Although the metal-ceramic system is still widely used to fabricate crowns and fixed partial dentures and is considered as the standard treatment in dentistry, aesthetic concerns have stimulated the development of new dental tooth-colored systems as PEEK.

BioHPP PEEK is 20% ceramic reinforced, semicrystalline, thermoplastic and radiolucent polymer for extreme durability especially for frameworks for fixed and removable dental prostheses. It has many advantages as low density, light weight, shock absorber, biocompatible and venerable with composite resin.

The aim of this study is to evaluate the clinical performance of milled BioHPP PEEK-based single crowns and compare them to metal-based single crowns.

Inclusion Criteria:

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 with teeth problems indicated for single posterior crowns:

   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.)
   6. Spacing between posterior teeth

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

Exclusion Criteria:

1. Patient less than 18 or 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. Lack of opposing dentition in the area of interest

Double blind