Perio cons in fpd /certified fixed orthodontic courses by Indian dental academy

PERIODONTAL CONSIDERATIONS
FOR FIXED PROSTHODONTICS.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


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Introduction
Anatomy
Terminologies
Pathogenesis
Examination
Placement of margins of restorations
Tissue dilation
Temporary and provisional crowns
Embrasures
Pontics
Gingival finish lines
Summary & conclusion
Review of literature
References

INTRODUCTION
Dental restorations and periodontal
health are inseparably inter-related. The
adaptation of the margins, the contours
of
the
restorations,
the
proximal
relationships and the surface smoothness
have critical biologic impact on the
gingival and supporting periodontal
tissues. In addition to esthetics, the
purpose of fixed prosthesis includes the
improvement of masticatory efficiency
and prevention of tilting and extrusion of
teeth which results further in occlusal
problems and food impaction.

In the fabrication of any fixed prosthesis
it is imperative that the periodontal
status of the involved abutment teeth be
determined.
This
enables
the
Prosthodontist to make a reliable and
accurate prognosis for the restoration.
Because periodontal disease is a major
cause of tooth loss in adults, it is
essential that the practioner be aware of
the basic concepts and modes of therapy
available in periodontics to develop an
appropriate diagnosis and treatment
plan.

ANATOMY
GINGIVA: The gingiva is the part of the
oral mucosa that covers the alveolar
processes of the jaws and surrounding
the necks of the teeth.
The gingiva is divided anatomically into
marginal, attached and interdental areas.
The marginal, or unattached, gingiva is
the terminal edge or border of the
gingiva surrounding the tooth like a
collar.

Gingival sulcus: It is the shallow crevice
or space around the tooth bounded by
the surface of the tooth on one side and
the epithelium lining the free margin of
the gingiva on the other. It is V shaped
and barely permits the entrance of the
periodontal probe. In clinically healthy
gingiva in humans, a sulcus of some
depth can be found. The depth of this
sulcus, as determined in histologic
sections, has been reported as 1.8 mm,
with variations of from 0 to 6 mm.

Attached gingiva: the attached gingiva is
continous with the marginal gingiva. It is
firm, resilient, and tightly bound to the
underlying periosteum of alveolar bone.
The facial aspect of the attached gingiva
extends to the relatively loose and
movable alveolar mucosa, from which it
is demarcated by the mucogingival
junction. The width of the attached
gingiva is another important clinical
parameter. It is the distance between the
mucogingival junction and the projection
on the external surface of the bottom of
the gingival sulcus or the periodontal
pocket.

Interdental gingiva: the interdental
gingiva occupies the gingival embrasure,
which is the interproximal space bemeath
the area of tooth contact. The interdental
gingiva can be pyramidal or have a col
shape.
Normal gingiva exhibiting no fluid
exudates or inflammation due to bacterial
plaque is pink and stippled. In a normal
healthy patient there is no visible flow of
sulcular fluid, but as disease progresses
the crevicular flow increases.

PERIODONTAL LIGAMENT: The
periodontal ligament is the connective
tissue that surrounds the root and
connects it with the bone. It is continous
with the connective tissue of the gingiva
and communicates with the marrow
spaces through vascular channels in the
bone. The periodontal ligament is
composed of collagen fibers arranged in
bundles that are attached from the
cementum of the tooth to the alveolar
bone of the jaw.

It provides attachment and support, nutrition,
synthesis and resorption, aids in shock
absorption, has formative and remodeling
properties, supplies nutrition to cementum,
bone and gingiva ( by way of blood vesels and
lymphatic drainage), and transmits tactile,
pressure and pain sensations thru its abundant
sensory nerve fibers ( by the trigeminal
pathway). It is subjected to constant flux of
change attributable to disease and masticatory
forces. The healthy periodontal ligament in
functional occlusion is about 0.25 ±0.1 mm
wide; it is widest at the margin and apex while
narrowest in the middle one third.

The two basic forms of periodontal
diseases are gingivitis and periodontitis.
GINGIVITIS: Gingivitis is the most
common form of gingival disease, it is
defined as inflammation of the gingiva.
The two earliest symptoms of gingival
inflammation, which precede established
gingivitis are, (1) increased gingival fluid
production rate, and (2) bleeding from
the gingival sulcus on gentle probing.

PERIODONTITIS: Periodontitis is an
inflammatory disease of the gingiva or
the deeper tissues of the periodontium
and is characterized by pocket formation
and bone destruction. Periodontitis is
considered
a
direct
extension
of
neglected gingivitis. Periodontitis is
caused by extrinsic irritating factors and
is complicated by intrinsic disease,
endocrine
disturbances,
nutritional
deficiencies, periodontal traumatism and
other factors.

When a loss of connective tissue
attachment occurs, the lesion transforms
from gingivitis into periodontitis, a
disease that may be characterized by
alternating periods of quiescence and
exacerbations. The extent to which the
lesion progresses before it is treated will
determine the amount of bone and
connective tissue attachment loss that
occurs and will subsequently affect the
prognosis of the tooth with regard to
restorative demands.

ETIOLOGY:
Most gingival and periodontal diseases result
from microbial plaque, which cause
inflammation and its subsequent pathologic
processes. Other contributors to inflammation
however are calculus, acquired pellicle, material
alba and food debris.
TERMINOLOGIES:
MICROBIAL PLAQUE: It is a sticky substance
composed of bacteria and their by- products in
an extra cellular matrix and also containing
substances from the saliva, diet and serum. It
is basically a product of the growth of bacterial
colonies and is the initiating factor in gingival
and periodontal disease. Left undisturbed it will
gradually cover the entire tooth surface and can
be removed only by mechanical means.

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CALCULUS: Dental calculus is a chalky or
dark deposit attached to the tooth
structure. It is essentially microbial
plaque that has undergone mineralization
with the passage of time.
ACQUIRED PELLICLE: Pellicle is a thin
brown or grey film of salivary proteins
that develops on teeth after they have
been cleaned.
MATERIAL ALBA: This is a white coating
composed of micro-organisms, dead
epithelial cells and leukocyte that is
loosely adherent to the tooth. It can be
removed by water spray or rinsing.

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OCCLUSAL TRAUMATISM: Occlusal
traumatism can be defined as a force
originating by movement of the maxillary
and mandibular teeth in a way that
creates a pathologic lesion.
PRIMARY OCCLUSAL TRAUMA: It is a
pathologic lesion that has been created
by a force strong enough to disturb a
normal intact periodontium.
SECONDARY OCCLUSAL TRAUMA: It is a
lesion created by a normal function on a
weakened periodontium because of
periodontal disease.

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PERIODONTAL POCKET: It is a diseased
periodontal attachment unit. It is caused
by the apical migration of the epithelial
attachment with loss of connective tissue
attachment and eventually osseous
support. The pocket may also result from
the enlargement of the gingival tissue.


