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Dent Clin N Am 48 (2004) 417–431
Cervical margin design
with contemporary
esthetic restorations
Guided by:
Dr. Akshey Shar...
Metal ceramic and all-ceramic crowns are used
frequently to restore esthetics and function.
One of the essentials for su...
Wherever esthetics permit – supragingival
margins
High esthetic demands – intra-crevicular margin
placement (requires pr...
Margin placed
a short
distance from
free gingival
margin
Minor amount
of gingival
recession
Exposure of
margin and
estheti...
Potential landmarks for accurate margin placement
1. place cervical margins 0.5 mm apical to the Free
Gingival Margin
2. s...
Error - Flattening the cervical margin in the inter-
proximal areas leads to violation of biologic width
and elicits a chr...
Criteria for margin selection
1. The selected margin must provide a predictable
level of marginal integrity.
2. To minimiz...
Problems from improper preparation and
placement of cervical margins
1. biologic width violation (function of margin place...
Margins to consider for
metal ceramic restorations
Knife-edge margin
1. Termination is difficult to read on a gypsum die, fit
is often compromised
2. Thin margins are prone ...
Chamfer margin
1. Relative inherent lack of specificity of depth
2. Due compromised marginal integrity as a result of
dist...
3 cervical margins seem to meet the criteria for marginal
integrity -shoulder, shoulder-bevel and slant shoulder.
Shoulde...
These restorations have used a shoulder-bevel margin that provides
optimum
marginal integrity and a smooth, polished surfa...
The use of a shoulder margin with a porcelain labial
margin results in smooth, glazed porcelain in the gingival
crevice.
The slant shoulder can be used with a metal collar or with the
so-called disappearing margin.
If metal collar is used, i...
Third criterion- esthetics
Shoulder-bevel – polished metal collar of 1 mm or more
Steep bevel of approximately 60° shoul...
If esthetics is important, the clinician has
three options.
All ceramic crown - excellent esthetics,
improved longevity,...
When a metal-ceramic restoration is indicated, the
porcelain labial margin (shoulder) and the disappearing
margin (slant ...
The disappearing margin effectively
hides the metal margin but often results
in cervical opacity.
If patients accept chara...
The margin of choice in esthetic situations when using
metal-ceramic crowns is a shoulder design with a porcelain
labial ...
These metal-ceramic restorations with porcelain labial
margins provide acceptable esthetics when the margins are
hidden wi...
The preparation for porcelain labial or buccal margins
mandates a shoulder margin on the buccal half of the
tooth and a s...
Controversies
Use of 360° porcelain margin (improved light transmission)
Termination of gingival extension of the metal
...
Discussion
When preparing teeth for esthetic crown restorations, the
clinician must determine which cervical finish line ...
With metal-ceramic crowns, knife-edge margins and chamfer
margins should generally be avoided due to concerns with fit.
...
Slant shoulder margins are necessary when the tooth preparation
extends some distance on the root surface.
In situations...
An analysis of margin configurations for metal-ceramic
crowns
Donovan, T and Prince, J 1985, J Prosthet Dent, vol. 53, no....
Sloped shoulder
Advantages
1. Minimum metal display
2. Less intrusion into crevice
3. Simplified laboratory technique
Disa...
Margin designs for esthetic restoration: An
overview
Chatterjee, Journal of Advanced Oral Research, Vol 3; Issue 1: April ...
*Gardner et al. (1997) compared the load necessary to
cause porcelain failure on traditionally fabricated
metal–ceramic cr...
*Bishop K et al. (1996) reviewed margin design for
porcelain fused to metal restorations which extend onto
the root.
*A 90...
*Omar et al. (1987) conducted a scanning electron
microscopy of the marginal fit of ceramo-metal
restorations with faciall...
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Cervical margin design

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Cervical margin design

  1. 1. Dent Clin N Am 48 (2004) 417–431 Cervical margin design with contemporary esthetic restorations Guided by: Dr. Akshey Sharma Dr. Pardeep Bansal Dr. Gagandeep Chahal Presented by: Dr Aditi Ghai PG 2nd year Dept of Prosthodontics D.I.R.D.S, Faridkot
  2. 2. Metal ceramic and all-ceramic crowns are used frequently to restore esthetics and function. One of the essentials for success with either option is proper tooth preparation, which includes proper selection and preparation of the cervical margin of the preparation. Regardless of the margin geometry, proper placement of the prepared gingival margin in relation to the free gingival margin, the epithelial attachment, and the alveolar housing is imperative.
