Clinical Evaluation and Patient Satisfaction of Shade Matching Between Natural Teeth and Monolithic All-ceramic Crowns Fabricated From Two Materials

evaluation of color difference between zirconia reinforced lithium silicate (celtra press) VS lithium disilicate (Emax) in relation to natural tooth structure to determine which monolithic material will provide restoration with exact shade and optical properties as natural tooth structure.

Inclusion Criteria: * 1\. Age range of the patients from 20-45 years old; able to read and sign the informed consent document, illiterate patient will be avoided. 2\. Patients able physically and psychologically to tolerate conventional restorative procedures. 3\. Patients with no active periodontal or pulpal diseases, having teeth with good restorations. 4\. Patients with teeth problems indicated for full coverage restoration ( coronal fracture where partial coverage would lack retention, malposed or malformed teeth). 5\. Patients with root canal treated teeth requiring full coverage restorations with contralatral tooth not filled orfractured. 6\. Patients willing to return for follow-up examinations and evaluation. Exclusion Criteria: 1. Patients in the growth stage with partially erupted teeth. 2. Patients with poor oral hygiene and motivation. 3. Pregnant women's to avoid any complication that may occur in dental office due to pregnancy or due to injected anesthetic solution. 4. Patients with psychiatric problems or unrealistic expectation 5. Patients have no opposite occluding dentition in the area intended for restoration\\ 6. Patients suffer from parafunctional habits. 7. deep discoloration of abutment . 8. Smokers and heavy caffeine consumers. \-