First, Participants in this study will be recruited according to inclusion criteria. Proper examination for the participants (clinically and radiographically). Preparation for endodontically treated molar for receiving high performance polymer endocrown. Checking and verification for the restoration (trying) and assessment of marginal and internal fit by replica technique. Then final cementation of endocrown.

Examination and diagnosis:

Selection and examination of the patients according to inclusion and exclusion criteria. Diagnosis of the patient's chief complaint and teeth that will be involved in this study will be done.

Primary alginate impressions for diagnosis on primary casts and for mounting. The patients will be asked to maintain good oral hygiene measures by using tooth brush twice daily.

Taking a professional pre-operative photo.

Tooth preparation procedure:

Preparation of endocrown with two preparation designs on endodontically treated molars.

After tooth preparation, the final impression will be taken for each participant using polyvinyl siloxane impression and temporization of cavity using light curable temporary material.

Restoration trial appointment:

Endocrown try in and assessment of marginal and internal fit using replica technique with light body rubber impression.

Fabrication of final restoration:

Delivery of high performance polymer endocrown will be fabricated according to the two preparation designs; butt and bevel.

Inclusion Criteria:

1. Patient age range from 18 years -50 years old. They should be able to read and write so they can sign the informed consent.
2. Patient should have a good physical and psychologically state to be able to withstand the steps of the restoration procedure.
3. Have a molar with root canal filling with no active periodontal or apical involvement.
4. Patients having root canal treatment teeth indicated for endocrown treatment with 3 or 4 axial walls remaining.
5. Patient with axial wall length not less than 3 mm and not more than 5 mm.
6. Patient should have good oral hygiene and motivation.

Exclusion Criteria:

1. Patient with periodontal or apical involvement or improper root canal treatment.
2. Severe loss of the tooth structure in which the amount of the remaining tooth structure is less than 2mm.
3. Patient with poor oral hygiene or with occlusal instability
4. Patient with improper physical or psychological state.
5. Patient not pregnant or lactating.

The participants and recruiters will not know the study group to which the next participant will be assigned.

The trial participants, outcome assessors, and data analysis will be blinded after assignment to interventions.

Emergency un-blinding: In cases of emergency to decrease or prevent any harms for the participants.