Evaluation of Mandibular Posterior Zirconia Crowns With Different Ti-Base Surface Treatments.

This is a three-arm, parallel-group, superiority randomized controlled trial. The research question addresses the impact of silica coating (CoJet Sand) and primer (Z-Prime Plus) on the survival of mandibular posterior screw-retained zirconia crowns.+3The primary intervention involves treating the titanium base (Ti-Base) abutment surface using 30-mm $SiO\_2-Al\_2O\_3$ particles at 2.0 bar pressure. The three groups are:Group I (Control): No surface treatment.Group II: Tribochemical silica coating alone.Group III: Tribochemical silica coating followed by Z-Prime Plus application.Survival is evaluated using modified United States Public Health Service (USPHS) criteria at baseline, 6 months, and 12 months. Biological health is assessed via the modified plaque index (mPI) and modified Sulcus Bleeding Index (mSBI).