: Ana Lucia
authors.initials: AL
authors.lastname: Machado
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D000044:Dental Abutments; D001840:Dental Bonding; D003743:Dental Enamel; D003799:Dental Stress Analysis; D003781:Denture Retention; D003832:Denture, Partial, Removable; D005899:Glass Ionomer Cements; D006801:Humans; D007180:Incisor; D008422:Materials Testing; D012117:Resins, Synthetic; D033081:Shear Strength; D012822:Silicon Dioxide; D015040:Zirconium
chemical_list: D003188:Composite Resins; C079765:Fuji II LC cement; C439808:Fuji IX GP Fast; D005899:Glass Ionomer Cements; D012117:Resins, Synthetic; C083568:Z100 composite resin; D012822:Silicon Dioxide; D015040:Zirconium