  3. 3. Wherever esthetics permit – supragingival margins High esthetic demands – intra-crevicular margin placement (requires precision)
  4. 4. Margin placed a short distance from free gingival margin Minor amount of gingival recession Exposure of margin and esthetic failure Margin too deep Biological width violation Chronic gingival inflammation
  5. 5. Potential landmarks for accurate margin placement 1. place cervical margins 0.5 mm apical to the Free Gingival Margin 2. sound through the attachment to probe the crest of the alveolar bone and to place cervical margins at least 4mm coronal to that alveolar crest With either, prepared cervical margin should follow the scalloped anatomy of the alveolar bone, the attachment, and the gingival tissues.
  6. 6. Error - Flattening the cervical margin in the inter- proximal areas leads to violation of biologic width and elicits a chronic inflammatory response.
  7. 7. Criteria for margin selection 1. The selected margin must provide a predictable level of marginal integrity. 2. To minimize plaque accumulation, the selected margin must present smooth materials to the gingival sulcus. 3. In some situations, the margin also must provide acceptable esthetics.
  8. 8. Problems from improper preparation and placement of cervical margins 1. biologic width violation (function of margin placement; independent of margin design) 2. metal margins showing through thin marginal gingiva 3. recession exposing the tooth/restorative interface (improper soft tissue management; independent of margin design) 4. opacity in the cervical third of the restoration 5. roughness of the cervical margin which contributes to plaque accumulation
  9. 9. Margins to consider for metal ceramic restorations
  10. 10. Knife-edge margin 1. Termination is difficult to read on a gypsum die, fit is often compromised 2. Thin margins are prone to distortion during ceramic firing 3. Potential for metal display – lack esthetics 4. Limited use - root has been amputated due to periodontal disease or with cusp fractures where a knife-edge margin cannot be avoided
  11. 11. Chamfer margin 1. Relative inherent lack of specificity of depth 2. Due compromised marginal integrity as a result of distortion of the metal framework during porcelain firing 3. Distortion depends on composition of metal alloy (melting pt.) and cervical geometry of the margin
  12. 12. 3 cervical margins seem to meet the criteria for marginal integrity -shoulder, shoulder-bevel and slant shoulder. Shoulder and shoulder-bevel margin seem to resist distortion due to the inherent bulk of metal at the margin Also meet the criterion related to the use of smooth materials in the gingival crevice The shoulder can be used with a metal margin, which can be highly polished, or with a porcelain margin, which results in glazed porcelain in the sulcus. The shoulder-bevel margin has a collar of metal 1 mm or more in width and thus places highly polished metal in the sulcus.
  13. 13. These restorations have used a shoulder-bevel margin that provides optimum marginal integrity and a smooth, polished surface.
  14. 14. The use of a shoulder margin with a porcelain labial margin results in smooth, glazed porcelain in the gingival crevice.
  15. 15. The slant shoulder can be used with a metal collar or with the so-called disappearing margin. If metal collar is used, it can be highly polished and thus can be acceptable as it relates to plaque accumulation Disappearing margin is rough due to the presence of three different materials at the terminus -- oxidized metal (75 times rougher than polished metal), -- opaque porcelain (rougher than glazed porcelain), and -- body porcelain (porous because it tends to shrink toward the greater mass of porcelain coronal to the margin).
  16. 16. Third criterion- esthetics Shoulder-bevel – polished metal collar of 1 mm or more Steep bevel of approximately 60° should be used to maximize the slip-joint effect and close the margin Best initial fit, maintained after firing cycles Problem with esthetics used where esthetics is not important. The margin can be placed partially in the sulcus, in an equi- gingival position, or a supragingival position. Metal display – informed consent
  17. 17. If esthetics is important, the clinician has three options. All ceramic crown - excellent esthetics, improved longevity, avoid on posteriors. A shoulder margin with rounded internal angle should be prepared to end at approximately 90° to the external angle of the labial or buccal surface. A slight slant of no more than 5° is acceptable. The margin should be as smooth as possible, and, to provide optimum esthetics and strength, should be between 1.2 and 1.5 mm in depth (adequate bulk, cervical margin in compression during function).
  18. 18. When a metal-ceramic restoration is indicated, the porcelain labial margin (shoulder) and the disappearing margin (slant shoulder) can be used. Slant shoulder – inherent roughness – only where indicated, that is when the cervical margin of the restoration must be placed a considerable distance down the root surface. Low smile line - slant shoulder with a metal collar If the smile exposes the cervical portion of the restoration - disappearing margin (hides metal but opacious appearance – masked with intrinsic coloration)
  19. 19. The disappearing margin effectively hides the metal margin but often results in cervical opacity. If patients accept characterization, cervical opacity can often be masked with internal coloration.
  20. 20. The margin of choice in esthetic situations when using metal-ceramic crowns is a shoulder design with a porcelain labial margin. thickness of ceramic material at the margin so that a predictable esthetic result is assured excellent strength places glazed porcelain in the gingival sulcus The porcelain margins illustrated combine good marginal integrity with excellent esthetics.
