Effects of post placement on endodontically treated teeth.

The effect of endodontic therapy, post-hole preparation, and post placement on tooth models of maxillary central incisors was investigated. Two-dimensional photoelastic analysis of birefringent models, under load in a polariscope, indicated the relative stress magnitudes and concentrations at the cervical and apical regions. Within the limits of the method, the results suggest that enlargement of the canal increases cervical stresses and that post placement will decrease stresses in this region. Nevertheless, conservative enlargement of the root canal may render post placement unnecessary for largely intact teeth. Post length appeared more important than post diameter in determining relative stresses at the cervical region. However, short wide posts led to elevated stress concentrations in this region. Post placement beyond two thirds of the root depth did not further decrease cervical stresses but usually increased stresses in the apical region.