International Arab Journal of Dentistry


The aim of this in-vitro study was to investigate the effect of the resin cement film thickness on the resistance to fracture of endodontically treated teeth. Forty-eight central incisors were endodontically treated. Fortyeight cast custom post and cores (CCPC) were fabricated using non-precious metal alloy and cemented into their respective canals using self-adhesive resin cement Rely X™ U200 (3M, ESPE). The teeth were divided in three groups based on the cement thickness: In group A, the CCPC was congruent with the canal space. The canal space in groups B and C was enlarged by 100 and 350 microns respectively using Parapost X™ drills (Coltene-Whaledent,USA). The roots were loaded until fracture. In group A, 7 (46, 7%) roots fractured at an average load of 139.89 N (±19.144). In group B, 11 (68.8%) roots fractured at an average load of 199.68 N (±35.06) and in group C, 16 (100%) roots fractured at an average load of 196, 51 N (±52.28). No significant difference was detected between groups B and C, with 50% and 62.5 % respectively of the fractured specimens considered restorable. The specimens in group A failed since the post and cores dislodged from their respective roots at significantly lower pressure loads. Increasing the thickness of the cement layer can enhance the resistance to fracture of the endodontically treated teeth restored with CCPC.