Objective: This study evaluated the effect of preparation designs and surface treatment on the fracture resistance of zirconia inlay retained fixed dental prosthesis (IR-FDPs).
Material and Methods: Twenty secondary premolar and twenty secondary molar were used in this study. Twenty zirconia IR-FDPs were constructed, divided into two main groups, ten specimens each, according to abutment preparation (box & tube shape), each main group was subdivided into two sub groups according to surface treatment (Air abrasion & MDP primer surface treatment). The IR-FDPs were cemented using dual cure resin cement, then the specimens were subjected to thermo-mechanical cyclic loading (TMCL). The fracture resistance was measured.
Results: The results showed that there was no statistically significant difference between air abrasion and MDP for both designs (box & tube shape).The effect of design,showed that there was statistically significant difference for both surface treatments between tube and box design where box design showed higher fracture resistance than tube design for both surface treatments.
Conclusion: Inlay retained fixed dental prosthesis (IR-FDPs) with box shape provide more fracture resistance than with tube shape. The air abrasion surface treatment shows similar fracture as the MDP primer surface treatment.