Shear bond strength of restorations applied to un-complicated crown fractures: an in vitro study

Study was designed to evaluate shear bond strengths of different restorative techniques of uncomplicated enamel-dentin fractures in permanent incisors.

Forty human mandibular incisors were divided into four groups. One-third of their anatomical crowns from the incisal edges were cut off in three groups, representing an uncomplicated enamel-dentin fracture. Intact teeth in group 1 were used as control. In group 2, edge fragments were reattached by flowable composite (Filltek Flowable Supreme XT). In group 3, teeth were restored with universal resin composite (Filtek Z 250). In group 4, pre-impregnated glass fiber sheet (everStickNet) was positioned onto fractured surface, and then restorations were completed with resin composite. Three-step etch-and-rinse adhesive system (Adper Scotchbond Multi Purpose) was used in all test groups. Shear bond strengths of all samples were determined in universal testing machine, and data were analyzed with Kruskal-Wallis followed by Mann-Whitney U tests. Failure types were observed by light microscope.

Shear bond strength of sound teeth was significantly higher than those of restored teeth (P < 0.05). Mean shear bond strengths of the reattached teeth were lower than the other two restoration types; however, differences were not statistically significant (P > 0.05).

Load-bearing capacity of restored teeth was not as high as sound teeth in the uncomplicated crown fracture. However, shear bond strength of different types of restorations seems close to each other.