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PATHOGENESIS:
INITIAL LESION: The initial lesion is localized in
the region of the gingival sulcus and is evident
at approximately 2-4 days of undisturbed
plaque accumulation from a baseline of gingival
health. The vessels of the gingiva become
enlarged and vasculitis occurs, allowing a fluid
exudate of the polymorphonuclear leukocytes
to form in the sulcus. Collagen is lost
perivascularly, and the resultant space is filled
with proteins and inflammatory cells. The most
coronal portion of the junctional epithelium
becomes altered. Clinically this stage is not
apparent.

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EARLY LESION: Although there is no
distinct division between the stages of
lesional formation, the early lesion
appears within 4-7 days of plaque
accumulation. This stage of development
exhibits further loss of collagen from the
marginal gingiva. In addition an increase
in gingival sulcular fluid flow occurs with
the increase in inflammatory cells and
accumulation of lymphoid cells adjacent
to the junctional epithelium. The basal
cells of the junctional epithelium begin to
proliferate and significant alterations are
seen in the connective tissue fibroblasts.

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ESTABLISHED LESION: Within 7-21 days
the lesion enters the established stage. It
is still located in the apical portion of the
gingival sulcus and the inflammation is
centered in a relatively small area. There
is continuing loss of connective tissue,
with persistence of the features of the
early lesion. This stage exhibits a
predominance of plasma cells, the
predominance of immunoglobulins in the
connective tissue, and a proliferation of
the junctional epithelium. Pocket
formation, however, does not necessarily
occur.

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ADVANCED LESION: It is difficult to pinpoint
the time at which the established lesion of
gingivitis results in a loss of connective tissue
attachment to the tooth structure and becomes
an advanced lesion, or overt periodontitis. Upon
conversion to the advanced stage the features
of an established lesion the features of an
advanced lesion persist. The deeper layers of
the connective tissues becomes involved with
the ingress of inflammatory cells that enhance
osteoclastic activity, resulting in a breakdown of
the alveolar process if at the same time the
tooth is under occlusal trauma this area will
change. There can be a concomitant lesion of
the periodontal disease with the occlusal
traumatic lesion enhancing the loss of bone
around the tooth. Periodontal pockets are
formed with increased probing depths.

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EXAMINATION:
VISUAL EXAMINATION:
It is important during the examination to
evaluate the color, consistency, texture and
shape of the gingival unit. It is also critical to
recognize the initial stages of a marginal lesion.
An adequate light source is essential to
differentiate between normal and diseased
tissues.
(Normal gingiva: Colour – coral pink,
physiologic melanin pigmentation, scalloped
contour on facial or lingual surface, firm and
resilient consistency, stippled attached gingiva,
normal size, shape and position).

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PROBING:
The thinnest probe is desired. The probes
are calibrated in mm. The Prosthodontist
should probe six areas around the tooth.
Evaluation should include bifurcation and
trifurcation areas on the molars and
maxillary first premolars. During probing
the Prosthodontist should check for
bleeding or exudation, these are also
signs of periodontal disease. Clinically the
bleeding of the gingiva during probing is
the sign of ulceration of sulcular
epithelium. Specially treated paper to
monitor the intracrevicular fluid is used.

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MOBILITY:
A classification of 1-3 is used. With 1
representing the early stage of mobility
and 3 representing a tooth mobile in all
direction and depressible in the socket.
Mobility is an indication of the loss of
tooth attachment to the jaw. This can be
seen radio graphically as a widened
periodontal ligament space caused by
occlusal trauma or orthodontic tooth
movement. It can also be caused by
periodontal diseases.

RADIOGRAPHS:
 They provide essential information to
supplement the clinical examination. The most
useful type in evaluating the tooth to bone
relationship is the long cone technique. The
areas to be reviewed on the radiographs are:
a). Alveolar crest resorption.
b). Integrity of thickness of the lamina dura.
c). Evidence of generalized horizontal bone loss.
d). Evidence of vertical bone loss.
e). Widened periodontal ligament space.
f). Density of trabeculae of both arches.
g). Size and shape of the roots compared to the
crown to determine crown to root ratio.

The radiographs can determine the area of root
embedded in bone, this is crucial in determining
the patient’s prognosis. Often patients with short
conical root will display minimal bone loss but
maximal mobility, and the prognosis is thus poor.
Other patients can loose 50 per cent of the bone
but not exhibit mobility, and yet have an
encouraging prognosis because they have normal
shaped roots.


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HABITS:
The major habit to consider is bruxism.
Visual examination of wear facets and
radiographic interpretation of thickened
lamina dura and widened periodontal
ligament space determines whether a
patient grinds in his sleep. One condition
that indicates bruxism is a complete arch
that exhibits mobility despite adequate
osseous support.


PLACEMENT OF MARGINS OF RESTORATIONS:
Except for the risk of subgingival decay and
esthetic considerations, it is best to terminate
preparations above the gingival margins. If
periodontal therapy has been performed and
the gingiva has receded, the preparation should
end at the cemento-enamel-junction. Even if
the tissue does not recede the margin of the
tooth preparation should be away from the soft
tissues. Crown margins when placed sub
gingivally should be located at the base of the
gingival sulcus. The gingival fibers can then
brace the gingiva against the tooth and the
margin of the completed restoration.

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The margins of the preparation are not usually
placed at the crest of the marginal gingiva
regardless of how precise the margin of the
restoration. Microscopically the margins of the
restoration are rough and are excellent site to
harbor bacteria. Since the margins of the
gingiva rapidly collect plaque, this is the site of
recurrent decay. If decay does not result, the
plaque causes periodontal disease at this most
critical area which is not self cleansing.
Conversely, restorations should not be forced
subgingivally into the connective tissue, but
placed in the intra crevicular space without
violating the biological width. Tearing of the
epithelial attachment causes it to migrate
apically and the sulcus to deepen into a pocket.

SUPRAGINGIVAL MARGINS:
Whenever possible margins are prepared
supragingivally on the enamel of the clinical
crown. In addition to the favorable reaction of
the gingiva, other advantages are gained, a
common path of insertion; wider shoulder tooth
preparations can accommodate an adequate
bulk of porcelain veneering material in the
cervical area without pulpal injury and metal
margin finishing techniques are easier. Crown
margins on exposed root surfaces but still
supragingival, are necessary for extensive fixed
partial dentures to secure longer retainers while
encouraging gingival health.

INTRACREVICULAR MARGIN PLACEMENT:
This term for margin placement implies
confinement within the gingival crevice. It is
preferable to the term subgingival since it’s
more specific. Despite the advantages of
supragingival margins there are clinical
situations requiring intra crevicular placement
even in the periodontally treated teeth. They
are:
a). Esthetics.
b). Caries beyond the gingival crest.
c). Cervical erosions.
d). Adequate crown retention in short or broken
down clinical crowns.
e). Elimination of persistent root hypersensitivity.

