CLINICIAN TECHNIQUE GUIDE


"Improving Patient Care Through Research & Education"

EDITORS

John W. Farah, D.D.S., Ph.D.
John M. Powers, Ph.D.

EDITORIAL BOARD

Peter Yaman, D.D.S., M.S.
William A. Gregory, D.D.S., M.S.
Santine Anderson, D.D.S.
Sabiha Bunek, D.D.S.
Lori Brown, D.D.S.
Alexandra Jacquery, D.D.S., M.S.
Brent Kolb, D.D.S.
Nizar Mansour, D.D.S.
Charles I. McLaren, D.D.S., M.S.
Thomas Poirier, D.D.S.
Kathy O’Keefe, D.D.S., M.S.
John Shamraj, D.D.S.
William T. Stevenson, D.D.S.
Robert Stevenson, D.D.S.
Victoria Thompson, D.D.S.
David Traynor, D.D.S.
Gytis Udrys, D.D.S.

EXECUTIVE TEAM

Mary E. Yakas, B.A., CMC
Annette M. Frederick
Jackie Lane, M.A.Ed.
Jennifer Kalasz
Pari Karani
Jennifer Lill, M.A.Ed.
Tony Malmsten
Tricia G. Price
Rhonda L. Tucker, B.S.
Nelson Williams

DIRECTOR OF RESEARCH

Ron Yapp, M.S.

THE DENTAL ADVISOR

3110 West Liberty
Ann Arbor, MI 48103
Toll free: 800.347.1330
E-mail: info@dentaladvisor.com
Web Site: www.dentaladvisor.com

TOOTH PREPARATION GUIDELINES FOR ZIRCONIA CROWNS

Tooth Preparation Guidelines

  • Uniform, circumferential, tooth reduction of 1.0-1.5 mm
  • Circumferential chamfer
  • Occlusal reduction of 2 mm
  • Rounded line angles
  • Reduce linguals of anteriors with football diamond to create concave lingual

Why Tooth Preparation Design is Important

  • Uniform reduction results in optimum ceramic strength
  • Adequate reduction leads to better esthetics
  • Smooth edges result in lower stress
  • Lower stress decreases potential for fracture
  • Ceramic restorations require a passive fit
  • Scanners read smooth preparations more accurately

Note: Tooth reduction for zirconia-based crowns is less than that for PFM or traditional all-ceramic crowns. The reasons are that zirconia is very strong (>1000 MPa) and no opaque layer is required.1A

Figure 1. Tooth reduction guidelines for anterior (1A) and posterior (1B) teeth.
Figure 1
Figure 2. Examples of preparations for PFM and all-ceramic crowns with more tooth reduction.
Figure 2

Figure 3. Examples of preparations for zirconia-based crowns.

Note: (3C) How thin a zirconia crown can be.
Figure 3

Favorite Burs and Steps

  1. Open contacts with #2 round or 330 carbide (S.S.White).
  2. Reduce tooth circumferentially with beveled cylinder 1812.8 C or 1812.8 F (NeoDiamond).
  3. Further reduction, especially for molars, with pointed taper 1718.8 C or 1718.8 F (NeoDiamond).
  4. Occlusal reduction and chamfer prep with C2, 855L-018 C 6.4 or C2, 855L-018 F 6.4 (Strauss Diamond).

Figure 4. Examples of pointed and round end taper burs and tooth preparation.


Figure 4
Copyright ©2009, Dental Consultants, Inc. All rights reserved. Printed in the U.S.A. (ISSN 0748-4666)