Abstract:
Objective Fatigue testing of restorative material has been appreciated as an appropriate
method to evaluate dental restorations. This study aims to investigate the influence
of periodontal ligament (PDL) simulation on fatigue and fracture tests results of
zirconia crowns.
Materials and Methods A standard tooth preparation for all ceramic zirconia crown
was made on a typodont mandibular molar. The prepared master die was duplicated
using epoxy resin to produce 40 replicas. PDL simulation was made by surrounding the
root of 20 dies with a 0.3-mm thick silicon layer. The other 20 specimens had no PDL
simulation. Zirconia crowns were fabricated using computer-aided design/computer-
aided manufacturing technology and cemented to the epoxy resin dies. Ten crowns
from each group were subject to chewing simulation with simultaneous thermocycling
(5?55?C). All specimens were then loaded until failure in universal testing machine.
Statistical Analysis Statistical analysis was conducted using SPSS software. Shapiro?
Wilk test confirmed the normal distribution of data. Descriptive statistic was performed
and differences between the groups were analyzed using paired samples t-test.
Results All fatigued crowns survived chewing simulation; no failure was observed
after finishing simulation. The highest mean fracture load recorded was 3,987 ? 400 N
for the no fatigue/no periodontal simulation group. Comparing the mean fracture load
of the two groups with periodontal simulation and the two groups with no periodontal
simulation showed no statistically significant difference (p > 0.5).
Conclusion Considering the testing set-up applied in this study, simulating PDL
using resilient materials does not affect the in vitro survival and fracture resistance of
zirconia crowns.