The preparation for a metal-ceramic crown requires significant tooth reduction to provide sufficient space for the restorative materials. To achieve better esthetics, the facial margin of an anterior restoration is often placed subgingivally, which increases the potential for periodontal disease. However, a supragingival margin can be used if significant cosmetic concerns do not prohibit it or if the restoration incorporates a porcelain labial margin (see Chapter 24).
Compared to an all-ceramic restoration, the metal-ceramic crown may have slightly inferior esthetics, but it can be used in higher-stress situations or on teeth that would not provide adequate support for an all-ceramic restoration.
Because of the glasslike nature of the veneering material, a metal-ceramic crown is subject to brittle fracture (although such failure can usually be attributed to poor design or fabrication of the restoration). A frequent problem is the difficulty of accurate shade selection and of communicating it to the dental ceramist. This is often underestimated by the novice. Since many procedural steps are required for both metal casting and porcelain application, laboratory costs generally place the metal-ceramic restoration among the more expensive of dental procedures.
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