Shear bond strength fatigue limit of rest seats made with dental restoratives.
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.
Lopes
José Fernando Scarelli
JF
Department of Prosthodontics, Sacred Heart University, Bauru, Brazil.
Vergani
Carlos Eduardo
CE
Giampaolo
Eunice Teresinha
ET
Pavarina
Ana Cláudia
AC
Machado
Ana Lucia
AL
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
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