investigating the effect of glazing and polishing on the color difference between natural teeth and all ceramic crowns made from celtra press (zirconia reinforced lithium silicate ceramic).

Two groups of patients will be selected according to special inclusion criteria N=5 in each group total of 10 patients, one of the two groups will receive a glazed zirconia reinforced lithium silicate ''celtra press'' crowns and the other group will receive a polished ones of the same material , after crowns delivery color difference (ΔE) between the natural teeth and the celtra press crown will be measured by a spectrophotometer device (intra oral) and patient satisfaction will be recorded.

Inclusion Criteria:

• Age range of the patients from 20-45 years old; able to read and sign the informed consent document, illiterate patient will be avoided.
• Patients able physically and psychologically to tolerate conventional restorative procedures.
• Patients with no active periodontal or pulpal diseases, having teeth with good restorations.
• Patients with teeth problems indicated for full coverage restoration ( coronal fracture where partial coverage would lack retention, malposed or malformed teeth).
• Patients with root canal treated teeth requiring full coverage restorations with contralatral tooth not filled or fractured.
• Patients willing to return for follow-up examinations and evaluation.

Exclusion Criteria:

• Patients in the growth stage with partially erupted teeth.
• Patients with poor oral hygiene and motivation.
• Pregnant women's to avoid any complication that may occur in dental office due to pregnancy or due to injected anesthetic solution.
• Patients with psychiatric problems or unrealistic expectation
• Deep discoloration of abutment .