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Indications and clinical technology of manufacture of artificial crowns Slide 2 An artificial crown is a fixed prosthetic restoration that covers more than half of the coronal portions of the tooth. There are several types of crowns. They may be made of gold, porcelain, acrylic, or a combination of these materials. Along with onlays, which are classified as extracoronal restorations, are the various kinds of crowns that make up the bal ance of the extracoronal category An artificial crown is a fixed prosthetic restoration that covers more than half of the coronal portions of the tooth. There are several types of crowns. They may be made of gold, porcelain, acrylic, or a combination of these materials. Along with onlays, which are classified as extracoronal restorations, are the various kinds of crowns that make up the bal ance of the extracoronal category Slide 3 Partial Crown A partial crown is a cast restoration made entirely from metal and covers more than half but not all of the tooth's clinical crown. A partial crown A partial crown is a cast restoration made entirely from metal and covers more than half but not all of the tooth's clinical crown. A partial crown is named according to the fractional amount of the clinical crown it covers is named according to the fractional amount of the clinical crown it covers Slide 4 Complete Crown A complete crown covers the entire anatomy of a tooths clinical crown. There are se veral types of complete crowns A complete crown covers the entire anatomy of a tooths clinical crown. There are se veral types of complete crowns Slide 5 Complete metal crown Complete metal crown Slide 6 Complete veneered crown Slide 7 Fig. 2-1. The optimum restoration should satisfy biologic, mechanical, and esthetic requirements. Slide 8 Fig. 2-2. Damage to adjacent teeth is prevented by making a thin "lip" of enamel as the bur passes through a prox imal contact. Slide 9 Fig. 2-3. Mouth mirror protecting the soft tissues during tooth preparation Slide 10 Fig. 2 - 4. a considerable amount of care is needed when preparing a tooth for a complete crown because of the extensive nature of the reduction, with many dentinal tubules sectioned. Each tubule communicates directly with the dental pulp. Slide 11 Slide 12 Fig. 2-5. Conservation of tooth structure by using partial- coverage restorations. In this case, they are used as FPD abutments to replace con- genitally missing lateral incisors. Slide 13 Fig. 2-6. Excessive taper results in considerable loss of tooth structure (shaded area). Slide 14 Fig. 2-7. An anatomically prepared occlusal surface results in adequate clearance without excessive tooth reduction. A flat occlusal preparation will result in either (1) insufficient clearance or (2) an excessive amount of reduction Slide 15 Slide 16 Fig. 2-9. Examples where subgingival margins are indicated. A, To include an existing restoration. B, To extend apical to the proximal contact (adequate proximal clearance). C and D, To hide the metal collar of metal-ceramic crowns. Slide 17 Fig. 2-10. A and B, Poor preparation design, leading to increased margin length. C, A rough, irregular margin will make the fabrication of an accurately fitted restoration almost impossible. D, An accurately fitting margin is possible only if it is prepared smoothly. Slide 18 Fig. 2-11. Precise control of the orientation of the diamond is very important. A, Tilting away from the tooth creates an undercut. B, Tilting toward the tooth results in excessive convergence. Slide 19 All unsupported enamel must be removed. Fig. 2-12. A chamfer should not be wider than half the bur used to form it. Otherwise, a lip of unsupported enamel will be left. Slide 20 Fig. 7-31. The recommended convergence angle is 6 degrees. This is a very slight taper. (The angle between the hands of a clock showing 12:01 is 5 1/2, degrees.) Slide 21 Internal features effectively increase resistance. Fiji- 7-33. Retention form of an excessively tapered preparation can be increased by adding grooves or pin holes, because these will limit the paths of withdrawal. Slide 22 Fig. 7-47. Recommended tooth preparation for a metal-ceramic restoration. The facial reduction has two distinct planes. Slide 23 Slide 24 Slide 25 Slide 26 Slide 27 Slide 28 Slide 29 Slide 30