Fracture resistance of fiber posts: combinations of several small posts vs. standardized single post

To determine the fracture resistance of different sizes of standardized single fiber posts and the combinations of multiple small experimental posts.

Single posts in three different sizes (1, 2 and 3; DT Light Posts, RTD; DT), as control, and seven different combinations of experimental small posts (Abrasive Technology), reproducing the sizes of several endodontic files were cemented in endodontic resin blocks. The combinations of small posts were made combining 2-4 small posts so as to reach the sizes of standardized DT posts. The posts were loaded at an angle of 45 degrees to the long axis of the block using a crosshead speed of 1 mm/minute until specimen failure. Ten posts/combinations were tested. Statistical analysis was performed using one-way ANOVA followed by Tamhane test for the post hoc comparisons (P < 0.05).

For the single posts, fracture resistance increased when increasing the diameter of the post. The use of multiple posts resulted in fracture resistances comparable to that of the single post for two of the three diameters studied (DT1 and DT2). For the largest diameter (DT3), the use of multiple posts resulted in lower fracture resistances than did the single post.