P: Population: Patients requiring single unit implant restoration in esthetic zone I: Intervention: Polymer-infiltrated-ceramic-network abutment crown (VITA Enamic-VITA Zahnfabrik) C: Comparison: Lithium disilicate ceramic abutment crown (IPS e. max-Ivoclar Vivadent) O: Outcome: patient satisfaction , crestal bone loss and periodontal parameters T: Time: 12 months S :Randomized controlled trial research question:For patients receiving implants in esthetic zone, Does the use of polymer-infiltrated-ceramic-network hybrid abutment crown offer better patient satisfaction , less bone loss and better peri-implant clinical parameters when compared to lithium disilicate hybrid abutment crowns?

Inclusion Criteria:

1. Patients above 18 years old.
2. Patients able to read and sign the informed consent document.
3. Medically free patients or with controlled systemic disease.
4. Patients with good bone quality and quantity evaluated using C.B.C.T.
5. Patients willing to return for follow-up examinations and evaluation.
6. Patients having single missing recently extracted premolar tooth.

Exclusion Criteria:

1. Young patients in growth stage.
2. Patients with unsuitable implantation sites (patients with major boney defects or sever bone resorption)
3. Pregnant women to avoid any complication that may occur in dental office.
4. Patients with uncontrolled systemic disease (hypertensive patient or uncontrolled diabetic patient)
5. Psychiatric problems or unrealistic expectations.
6. Multiple adjacent missing teeth.
7. Patients with bad oral hygiene. -

double blind :outcome asessor,participant