Six-month clinical evaluation of two dentin adhesives applied on dry vs moist dentin

Purpose: Acid-etched dentin has been described to easily collapse when it is dried with air after being rinsed with water under laboratorial "ideal"conditions. Manufacturers of modern dentin adhesives recommend leaving dentin moist, regardless of the solvent used in their proprietary dentin adhesives. Nevertheless, many clinicians still dry the cavity preparation after rinsing off the etching gel to check for the enamel frosted aspect. The null hypothesis to be tested in this clinical study was that drying dentin with air upon rinsing off the acid would not result in lower short-term retention rates than when the cavity was left visibly moist. Materials and Methods: Upon Internal Review Board approval, thirty-five patients were enrolled in this study. A total of 128 restorations divided into four groups were inserted and evaluated at baseline: (A) Prime & Bond NT, an acetone-based adhesive, applied on moist dentin; (B) Prime & Bond NT applied on dentin dried with air for 3 to 4 s; (C) Single Bond, an ethanol- and water-based adhesive, applied on moist dentin; (D) Single Bond applied on dentin dried with air for 3 to 4 s. A microfilled composite resin was used for all restorations. Results: At 6 months after initial placement, 119 restorations (a 93% recall rate) were re-evaluated. Retention rates at 6 months were 97% (one failure) for Single Bond/moist dentin and 100% for the remaining three groups; however, they were not significantly different (retention rate vs dentin adhesive; retention rate vs moisture). Conclusion: Dentin substrate in noncarious lesions may be less sensitive to variations in dentin moisture than the "ideal"dentin substrate used under laboratory conditions.