Converting one-step into two-step self-etch system improves its clinical performance

Objectives: A 18-month randomized, controlled prospective study evaluated, in an intra-individual comparison, the clinical performance of two one-step self-etch adhesives in non-carious cervical lesions [NCCL] applied as recommended or with an extra layer of hydrophobic adhesive. Methods: Thirty patients, with at least four similar sized NCCL participated in this study. After sample size calculation, 120 restorations were placed, according to one of the following groups: Clearfil S3 Bond [CS] and iBond [IB] applied according to manufacturer's instructions and Clearfil S3 Bond [CSB] and iBond [iBB] applied as recommended plus an extra layer of hydrophobic resin layer [Bond, Scotchbond Multi Purpose]. The restorations were placed incrementally using a composite resin. The restorations were evaluated at baseline and after 18 months according to the modified USPHS criteria. Statistical analysis was made with Friedman repeated measures analysis of variance by rank and Wilcoxon sign-ranked test for significance at each pair (alfa=0.05). Results: All restorations were evaluated at 18 months. The retention rate of the group IB after 18 months (60%) was statistically lower than groups CS (77.3%), IBB (83.4%) and CSB (93.4%). Although the application of an extra layer of a hydrophobic resin improved the retention rate of both adhesives, this was only statistically significant for iBond. Marginal discoloration occurred in all groups, being statistically worse in group IB, which was scored as beta in 94.4% of the cases. Conclusions: iBond applied according to the manufacturer's recommendations showed a very low retention rate after 18 months. The use of a bond layer of Scotchbond Multi Purpose associated with iBond adhesive can improve its clinical performance.