1) Margin placement is an important consideration in maintaining healthy gingival tissues. Options for margin placement include supragingival, equigingival, and subgingival. 2) The biologic width is the dimension of space occupied by healthy gingival tissues between the sulcus and underlying bone. Violations of the biologic width can be identified clinically or radiographically and corrected surgically or orthodontically. 3) Provisional restorations must have adequate marginal fit, crown contour, and surface finish to maintain gingival health during treatment. Marginal openings, overcontouring, and subgingival debris can cause inflammation.

1. Biologic Consideration
By SHAMIN JOSHI
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2. Biologic Considerations
• Margin Placement and Biologic Width
• Tissue Retraction
• Provisional Restorations
• Marginal Fit
• Crown Contour
• Subgingival Debris
• Hypersensitivity to Dental Materials
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3. Margin Placement and Biologic
Width
• most important aspects of understanding periodontal-restorative
relationship is the location of the restorative margin to the
adjacent gingival tissue.
• Restorative clinicians must understand the role of biologic width
in preserving healthy gingival tissues and controlling the gingival
form around restorations
• There are three options for margin placement:
1 ) Supragingival,
2 ) Equigingival (even with the tissue), and
3 ) Subgingival 3

4. Advantages of extending restoration gingivally
1) to create adequate resistance and retentive form in the preparation
2) to make significant contour alterations because of caries or other tooth
deficiencies
3) to mask the tooth/restoration interface by locating it subgingivally.4

