Is There an Association Between Clinical and SEM Quantitative Marginal Analysis in a 90-month Trial?

Purpose: To assess possible correlations between clinical outcomes and SEM marginal analysis in a prospective long-term clinical study using two adhesives in incisors and canines.

Materials and methods: Thirty-five patients received class III and IV restorations with two different adhesives, either the one-step self-etch adhesive iBond Gluma inside (1-SE) or the two-step etch-and-rinse adhesive Gluma Comfort Bond (2-ER) combined with the fine particle hybrid composite Venus. The restorations were clinically evaluated (modified USPHS criteria) over 90 months. Based on resin replicas, a quantitative marginal SEM analysis was performed using the criteria "gap", "perfect margin", "overhang", and "underfilled". The results of the quantitative marginal analysis were statistically compared and related to clinical evaluations. The SEM data were analyzed statistically using the Kolmogorov-Smirnov test, Wilcoxon test, and mixed models test.

Results: Of the 35 subjects at baseline, 16 (1-SE) and 17 (2-ER) were clinically re-examined after 90 months. 13 patients were included in the SEM analysis due to uninterrupted documentation over 90 months or until restoration loss. SEM analysis showed larger discriminative power between groups than did the clinical examination, but the trend was the same. Marginal analysis ("gap", "perfect margin") showed significant differences between the materials after 12 months, which clinically began to show a trend from 12 months, and were statistically verified after 48 and 90 months. "Overhang" and "underfilled" did not reveal significant differences between the systems or over time.

Conclusion: SEM marginal analysis using the replication technique is a powerful tool to reveal differences between adhesives. Compared to clinical evaluation, group differences can be detected earlier, with both outcome parameters confirming each other over long observation periods.