Functional crown lengthening is a procedure performed when there is not enough exposed tooth structure upon which to place a restoration. It is often done when a tooth fractures at or below the gumline or when the tooth is significantly decayed. In order to save and properly restore the remaining tooth, a periodontist may remove gum tissue and/or bone to expose more healthy tooth structure. As a result, a crown-lengthened tooth will probably appear longer, since more of the tooth has been exposed.