An in vitro study of two different cements' influence to the fracture resistance of upper central incisors restored with post-and-core systems

Objective:An in vitro study was conducted to measure the fracture resistance of upper incisors restored with post-and-core systems.The posts were cemented by two different cements: Super-bond CB and zinc phosphate cement.Method:16 upper central incisors were divided into two equal groups at random.Super-bond CB was used for one group and zinc phosphate cement for the other.These teeth were prepared for cast post-and-core and complete crown restoration after routine root canal therapy and then tested by a universal testing machine until those fractures occurred by applying loads at an angle of 45 degrees.Data were analyzed statistically and modes of failure were also compared.Result:The fracture resistance of the roots in which the posts were cemented with Super-bond CB was 914±145 N and the one of those where zinc phosphate cement was used was 591±106 N.Two groups showed statistical significance(P0.01).Most of the teeth demonstrated cervical root fracture.Conclusion:Super-bond CB results in significantly higher fracture resistance than zinc phosphate,which suggests that the choice of cement is important to the maximum fracture resistance in endodontically treated teeth.