Metal crowns are used to protect damaged teeth and maintain the function of the tooth. The laboratory casting could involve the whole crown structure. This full jacket crown is often used when the tooth trauma has fractured a large amount of tooth structure. These teeth are often non-vital and have previously been treated with root canal therapy. Since a dead tooth is intrinsically weaker than a living tooth, the protection of the remaining crown is imperative to keeping this tooth from further fracturing.
Unlike a fractured non-vital tooth, teeth that have undergone abrasion or wear on their distal (back surfaces) are often living. The most common reason for this type of damage is in animals that bite on fences and cages. In order to protect from further wear and buttress up the strength of the tooth, a ¾ metal crown can be used. This covers the tooth crown on the sides, back and top of the crown.