An in vitro study into the effect of the ferrule preparation on the fracture resistance of crowned teeth incorporating prefabricated post and composite core restorations.

AIM: This in vitro study investigated the effect of a ferrule preparation on the fracture resistance of crowned central incisors incorporating a prefabricated post (Parapost) cemented with Panavia-Ex and with a composite core.
METHODOLOGY: The test group consisted of 10 post crowned natural central incisor teeth with a 2-mm wide ferrule preparation, whilst the control group of 10 teeth had no ferrule. The specimens were mounted on a Lloyd universal testing machine and a compressive load was applied at an angle of 135 degrees to the palatal surface of the crown until failure occurred.
RESULTS: In both groups, failure occurred at higher loads compared with previous studies. The mean failure load was 1218 N for the unferruled group and 1407 N for the ferruled group. Statistical analysis showed no significant difference between the groups.
CONCLUSIONS: Under the conditions of this study, when composite cement and core materials are utilized with a Parapost prefabricated system in vitro the additional use of a ferrule preparation has no benefit in terms of resistance to fracture.