INTRACREVICULAR DEPTH:
The average crevice depth according to
GARGIULO et al was between 0.5-1 mm
whether adjacent to enamel or root surfaces.
Therefore, the ideal intracrevicular position for
the margins is 0.5 mm beneath the gingival
crest, especially when the crevice is adjacent to
root surfaces. While the average crevicular
depths are nearly identical for enamel or root
surfaces, the average length of the junctional
epithelium on the root is between 0.5 and 1
mm shorter than that on enamel. Thus
overextension of margin placement beneath the
gingiva on root surfaces impinges on gingival
connective tissues.

PULPAL INVOLVEMENT:
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In posterior regions, intracrevicular margin placement
after the gingival margins have receded is
accomplished with minimal pulpal trauma if chamfer or
knife edge margins are prepared.

WOUND HEALING CONSIDERATIONS

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The time elapsed after completion of the periodontal
treatment is crucial when intra crevicular margins are
anticipated. Healing of extensive periodontal surgery
usually requires at least 3 months and often more to
establish a new biologic width, crevice and stable
position of gingival margin and papilla. Even areas
treated by scaling, root planning and plaque control
may take more than 1 or 2 months for their gingival
margins to stabilize. Gingival margins after surgery
migrate coronally but recede apically after scaling and
root planning. Margins prematurely placed
intracrevicularly in the second situation often becomes
exposed as healing progresses and the result may be
unesthetic.

AVOID THE GINGIVAL THIRD:
The risk of irritation to the gingiva is
reduced by restorations that terminate
coronal to the gingival margin. Whenever
possible inlays, pin ledges, and three
quarter crowns should be used as
individual restorations and retainers for
fixed prosthesis. This does not mean
substituting other restorations for
purposes that can only be fulfilled by full
crowns.

ATTACHED GINGIVA:
The gingiva adjacent to intracrevicular crown
margins is an important pre-preparation
consideration. The various steps in the
fabrication of a crown are traumatic to the
gingival sulcus and recession is common. The
friable mucosa is especially vulnerable during
instrumentation. Empirical estimates have
suggested 5 mm of keratinized tissue
composed of 2 mm of free gingiva and 3 mm of
attached gingiva for subgingival margins. This
may be excessive since it is recommended that
the placing margins no further than 1.5 to 2
mm beneath the gingival crest, whereas others
concluded that beyond 0.5 – 1 mm is
excessive.

Nevertheless the avoidance of traumatic
gingival recessions usually depends on a
zone of thick keratinized gingiva 4-5 mm
in width of which 2-3 mm is attached.
Despite tissue keratinization if the probe
is seen thru the free gingival margin, the
ability to resist trauma is doubtful. The
surgical placement of a thickness free
autogenous gingiva graft is indicated
before the final tooth preparation.


ATRAUMATIC PREPARATION:
The free and attached gingiva resists
insults more effectively if the connective
tissue fibers are intact and not inflamed.
DRAGOO and WILLIALS have
demonstrated that the placement of
retraction cord into the sulcus before
preparation protects the epithelium from
damage.


GINGIVAL RETRACTION FOR TAKING
IMPRESSIONS:
When taking plastic impressions it is often
necessary to retract the gingiva to gain
access to the gingival margin of the
preparation. There are methods for
retracting the healthy gingiva. They are
not for the removal, displacement, or
shrinkage of inflamed swollen gingival
tissue. The gingiva must be healthy and
its position on the tooth established
before the impression is made. There are
several terms for the process of exposing
margins when making impressions of
prepared teeth.

Tissue dilation is synonymous with tissue
retraction or displacement. Tissue
management is the key factor in
accurately duplicating subgingival
margins.
In performing tissue dilation, the
Prosthodontist must recognize the
importance of using a regimented
approach from diagnosis to cementation
of the restorations. The gingival tissue
should be healthy before restorative
procedures begin, particularly with
complete restorations that require a
margin below the crest of the gingiva.

TISSUE HEALTH:
The rationale for tissue dilation does not
originate with exposing gingival margins,
since the health of the gingival tissues is
crucial for success. Acceptable healthy
gingival tissue is essential, as inflamed,
redundant tissue is a liability to tissue
dilation. Also, after impressions are made
the tissue should be supported by
appropriate treatment restorations on the
newly prepared teeth. Tissue shrinkage
may occur after gingival margin
placement or from irritation caused by
treatment restorations.

In addition, patients receiving restorative
procedures should be introduced to a
regimental oral hygiene program. If
gingival surgery was done, tissue should
be mature before tooth preparation and
tissue dilation. The healing of the gingival
tissues after periodontal surgery varies,
but a minimum of 3 to 5 weeks is
recommended before preparation and
tissue dilation.


TISSUE DILATION:
Classification
The classification for tissue dilation is as
follows:
1. Mechanical - the tissue is displaced or
dilated strictly by mechanical methods.
2. Mechanical-chemical - a cord is used for
mechanically separating the tissue from
the cavity margin and is impregenated
with a- chemical for hemostasis as
impression are made.

3. Surgical - a ribbon of gingival tissue is
removed from the sulcus around the cavity
margin with dental electrosurgery. The
procedure creates a space in the tissue
surrounding the tooth, control seepage, and
provides a trough for the impression material.
Another method is gingitage-the literature has
indicated successful exposure of the cavity
margin with healing comparable to dental
electrosurgery. In this technique, special
diamond stones remove the sulcus epithelium
as the margins are finished beneath the crest of
the gingiva.
The cast metal preparation is constructed to
minimize tissue laceration with sub gingival
margins. Tissue laceration can be reduced by
avoiding sub gingival margins and creating a
sulcus space by dilation with a mechanical or
mechanical -chemical method.

The entire procedure is commonly repeated
before making an additional impression. When
using the surgical method tissue dilation is not
repeated. Only cleansing and spot coagulation
to control bleeding in the created sulcus is
necessary. Additionally some dentists prefer to
pack an astringent medicated cord into the
surgical through to control seepage.
Elastomeric impression material does not
displace blood, salvia, debris, or tissue. The
tissue therefore is displaced laterally, or a
ribbon of tissue is removed to expose the tooth
preparation margin before the impressions. The
tissue adjacent to the exposed preparation
margin must also be reasonably dry and clean
for accurate impressions.

Mechanical tissue Dilation
Mechanical dilation is possible, but most
is carefully performed to minimize
trauma. Oversized copper bands are
contoured to the gingiva and restricted
towards the preparation margin when
gently seated over the tooth. A resin or
compound plug is placed on the top for
stability, and band is vented for escape of
excess elastomeric impression materials.
A loop of dental floss is threaded through
the vent to ease band removal after the
impression material has set.

