Prosthetic Complications in Full-arch Screw-retained Implant Restorations Using Monolithic Zirconia Versus Titanium Frameworks: A Randomized Clinical Trial

Inclusion Criteria:

1. Aged 18 years or older.
2. Able to understand the study procedures and provide written informed consent.
3. In good general health, classified as American Society of Anesthesiologists (ASA) Physical Status Class I or II.
4. Completely edentulous in the arch to be treated (maxilla and/or mandible).
5. A candidate for a full-arch, screw-retained implant-supported prosthesis, requiring 4 to 6 implants in the treatment arch.
6. Sufficient bone volume at planned implant sites to place implants of at least 3.5mm in diameter and 8mm in length.
7. Adequate crown height space (15-22 mm) for a fixed prosthesis.
8. A zone of keratinized mucosa at the crest of the ridge measuring at least 2 mm in width.
9. Opposing arch is fixed full-arch implant-supported prosthesis.
10. Demonstrates acceptable oral hygiene and the motivation to maintain it.

Exclusion Criteria:

1. Medical contraindications:

   • Uncontrolled diabetes (HbA1c > 7.0%).
   • History of radiotherapy in the head and neck region.
   • History of intravenous bisphosphonate therapy.
   • Immunosuppressed or immunocompromised status.
   • Any other uncontrolled systemic disease that constitutes a contraindication for oral surgery.

2. Behavioral Factors:

   • Heavy smoking, defined as consumption of more than 10 cigarettes per day.
   • Presence of parafunctional habits (e.g., bruxism, clenching) as diagnosed by clinical examination.

3. Local Oral Factors:

   • Active, untreated periodontal disease in any remaining dentition.
   • Presence of acute oral infection or pathology at the intended surgical site.
   • Crown height space less than 15 mm or more than 22 mm.
   • Insufficient keratinized mucosa (< 2 mm width) that cannot be corrected with a simple surgical procedure prior to implant placement.

4. General:

   • Pregnancy or lactation.
   • Participation in another interventional clinical trial.
   • Perceived inability to comply with the study protocol and follow-up schedule.