Dental posts enable restorations that would otherwise be impossible due to inadequate tooth structure. A post or fiberglass rod is considered a base restoration because it allows the build-up of tooth structure and root systems so that crowns can be placed. Pre-sized posts take less time to install, and there are many options for finding a good fit. Fiber posts are radiopaque; this makes the post visible on an x-ray. The dentist should keep a variety of markers on hand; this enables him to choose the best fitting post and shape for each treatment.