The dentist must not exert excessive
pressure on the band, or the tissue may
be stripped from the tooth. Since tissue
dilation can be accomplished effectively
by other method s mechanical dilation
has limited application, but is a superb
method to confirm gingival margins, ie
multiple abutments, full arch impressions
with one or two questionable margins.


Mechanical Chemical Dilation
Mechanical chemical dilation consists of
cords impregnated with chemical that are
eased into the intracrevicular space
beneath the preparation margin without
force. The area must be kept dry but not
dessicated if the hemostatic chemical in
the cord is to have maximum
affectiveness .After 5 to 10 minutes, the
cord is gently removed and the sulcus
surrounding the preparation margin is
exposed and hemostasis maintained.
If bleeding is still evident, the crevice is
repacked for an additional 5 minutes.

If the area has been isolated with cotton
rolls, the packed cord is damped before
removal, as occasionally a dry cord
adheres to the sealed capillaries and, on
removal, cause bleeding. subgingivally ,
the packing insrument is directed towards
the area where the cord is already
secure. Pushing away from the area
previously retracted dislodges the cord.
Cords impregnated with alum or
aluminium choloride provide a styptic
action to control the seepage. Hemostatic
agents like epinepheine are not
recommended in patients with cardiac
problems.

Surgical Tissue Dilation
Continues visualization of the subgingival
margin is difficult for the dentist. Cords
chemicals, rubber or leather rings, copper
stainless steel and aluminium bands with
other materials have been suggested for
this purpose. With refinement of dental
electro surgery, many of the problems of
securing impressions of multiple
abutment preparation can be alleviated.


Electrosurgery requires profound local
anesthesia. Odor is controlled by an
outside ventilated oral evacuator system.
Plastic suction tips are used, since
momentary contact of an activated
working electrode with a metal aspirator
tip causes spot coagulation where ever
the metal touches the tissue. For the
same reason, plastic mounted mouth
mirrors are indicated. The passive or
indifferent plate is positioned under the
patient's shoullder for biterminal
application. Monoterminal applications
are rare.

CURRENTS AND ELECTRODE SELECTION
Selection of electrodes varies, depending on
the tooth and its arch position. This procedure
can be performed without patient discomfort in
relatively bloodless field. With each electrode
the basics of electrosurgery are sustained. The
working electrode must be clean and without
carbonization. In exacting marginal dilation, a
carbonised electrode has a tendency to drag,
tearing the tissue and causing bleeding. If a
straight wire tip, varitip, or minute continuous
loop electrode is used; they should be cleaned
between each application.

The depth of tissue removal is determined by
the morphology of the tissue and the biologic
width. The tissue should extend about 0.3 to
0.5 mm below the margin of the cast
restoration for definite margin detection in the
impression and on the master dies. When using
a continuous loop there is usually a small
amount of tissue left beneath of the margin
because of the shape of the loop. This tissue
tag is removed using a single-wire or variabletip electrode wire. The variable-tip electrode
wire can be adjusted to the desired length. The
troughting procedure is pressureless, and if
additional tissue refinement is required, a time
laps of at least 5 second is needed to dissipate
heat.

Posner Electrode
With the AP 1½ electrode, the insulated
portion of the electrode is directed
around the tooth, removing the gingival
sulcular epithelium. The 1½ disignation of
the AP 1½ mm beyond the insulation.
This offers a precise, uniform 1½ mm
sulcus depth incision. If less trough depth
is desired, part of the tip is removed to
create the desired depth at 0.5 mm, 0.75
mm, or 1.0 mm.

Electrode Tip
Variable-tip or straight-wire electrodes are popular.
Tooth preparation with the desired margin is
completed, and margins are terminated above the
soft tissue. The single wire of the variable tip is
adjusted to the desired subgingival depth, and the
tooth is then circumscribed by repeated
approaches around the tooth in segments. First the
lingual subgingival trough; then the facial surface;
and then the mesial and distal surfaces are
established. This prevents heat accumulation in the
tissue. For most dentists, it is virtually impossible
to circumscribe a tooth with one or two connecting
passes. If a straight-wire electrode or the variabletip electrode is used, the operator may find that
the electrode is too fine to remove enough tissue
to provide adequate bulk of impression material in
the sulcus.

This is especially true if the end of the working
electrode is positioned parallel with the long
axis of the tooth. By angling the working
electrode at approximately 15 to 20 degrees
and carrying the tip through the tissue until it
rests against the tooth, a small wedge of tissue
can be removed. If bleeding occurs, it is usually
interproximal and controlled with the same
electrode using coagulation current. Another
method uses equal parts of hydrogen peroxide
and water to arrest slight local hemorrhage.
After the area is dry, the extended sulcus is
debris free and the root and crown easily
visualized. The margins can then be finished to
the desired depth, the area again flushed with
water and peroxide and the impressions
secured.

In the anterior quadrants where the
gingiva is especially thin, the angle of the
working electrode is changed to be more
nearly parallel to the long axis of the
tooth.
Again with the segmented approach, the
sulcular epithelium is removed, and if a
narrow facial-lingual sulcus has been
created, the cord is placed before the
impression to retract the tissue away
from the tooth. It is axiomatic that the
treatment restoration be suitably adapted
to the existing margins without luting
material impinging on the regenerating
sulcular epithelium.

Dental impressions ideally extend 0.3 to 0.5 mm
below the preparation margin to ensure accuracy.
Electro-surgical removal of a ribbon of tissue
around the preparation margin provides necessary
space for adequate bulk of the elastic impression
material.
After securing the final impression or impressions,
tincutre of myrrh and benzoin (Oringer's solution)
is placed on the surgical area and air dried, this
procedure is repeated three to five times before
the treatment restoration is placed. Orabase may
replace or supplement myrrh and benzoin in this
procedure. The tissue healing is rapid, and the
subgingival trough heals in 5 to 7 days. Discipline
is imperative to the uneventful exposure of the
cavity margin for making impressions for cast
restorations. Tissue trauma, expenditure of time,
and the shrinkage of tissue restricts traditional
mechanical tissue dilation.

The mechanical-chemical method with
cords can reduce trauma to the tissue but
may produce a thin layer of impression
material at the preparation margin once
the cord is removed, since the tissue
returns immediately to its original
position. If a thin layer of
Impression material persists; marginal
distortion of the individual dies results
because of insufficient material in a
critical area.

Dental electrosugery provides a rapid
efficient method for tissue dilation, with
adequate impression material in crucial
areas. It does not cause significant
shrinkage of the tissue or patient
discomfort if appropriate post operative
medication is used.
The key factors for successful electro
surgery are: profound anesthesia;
appropriate current selection; a light
stroke with a 5 second time interval
between applications of the electrode;
and maintaining the biologic width after
tissue healing.

