There is a literature review in the March 2010 issue of The Journal of Evidence-Based Dental Practice regarding failures of posts. The writers examined multiple randomized control trials evaluating failures of endodontically-treated permanent teeth with different post types. The trials compared metal posts to fiber posts. The results of the review showed fewer failures with carbon fiber posts as opposed to metal posts.
This seems to be concordant with the widely accepted thoughts about posts. Carbon fiber posts have a modulus of elasticity closer to natural tooth than do metal posts. In addition, carbon fiber posts are generally passive and tapered which decreases chances of perforation or root fracture when preparing. One disadvantage to carbon fiber posts is the necessity to “bond” them in with a self-etching resin. Bonding is very problematic at depths in the root and can create a point of weakness if the proper technique is not followed.
As an industry, we are doing less and less posts. I feel the literature supports this, however there are some teeth that just need posts no matter what. I find that these teeth are more often premolars and anterior teeth in my practice. Because of this, I general use the smallest posts available. Probably the biggest key to post success is amount of vertical tooth structure and ferrule remaining. In dire situations with little ferrule, no post system has a shot of success.
As far as my practice goes, I use 3M’s Rely-X post system. I find the system to be easy to use with few steps and yields good results. There are plenty of other good systems on the market. As with anything the key to success is your familiarity and comfort.