Crown Lengthening and Ferrule Effect

Crown lengthening is a surgical procedure that will make it possible for caps and other prosthetic devices to be placed on a destroyed tooth, thus protecting the tooth and avoiding tooth loss. In addition to the biological width of the gum tissue, the dental surgeon should also consider the ferrule width. A ferrule for teeth is a band of solid tooth structure that may be created around the treated tooth, which will protect the tooth from fractures, especially if the tooth is desensitized or endodontically treated.

The Ferrule and Crown Lengthening

The biologic width required for a crown lengthening is approximately 2.05 mm. In addition to this portion of bone that needs to be removed for a proper lengthening procedure, some dental surgeons may also allocate an additional 1 to 2 mm for a ferrule. A tooth ferrule is a band of solid tooth structure that will support the crown. A metallic ferrule may also be considered if there is not enough solid tooth structure. Having a solid structure around the treated tooth is often referred to as the ferrule effect, which strengthens the tooth.

The Importance of Ferrule

The ferrule has a protective role, holding together the treated tooth, and will also support the crown of the tooth. The ferrule is not used by all dental surgeons, but studies show that patients that have a ferrule have had a lower incidence of bone fracture than patients that don’t. Some dentists will refuse to use a ferrule, as more of the remaining alveolar bone will have to be removed.