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2. CONTENTS
Introduction
Periodontium
Biological width
Evaluation of biological width
Evaluation of periodontal width
Location of the margin
Supragingival
Subgingival
Crown lengthenng procedures
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3. Periodontal health and restorative procedures
Various finish lines
Soft tissue management
Restorative materials
Functional effects
Techniques to improve the fit of the cast restrotation
Maintenance phase
Summary and conclusion
References
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5. PERIODONTIUM
GINGIVA
Its the part of the mucosa that covers the alveolar process
of the jaws and sorrounds the necks of the teeth.
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6. PERIODONTAL LIGAMENT
o It’s the connective tissue that sorrounds the root and connects it to
the bone
o Its mainly made of collagen fibres - principle fibres
o Attachment complex – Supracrestal fibres
o - Junctional epithelium
o BIOLOGICAL WIDTH or the Subcrevicular attachment complex
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7. BIOLOGICAL WIDTH
It’s the dimension of space that the healthy gingival tissues occupy
above the alveolar bone.
It refers to the combined connective tissue-epithelial attachment from
the crest of the alveolar bone to the base of the sulcus.
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9. Nevins and Sukrow in 1984 recommended that for the maintenance
of healthy periodontium, no restoration should violate the
attachment ,even though its not possible for a clinician to identify
the most coronal extent of the junctional epithelium.
Wilson and majnard cautioned against extending restorations so far
subgingivally that the attachment complex is damaged.They stated
that “Some distance of unprepared tooth structure should remain
between the finished line and junctional epithelium and this distance
should be ideally 0.5mm.
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10. Eissman et al recommended that restorations not be
placed at or near the alveolar crest and there must be
2mm of root surface between the alveolar crest and the
restoration to provide for biological width.
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11. Evaluation of the biological width
Radiographs
Probing
Sounding of bone
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12. Evaluation of the periodontal health:-
Clinical examination
Probing
Intracrevicular fluid
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13. Gingival index:-(Loe and Silness)
0 Normal gingiva
1 Mild inflamation
Slight change in colour and edema.No
bleeding on probing
2 Moderate inflammation
Redness and edema .Bleeding on probing
3 Severe inflamation
Marked redness,edema and
ulcerations.Spontaneous bleeding
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14. The Supporting tissues should be in a state of
health prior to preparation of a tooth for any
restoration.
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16. Supragingival margin:-
Least traumatic to the soft tissues
Margin placement…
Clinical verification…
Easily finished
Impressions are easily made
Most accessible for cleansing
Restorations can be easily evaluated
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17. Subgingival margins:-
Clinical crown is short…
Old restorations…
Esthetic appearance
Caries, abrasion or erosion…
Root sensitivity
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18. The healthy, stable gingival margin is the reference of
choice
Acc to Wilson and Maynard, the restorations are placed no
deeper than 0.5mm into the sulcus so that they can be
reached by the patients hygienic efforts
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20. Criteria for subgingivl margin placement:-
Emergence profile
Margins are closed and properly finished
Adequate band of attached gingiva
Margin should not violate the biological width
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21. Crown lengthening procedures:-
It’s a procedure similar to the apical repositioning of the flap with
concomitant ostectomy or osteoplasty.
Indications –
Short clinical crown
Restoration impinge on the biological width
Hopless teeth
Crown lengthening procedure -
Surgical methods
Orthodontic method
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23. Review of literature:supragingival/subgingival
Guy.M.Newcomb in 1974 conducted a study on “The relationship
between the location of subgingival crown margins and gingival
inflamation” and concluded that the nearer a subgingival crown
margin approaches the base of the gingival crevice, the more likely
its that severe inflammation will occur.
D.A.Orkin and D. bradshaw in 1987 conducted a study on the
“Relationship of the positions of crown margins to gingival health”
and showed that gingival tissues tend to bleed 2.42 times more
frequently with subgingival margins and have 2.65 times higher
chance of gingival recession
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24. D.A.Felton in 1991 conducted a study on “Effects of in vivo
crown margin discrepancies on the periodontal health” in
his study he strongly supported the placement of
supragingival margins for artificial crowns and FPD’s.
William.G.Reeves in his review article concluded that more
supragingivally a restorative margin is placed,the less
chance that the margin will contribute to gingival
inflammation.
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25. Periodontal health and restorative procedures:
Tooth preparation
Temporary restorations
Functional effects of the reconstruction impinging on the
periodontium
Principles of tooth preparations:-
Preservation of tooth structure
Retentation and resistance form
Structural durability
Marginal integrity
Preservation of the periodontium
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26. Marginal integrity
The restoration can survive in the biological environment …
The configuration of the preparation finish lines dictates…
For evaluation following guidelines for margin design are described:
Ease of preparation without overextension or unsupported enamel
Ease of identification in the impression and on the die
Sufficient bulk of the material
Conservation of the tooth structure
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27. Finish lines
The most important consideration in selecting a cervical margin design
is its ability to consistently and predictably provide excellent
marginal integrity.
Knife edge
Chamfer
Shoulder
Shoulder with bevel
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28. Knife edge
Conservation of the tooth structure
Permits an acute margin of the metal
Disadvantages:
The axial reduction may fade out
Thin margin may be difficult to accurately wax and cast
More susceptible to distortion
Results in overcontouring
Indications:
Lingual surface of mandibular posterior teeth
The surfaces towards which tooth has tilted
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29. Chamfer
It provides distinct margin
Adequate bulk to the restoration
Easier to control
Round end tapered fissure bur or torpedo bur
Care needed to avoid unsupported lip of enamel
Indications:
Cast metal restorations
Lingual margin of the metal ceramic crowns
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30. Shoulder
Bulk of the restoration
Wide ledge provides resistance to occlusal forces
Provides space for healthy restorative contours
Maximum esthetics
It offers resistance against distortion during processing
Disadvantages:
Requires destruction of more tooth structure
The sharp 900
internal line angle…
Indications:
All ceramic restorations
Facial magins of metal-ceramic crowns
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31. Radial shoulder:
Stress concentration is less in the tooth structure
Shoulder with bevel:
Used as a gingival finish line on the proximal box of inlays and onlays
Gingival esthetics is not critical…
Shoulder is already present…
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32. Biological width violations are primarily a function
of margin placement and are independent of
margin design. – Donovan TE
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