5. Biologic Width
• dimension of space that the healthy gingival tissues occupy between
the base of the sulcus and the underlying alveolar bone is
comprised of the junctional epithelial attachment and the connective
tissue attachment. The combined attachment width is now identified
as the biologic width.
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6. Biologic Width Evaluation
• to identify interproximal violations of biologic width.
• Methods
1 ) Clinical ( discomfort when the restoration margin levels are being assessed with a
periodontal probe, it is a good indication that the margin extends into the attachment
and that a biologic width violation has occurred. o PT )
2) Radiographs ( for interproximjal violation but mesiofacial and distofacial line angle nt
seen properly )
3) Bone sounding ( probing under anesthesia )
• If this distance is less than 2 mm or more
at one or more locations, a diagnosis of
biologic width violation can be confirmed.
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7. .
• In 1994, Vacek et al also investigated the biologic width
phenomenon they also reported a range of biologic widths as narrow
as 0.75 mm in some individuals, whereas others had biologic widths
as tall as 4.3 mm .
• The biologic width can be identified for the individual patient by
probing to the bone level and subtracting the sulcus depth from the
resulting measurement.
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8. Correcting Biologic Width
Violations
• Biologic width violations can be corrected either by ;-
1) Surgically
removing bone away from proximity to the restoration margin
2) orthodontically extruding the tooth and thus moving the margin away from
the bone.
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9. Surgery
• Surgery is the more rapid of the two treatment options (also crown
lengthening )
• In these situations the bone should be moved away from the margin by the
measured distance of the ideal biologic width , with an additional 0.5 mm as
a safety zone.
• Disadvantage
1) gingival recession after removal of bone
2) papillary recession ( interproximal removal )
3) creation of an unesthetic triangle of space
below the interproximal contacts.
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10. Extrusion
• .
1) low force - tooth will erupt slowly, bringing alveolar bone and gingival
tissue with it until the bone level has been carried coronal to the ideal level
by the amount that needs to be removed surgically to correct the
attachment violation. The tooth is stabilized and then surgerically corrected
.
2) Rapid orthodontic extrusion - tooth is erupted to the desired amount over
several weeks. (supracrestal fiberotomy is performed circumferentially
around the tooth weekly ,stabilized for at least 12 weeks to confirm the
position of the tissue and bone )
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11. Margin Placement Guidelines
• The first step in using sulcus depth as a guide in margin placement is to
manage gingival health. Once the tissue is healthy, the following three
rules can be used to place intracrevicular margins
• Rule 1: If the sulcus probes 1.5 mm or less, place the restoration
margin 0.5 mm below the gingival tissue crest. This is especially
important on the facial aspect and will prevent a biologic width violation
in a patient who is at high risk in that regard.
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12. • Rule 2: If the sulcus probes more than 1.5 mm, place the margin
half the depth of the sulcus below the tissue crest.
This places the margin far enough below tissue, so that it will still be
covered if the patient is at higher risk of recession.
• Rule 3: If a sulcus greater than 2 mm is found, especially on the
facial aspect of the tooth, evaluate to see if a gingivectomy could be
performed to lengthen the teeth and create a 1.5-mm sulcus. Then
the patient can be treated using Rule 1.
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13. Clinical Procedures in Margin
Placement
• The placement of supragingival or equigingival margins is simple
because it requires no tissue manipulation.
• With regard to overall tooth preparation, the amount reduced is
dictated by the choice of restorative materials.
• Before extending subgingivally , the preparation should be
completed to the free gingival margin facially and interproximally .
• This allows the margin of the tooth preparation to be used as a
reference for subgingival extension once the tissue is retracted .
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14. Tissue Retraction
• Once the supragingival portion of the preparation is completed, it is
necessary to extend below in appropriate depth in the sulcus,
• tissue must be protected from abrasion, which will cause hemorrhage and
can adversely affect the stability of the tissue level around the tooth.
• Access to the margin is also required for the final impression, with a clean,
fluid-controlled environment.
• Tissue management is achieved with
gingival retraction cords
Thin, fragile gingival tissues and
shallow sulcus situations usually dictate that
smaller diameter cords be chosen to achieve
the desired tissue displacement.
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15. For a Rule 1 margin (sulcus
depth 1.5 mm or less),
• the cord should be placed so that the top of the cord is located in the sulcus
at the level in which the final margin is to be established (0.5mm)
• With this initial cord in place, the preparation is extended to the top of the
cord
• To create space and allow access for a final impression,needs second
retraction cord that it displaces the first cord apically and sits between the
margin and the tissue .
• For the final impression, only the top cord is removed, leaving the margins
visible and accessible to be recorded with the impression material The initial
cord remains in place in the sulcus until the provisional restoration is
complete
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16. For Rule 2 situations in which
the sulcus is deeper
• two larger diameter cords are used to deflect the tissue before extending the
margin apically .
• The top of the second cord is placed to identify the final margin location at
the correct distance below the previously prepared margin, which was at the
gingival tissue crest level
.
• The margin is lowered to the top of the second cord then a third cord is
placed in preparation for the impression .
• In the patient with a deep sulcus in which the margin may be 1.5 to 2.0 mm
below the tissue crest, electrosurgery is often required to remove any
overlying tissue in the retraction process )
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17. Provisional Restorations
• Three critical areas must be effectively managed to produce a favorable
biologic response to provisional restorations.
1) marginal fit,
2) crown contour
3) surface finish
• Its helps to maintain the health and position of the gingival tissues during
the interval until the final restorations are delivered.
• Provisional restorations that are poorly adapted at the margins, that are
overcontoured or undercontoured, and that have rough or porous surfaces
can cause inflammation, overgrowth, or recession of gingival tissues.
• As a result it compromises final restoration .
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18. Marginal Fit
• Marginal fit has clearly been implicated in producing an inflammatory
response in the periodontium.
• It has been shown that the level of gingival inflammation can increase
corresponding with the level of marginal opening.
• Margins that are significantly open are capable of harboring large numbers
of bacteria and may be responsible for the inflammatory response
• However, the quality of marginal finish and the margin location relative to
the attachment are much more critical to the periodontium .
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19. Crown Contour
• Ideal contour provides 1) access for hygiene
2) fullness to create the desired gingival form
3) pleasing visual tooth contour in esthetic areas.
• Evidence demonstrates a relationship between overcontouring and gingival
inflammation, whereas undercontouring produces no adverse periodontal
effect.
• most frequent cause of overcontoured
restorations is inadequate tooth
preparation by the dentist, which
forces the technician to produce a
bulky restoration to provide room
for the restorative material.
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20. Subgingival Debris
• Leaving debris below the tissue during restorative procedures can create an
adverse periodontal response. The cause can be retraction cord, impression
material, provisional material, or either temporary or permanent cement.
• The diagnosis of debris as the cause of gingival inflammation can be
confirmed by examining the sulcus surrounding the restoration with an
explorer, removing any foreign bodies, and then monitoring the tissue
response.
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21. Hypersensitivity to Dental
Materials
• Inflammatory gingival responses have been reported related to the use of
non precious alloys in dental restorations (nickel, )
• Hypersensitivity responses to precious alloys are extremely rare, and these
alloys provide an easy solution to the problems encountered with the
nonprecious alloys.
• More importantly, tissues respond more to the differences in surface
roughness of the material rather than to the composition of the material.The
rougher the surface of the restoration subgingivally, the greater are the
plaque accumulation and gingival inflammation.
• porcelain, highly polished gold, and
highly polished resin all show similar
plaque accumulation. 21

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