Color stability and marginal discoloration of ceramic laminates cemented with light-polymerizing and dual-polymerizing luting agent: a 9-year split-mouth randomized clinical trial.

Abstract

Objectives: This split-mouth randomized clinical trial aimed to evaluate the color stability and marginal discoloration of ceramic laminates cemented to enamel using light- and dual-polymerizing cement.

Materials and methods: 10 participants had 0.3-mm-thick ceramic laminates cemented to the buccal surface of the second premolars according to two experimental groups (light- or dual-polymerized cement). Variolink II light-polymerized cement was randomly used on one side, and Variolink II dual-polymerized cement was used on the contralateral side. The operator, participants, and evaluator were blinded to the polymerization mode. Color assessments were performed using a spectrophotometer (CIELab system) at 24 h (baseline) and 9 years post-cementation. Color alterations were quantified using the CIELab* (ΔE_ab) and CIEDE2000 (ΔE₀₀) formulas. Marginal discoloration was evaluated according to the US Public Health Service guidelines. The Wilcoxon test was used to compare light- and dual-polymerization modes for ΔE*_ab and ΔE*₀₀ (α = 0.05). Marginal discoloration was assessed using a Wilcoxon test (α = 0.05).

Results: Wilcoxon tests did not reveal a significant difference in ΔE*_ab and ΔE*₀₀ between light- and dual-polymerized cement (P > .05). At the 9-year evaluation, the mean (standard-deviation) ΔE*_ab values for the photo- and dual-polymerizing modes were 3.71 (1.32) and 5.30 (3.55), respectively. The mean (standard-deviation) ΔE*₀₀ values for the photo- and dual-polymerizing modes were 2.69 (0.89) and 3.92 (2.96), respectively. The color change surpassed clinically acceptable thresholds (ΔE*_ab>3.46 and ΔE*₀₀>2.25) in both groups. All veneers in the light- and dual-curing modes exhibited marginal discoloration. Wilcoxon tests revealed a statistically significant increase in marginal discoloration from baseline to 9 years for light- and dual-polymerized cements (P < .05).

Conclusions: After 9 years, the color stability of the restorations was similar for both curing modes, surpassing clinical acceptability. Marginal discoloration occurred in all veneers in the light- and dual-polymerizing modes.

Clinical relevance: After 9 years, ceramic veneers luted with light- or dual-polymerized resin cement may exhibit color changes exceeding the threshold of clinical acceptability, along with a high incidence of marginal discoloration. Clinicians should consider these factors when selecting luting agents for long-term esthetic outcomes.