TEMPORARY AND PROVISIONAL CROWNS:
Temporary and provisional crowns with
intracrevicular margins are usually
associated with gingival recession. The
gingiva recovers its original position after
the permanent crown is in place, but the
possibility of permanent recession
increases the longer the temporary
restoration is in place. Gingival recession
is avoided around temporary crowns by
careful preparations and by making
contours of the treatment restoration
resemble those of the natural teeth.

EMBRASURES:
Restorative dental procedures too often result
in the restorative materials taking up place that
is normally occupied by the interdental papilla.
This problem has been accentuated with the
advent of restorations in which porcelain is
bounded to metal. The problem begins when
there is under preparation of the tooth, so that
the technician is left with no other choice
except to place an excessive amount of
restorative material into the inter proximal
space. During the preparation of dies for cast
preparation, the technician first removes all the
replicated gingival tissue to gain access to the
margins, thus it is impossible to visualize the
space available for dental restorations in the
inter proximal enclosure areas.

If two models are poured from the same
impression and the second one is used as an
indication of how much space is currently
occupied by the gingival tissues, the technician
can have a better understanding of what the
contour of the final restoration should be. Over
crowding of the inter dental space results in a
narrowed embrasure area that makes
maintaining oral hygiene difficult. The space
available for gingival tissues is reduced also, so
that a thin strand of collagen is often all that
can occupy this place. This reduction in the
space available for the gingiva means that the
space where collagen should form an effective
seal in association with the junctional
epithelium is diminished.

This may lead to periodontal destruction,
pocket formation and bone loss. In fixed bridge
work the soldered joint is frequently carried too
far in an apical direction and so it invades the
embrasure space from its coronal aspect. This
also leads to inadequate space for the
interdental papilla. For patients who require
increased strength in a soldered joint it is best
obtained by extending the soldered joint
buccally and lingually. The Prosthodontist and
not the technician should determine the size of
the soldered joint because he is aware of how
much gingiva is available in the inter proximal
embrasure.

BIOLOGIC WIDTH EMBRASURES:
The teeth touch in area called proximal
contact, the spaces below the contact are
known as embrasures. In health, the
embrasures are usually filled with tissue.
Embrasures protect the gingiva from food
impaction and deflect the food, to
massage the gingival surface. They
provide spillways for food during
mastication and relieve occlusal forces
when resistant food is chewed.
The proximal surfaces of dental
restorations are important because they
determine the embrasures essential for
gingival health.

In disease and periodontal therapy this
tissue is reduced, the new restorations
create another embrasure that will locate
the restorations close to the new level of
the gingiva. The proximal surfaces of
crowns should taper away from the
contact area on all surfaces. Excessively
broad proximal contact areas and
inadequate contour in the cervical areas
suppress the gingival papillae. These
prominent papillae trap food debris,
leading to gingival inflammation.

Proximal contacts that are too narrow
buccolingually
create
enlarged
embrasures without sufficient protection
against interdental food impaction. The
inter dental brush (proxa brush) and
dental floss are effective in deplaquing
the tooth surface at the gingival margin.
The proximal contact should be such that
the brush snuggly fits in the embrasure
areas.


PONTICS:
Porter recommends the elimination of
embrasures between pontics to simplify oral
hygiene and curtain saliva expectoration.
The ridge lap and conical shape designs are
infrequently recommended. The ridge lap
creates an uncleansible contact area leading to
inflammation of the edentulous mucosa below
the prosthesis.
The spheriodal pontic contacts without pressure
the top of the ridge at the buccal surface,
depending upon the relationship of the residual
ridge to the opposing dentition. All in all a
pontic should have only minimal passive
contact with the ridge, excessive pressure
causes inflammation and proliferation of the
tissues. The pontic should not blanch the
tissues or be placed on the movable mucosa.

CONTOURS OF RESTORATIONS:
The facial and lingual contours of restorations
are also important in the preservation of
gingiva health. The most common error in
creating the contours of the tooth in dental
restorations is over contouring of facial and
lingual surfaces. This overcontouring generally
occurs in the gingival third of the crown and
results in an area where oral hygiene
procedures are unable to control plaque.
Consequently plaque accumulates and gingiva
becomes inflamed. Over contouring on the
buccal or labial surfaces frequently in porcelain
fused to metal crowns owing to the technicians
attempt to obtain a thickness of porcelain
adequate to mask the underlying metal and
provide an aesthetic appearance to the crown.

Hence, it is important for the Prosthodontist to
remove enough tooth material during tooth
preparation. In patients in whom periodontal
disease causes the gingival margin to be in a
much apical position than it was during health,
the facial and lingual contours become even
more significant. In these cases the bulge on
the facial contour of the crown which would be
sub gingival normally appears supra gingivally.
This makes the position of the exposed root
immediately apical to the bulge less accessible
for oral hygiene with resultant plaque
accumulation and gingival inflammation.

OCCLUSAL SURFACE:
They should restore occlusal dimensions
and cuspal contours in harmony with
remainder of the natural dentition after
occlusal abnormalities have been
eliminated by occlusal adjustment. The
occlusal surface of the teeth should not
be arbitrarily narrowed. Proper occlusal
relationships are more important than the
width of the occlusal table in the
attainment of physiologic occlusal
surfaces. The anatomy of the occlusal
surface should provide well formed
marginal ridges and occlusal sluiceways
to prevent inter proximal food impaction.

EFFECT OF SURFACE FINISH ON THE
PERIODONTIUM:
The surface of the restorations should be as
smooth as possible to limit plaque
accumulation. All restorations should have a
very high polish and smooth surface texture.
CEMENTATION:
Retained cement particles irritate the gingiva
and should be removed. It is important that the
restoration be sealed as close to the tooth
preparation as possible. After cementation it is
very important that no cement is left in the
interproximal spaces. Oral hygiene procedures
become a problem if the cement is left behind.
Hence floss should be passed along the
interproximal margins to ensure that no cement
is left back and the margins are free.

GINGIVAL FINISH LINES:
Margins are one of the most important
and weakest lines in the success of any
fixed partial denture restorations. Tooth
preparations for fixed prosthodontics
requires a decision regarding the
marginal configurations. The design
dictates the shape and bulk of the casting
and influences the fit at the margin.
Although many factors such as materials,
esthetics and access influence this
selection, most dentists probably have a
preferred design. However, there is
disagreement about what constitutes
ideal margin, geometry and width.

GINGIVAL TERMINATION OF TOOTH
PREPARATION:
Tooth preparations terminate in a finish
line. Some terminate on the occlusal and
axial surfaces and are referred to as cavo
surface angles. The most controversial,
however, are the gingival finish lines.
The previous recommendations were to
extend crown margins into the
intracrevicular space because the gingival
crevice was supposed to be immune to
caries. Deviation from this norm was
supposed to be irresponsible, despite the
fact that strong evidence supported
supragingival margins.

