الفهرس 
ABSTRACTOnly 14 pages are availabe for public view
 |  | from | 109 |  |  |
| | | from | 109 | | |
Abstract
Aim: To test and compare the impact of two different fabrication methods on the loadbearing capacity of full anatomical peek crowns. Materials and Methods: Twenty PEEK crowns
were constructed by two different fabrication methods and divided into two groups of n = 10 each
(PEEK CAD and PEEK Pressed). All crowns were constructed over a master die. For the PEEK
CAD crowns, the master die was sprayed with scan spray and scanned by the 3Shape E4 scanner,
Trios® 3. Ceramill4E2 Exocad CAD/CAM software and a 4-axis milling machine were used for
design. For the PEEK-pressed crowns, wax copings were milled using the same STL file with the
same dimensions used for designing and milling the previously constructed CAD PEEK crowns.
Auto-polymerized resin was used to produce 20 duplicate resin dies, and the fitting surface of all
crowns in both groups was sandblasted with 110µm alumina particles. All crowns were cemented
over their
corresponding epoxy dies using the (hand-mixed) dual-cured, self-adhesive resin cement
(RelyXTM U200) (3-kg seating force). After 24 hours in a 37°C water incubator, samples were
mechanically aged (75,000 cycles, 50 N load) with simultaneous thermocycling (2500 cycles, 5-55
°C, dwell time of 25 seconds).
All samples were individually mounted on a computer-controlled universal testing machine
(Model 3345; Instron Industrial Products, Norwood, MA, USA) with a load cell of 5 N until failure
was recorded using computer software (Instron® Bluehill Lite Software). The load required to
fracture was recorded in Newton, and failure modes were observed using a scanning electron
microscope and recorded.
Results: It was found that the CADCAM PEEK group recorded a statistically nonsignificant higher mean value with M = 2213.3 (SD = 275.88) than the PRESS group with M =
2108.5 (SD = 235.89). In the CAD group, the failure mode patterns were predominantly repairable
(80%), with a minor record for catastrophic ones (20%). In the Press group, all samples
demonstrated a repairable failure mode pattern (100%) with no record of a catastrophic failure
mode (0%). The chi square test revealed that the difference in failure modes recorded for both
groups was statistically significant (p=<0.0001<0.05).
Conclusion: In this research, there was no statistically significant difference between the
mean fracture loads of monolithic single crowns produced by CAD/CAM and those pressed from
PEEK/C pellets.
Keywords: PEEK, CAD-CAM, Press, fracture resistance, thermomechanical.