Clarke V. Filippi, DDS – Modesto & Central Valley CACrown lengthening (or crown exposure) may be required when your tooth needs a new crown or other restoration. Having the edge of a restoration too deep below the gum tissue and not accessible for oral hygiene, or too close to the bone causes a chronic irritation to the area and can lead to cavities. This procedure involves adjusting the level of the gum tissue and bone around the tooth to create a new gum-to-tooth relationship. This allows your general dentist to reach the edge of the restoration, to ensure a proper fit between the tooth and the crown. Crown lengthening can also provide adequate tooth structure to support and retain the new restoration. Afterward the edge of the restoration is also more cleansable when you brush and floss which helps prevent decay and gum disease.