Coronal retention of the restoration of RCT teeth is usually compromised, thus intraradicular posts combined or not with core material may be required.

The drawbacks of the conventional treatment created a necessary demand to have alternative treatment options. Among these options is the endocrown restoration. The pulpal chamber cavity provides retention and stability. Its trapezoidal shape in mandibular molars and triangular shape in maxillary molars increase the restoration's stability. The saddle form of the pulpal floor increases stability. This anatomy, along with the adhesive qualities of the bonding material, make no need for additional preparation or further use of post-involving root canals.

Aim of the study:

The aim of this study is to evaluate the effect of using reinforced lithium silicate endocrowns on the recurrent caries, patient satisfaction and retention in comparison to post retained reinforced lithium silicate crowns.

The study is held to evaluate recurrent caries,patient satisfaction and retention of endodontically treated teeth restored with Endocrowns versus Post Retained Crowns using Reinforced Lithium Silicate after one year follow up .

The clinical performance of ceramic endocrowns showed a survival rate of 99 % and the success rate of 89.9 % in a 10 year retrospective study done by Bellflamme et al. 2017.

Endocrowns; a recently developed line of treatment, take the advantage of the rapidly growing discipline of adhesion to glass ceramics. As the retention and recurrent caries are decisive factors in the prognosis of a restoration' they have to be thoroughly investigated.

Patients with endodontically treated lower first molars will be collected.after teeth preparation to receive endocrowns and crowns ,secondary impressions will be taken .The Patients will be divided randomly into two groups .One group will receive reinforced Lithium Silicate Endocrowns (intervention)and the other group will receive reinforced Lithium Silicate Crowns (control) retained with fiber posts.

Inclusion Criteria:

• • Patient age range of 18-55 years.

  • Patients physically and psychologically able to tolerate conventional restorative procedures.
  • Co-operative patients approving to participate in this trial.
  • Patients with root canal treated lower first molars requiring full coverage restoration.
  • Patients willing to return for follow-up examinations and assessments.
  • Endodontically treated teeth with absence of clinical diagnosis of periapical pathosis, fistula, swelling of periodontal tissues, abnormal tooth mobility and history of sensitivity to pressure

Exclusion Criteria:

• Patients in the growth stage with partially erupted teeth.
• Patients with poor oral hygiene.
• Disabilities which will not be cooperative patient for the study.
• Systemic diseases or severe medically compromised patients as uncontrolled diabetes or oral cancer.
• Patients suffer from parafunctional habits
• Teeth with fractured roots
• Teeth with lesions extending apical to the cemento-enamel junction
• Poor oral hygiene.

Participants and outcome assessor will be blinded to avoid performance, detection and analysis bias. Only main investigator will be aware of the allocated patients in each group and the specific type of intervention given to every patient