| الملخص | The nickel chrome preformed metal crown-commonly called the preformed metal crown-has proved to be the most successful restoration for large cavities in primary teeth (Figure 5.1). Following the treatment of pulpally involved teeth, a restoration is required that will satisfy several criteria. Ideally, it should have the same lifespan as that remaining for the tooth and should provide protection to the remaining tooth structure that has been rendered weak and brittle after pulp therapy. Several studies have examined the lifespan of amalgam restorations in primary teeth and found that a significant number need to be replaced within the lifespan of the teeth. Our research has shown that, once fitted, preformed metal crowns rarely need to be replaced. In contrast, amalgams, composites, and glass ionomer cements must often be replaced, except in those cases where they have been used for the restoration of small one- or two-surface cavities. In addition to providing full coverage of teeth weakened by large removal of tooth substance, preformed metal crowns also provide protection from future carious attack in those teeth, especially in 'high-caries-risk' children, who are prone to developing new and secondary lesions. |
