What role do luting cements play in zirconia crown survival?

Abstract

A commentary on: Torres C, Mailart M C, Ávila D et al. Influence of glass ionomer-based luting cements on the clinical success of zirconia crowns: randomized clinical trial. Oper Dent 2025; 50: 144-156.

Design: This 24-month prospective, split-mouth randomised clinical trial compared the performance of conventional glass ionomer cement (GIC) and resin-modified glass ionomer cement (RMGIC) for luting full-coverage ceramic-fused-to-zirconia crowns.

Participants: Thirty participants were enrolled; 27 attended the 12-month review and 24 were assessed at the 24-month follow-up. Inclusion criteria included adults who needed two anterior or two posterior crowns. Silicone impressions were used to fabricate casts, which were scanned for CAD/CAM milling of zirconia copings. Clinical outcomes were assessed at 7 days, 12 months, and 24 months by calibrated, blinded examiners.

Data analysis: The primary outcome was crown retention; whilst secondary outcomes included fracture, wear, pulpal response, patient satisfaction, plaque and bleeding indices, and marginal integrity. Assessments followed modified USPHS and FDI criteria. An intention-to-treat analysis using last observation carried forward was applied. Fisher's Exact test compared anterior and posterior outcomes, while Kaplan-Meier estimates and log-rank tests were used to evaluate restoration survival (p < 0.05).

Results: Success rates recorded were 93.3% for GIC and 100% for RMGIC. For anterior crowns, GIC success declined to 83.3% at two years, while RMGIC maintained a 100% success rate throughout. Posterior crowns showed 100% success in both groups, with no loss of retention or secondary caries recorded.

Conclusions: Both GIC and RMGIC demonstrated favourable short-term outcomes. However, anterior crowns cemented with GIC were more prone to failure, suggesting that crown location should inform cement selection. Optimising luting agent choice may improve long-term clinical success.