Effect of timing for core preparation in the tooth fabricated with post and core casting on the tensile strength

Several factors are affect retention of post and core. One of the most common problem is time of core preparation after post cementation. The purpose of this in vitro study was evaluate the influence of timing of coronal preparation on the tensile strength of cast post and cores cemented.
Method and material: In this in vitro study 30 extracted intact human premolars were selected. Each tooth was sectioned 16 mm from the root apex. After endodontic treatment of teeth the root canals were prepared for post fabrication. post and cores were cast in Ni-Cr alloy and cemented with zinc phosphate cement then divided into 3 groups: 1) core preparation immediately after cementation 2) core preparation 24 hours after cementation 3)control (without preparation).The tensile strength test was performed by a universal testing machine (zwick roell) with speed of 0.5 mm/min .The obtained data statically analyzed using one-way ANOVA test.
Significant differences were found in tensile strength between 3 groups. Tensile strength were, 176.83±43.15 for group1, 120.06±24.27 for group2 and 186.76±44.61 for group3. There is no significant difference between groups 1 and 2.(p=1.000)
It concluded that core preparation immediately after setting and cementation with zinc phosphate has significant influence the tensile strength of post and cores but core preparation 24 hours after setting has not significant effect on the tensile strength of post and cores.