JMSCR Volume||2||Issue||5||Page 1242-1248||May 2014
www.jmscr.igmpublication.org
2014
Impact Factor-1.1147 ISSN (e)-2347-176x
Biologic Width and Its Importance in Dentistry Author
Preetha Selvan Saveetha Dental College Email id:
[email protected]
Abstract Biological width and the health of the periodontium are inseparable. Any violation of the biological width impairs the normal periodontium. This article gives a brief overview about the concept of biological width and it's importance in implants and restorative dentistry. Key words: Biological width, periodontium, margin placement, violation of biological width, periodontitis
INTRODUCTION Biological width is defined as the dimension of
A similar study performed by Vacek et al 1994
soft tissue which is attached to the portion of the
[2]
tooth
alveolar
concluded that the connective tissue attachment
bone.(Gargiulo et al 1961) Gargiulo et al
was the most consistent measurement based on the
described the dimensions and relationships of the
mean measurements of 1.34 mm for sulcus depth ,
dentogingival junction in humans. Following his
1.14 mm for epithelial attachment and 0.77 mm
work, the biological width was found to be 2.044
for connective tissue attachment .
which represents:a sulcus depth of 0.6mm,an
Further studies by Newcomb (1974) [3 ] ,Gunay et
epithelial attachment of 0.97mm and connective
al (2000), [4 ]Maynard and Wilson (1979) [5 ]
tissue attachment of 1.07mm. [1]
,Tal et al (1986)
coronal
to
the
crest
of
by
evaluating
cadaver
tooth
surfaces
[6 ]and Nevins and Skurow
(1984) [7] suggest that violation of biological width must be prevented. Preetha Selvan JMSCR Volume 2 Issue 5 May 2014
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2014
CONCEPT OF BIOLOGICAL WIDTH
If this distance is less than 2mm at one or more
Encroachment of the biological width becomes of
locations, a diagnosis of biological width violation
particular
the
can be confirmed. This measurement must be
restoration of a tooth that has fractured or been
performed on teeth with healthy gingiva and
caries near the alveolar crest. [8]
should be repeated on more than one tooth to
Maynard
concern
and
Wilson
periodontium into physiologic,
when
considering
(1979)
divided
the
3 dimensions: superficial
crevicular
physiologic
and
ensure accurate assessment and reduce individual and site variations. [10] In 2000,Kois proposed
three categories of
subcrevicular physiologic. [5]
biological width based on total dimension of
The superficial physiologic dimension represent
attachment and the sulcus depth following bone
the free and attached gingival surrounding the
sounding
tooth, while the crevicular physiologic dimension
crest,high crest,low crest. [11]
represents the gingival dimension from the
Normal crest patients: The midfacial measurement
gingival margin to the junctional epithelium. The
is 3mm and the proximal measurement range from
subcrevicular physiologic space is analogous to
3mm to 4.5mm . It occurs approximately 85% of
the biologic width described ( Gargiuloetal 1961) ,
the time. The gingival tissues tend to be stable in
consisting of the junctional epithelium and
patients.
connective tissue attachment. [9]
High crest patients:It occurs in approximately 2%
Maynard and Wilson claimed that all three of
of the time. There is one area where the crest is
these dimensions affect restorative treatment
seen more often, in a proximal surface adjacent to
decisions and the clinician should conceptualize
an edentulous site. In these patients, the mid- facial
all three areas and the interplay between them and
measurement is less than 3mm.
restorative margins. [5]
Low crest patients:It occurs approximately 13%of
In particular, authors claimed that to prevent the
the time. The mid-facial measurement is greater
placement
than 3mm and the proximal measurement is
of
'permanent
calculus',margin
measurements.
They
are
normal
placement into the subcrevicular physiological
greater than 4.5mm. [10]
space should be avoided.
Radiographic interpretation can also be used for
CLINICAL EVALUATION OF BIOLOGICAL WIDTHBiological width is determined in clinics using
identification of inter proximal
periodontal probe. The biological width can be identified by probing under local anesthesia (referred to as 'sounding to bone')subtracting the sulcus depth from the surrounding measurements.
violations of
biological width but they are not diagnostic because of tooth superimposition . [12] MARGIN PLACEMENT There are three options available
for the
placement of margins:supra gingival,equigingival and sub gingival.
Preetha Selvan JMSCR Volume 2 Issue 5 May 2014
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1. Supragingival
VIOLATION OF BIOLOGICAL WIDTH
It has the least impact on the periodontium. This
Authors have compared Bermuda triangle to
margin has been applied in non-esthetic areas due
biological width. Like the Bermuda triangle where
to the marked contrast in color and opacity of
a number of aircraft and sea vessels are said to
traditional restorative materials against the tooth.
have disappeared,the margins of the prosthetic
[8]
crowns are extended so much that the dentist loses
Advantages
the access and vision where the margin is actually
1. Preparation of the tooth and finishing of the
located, in the sulcus region. This leads to
margin is easiest.
periodontal complications and eventually leading
2. Duplication of the margins with impressions
to prosthetic failure. [16]
that can be removed past the finish line without
Signs of biological width biological width
tearing
violation:
3. Fit and finish of the restoration and removal of
1. Chronic progressive gingival inflammation
excess material is easiest.
around the restoration.
