Wear of Enamel Antagonist to Two Different Types of Monolithic Zirconia Monolithic Zirconia

Inclusion Criteria: \- All subjects are required to be: 1. From 18-50 years old, be able to read and sign the informed consent document. 2. Have no active periodontal or pulpal diseases, have teeth with good restorations. 3. Psychologically and physically able to withstand conventional dental procedures. 4. Patients planned for a single coverage restoration in the posterior area. 5. Patients with a natural (not crowned) opposing antagonist. 6. Able to return for follow-up examinations and evaluation. Exclusion Criteria: * Patient less than 18 or more than 50 years 2. Patients with severe clenching or bruxing habits. 3. Patient with active resistant periodontal diseases 4. Patients with poor oral hygiene and uncooperative patients 5. Pregnant women 6. Patients in the growth stage with partially erupted teeth 7. Psychiatric problems or unrealistic expectations 8. Lack of opposing dentition at the area of interest. 9. Presence of dental prosthesis in the opposing arch at the area of interest.