Conversely, subgingival margins are
considered necessary for the following
reasons:
a). Esthetics.
b). Presence of existing restorations
extending into the intracrevicular space.
c). Insufficient vertical length for
retention.
d). Higher D.M.F rate of younger
patients.
One commonly ommited fact is that the
soft tissue approximating the tooth is
usually unhealthy before preparation.

Therefore, the removal of tissue with
questionable architecture and re growth of
healthier tissue is a rational direction of
treatment. Interceptive periodontics resulting
from the early recognition of tissue symptoms
is recommended.
Question, where the finish lines should be
placed for proper contour of the restoration
requires analysis. The sub gingival area is not
an immune area. Additionally, if there is any
validity to the theory of passive eruption, the
sub gingival margin could become supra
gingival in a short time. Therefore, the dentist’s
evaluation should include enquiry into the
longevity of the restoration.

MARGIN PLACEMENT:
Whenever possible, the margin of the
preparations should be supra gingival.
Sub gingival margins of cemented
restorations have been identified as a
major factor in periodontal diseases,
particularly where they encroach upon
the epithelial attachment. Supra gingival
margins are easier to prepare accurately
without trauma to the soft tissues. They
can usually also be situated on hard
enamel whereas sub gingival margins are
often on dentin or cementum.

Other advantages of supra gingival
margins include the following:
a). They can be easily finished.
b). They are more easily kept clean.
c). Impressions are more easily made, with
less potential for soft tissue damage.
d). Restorations can be easily evaluated at
recall appointments.


However, a sub gingival margin is justified if
any of the following pertain:
a). Dental caries, cervical erosions or
restorations extend sub gingivally and a crown
lengthening procedure is not indicated.
b). The proximal contact area extends to the
gingival crest.
c). Additional retention is needed.
d). The margin of a metal ceramic crown is to
be hidden behind the labiogingival crest.
e). Root sensitivity cannot be controlled by
more conservative procedures.
f). Modification of the axial contour is indicated.

MARGIN ADAPTATION:
The junction between a cemented restoration
and the tooth is always a potential site for
recurrent caries because of the dissolution of
the luting agent. Where possible it should be
kept as short as possible. Rough or irregular
junctions greatly increase the length of the
margins and reduce the possibility of obtaining
a good fitting restoration. The importance of
smooth margins is emphasized. Time spent
obtaining a smooth margin will make the
subsequent steps of tissue displacement,
impression making die formation, waxing and
finishing much easier and ultimately will
provide the patient with a longer lasting
restoration.

MARGIN GEOMETRY:
The cross-sectional configuration of the margin has
been the subject of much analysis and debate.
Different shapes have been described and advocated.
For evaluation the following guidelines should be
considered:
a). It should be easy to prepare without over extension.
b). It should be readily identified in the impression and
on the die.
c). It should give a distinct margin to which the wax
pattern can be finished.
d). It should provide for sufficient bulk of material. This
will enable the wax pattern to be handled without
distortion as well as give the restoration strength and,
where porcelain is used esthetics.
e). It should be as conservative as possible provided
the other criteria are met.

TYPES OF FINISH LINES:
Feather edge or shoulder less: Feather
edge or shoulder less crown preparations
should be avoided because although they
are conservative preparations; they fail
to provide adequate bulk at the margins.
Over contoured restorations are often the
result of featheredge margins; this is
because the technicians can handle the
wax pattern without distortion only by
increasing the bulk of the margins.

•A. Feather edge
•B. Chisel
•C. Chamfer
•D. Bevel
•E. Shoulder
•F. Sloped shoulder
•G. Beveled shoulder


A variation of the feather edge, the chisel
edge margin, is formed when there is a larger
angle between the axial surfaces and the
unprepared tooth structure. Unfortunately this
is frequently associated with an excessively
tapered preparation or one in which the axial
reduction is not correctly aligned with the long
axis of the tooth.
Under most circumstances, feather edge and
chisel edges are unacceptable. Historically
their main advantage was that they facilitated
the making of modeling compound
impressions in copper bands. Since there was
ledge on which a band could catch.

Chamfer margin: is particularly suitable for cast
metal crowns and the metal only portion of metal
ceramic. It is distinct, leaves adequate bulk of
material, and can be placed with precision.
Probably the most suitable instrument for making
a chamfer margin is a tapered diamond bur with
a rounded tip the margin being formed as the
exact image of the instrument. The accuracy of
the margin depends on having a high quality
diamond and true running hand piece. The
gingival margin is prepared with the diamond
held precisely in the path of withdrawl of the
restoration. Tilting it away from the tooth will
create an undercut whereas angling it towards
the tooth will lead to over reduction and loss of
retention. The chamfer should never be prepared
wider than half the tip of the diamond, lest an
unsupported lip of enamel result.

Under some circumstances a beveled
margin is more suitable for cast
restorations, particularly if a ledge or
shoulder already exists, possibly from
dental caries, cervical erosion or a
previous restoration. The objective in
beveling is three fold
• To allow the cast metal margin to be bent
or burnished against the prepared tooth
structure.
• To minimize the marginal discrepancy
caused by the complete crown that fails to
seat completely and
• To protect the unprepared tooth structure
from chipping.

Because a shoulder margin allows for room
for porcelain, it is recommended for an all
ceramic crown and the facial part of a metal
ceramic crown. It should form a 90 degree
angle with the unprepared tooth surface. An
acute angle is likely to chip.
Some authorities have recommended a heavy
chamfer rather than a shoulder margin, and
some find a chamfer easier to prepare with
precision. However, experimental studies
show that a metal framework with a shoulder
margin distorts less than a chamfer margin
during porcelain fixing presumably because of
the additional bulk provided by the shoulder.

To conclude, the margin is one of the
components of the cast restoration most
susceptible to failure, both biologically and
mechanically. Most of the investigative proof
shows that supragingival margins are kinder to
the gingival than are subgingival margins.
However, practicality dictates that supragingival
margins are not always usable. There is some
indication that quality of the margin may be of
as much importance to gingival health as
location. Research on the configuration of
margins seems to agree with the majority of
authors writing technical articles. Most agree
that feather edge or knife edge margins are not
always the most acceptable. Apparently bulky
margins with rounded internal line angles are
best.

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





Complete shoulders are the classic finish lines
for complete porcelain crowns.
Beveled shoulders are used in preparations for
veneers and selected posterior teeth.
The chamfer possessed internal bulk and
satisfactory margin adaptation extra
coronally; it is the traditional gingival
termination for posterior crowns and the
lingual surfaces of anterior ceramic / metal
crowns.
Knife edge finish lines are used for younger
patients, pin ledge three quarter crowns,
inaccessible areas of the oral cavity, and finish
lines on the cementum.

