Nine-year Clinical Performance of a HEMA-free One-step Self-etch Adhesive

Objectives: One-step self-etch adhesives are among the most popular adhesives to bond direct composites to tooth tissue, because of their single-bottle approach and perceived ease-of-use. The hypothesis tested was that a one-step self-etch adhesive performs equally well in a controlled clinical trial as a golden standard three-step etch-and-rinse adhesive.
Methods: 276 non-carious cervical lesions in 52 patients were restored with Gradia Direct Anterior (GC, Tokyo, Japan). These restorations were bonded either with the one-step self-etch adhesive G-Bond (GC) or with the three-step etch-and-rinse adhesive Optibond FL (Kerr, Orange, CA, USA). The restorations were evaluated after 6 months, 1 year, 2, 3, 5 and 9 years of clinical service regarding retention, marginal adaptation, microleakage, caries occurrence and sensitivity. Data were analyzed using a logistic regression model with generalized estimating equations (GEE) to account for the clustered data.
Results: 43 of these patients attended the 108m recall (recall rate: 83%). After 9 years, G-Bond exhibited a retention rate of 89%, which was not significantly different (p=0.6967) from the retention rate of Optibond FL (90%). Additionally 24 restorations (12 G-Bond, 12 OptiBond FLrestorations) were regarded as 'clinical failure', mainly because of extensive micro-leakage or poor marginal adaptation, therefore the 'overall clinical success' rate after 9 years was 79% and 80% for the one-step self-etch and etch-and-rinse adhesive respectively. Only 2 restorations (one from each group) in a single patient demonstrated clinical signs of caries. The only significant difference observed between both adhesives was that the control etch-and-rinse adhesive was more likely to exhibit perfect marginal adaptation and/or no microleakage (odds ratios 6.0 and 2.1 respectively; p<0.001). After nine years, only 18 restorations (3 G-Bond and 15 OptiBond FL restorations) did not have any defect; incisal microleakage was recorded for 95% of the G-Bond restorations, as compared to 65% of the OptiBond FL restorations.
Conclusions: After nine years, the HEMA-free one-step self-etch adhesive performed clinically equally successful as the three-step etch-and-rinse adhesive, only an increased number of clinically insignificant defects was observed for the one-step self-etch adhesive.