(PR31) The Effectiveness of Horizontal Posts in Preventing Post-Endodontic Fractures

Endodontically treated posterior teeth should be restored with full coverage restorations to prevent tooth fractures. Fiber posts positioned horizontally in a buccolingual direction have been found to increase fracture resistance in composite resin restorations. This in vitro study aimed to investigate and compare the effects of horizontal fiber posts on the fracture strength of endodontically treated molars restored with composite resin or a full-coverage lithium-disilicate crown constructed by computer-aided design/computer-assisted manufacturing (CAD/CAM). 60 human third molars with no caries or defects were selected. All teeth underwent endodontic treatment following mesial-occlusal-distal cavity preparation except for the control group, and were randomly divided into five groups (n=12): G1 (control, intact teeth), G2 (composite resin restoration), G3 (composite resin restoration with horizontal fiber posts), G4 (CAD/CAM lithium-disilicate crown), and G5 (CAD/CAM lithium-disilicate crown with horizontal fiber posts). The fracture resistance was tested with a universal testing machine. Data was statistically analyzed using one-way analysis of variance and Tukey's honestly significant difference test (α=0.05). Significant differences were identified between G1 and the other groups (P <0.05) and none among G2, G3, G4, and G5 (P>0.05). G2 showed the highest number of non-repairable fractures, significantly different from G4 (P <0.05). The fracture resistance of endodontically treated molars with horizontal fiber posts was comparable to that of CAD/CAM lithium-disilicate crowns. Composite resin restoration has similar fracture resistance to horizontal posts and crowns but could result in more frequent non-repairable fractures.