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

Clinical Evaluation of Mandibular Posterior Screw-retained Zirconia Crown With Various Ti-Base Abutment Surface Treatments: Randomized Controlled Clinical Trial

This clinical trial evaluates how different surface treatments on a metal base (Ti-Base) affect the success of dental crowns on implants. Patients receiving a zirconia crown for a missing lower back tooth are divided into three groups: one group receives no special treatment on the metal base, one group receives a silica coating, and the third receives both a silica coating and a chemical primer. The study monitors these crowns for one year to see which treatment best prevents the crown from coming loose or breaking, while also checking the health of the surrounding gums.

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).

Inclusion Criteria:

• Age 18 - 55 years
• Missing mandibular first molar with opposing natural teeth
• Good oral hygiene and general health (ASA I or II)
• Smoking ≤ 10 cigarettes/day

Exclusion Criteria:

• Poor oral hygiene
• Severe wear facets, clenching, or bruxism
• Heavy smokers (>10 cigarettes/day)