Nanoleakage with Three Generations of Self-etching Adhesives

Objectives: Recently, the resin bonding system has been simplified to shorten the clinical procedures. Bond strength with one-bottle/one-step type adhesives has been improved upto the same level of that with two-step types. The purpose of this study was to examine nanoleakage of one-bottle/one-step adhesive compared with two-bottle/one-step and two-step adhesives under the FE-SEM, using the silver nitrate staining technique. Methods: A newly designed one-bottle/one-step adhesive system, Bond Force (Tokuyama Dental), two-bottle/one-step system, One-up Bond F Plus (Tokuyama Dental), and two-step system, Mac-Bond II (Tokuyama Dental), were used. Cervical V-shape cavities were prepared along the cement-enamel junction of 18 extracted human premolars. After each six cavities were restored with one of three adhesive systems and EsteliteΣ composite according to the manufacturer's instructions, half of the teeth for each system was subjected to thermocycling (5°C - 55°C, 6,000 times). Then, all of the specimens were immersed in a 50%(w/v) silver nitrate solution for 24 hours, and soaked in the photo-developing solution under fluorescent light for 8 hours. The resin-dentin/enamel interfaces were observed under the FE-SEM to evaluate nanoleakage. Results: Bond Force, which did not have hybrid layer previously reported, showed no nanoleakage. Mac-Bond II and One-up Bond F Plus, which had traditional hybrid layer, showed a little nanoleakage only from the gingival margins. The thermocycling accelerated nanoleakage slightly. Conclusions: It was concluded that the brand-new bonding system which did not have hybrid layer previously reported demonstrated no nanoleakage, but that other two systems having hybrid layer showed nanoleakage only from the gingival margins, and that thermocycling accelerated nanoleakage.