SUMMARY AND CONCLUSION
One of the primary goals of restorative therapy
is to establish a physiologic periodontal climate
and facilitate the maintenance of periodontal
health. Traumatic occlusal relationships should
be eliminated before restorative procedures are
begun and restorations should be constructed
in conformity with the newly established
occlusal patterns. If this is not done the
prostheis will perpetuate occlusal relationship
injurious to the periodontium. Subgingival
margins should be avoided as far as possible
except in cases of caries, extending apically,
short crowns hence to obtain retention, and in
labial surfaces of anterior maxillary teeth in
patients who demand for esthetics as a primary
criteria.

In impression making, ginival retraction
methods should be followed deligently keeping
the ginival health in mind. All interim
restorations should be so constructed that they
cause no trauma to the gingival during the time
they are in the mouth. The teeth should taper
away from their proximal contacts to get good
healthy embrasures. Over contouring of the
facial and lingual surfaces should be avoided.
Over contouring in gingival third causes plaque
accumulation and gingival inflammation. Pontic
design greatly influences gingival health. If
esthetics is a primary concern a spheriodal
Pontic for the posteriors and a modified ridge
lap for the anteriors is ideal.

The occlusal surfaces should be
designed to direct masticatory forces
along the long axis of the tooth. The
occlusal table should not be too wide to
prevent undue pressure on the
periodontium of the abutment teeth. A
sanitary Pontic is the periodontium’s best
friend. Lastly the surface of restorations
should be as smooth as possible to limit
plaque accumulation. But eventually after
taking all these precautions, patient
education and motivation towards plaque
control and healthy oral habits is the
secret of every treatment success.

REVIEW OF LITERATURE:
1. Melvin L. Morris 1962 did a study on
artificial crown contours and gingival
health. According to him the theory of
the artificial bulge in the crown is an
inaccurate view of gingival coronal
anatomy and physiology. This rational
produces crown that are contoured in
excess of anything in Nature and Causes,
rather than prevents, gingival
inflammation.

2. Sheldon Stein in 1966 did a research on
Pontic residual ridge relationship. Pontic design
was the foremost factor in obtaining
inflammatory free pontic ridge relationships.
The ideal design was shown to be a modified
ridge lap in the posterior region and a lap
facing in the anterior region, with a pinpoint
contact on the facial contiguous slope of the
residual ridge. The ideal design should include
surface smoothness and a fine finish. No
distinguishing advantage was found with
porcelain acrylic resin. A successful artificial
tooth replacement was characterized by a
healthy tissue response with the appearance of
a lack of contact between the residual ridge and
under surface of the pontic.

3. James S. Marcum in 1967 did a study on
Crown Marginal depth and gingival tissue 66
gold crowns were placed and finished above,
below and even with the gingival crest in 6
dogs. The crowns were left in place until the
dogs were put to death at time intervals one,
two and three months. Two dogs were
sacrificed at each interval and block specimens
of the teeth and gingiva were taken at this
time.
Control specimens of unoperated teeth were
also taken. The block specimens were
decalcified, sectioned stained, histologically
examined and graded for security of
inflammatory response. 600 metological slides
of the tissue sections were graded as having
evidence of none, slight, moderate and severe
gingival inflammation.

The investigation showed that crowns
with margins located at a even with the
gingival crest caused the least
inflammatory response. The length of
time "the restoration was in place had
little, if any, effect upon severity of
degree of inflammation.
However it appears from results of this
investigation that crowns with margins
finished even with the gingival crest
would be least likely to cause gingival
inflammation.

4. Edmand Cauazos in 1968 did a study
on tissue response to fixed partial
denture pontics. This study
demonstrates that the adaptation of a
Pontic "to the ridge or the amount of
relief (scraping of the cast) provided in
the cast is highly significant and directly
proportional to the amount of
unfavourable tissue change.
Absolute minimal contact (O.O .25 mm
of cast scraping) produces nochange.
When the cast scraping was increased to
1 mm, tissue changes were produced
varying from mild inflammation to acute
ulceration.







5. Joseph Clayton in 1970 did a study to compare the
surface roughness, following final finishing and
polishing, of pontics constructed from cast gold, acrylic
resin and glazed porcelain.
With a profilometer statistical analysis indicated that
the test surfaces of glazed porcelain were significantly
rougher than the polished test surfaces of acrylic resin
or cast gold.
There was no significant difference in surface
roughness between the polished acrylic resin and
polished cast gold sample pontic surfaces. Clinical test
showed that plaque formation occurred on polished
surfaces of pontics constructed of cast gold, acrylic
resin and glazed porcelain. The surfaces of these
pontics were as smooth as the sample pontics which
were measured in this study.
Therefore pontic surfaces which are as smooth as
possible must be cleaned regularly to prevent the
accumulation of dental plague.

6. Martin Henry Berman in 1973 did a study on
the interrelationship between complete
coverage restoration and the gingival sulcus.
The terminal margin plays an important role in
maintaining gingival health. periodontal
disease is minimal with restorations which do
not invade the sulcus, but the caries attack
rate, retention and esthetic requirements may
compel entry into the sulcus. The technique
described in this report permits entry into the
sulcus with permanent damaging.
7. Dayton Krajicek in 1973 presented a paper
on periodontal consideration in prosthetic
patients. He mentions that Crown contours
should be adequate to deflect food and
contoured gradually so as to permit clearing
and to avoid forming a food trap. Margins
should be placed supragingivally as far as
possible.



8. William A Richter in 1973 did a study in the
influence of Crownmargin location on the gingival
tissue for 12 cast complete crown. Evaluation were
made yearly upto three years.To avoid significant
variables, each of the 12 crowns was designed with
both sub gingival and supra gingival margins on the
gingival margins of facial surface. A comparison of the
two margins location using four different methods of
evaluation revealed no difference in the
1) health of the gingiva,
2) change in sulcus depth,
3) gingival contour and
4) plague accumulation.
In view of reported gingival problems near restoration
margins, the result of this study suggest that the fit
and finish of full crown restorations may be more
significant to gingival health than the location of finish
lines.

9.Dominick C. Larato in 1975 did a study
on margin extension, brushing and
gingival pocket depth. A total of 111
males vetern patients ranging in age 21
73 years were selected for the study.
Each had at least one tooth which was
restored with a complete cast gold
veneer crown and a nonrestored
contralateral tooth with no clinical or
radiographic evidence of cervical caries.
All artificial crowns had sub gingival
margins. The gingival tissues adjacent to
the crown and unrestored teeth were
probed to determine individual pocket
depths.

