Perio cons in fpd/ orthodontic straight wire technique

PERIODONTAL CONSIDERATIONS
FOR FIXED PROSTHODONTICS.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
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 IntroductionIntroduction
 AnatomyAnatomy
 TerminologiesTerminologies
 PathogenesisPathogenesis
 ExaminationExamination
 Placement of margins of restorationsPlacement of margins of restorations
 Tissue dilationTissue dilation
 Temporary and provisional crownsTemporary and provisional crowns
 EmbrasuresEmbrasures
 PonticsPontics
 Gingival finish linesGingival finish lines
 Summary & conclusionSummary & conclusion
 Review of literatureReview of literature
 ReferencesReferences www.indiandentalacademy.comwww.indiandentalacademy.com

INTRODUCTIONINTRODUCTION
Dental restorations and periodontalDental restorations and periodontal
health are inseparably inter-related. Thehealth are inseparably inter-related. The
adaptation of the margins, the contoursadaptation of the margins, the contours
of the restorations, the proximalof the restorations, the proximal
relationships and the surface smoothnessrelationships and the surface smoothness
have critical biologic impact on thehave critical biologic impact on the
gingival and supporting periodontalgingival and supporting periodontal
tissues. In addition to esthetics, thetissues. In addition to esthetics, the
purpose of fixed prosthesis includes thepurpose of fixed prosthesis includes the
improvement of masticatory efficiencyimprovement of masticatory efficiency
and prevention of tilting and extrusion ofand prevention of tilting and extrusion of
teeth which results further in occlusalteeth which results further in occlusal
problems and food impaction.problems and food impaction.

In the fabrication of any fixed prosthesisIn the fabrication of any fixed prosthesis
it is imperative that the periodontalit is imperative that the periodontal
status of the involved abutment teeth bestatus of the involved abutment teeth be
determined. This enables thedetermined. This enables the
Prosthodontist to make a reliable andProsthodontist to make a reliable and
accurate prognosis for the restoration.accurate prognosis for the restoration.
Because periodontal disease is a majorBecause periodontal disease is a major
cause of tooth loss in adults, it iscause of tooth loss in adults, it is
essential that the practioner be aware ofessential that the practioner be aware of
the basic concepts and modes of therapythe basic concepts and modes of therapy
available in periodontics to develop anavailable in periodontics to develop an
appropriate diagnosis and treatmentappropriate diagnosis and treatment
plan.plan. www.indiandentalacademy.comwww.indiandentalacademy.com

ANATOMYANATOMY
GINGIVA:GINGIVA: The gingiva is the part of theThe gingiva is the part of the
oral mucosa that covers the alveolaroral mucosa that covers the alveolar
processes of the jaws and surroundingprocesses of the jaws and surrounding
the necks of the teeth.the necks of the teeth.
The gingiva is divided anatomically intoThe gingiva is divided anatomically into
marginal, attached and interdental areas.marginal, attached and interdental areas.
TheThe marginal,marginal, or unattached, gingiva isor unattached, gingiva is
the terminal edge or border of thethe terminal edge or border of the
gingiva surrounding the tooth like agingiva surrounding the tooth like a
collar.collar.

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

Attached gingiva:Attached gingiva: the attached gingiva isthe attached gingiva is
continous with the marginal gingiva. It iscontinous with the marginal gingiva. It is
firm, resilient, and tightly bound to thefirm, resilient, and tightly bound to the
underlying periosteum of alveolar bone.underlying periosteum of alveolar bone.
The facial aspect of the attached gingivaThe facial aspect of the attached gingiva
extends to the relatively loose andextends to the relatively loose and
movable alveolar mucosa, from which itmovable alveolar mucosa, from which it
is demarcated by the mucogingivalis demarcated by the mucogingival
junction. The width of the attachedjunction. The width of the attached
gingiva is another important clinicalgingiva is another important clinical
parameter. It is the distance between theparameter. It is the distance between the
mucogingival junction and the projectionmucogingival junction and the projection
on the external surface of the bottom ofon the external surface of the bottom of
the gingival sulcus or the periodontalthe gingival sulcus or the periodontal
pocket.pocket. www.indiandentalacademy.comwww.indiandentalacademy.com

