Clinical performance of monolithic zirconia crowns on titanium-zirconium reduced-diameter implants in the molar area: Interim data at three years of a randomized controlled trial.

Abstract

The aim of the present study was (i) to evaluate the clinical performance of reduced-diameter implants placed in the molar area and (ii) to test whether monolithic zirconia implant-supported crowns lead to similar clinical outcomes compared to porcelain-fused-to-metal crowns. A total of 76 patients needing a single implant crown in the posterior region were recruited. All patients received a titanium-zirconium reduced-diameter implant (Straumann Roxolid, Tissue Level, Standard Plus, diameter 3.3 mm, regular neck) randomly allocated to receive either a (1) monolithic zirconia crown (test) or (2) porcelain-fused-to-metal crown (control). Implant survival, prosthetic outcomes, and patient-reported outcomes were assessed at crown delivery and after 3 years of follow-up. Marginal bone levels (MBL) as well as clinical parameters including probing depth (PD), bleeding on probing (BOP), and plaque levels (PCR) were also recorded. A total of 59 patients were available at the 3-year follow-up; 32 patients with a monolithic zirconia crown (TEST) and 27 patients with a porcelain-fused-to-metal crown (CONTROL). 14 implants (11 implant fractures/3 aseptic losses) were lost leading to an estimated implant survival rate of 80% ± 5.1% (95% CI 70.8%-90.8%). Prosthetic complications were limited to the control group and involved minor chippings. This type of reduced-diameter implant to support single implant molar crowns in the molar area cannot be recommended. Monolithic zirconia crowns appear to be a viable option in the posterior region showing similar prosthetic outcomes to porcelain-fused-to-metal crowns.