الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
This study was performed to evaluate the marginal fit and fracture
resistance for two designs of fixed partial dentures that were milled from zirconia
blocks using two different techniques.
The tested designs of fixed partial dentures were full coverage and inlay
retained FPD that were fabricated by manual copy milling technique (MAD/MAM
,Zirkonzahn) and computerized milling technique ( CAD/CAM Cerec in-lab).
A prefabricated maxillary model was used in which the second premolar
removed and two artificial teeth representing first premolar and first molar
received full coverage preparation design. Then another two artificial teeth
representing first premolar and first molar were used to receive inlay preparation
design. The two prepared designs were duplicated into nickel chromium models
for fabrication of the different all-ceramic FPDs.
regarding the marginal fit test, the marginal gap distance of the all-ceramic
FPDs with different designs were measured on the nickel chromium models in
(μm) using the USB digital microscope. Results revealed that FPDs fabricated by
CAD/CAM technique had higher statistically significant marginal fit than FPDs
fabricated by MAD/MAM copy milling technique in the two tested FPDs
designs.
Concerning the fracture resistance test, All-ceramic FPDs with different
designs were cemented on epoxy resin models and then loaded vertically in a
compressive mode until fracture using the universal testing machine. The strength
SUMMARY&CONCLUSIONS
100
values in (N) were calculated and showed that full coverage FPDs exhibited the
higher statistically significant fracture resistance values than inlay retained FPDs
regardless of the milling technique which did not affect the fracture resistance.
Within the limitations of this study, the following conclusions could be
drawn:
1. Milling techniques & FPD design significantly affected the marginal fit of
all-ceramic FPDs.
2. Milling technique did not affect the fracture resistance of the tested FPDs.
3. FPD design had a great effect on their fracture resistance with the superiority
of the full coverage design
4. Although showed lower fracture resistance values than full coverage FPDs,
inlay retained FPDs values were higher than the maximum masticatory
forces as well as marginal gap distance below maximum acceptable values.
5. There was an inverse correlation between marginal gap and fracture
resistance of FPDs. An increase in marginal gap of a FPDs was associated
with a decrease in its fracture resistance and vice versa.
Clinical Recommendations:
This study recommends the use of zirconia ceramic inlay retained FPDs
instead of full coverage restorations as the fracture resistance values obtained in
this study were superior to the assumed maximum mastication forces and the
marginal gap distance was within the acceptable limits.