Dentin Bond Strength Evaluation of Four Adhesive Systems

Objective: The objective of this in vitro study was to evaluate the microtensile bond strength of four adhesive systems to human dentin.

Method: Twenty-eight human third molars had their occlusal enamel removed with a diamond saw (Buehler Ltd) to expose the dentin surface. The dentin surfaces were abraded with SiC 600 paper, under cooling with water for 10 seconds, to standardize the smear layer and to create a flat surface. The teeth were randomly divided into four experimental groups (n = 7): Gluma Comfort Bond (GCB - Heraeus Kulzer), Optbond FL (OFL - Kerr), One Coat Bond SL (OCB - Coltene) and Peak Universal Bond (PUB - Ultradent Prod.). The adhesives were applied following the instructions of each manufacturer. Filtek Supreme composite (3M ESPE) were incrementally built on dentin surfaces (6 mm thickness) and the teeth were stored for 24h at 37^oC. Restored teeth were vertically and serially sectioned with a diamond saw under water lubrication to obtain bonded specimen (area of approximately 1.0 mm²), which were tested in a universal testing machine (EZ Test, Shimadzu). Data were analyzed by one-way ANOVA and Tukey test (α=5%).  

Result: The bond strength means (SD) to dentin were (MPa): GCB: 50.4(8.4)a; OFL: 67.7(5.1)b; OCB: 59.4(8.2)ab; PUB: 51.2(10.0)a.

Conclusion: The OFL three-step etch-and-rinse adhesive system showed higher bond strength to dentin than GCB and PUB. The bond strength of two-step etch-and-rinse systems (GCB, OCB and PUB) to dentin did not differ among them.