Three Materials for Monolithic Crowns on Zirconia Implants: One-Year Results of a Randomized Clinical Trial

Purpose: to compare the survival rate, the technical, aesthetic, and biological outcomes of three different materials for monolithic crowns on zirconia implants in a randomized clinical trial. Materials and methods: a total of 44 patients were randomly divided into three groups and restored with monolithic implant-supported single crowns: zirconia (Zr), polymer- infiltrated ceramic (PIC), and polymer (P). Follow-up evaluations were conducted after one year. Clinical assessments included survival rates, modified United States Public Health Service (USPHS) scores, White Esthetic Scores (WES), plaque index (PI), bleeding on probing (BoP), and probing depth (PD). Results: After one year, survival rates for monolithic Zr and PIC crowns were 100%, while the P crown group showed a survival rate of 84.6%. At baseline, the PIC crowns achieved the highest USPHS scores; however, this group also showed a noticeable decline over time. The WES remained stable for the Zr but declined significantly for the other groups due to changes in surface texture. PIC exhibited a significant increase in plaque accumulation. Conclusions: Regarding the survival rate, no statistically significant differences were observed between the groups. However, a lower survival rate in the P crown group and superior surface stability in the Zr crowns were noted. Within the limitations of the small sample size and short follow-up period, Zr crowns may be recommended for the restoration of one-piece zirconia implants.