4. Verification of the marginal integrity of
2. Bleeding on probing.
restoration is easiest.
3. Localized gingival hyperplasia with minimal
5. The Supragingival margins are least irritating to
bone loss.
the gingival tissues . [13]
4. Gingival recession
2. Equigingival Margin
5. Pocket formation
It was thought that placement of equigingival
6. Clinical attachment loss.
margins caused more plaque accumulation than
7. Alveolar bone loss. [1]
supragingival or sub gingival margin resulting in
BIOLOGICAL WIDTH IN IMPLANTS
gingival inflammation. But,today the restorative
In an investigation [17] to determine the position
margins can be esthetically blended with the tooth
of the implant-abutment interface relative to the
and
crest of the bone and peri- implant tissues,it was
finished
to provide a smooth,polished
interface at the gingival margin.
revealed
that
when
the
implant-abutment
3. Subgingival Margin
connection was placed at the gingival level
Authors have correlated that subginival restoration
supracrestal to the alveolar bone,the biologic
demonstrated more quantitative and qualitative
width
changes in the micro flora,increased plaque
dentition.
index,gingival index,recession,pocket depth and
When the interface was placed at deeper level,the
gingival fluid.( [14], [15])
biologic with increased accordingly. When the
measurement was similar to
natural
restoration margin is placed far below the gingival tissue crest,it will impinge on the gingiva and Preetha Selvan JMSCR Volume 2 Issue 5 May 2014
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JMSCR Volume||2||Issue||5||Page 1242-1248||May 2014 constant
inflammation
is
created.
Highly
2014
Restoration overhangs
scalloped,thin gingiva is more prone to recession
Restorative overhangs pose a significant concern
than a flat periodontium with thick fibrous tissue.
as their prevalence has been estimated at 25-76%
However,the implant level should always be
for all restored surfaces.( Brunsvold & Lane 1990)
placed subginivally to allow development of
Studies by GIlmore and Sheikam(1971), Highfield
desired profile and aesthetics. ([18]- [23])
and Powell(1978), Jeffcoat and Howell (1980),
BIOLOGICAL WIDTH IN RESTORATIVE
Lang et al (1983), Chen et al (1987), Pack et al
DENTISTRY
(1990) indicated that bacterial accumulations with
The relationship between restorative dentistry and
overhanging restorations contributed to gingivitis
periodontics
and periodontal attachment loss.
is
interdependent.
Restorative
procedures must be based not only on mechanical
Instead of curettes and sonic scalers, motor driven
specification but also fulfill biologic requirement.
diamond tips can be used to remove overhanging
[24]
restorations. [28]
If there are no signs of inflammation before the
Surgical crown lengthening
restoration,then the following rules can be
Teeth with subginival caries or shortened by
followed:
extensive caries, short clinical crowns with or
1. If gingival sulcus is 1.5mm or less,then place
without
the margin one half the depth of the sulcus below
shortened by incomplete exposure of the anatomic
the tissue crest. Thus, the margin is far enough
crowns
below the tissue so that it is still covered if the
lengthening.
patient is at higher risk of recession
Surgical crown lengthening procedures:
2. If gingiva sulcus is greater than 2mm,then the
1. External Bevel Gingivectomy
margins of restoration
0.7mm
It eliminates excessive pocket depth and exposure
subginivally. This places the margin far enough
of additional coronal tooth structure. It is
below the tissue so that it is still covered if the
indicated in crown lengthening of multiple teeth in
patient is at higher risk of recession,
a
3. If gingival sulcus is more than 2mm,especially
lengthening of single teeth in esthetically zone.
in an esthetically zone from vestibular side then
2. Apically Displaced Tooth
gingivectomy is recommended and margins of
When the tooth is apically displaced, osteotomy is
restoration is prepared 0.5mm subginivally. ([25]-
done. The osseous contour and height of supra
[27])
gingival crest is estimated by ''sounding''to bone.
is prepared
Preetha Selvan JMSCR Volume 2 Issue 5 May 2014
esthetically
are
quadrant
deficiencies
indicated
and
for
and
surgical
contraindicated
in
teeth
crown
crown
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2014
REFERENCES
Orthodontic tooth movement will cause the entire
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attachment apparatus and dentogingival junction
Mitotic activity of human oral epithelium
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indicates in sites where removal of attachment of
Oral
bone from adjacent teeth must be avoided. It is
1961;14:474-92.
contraindicated in individuals who have only a
Surg
2) Vacek
JS,
Oral
Gher
Med
Oral
Path
ME,
Assad
DA,
few teeth remaining.
Richardson AC, Giambarresi LI. The
3. Forced Tooth Eruption With Fibrotomy
dimensions of the human dentogingival
When fibrotomy is performed the crestal bone and
junction. Int J Periodontics Restorative
gingival margin are retained at the pretreatment
Dent 1994;14(2):154-65.
location. It is indicated where the location of
3) Newcomb GM. The relationship between
gingival margin should be unchanged. It is
the location of subgingival crown margins
contraindicated in teeth associated with angular
and
bone defects and ectopically erupting tooth.
Periodontol1974;45(3):151-4.
gingival
inflammation.
J
If the margins of the final restoration will be
4) Gunay H, Seeger A, Tschernitschek H,