Influence of Various Storage Media on Shear Bond Strength and Enamel Fracture When Debonding Ceramic Brackets: An In Vitro Study

This study aimed to investigate the influence of different storage media on the shear bond strength and the risk of enamel fracture of human teeth measured in vitro. A total of 360 teeth stored in 96% ethanol and 360 teeth stored in 0.1% thymol solution were bonded with Fascination® and Fascination®2 brackets (Dentaurum, Ispringen, Germany) (360 per group) using 3 different light curing units and 3 different adhesives. Debonding was performed according to International Standards Organization specification DIN EN ISO 10477 using a universal testing machine with a crosshead speed of 1 mm/min. The teeth stored in 0.1% thymol solution showed significantly higher shear bond strengths (P < 0.001, Mann–Whitney-U test) (median, 16.7 MPa) than teeth stored in 96% ethanol (median, 13.2 MPa). The teeth stored in 0.1% thymol solution showed significantly less enamel fractures than the teeth stored in 96% ethanol solution (P < 0.001, Kruskal–Wallis test). The storage medium significantly influences the shear bond strength, measured in vitro on human teeth. For shear bond strength testing 0.1% thymol solution is to be preferred to 96% ethanol. However, even with thymol as the storage medium the enamel fracture rate seems to be higher than that in vivo.