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Restorative Dentistry Supporting Your Practice

What should one consider when preparing a tooth for an all-ceramic restoration? How do I cement an all-ceramic restoration?

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Preparation for all ceramic restoration requires sufficient tooth reduction to provide adequate space for porcelain, a definite finish line and smooth and rounded line angles to reduce stress concentration within the ceramic material. Adequate tooth reduction can be achieved by utilizing a silicone putty reduction guide, depth grooves, known dimension burs and measurements of temporary restorations. All-ceramic restoration margins can be placed either supragingival or equigingival as they areexcellent tooth-colored esthetic materials.

Tooth preparation guidelines

  • Axial reduction of 0.8-1mm.
  • Occlusal reduction 2mm.
  • Incisal reduction 1.5-2mm.
  • Chamfered or rounded shoulder finish line.
  • Maximum taper of 6 degree.
  • No undercuts.
  • No box and groove preparation

Cementation Protocols

Cementation procedures depend on the composition and the strength of the material which is used. For example, in order to improve the strength of glass ceramics, the material should be etched with hydrofluoric acid and bonded to tooth structure using a silane-coupling agent. However, stronger materials such as alumina, zirconia cannot be etched and they are usually cemented or adhesively bonded to tooth structure.

  • Feldspathic porcelain and leucite/lithium disilicate ceramics should be cemented with resin cement.
  • Alumina and Zirconia should be cemented either with conventional cements such as resin modified glass-ionomer, glass ionomer, resin cement or zinc phosphate cement or via surface activation and phosphate monomer-containing resin cements.
  • Zirconia can also be cemented via using zirconia primer and resin cement

Reference

  • Wilson, N. (2015) Principles and Practice of Esthetic Dentistry: Essentials of Esthetic Dentistry. Philadelphia, PA: Elsevier

1 Comment

  1. Belgin Gunay February 20, 2016

    I would like to learn more about cementation techniques/materials. The past 2 years I have been using almost exclusively Zirconia crowns and cement them with Multlink resin modified glass ionomer cement and more than 6-7 crowns came off. I never had this problem with PFM’s, I follow every rule for prep and cementation but still having this problem. On technician’s suggestion, I started using Z prime and I am hoping this will be the answer. The technician is of course sanding the inside of the crown before sending it to me.

    Reply

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