The results are
1. The average pocket depth adjacent to non
restored teeth was.2.7mm.
The average pocket depth adjacent to teeth
having crowns will sub gingival margins was
3.4mm.
2.54 nonrestored teeth had at least one
pocket depth greater than 3mm while 84
crowned teeth had at least one or more
measurements greater than 3 mm.
3. No positive relationship could be found
between tooth brushing frequency and the
pocket depth adjacent to teeth restored with
complete cast crowns.
4. In nonrestored teeth pocket depth
increased with reduced frequency of non
brushing.

10.Francisco Palomo and John Pedar in 1976 did
a study on periodontal relationship with regards
1. Placement of margins,
2. Marginal fit,
3. Inter dental space and contour of
restorations and
4. Surface texture
11. Jan Ruel, Peter Schrussler, Kenneth
Malament in 1980 did a study on the effect of
retraction procedures on the periodontium in
humans. On basis of wound healing and
gingival recession caused by the cord, electro
surgery and copper band, the copper band ret
raction method was the most satisfactory.
Retraction methods must be evaluated relative
to the impression procedure and fit of the
restoration.

12. Curtis M. Beker and Wayne Kaldanl in 1981
suggested that crown contours which promote
favourable tissue response follow these
guidelines
a) Buccal and lingual contours should be flat,
b) Embrasure spaces should be kept open,
c) Contact should be high (incisal 1/3 and
buccal to central fossa (except between first
and second molars)
d) Margins should be supra gingival wherever
possible. The pontic design of choice is the
modified ridge lap for posteriors and ridge lap
for anteriors.

13) Lee M. Jamson and William Malane in 1982
did a study on crown contours and gingival
response.The conclusions drawn were
1) Deflective contours and or over contouring
should be avoided in the cervical third and the
interproxinial surfaces of tooth restorations.
2) Over contouring of the inter proximal region
is common and harmful to periodontal health.
3) Adequate tooth reduction at the gingival
margins and inter proximally provides for
restoration materials and lessens the potential
for overcontouring in these critical regions.
4) Minimal disruption with the intra crevicular
space sheering tooth preparation allows a more
predictable, favourable periodontal response to
satisfactorily contoured restorations.

14) David L Kath in 1982 did a study on full crown
restorations and gingival inflammation in a controlled
population.
The amount of the crevicular fluid around full crown
restoration was measured with an instrument to
compare the gingival inflammation between restored
and unrestored teeth in the same patient. 38 full crown
restorations were compared to non restored teeth used
as controls in 26 patients. The results were as follows:
1. Full crowns have the potential for causing gingival
inflammation. However, not so in a highly motivated
patient.
2. Gingival inflammation surrounding full crown resto
rations may be controlled regardless of gingival margin
placement when the gingiva is healthy and restorations
are adequate and the patient is in a strict recall
programme.

15) John Soumson, Micheal Rewman and Thomas
Fleming in 1991 did a study assessing the efficacy of a
12%chlorhexidene gluconate rinse on the enhancement
and maintenance of gingival health in patients receiving
fixed prosthesis. Adjunctive use of chlorhexidine with
F.P.D. significantly reduced plague levels and improved
gingival health compared and controlled patients.
16) Martin Treelich, Lary C Breeding et al in 1991 did a
study testing the effect of fixed partial dentures on
hypermobile abutment teeth with substantially reduced
levels of periodontal attachment. One abutment tooth
and one control (nonabutment) tooth of the same type
and periodontal condition were selected for study in
adults.
Treatment consisted of periodontal therapy and a 3 or 4
unit F.P.D. after which all subjects were placed on a
quarterly maintenance schedule. No differences were
found between the mean baseline and 24 month
measures for all dependent variables at test or control
sites.

17) Martin a Treilhich, Christin Mekrash, Katx
et al in 1992 studied the periodontal response
to posterior fixed partial denture relevant with
different marginal configurations and locations.
One posterior proximal site restored with a
clinically acceptable F.P.D. and one matched,
unrestored posterior proximal site were
examined in 60 patients. Statistical analysis
showed that clinically acceptable F.P.D.'s which
had clinically detectable deviation from an ideal
(flat) retainer/tooth configuration were not
associated with increased probing depths, nor
were the sub gingival retainer margins to the
supragingival retainer margins. These findings
suggest that longterm exposure to variations
of F.P.D. margin configuration and location,
within clinically acceptable but less than ideal
parameters are not associated with destruction
of supporting periodontal tissues.

REFERENCES
1. Gengers, Snack, Vagels Over containing in resin
bonded prosthesis Plague accumulation and gingival
health J.P.D. 59:17:Jan 88.
2. Cuetis Becker, Wayne Kaldaht: Current theories of
crown contour margin placement and pontic design
J.P.D. 45:268:1981.
3. Dayton K Periodontal considerations for prosthetic
patients J.P.D. 30:15:July73.
4. DominickC.L. Effect of artificial crown margin
extensions and tooth brushing frequency on gingival
pocket depth.
5. David Koth: Full crown preparation and gingival
inflammation in a controlled population.
J.P.D. 48:681:1982.
6. Edmand C: Tissue response to fixed partial denture
prosthesis. J.P.D. 23:407:1970.
7. Francisco P. John pedar, Periodontal relationship and
F.P.D. J.P.D. 387:36:1976.

8. James Marcum: The effect of crown marginal depth
upon gingival tissues J.P.D. 17:479:1967.
9. Jon Ruel, Peter S., Keneth M: Effect of retraction
procedures on periodontium in humans J.P.D.
44:508:1980.
10. John Lorensonl6, Micheal N. Gingival enhancement
in F.P.D. 65:100107:1991.
11. Joseph Clayton: Roughness of pontic materials and
dental plague J.P.D. 23:407:1970.
12. Lee M. Jamson,William M: Crown contains and
gingival response J.P.D. 47:620:1982.
13. Martin Bermar. The complete coverage restoration
and the gingival sulcus J.P.D.: 29:301:1973.
14. Martin Frelich, Lasy c.: F.P.D. supported by
periodontally compromised teeth J.P.D.65:607:1991.
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F.P.D. retainer margins: configurment and location
J.P.D. 67:184:1992.www.indiandentalacademy.com

16. Melvin L. Mories Artificial crown contours
and gingival health J.P.D. 12:l146:Dec.'62.
17. Sheldan Stein: pontic residual ridge
relationship: A report J.P.D:16:251:1966.
18. William Richter, Veno: Relationship of crown
margin placement to gingival inflammation
J.P.D.30:156:1973.
19.Contemporary fixed prosthodontics –
Rosenstiel.
20.Fundamentals of fixed prosthodontics –
Shillingburg.
21.Clinical periodontology – Carranza
22. Tylman’s theory and practise of fixed
prosthodontics.

Perio cons in fpd /certified fixed orthodontic courses by Indian dental academy

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