Objective: The purpose of this study was to examine the influence of different testing environments (air and water) and cyclic fatigue on the fracture toughness (FT) and flexure strength (FS) of an indirect composite, BelleGlass ET. Methods: The rectangular bar specimens (3x3x3x25 mm) were fabricated according to the manufacturer's instruction. A 60 degree notch was machined 0.75 mm deep at the midspan for the specimens for fracture toughness. Specimens were aged at 37°C for six months in air and water. The specimens were tested in three point loading in either air or water at a loading rate of 2.0 mm per minute. The cyclic specimens were tested using a staircase approach (Draughn, 1979) of either 1000 cycles or until specimen fracture.

Results:  The means for static and cyclic loaded are presented below.

Mechanical                          Static                          Cyclic

 Properties             N       (MPa±SD)         N       (MPa±SD)

FS

        Air-Control              15     104.5±15.6         25       78.6±7.2

        Air-Aged                  15     109.5±11.3         25      78.3 ±10.6 

        Water-Control          15     137.6±16.8         25      97.3±14.3

        Water-Aged              15     90.5±13.0          25       61.7±9.5

FT      

        Air-Control              15     1.24±0.06            25      0.93±0.14

        Air-Aged                  15     0.96±0.05            25      0.74±0.10

        Water-Control          15     1.22±0.06            25      1.18±0.21

        Water-Aged             15     1.14±0.07            25       0.79±0.06

Statistical analysis indicated no significant differences in the flexure strength means except for the water control specimens, which was significantly higher. For fracture toughness, static loaded means were significantly higher than cyclic means, except for the water control specimens. Conclusions:  Cyclic loading and aging caused a decrease in the mechanical properties of the indirect composite, BelleGlass ET. Funding was provided by NIDCR grant HHS DE07979.

Back to the Dental Materials: VI - Polymer Materials-Mechanical Properties and Degradation Program
Back to the IADR/AADR/CADR 85th General Session and Exhibition (March 21-24, 2007)

Top Level Search