بررسي مقايسه اي مقاومت به شكست در دندان هاي درمان ريشه شده با دو نوع پست و كور

Comparison o f fracture resistance of endodontically treated teeth with tow different post and core system

Introduction: Most endodontically treated teeth need post and core to function properly. Although selection of type of post &core can be tedious. This study compared the effect of cast post and core and fiberglass post and core system on the fracture resistance and fracture pattern of endodontically treated teeth that restored with PFM restorations.Material and method: A total of 30 freshly extracted human canines were decoronated and endodontically treated. All specimens were divided in two groups . in the 1st groujp Teeth were restored with cast post & core and Cemented with zinc phosphate cement, in the 2n group Teeth were restored with fiberglass post&composit core and cemented with panavia F2 adhesive system. Each specimen were embedded in acrylic resin block and then scored in universal testing machine. A compressive load was applied at 45° to the long axis of the tooth with crosshead speed of lmm/min until fracture was happen.Result: The Fracture resistance of 2 groups according to the (t) test analysis didnʹt have any significant difference. The analysis showed the mean fracture resistance of the teeth restored with cast post&core system was 1489.33 ± 1045.34 N and mean facture resistance of the teeth restored with fiber glasspost &composit core was 1195.93 ± 624.12 N,there was not a significant difference between the 2 subgroups (Pvalue=0.359). Fracture that occur in teeth restored with fiberglass post and composite core usually are restorable but in tooth restored with cast post and core system %80 of fractures are not restorable. Discussion : Fracture resistance of teeth in two groups studied were not statistically different although fracture of teeth restored with Fiber glass post occurred more coronally and therefore were more repairable, fracture of teeth restored with cast post &core occurred more apically and that were not repairable. Therefore it is suggested to use Fiber glass post in appropriate cases.