If a deep restoration is required, a cement base is placed below metallic restoration. Such a base isulates the pulp of the tooth from the irritation of thermal sensations transmitted through metallic restorations.
A crown is a restoration a part or all of the coronal portion of a tooth. A full cast gold crown is suitable for the posterior portion of the mouth, where strength is needed and appearance is secondary. Often the entire crown portion of an anterior tooth requires restoration.
A crown made from a ceramic can be used because this material combines strength with excellent esthetic properties. A ceramic-fused-to-metal crown, which combines the esthetics of a ceramic veneer and the strength and fit of a cast metal crown may be used.
On occasion, the pulp of the tooth becomes infected and must be removed. Drilling through the crown allows access to remove the pulp and to clean out the root canal. Once the infection is controlled the root canal is failed-frequently with gutta-percha rubber- a restoration is placed in the access opening. If the croen of the tooth is degraded severaly, a metal post and core can be fabricated and cemented into the root canal. A ceramic or other restoration can be made and cemented to the core.
Esthetic veneers maybe used to cover unsightly areas of anterior teeth that are severaly discolored, malformed, or crowded. The veneer can be made from a resin composite that can be placed directly ir indirectly (cemented) or can be cemented ceramic veneer. Stained and deformed maxillary teeth can be treated using veneers.
The fixed partial dentures, sometimes called a bridge is used to replaced a missing tooth or teeth. The two tteth adjacent to the space must be prepared with abutment (anchor) restorations to support the artificial tooth (pontic) or teeth. Gold or nickel-chromium alloys are used for fixed partial dentures because of their strength, tarnish resistance, and ease of casting (fabrication). A fixed partial denture may be made with a facing of acrylic resin or veneered with porcelain. Cements are used to retain the fixed partial denture permanently in place on the abutment teeth. Again, different cement products are available.
A similar type of restoration, known as a resin-bonded bridge, or Maryland bridge, has been used for several years. The pontic is attached to the two abutment teeth by concave metal extentions that clasp the lingual and interproximal surfaces. These abutments are bonded to the enamel of the abutment teeth with adhesive cements. The enamel and metal surfaces should be etchad so that the resin adhesive cements from a micromechanical attachment.
to be continue….
taken from Dental Material, Robert G. Craig
Tidak ada komentar:
Posting Komentar