Biologic Width and Its Importance in Dentistry

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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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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

1) Garguilo AW, Wentz FM, Orban B.

attachment apparatus and dentogingival junction

Mitotic activity of human oral epithelium

to move with the root of the tooth coronally. It is

exposed to 30 percent hydrogen peroxide.

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,