The aim of this study is to evaluate the clinical behavior of zirconia crowns in dental esthetic zone with vertical versus conventional preparation techniques using a new gradient technology monolithic zirconia (5Y-TZP/3Y-TZP).

Introduction: A good relationship between dental restorations and the periodontium is one of the most important aspects to ensure clinical success both in terms of esthetics and function. Dental preparation for fixed prostheses can take various forms classified as horizontal preparation with a defined margin (chamfer), or vertical, or without a margin/finish line. According to some clinical reports, vertical preparation technique provides an increases in the gingival thickness and a greater stability of the gingival margin. Moreover, vertical preparation is characterized by being more conservative with tooth structure. Also, taking impressions is easier since it is a finish area and not a defined line.

Null hypothesis:

1. There will be no difference between vertical and conventional preparations in the clinical behavior of zirconia crowns in dental esthetic zone at baseline,3,6,9,12 months evaluation.
2. There will be no difference between vertical and conventional preparations in the patient satisfaction of zirconia crowns in dental esthetic zone at baseline,3,6,9,12 months evaluation.

Inclusion Criteria:

1. From 21-50 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 with teeth problems indicated for all ceramic crowns in esthetic zone;

   1. Badly decayed teeth
   2. Teeth restored with large filling restorations
   3. Endodontically treated teeth
   4. Malformed teeth
   5. Malposed teeth (Tilted, over-erupted, rotated, etc.)

5. Able to return for follow-up examinations and evaluation.

6. Thick gingival biotype.

Exclusion Criteria:

1. Patient less than 21or more than 50 years.
2. Patient with active resistant periodontal diseases.
3. Patients with poor oral hygiene and uncooperative patients.
4. Pregnant women.
5. Patients in the growth stage with partially erupted teeth.
6. Psychiatric problems or unrealistic expectations.
7. Patient with periodontal problems.
8. Patients with malocclusion or parafunctional habits.