What is the maximum post length allowed if the root is 16 mm long?

In determining the maximum post length allowed when the root length is 16 mm, the focus is primarily on maintaining optimal tooth structure and ensuring the post does not extend beyond the root's length. The rationale behind limiting the post length is to preserve the integrity of the remaining tooth structure and prevent any potential complications, such as perforation of the apical foramen.

When the root measures 16 mm, the recommended approach is usually to allow for a post length that does not exceed the remaining root structure. In this case, the maximum post length recommended is 11 mm, which balances the need for retaining adequate root structure while providing sufficient retention for the crown that will be placed above the post.

Options that suggest a post length equal to or greater than the root length (16 mm or 20 mm) exceed what is typically advised, as they risk encroaching upon the periodontal tissues and compromise the health of the tooth.

Thus, the choice of 11 mm reflects an understanding that while the post needs to be effective for support, it must also respect the boundaries established by the tooth root's length. This ensures a safer clinical outcome.