الفهرس 
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Abstract
The current study presents the option for manufacturing monolithic translucent zirconium dioxide (ZrO2) inlay-retained FPDs as a conservative solution. Zirconia is characterized by the high mechanical properties and the monolithic translucent part allows for a more esthetic appealing restoration. With the help of the resin cement breakthrough of MDP addition to help cementing the zirconia framework to the tooth structure, better retention should be achieved.
This study aims to evaluate the effect of three different designs proximal box design, occlusal & proximal box design, and butterfly wing design [modified inlay] with two different surface treatment protocols [sandblasting and tribochemical Silica coating] on the fracture resistance and retention of translucent zirconia inlay-retained fixed partial denture (IRFPD).
60 translucent zirconia IRFPDs were constructed using CAD/CAM technology. They were divided into two equal groups according to the testing methodology group I: Fracture resistance test [n=30] and group II: Dislodgment resistance test [n=30]. Each group was further divided into three equal subgroups according to the IRFPD design: Subgroup A [Proximal box design (n=10)], Subgroup B [occlusal & Proximal box design (n=10)] and Subgroup C [Butterfly wing [Modified inlay] design (n=10)].Each subgroup was further divided into two equal subdivisions according to the surface treatment protocols Subdivision i: Sandblasting [n=5] and Subdivision ii: Tribochemical salinization [n=5]
All zirconia inlay-retained FPDs were cemented to their respective epoxy resin models using Rely X U200 self-adhesive resin cement following the manufacturer’s recommendations. Before cementation, all epoxy models were sandblasted directly on the cavity preparation site by 110µm sandblast for 10 seconds at 0.2 MPa pressure
After cementation, all samples were subjected to cyclic loading. The epoxy model with the cemented IRFPD’s was loaded with a cyclic load using a metallic plunger attached to a cyclic loading machine.
All cemented inlay-retained FPD were subjected to fracture resistance and retention tests using a universal testing machine.
The fracture resistancewas determined by mechanical load to failure. The force was in compression mode which was applied at the center of the pontics (cross-head speed 1 mm/min, fracture threshold for shut-off 5 N).The load required to dislodge the restoration was recorded in newton.
For retention test, each model with its own bridge was secured into the lower fixed compartment of a materials testing machine. One orthodontic wire [(0.9- mm (0.036-inch)] engaging the pontic tissue surface was attached to the upper movable compartment of the machine. A tensile force was applied in pull mode at a crosshead speed of 1 mm/min. The load required to dislodge the restoration was recorded in newton.
All data were tabulated and statistically analyzed. Two-way Analysis of Variance (ANOVA) was used to study the effect of design, surface treatment and their interaction on mean fracture resistance and retention load. Bonferroni’s post-hoc test will be used for pair-wise comparisons when ANOVA test is significant.
According to the present findings, the inlay design supported by the extra butterfly wings gave significantly superior results than the other two designs with no significant difference between them.
The result of the present study revealed that there was no statistically significant difference between the two surface treatment protocols (sandblasting and tribochemical silica coating) regarding to the fracture resistance and retention of translucent zirconia inlay-retained FPDs.