  21. 21. These metal-ceramic restorations with porcelain labial margins provide acceptable esthetics when the margins are hidden with healthy gingival tissues.
  22. 22. The preparation for porcelain labial or buccal margins mandates a shoulder margin on the buccal half of the tooth and a shoulder bevel or chamfer on the lingual half. The premolar has been prepared for a porcelain shoulder margin, and the molar has been prepared for a shoulder-bevel margin.
  23. 23. Controversies Use of 360° porcelain margin (improved light transmission) Termination of gingival extension of the metal substructure relative to the shoulder margin (metal framework be cut back 1 mm from the shoulder margin) With all-ceramic crowns, the optimum finish line is a shoulder margin with rounded internal angle with a width of 1.2 to 1.5 mm. This depth may have to be reduced to 1.0 mm with triangular- shaped teeth. It should meet the external surface of the tooth at an angle of 90
  24. 24. Discussion When preparing teeth for esthetic crown restorations, the clinician must determine which cervical finish line is appropriate for each specific clinical situation. All cervical margins must be placed in the correct position relative to the free gingival margin, the epithelial attachment, and the alveolar housing. With all-ceramic crowns, the optimum finish line is a shoulder margin with rounded internal angle with a width of 1.2 to 1.5 mm. This depth may have to be reduced to 1.0 mm with triangular-shaped teeth. It should meet the external surface of the tooth at an angle of 90.
  25. 25. With metal-ceramic crowns, knife-edge margins and chamfer margins should generally be avoided due to concerns with fit. Shoulder-bevel margins are the margins of choice in situations where esthetics is not important because of their documented ability to provide optimum fit and the ability to polish the inherent metal collar. Shoulder margins with a labial or buccal porcelain margin are indicated in situations where esthetics is paramount. These margins should be prepared at 90° to the external tooth surface, should be exceptionally smooth, and should have a width of 1.2 mm. The metal substructure should be finished 1.0 mm from the shoulder margin to permit optimum light transmission without sacrificing strength.
  26. 26. Slant shoulder margins are necessary when the tooth preparation extends some distance on the root surface. In situations where these margins are not visible, they should use a metal collar. In situations where the smile exposes these margins, the disappearing margin approach should be used.
  27. 27. An analysis of margin configurations for metal-ceramic crowns Donovan, T and Prince, J 1985, J Prosthet Dent, vol. 53, no. 2, pp. 153 Esthetics, marginal integrity, and periodontal health are the three major determinants of marginal configuration with metal-ceramic crowns. The advantages, disadvantages, and indications for each type of margin configuration are as follows: Beveled shoulder Advantages 1. Marginal closure 2. Relative lack of distortion 3. Polished surface at margin Disadvantages 1. Bevel must be steep to be effective 2. Esthetics Indications: Nonesthetic regions
  28. 28. Sloped shoulder Advantages 1. Minimum metal display 2. Less intrusion into crevice 3. Simplified laboratory technique Disadvantages 1. Difficult tooth preparation 2. Potential distortion 3. Rough materials at margin edge Indications: Esthetic regions in patients with excellent oral hygiene
  29. 29. Margin designs for esthetic restoration: An overview Chatterjee, Journal of Advanced Oral Research, Vol 3; Issue 1: April 2012 *Jalalian E et al (2008) evaluated the effect of a sloping shoulder and a shoulder bevel on the marginal integrity of porcelain-fused-to-metal (PFM) veneer crowns *Marginal integrity of both preparation designs was found to be similar. *Since the sloping shoulder design offers biological and esthetical advantages over the shoulder bevel, its use is indicated for anterior restorations.
  30. 30. *Gardner et al. (1997) compared the load necessary to cause porcelain failure on traditionally fabricated metal–ceramic crowns cemented to metal tooth analogs with two different types of margins. *The load required to cause porcelain fracture in the crowns with porcelain facial margins was statistically significantly greater than the load required to cause porcelain fracture for crowns with metal collars
  31. 31. *Bishop K et al. (1996) reviewed margin design for porcelain fused to metal restorations which extend onto the root. *A 90 degree shoulder is probably the most commonly used margin design. This increases the risk of irreversible damage to the pulp, particularly on exposed roots. *So more conservative designs, such as the 135 degree shoulder or deep chamfer, should be considered
  32. 32. *Omar et al. (1987) conducted a scanning electron microscopy of the marginal fit of ceramo-metal restorations with facially butted porcelain margins. *The marginal openings for facially butted metal ceramic crowns were greater than the bevelled shoulder marginal design. *Aesthetics and the favourable contour of the facially butted porcelain are distinct advantages but are accompanied by increased laboratory time.
  33. 33. THANK YOU

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