Preparation of space for posting can be prepared manually or mechanically with rotary instruments, such as Peeso drills, Gates-Glidden burs, or other types of rotary instruments. Regard­ less of the type of instrument used, ac­ cidents and errors, such as perfora­ tions and stripping of root structures can occur. Specific information on the effect of rotary drill size on the thick­ ness of canal walls is not provided in the literature. Unfortunately, post cav­ ity preparation is sometimes consid­ ered as nothing more than a hole drilled into the canal to receive a post, with little attention given to the anatomy of the root.