Fracture Resistance of Root Canal Treated Maxillary Central Incisors Restored with FRC Post in Extensive Composite Restorations

Statement of problem: Using the post is one of the most important sequences in restoring endodontically treated teeth. It dates back more than 200 years as the most popular method of root canal treated teeth restoration; and still is an acceptable method of increasing retention and resistance in such teeth. When there is enough sound tooth structure, restoring the tooth with adhesive restoration is the best choice. New tooth-colored adhesive posts are compatible with conservative and esthetic technique. But the question still remained: how much of remaining tooth structure is enough to resist the forces, without using the post? The purpose of this comparative in vitro study was to determine compressive fracture resistance of crown in endodontically treated maxillary incisor teeth restored with or without adhesive tooth colored post and also in intact teeth. Thirty extracted maxillary central incisors were selected and allocated to three groups each of ten teeth. Group 1 teeth were kept intact as control. Group 2 were endodontically treated teeth with two approximal class III cavities in the middle one third of incisogingivally that were connected to access cavity, then restored with composite. Group 3 were endodontically treated and prepared teeth, similar to group 2 and received light post DT (RTDTM) and restored with composite. Then, the samples were loaded until fracture was happened in pull test machine. Mean values of forces required for fracture and mode of fracture were recorded. Mean fracture strength in group 1 was 68.67, in group 2, 41.44 and in group 3, 21.45 Kgf. Comparison of fracture resistance with one way ANOVA was statistically significant. Failure mode of group 3 was more repairable than group 2. Fracture strength in teeth resorted with post was less than the other groups. While considering more time and cost in using posts, this study does not recommend it in similar situations.