Clinical Evaluation of Zirconia-Reinforced Lithium Silicate (ZLS) Crowns: 2-Year Recall

Objectives: To compare a new ceramic crown (Celtra® Press, a lithium silicate with 10% zirconia) bonded with either an adhesive resin cement (Calibra® Ceram) with a universal adhesive (Prime & Bond Elect) or a self-adhesive resin cement (Calibra®Universal)
Methods: 38 patients received either one or two pairs of single-unit monolithic Celtra® Press crowns (80 total crowns; 24% anterior, 35% premolars, 40% molars). Crowns were fabricated by two external dental laboratories. Either Calibra® Ceram or Calibra® Universal was randomly selected to bond the first crown in the pair and the second crown was bonded with the other cement. The crowns were etched with 5% hydrofluoric acid for 20 seconds and silane applied (Calibra® Silane). After delivery, excess cement was cleaned and the cement was light cured for 20sec/surface through the crowns. Crowns were evaluated by modified FDI at approximately 2wks (baseline), 6mos, 1yr after treatment, and 2yr after treatment. 2yr FDI criteria were compared with a Mann-Whitney U test.
Results: 34 patients (71 crowns) were evaluated at 2yr recall (see Table). No restorative failures occurred and no signs of wear or cracking were observed on the crowns. Three crowns bonded with Calibra Universal debonded after 8, 16, and 19 months of service. Two were recemented and one was associated with tooth fracture. One crown required root canal treatment. There were no statistically significant differences in any FDI criteria between crowns cemented with either cement following 2 year of intraoral service.
Conclusions: Celtra® Press has acceptable performance following 2 year of clinical service when bonded with Calibra® Universal or Calibra® Ceram with Prime & Bond Elect. Bonding with Calibra® Ceram with Prime & Bond Elect seemed to show improved retention.