Fracture resistance of monolithic and veneered all-ceramic four-unit posterior fixed dental prostheses after artificial aging

Abstract

This study compared the fracture resistance of monolithic and veneered all-ceramic four-unit posterior fixed dental prostheses (FDPs) generated by computer-aided design/computer-aided manufacturing (CAD/CAM) after aging in a mastication simulator. Four-unit FDPs were designed from six different all-ceramic systems: 1) monolithic lithium disilicate (M-E), 2) monolithic zirconia (M-TZI), 3) veneered zirconia by conventional layering (V-L), 4) veneered zirconia by lithium disilicate pressing (V-P), 5) veneered zirconia by lithium disilicate fusing (CAD-F-E), and 6) veneered zirconia by feldspathic ceramic cementing (CAD-C-CB). The specimens were divided into control and aging groups (n = 10 per group). The aging process included both thermocycling and mechanical loading and was followed by fracture resistance testing. All specimens in the ME , M-TZI, and V-L groups survived; however, all specimens in the V-P group were fractured during artificial aging. The highest fracture resistance values were observed in the M-TZI group. According to the fracture resistance test, connector fractures were the most frequent type of failure. M-TZI and ME FDPs revealed no failures during aging and showed higher fracture resistance than the veneered groups. Among the veneered zirconia framework groups, V-L FDPs showed the highest success rate during aging, while the fracture resistance was similar among all the veneered zirconia groups.

Retention Strength of Polyetheretherketone Crowns Vs. Zirconia Crowns Restoring Molar Teeth: An in Vitro Study

“…The use of chewing simulators with additional artificial aging through thermocycling is a well-proven method to simulate the various clinical conditions in vitro, owing to their standardization and reproducibility [20,23] . The number of thermodynamic loading (TDL) cycles, representing 3 months of service, was chosen as an average for testing the longevity of service of ceramic crowns [13] .…”

“…Load was applied on the center of the occlusal surface of all crowns using a steel antagonist ball (2.5mm diameter) under standardized test parameters. This is nearly equivalent to 3 months of in vivo service time [13] . This was carried out in deionized water with simultaneous thermocycling for 300 cycles (5 °C to 55 °C every 60 s, with a dwell time of 12 s) [13] .…”

“…This is nearly equivalent to 3 months of in vivo service time [13] . This was carried out in deionized water with simultaneous thermocycling for 300 cycles (5 °C to 55 °C every 60 s, with a dwell time of 12 s) [13] . Retention Measurements: Retention of the crowns to their resin dies was tested via the pull-off test utilizing a Universal Testing Machine 11 (UTM) (Fig.…”

“…Failure mode observation: After dislodgement, the debonded surfaces of the resin dies and their crown intaglios were inspected using a USB digitalmicroscope 13 . The images were captured and then transferred to IBM personal computer equipped with the Image-tool software 14 to determine the failure mode, according to the location of the remaining cement on the debonded surfaces.…”

Effect of surface finishing protocols on color and translucency of zirconia reinforced lithium silicate glass-ceramic after thermo-mechanical aging and different staining solutions

“…This is in vitro method was used in several studies to simulates the oral environment. (31) This study followed the manufacturer's recommendations regarding sample thickness, different surface finishing protocols, and firing steps. The selected thickness of all specimens was 1.5 mm which is the minimum thickness of crown restoration using celtra materials.…”