Endodontically treated posterior teeth will be restored with zirconia crowns with two finish line designs(feather edge and rounded shoulder) and two occlusal reduction schemes(flat and planer).The crowns were designed with exocad software program .After cementation clinical performance in terms of marginal adaptation ,marginal discoloration, fracture and secondary caries was evaluated at 3 subsequent follow-up visits every 3months for 1 year.

Endodontically treated posterior teeth require full coverage coronal restoration, as they are more prone to fracture as compared to vital teeth .Over past two decades restorative dentistry there has been a paradigm shift in restorative dentistry towards monolithic zirconia crowns because of its superior esthetics ,excellent biocompatibility ,and continually improving biomechanical properties. For the long term clinical success of zirconia crowns tooth preparation designs particularly finish line designs and occlusal reduction play significant role. Different finish lines designs such as chamfer and shoulder, play a role in marginal fit of restoration .While assessing zirconia crowns of two finish line designs and two occlusal reduction schemes the participants were divided into three groups based on preparation design: the control group PS (planer occlusal and rounded shoulder) ; first interventional group (flat occlusal and feather); Second interventional group (flat occlusal and rounded shoulder) .To minimize bias the outcome assessor ,participants and statistician were blinded and only investigator will not blinded. After cementation on subsequent follow-up of one year with every three months interval United states Public Health Services Criteria (USPHS) is used for marginal adaptation ,discoloration, fracture and secondary caries, and gingival index score system is used for gingival response.

Second interventional group FS (Flat occlusal + rounded shoulder)

Inclusion Criteria:

• patients from both genders.
• age range 18-65 years.
• patients with endodontically treated posterior teeth.

Exclusion Criteria:

• vital teeth
• anterior teeth.
• edentulous patient.
• patient with history of significant systemic diseases.