Effect of Core Preparation on the Retention of Cast Post and Cores Luted with Glass Ionomer Cement

The objective of this study was to evaluate the influence of core preparation using high-speed handpiece on the retention of cast post and cores luted with glass ionomer cement and tested at 3 different times post cementation. 60 extracted single-rooted human teeth were selected. Root canals were prepared but not obturated. 60 Cast post and cores were then fabricated and luted with glass ionomer cement. Specimens were randomly divided into 2 groups of 30 each. One of these groups (3o teeth) had their cores prepared fora 4-minute period using diamond bur in a high-speed handpiece. This group was then further divided into 3 groups ( 10 teeth) and each subgroup was tested at 3 different time points (15 minutes, 1 hour, and 24 hours post cementation) while the other group of 30 teeth remained unprepared and divided similarly into 3 groups (10 teeth) to serve as controls. The forces required for vertical dislodgment of posts from their prepared post spaces were recorded using a universal testing machine. Data were statistically analyzed using two-way and one-way ANOVA and the Student's t-test. The retention of the posts significantly increased (from 100 N-to-25 1N) with delaying the time of testing (P<0.0001). In addition, the prepared groups had statistically significant reduction in post retention than the unprepared groups at 15 minutes and at 1 hour (P<0.05). Conclusion: Core preparation 15 minutes and 1 hour after post and core cementation significantly reduced post retention statistically.