Metal
Myths
Endodontically-treated teeth are more brittle and, therefore, are fracture-prone.
This particular myth is the reason many pulpless teeth are restored with full coverage. Presumably, the full coverage restoration will strengthen the tooth and keep it from fracturing. However, this fracture propensity of endodontically-treated teeth due to brittleness has never been proven. A much more likely explanation is that many endodontically-treated teeth have been decimated by caries or fracture, leaving very little sound tooth structure remaining. Lack of strong, intact tooth structure is the more plausible reason for the fracture of endodontically-treated teeth.
Posts reinforce the root.
There is no evidence for this either and, in fact, removing tooth structure for post preparation probably weakens the root. According to a recent study, this is particularly true for parallel-sided posts, which typically require more preparation than tapered posts.
Indication
The only reason to place a post is to help retain a coronal buildup. This means posts are only necessary when there is insufficient remaining coronal tooth structure to support a buildup by itself. The typical clinical situation where this scenario occurs is when only the root remains but all the coronal tooth structure is missing.
Types of Posts
Cast Gold
Still viewed with much reverence by traditionalists. But, due to the added costs of an impression or time spent fabricating a replica, a lab fee, and two appointments, this procedure seems to have lost advocates over the years. While there is certainly nothing inherently wrong with cast posts and cores, the concept itself is viewed as very impractical by many dentists.
Stock Metal
Available in numerous designs, most of which are composed of either stainless steel or titanium. Typically are accompanied by drills designed to prepare matched postholes. Even though metal posts have a track record, they have been implicated in, among other nefarious acts, contributing to the darker color of the soft tissue covering the roots of endodontically-treated teeth. This is presumably due to the shadowing they transmit through the roots. Metal posts can be placed either passively or actively by being screwed into a self-tapped posthole. Active placement has the best retention, but there is the ever-present risk of fracturing the root during the placement procedure.
Direct, Fiber-Reinforced, Composite Post and Core
Developed by Editorial Team Member Dr. David Hornbrook, this technique uses a fiber such as Ribbond. Please see The Techniques, Volume 1 for the step-by-step procedure. While it is certainly a creative procedure that precludes the necessity of keeping a supply of stock posts on hand, some dentists still prefer to use a prefabricated post rather than fashion one themselves.
Stock Metal-Free
Typically used when esthetics is critical. Most utilize fiber-reinforced resin of some kind that promises to flex with the tooth to reduce root fractures. While this may be true, it is a difficult theory to prove. Several evaluators questioned whether these more flexible posts are strong enough when there is virtually no coronal tooth structure remaining and the post is necessary to retain a complete coronal core. Nevertheless, several evaluators have reported their incidence of root fractures has declined after switching to a more flexible post system.
This category covers the more conventional, metal-based posts.
