INFLUENCE OF HUMAN TOOTH CRYOPRESERVATION ON DENTIN BOND STRENGTH

Objectives. The goal of this study was to evaluate the effects of cryo preservation of teeth on dentin bond strength as a function of remaini ng dentin thickness. Methods. Flat occlusal surfaces of human dentin w ere prepared in 54 freshly extracted teeth and 54 thawed, cryopreserve d teeth. In each group, 18 bonds were performed in superficial dentin, 18 in mid-coronal, and 18 in deep dentin. A resin composite cylinder, 3 mm in diameter and in height, was bonded orthogonally to the surfac e. After storage in distilled water at room temperature for 1 wk, the bonded cylinders underwent shear testing at a crosshead speed of 0.5 m m min(-1). The mean remaining dentin thickness was calculated after lo ngitudinally sectioning the debonded samples through the center of the bonded area. Non-parametric statistical analyses were used to correla te the shear bond strength with the remaining dentin thickness among t he storage modes and within the different dentin regions. Results. The lowest shear bond strength values were found in the deep dentin of bo th fresh and cryopreserved dentin, while the values in deep and mid-co ronal dentin were not significantly different in fresh and cryopreserv ed dentin. In the superficial and mid-coronal dentin of cryopreserved samples, the shear bond strength values were identical. There was a si gnificant difference between the shear bond strength values in the sup erficial dentin of fresh teeth compared to the values for cryopreserve d teeth. Significance. According to the experimental conditions, tooth cryopreservation shows some promise as a substitute for freshly extra cted teeth, provided that the experiments are performed in mid-coronal and deep dentin.