Degradation patterns of different adhesives and bonding procedures

Various types of resin adhesives and procedures are available in the clinical field, so comprehensive understanding of degradation is required for each material and bonding procedure. The objective of this study was to investigate the bond durability for different adhesives and bonding procedures. Resin-dentin bonded beams were prepared with the use of two adhesives (One-Up Bond F/self-etching primer system and One Bond/total-etch adhesive) and two experimental groups for the bonding procedure (wet and dry bonding of the total-etch adhesive). Those samples were soaked in water for 24 h(control), 6 and 12 months. After the water immersion, the bond strengths were measured by the microtensile bond test, and subsequently fractography was performed with the use of SEM. Statistically significant reduction of the bond strength (p < 0.05) was apparent after 12 months of water exposure in the range 22-48% of the control. The bonding resin was eluted from the hybrid layer of the self-etching and the total-etch adhesives for the wet bonding. Micromorphological alterations were found due to the hydrolysis of collagen fibrils with the total-etch adhesive for the dry bonding mode. These pathologic alterations were in accord with the bond strength.