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

PERIODONTAL LIGAMENTPERIODONTAL LIGAMENT: The: The
periodontal ligament is the connectiveperiodontal ligament is the connective
tissue that surrounds the root andtissue that surrounds the root and
connects it with the bone. It is continousconnects it with the bone. It is continous
with the connective tissue of the gingivawith the connective tissue of the gingiva
and communicates with the marrowand communicates with the marrow
spaces through vascular channels in thespaces through vascular channels in the
bone. The periodontal ligament isbone. The periodontal ligament is
composed of collagen fibers arranged incomposed of collagen fibers arranged in
bundles that are attached from thebundles that are attached from the
cementum of the tooth to the alveolarcementum of the tooth to the alveolar
bone of the jaw.bone of the jaw.www.indiandentalacademy.comwww.indiandentalacademy.com

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

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

PERIODONTITIS:PERIODONTITIS: Periodontitis is anPeriodontitis is an
inflammatory disease of the gingiva orinflammatory disease of the gingiva or
the deeper tissues of the periodontiumthe deeper tissues of the periodontium
and is characterized by pocket formationand is characterized by pocket formation
and bone destruction. Periodontitis isand bone destruction. Periodontitis is
considered a direct extension ofconsidered a direct extension of
neglected gingivitis. Periodontitis isneglected gingivitis. Periodontitis is
caused by extrinsic irritating factors andcaused by extrinsic irritating factors and
is complicated by intrinsic disease,is complicated by intrinsic disease,
endocrine disturbances, nutritionalendocrine disturbances, nutritional
deficiencies, periodontal traumatism anddeficiencies, periodontal traumatism and
other factors.other factors. www.indiandentalacademy.comwww.indiandentalacademy.com

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

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

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

 OCCLUSAL TRAUMATISM:OCCLUSAL TRAUMATISM: OcclusalOcclusal
traumatism can be defined as a forcetraumatism can be defined as a force
originating by movement of the maxillaryoriginating by movement of the maxillary
and mandibular teeth in a way thatand mandibular teeth in a way that
creates a pathologic lesion.creates a pathologic lesion.
 PRIMARY OCCLUSAL TRAUMA:PRIMARY OCCLUSAL TRAUMA: It is aIt is a
pathologic lesion that has been createdpathologic lesion that has been created
by a force strong enough to disturb aby a force strong enough to disturb a
normal intact periodontium.normal intact periodontium.
 SECONDARY OCCLUSAL TRAUMA:SECONDARY OCCLUSAL TRAUMA: It is aIt is a
lesion created by a normal function on alesion created by a normal function on a
weakened periodontium because ofweakened periodontium because of
periodontal disease.periodontal disease.www.indiandentalacademy.comwww.indiandentalacademy.com

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

PULPAL INVOLVEMENT:PULPAL INVOLVEMENT:
 In posterior regions, intracrevicular margin placementIn posterior regions, intracrevicular margin placement
after the gingival margins have receded isafter the gingival margins have receded is
accomplished with minimal pulpal trauma if chamfer oraccomplished with minimal pulpal trauma if chamfer or
knife edge margins are prepared.knife edge margins are prepared.
WOUND HEALING CONSIDERATIONSWOUND HEALING CONSIDERATIONS
 The time elapsed after completion of the periodontalThe time elapsed after completion of the periodontal
treatment is crucial when intra crevicular margins aretreatment is crucial when intra crevicular margins are
anticipated. Healing of extensive periodontal surgeryanticipated. Healing of extensive periodontal surgery
usually requires at least 3 months and often more tousually requires at least 3 months and often more to
establish a new biologic width, crevice and stableestablish a new biologic width, crevice and stable
position of gingival margin and papilla. Even areasposition of gingival margin and papilla. Even areas
treated by scaling, root planning and plaque controltreated by scaling, root planning and plaque control
may take more than 1 or 2 months for their gingivalmay take more than 1 or 2 months for their gingival
margins to stabilize. Gingival margins after surgerymargins to stabilize. Gingival margins after surgery
migrate coronally but recede apically after scaling andmigrate coronally but recede apically after scaling and
root planning. Margins prematurely placedroot planning. Margins prematurely placed
intracrevicularly in the second situation often becomesintracrevicularly in the second situation often becomes
exposed as healing progresses and the result may beexposed as healing progresses and the result may be
unesthetic.unesthetic.

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

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

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

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

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

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

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

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

TISSUE DILATION:TISSUE DILATION:
ClassificationClassification
The classification for tissue dilation is asThe classification for tissue dilation is as
follows:follows:
1.1. Mechanical -Mechanical - the tissue is displaced orthe tissue is displaced or
dilated strictly by mechanical methods.dilated strictly by mechanical methods.
2.2. Mechanical-chemicalMechanical-chemical - a cord is used for- a cord is used for
mechanically separating the tissue frommechanically separating the tissue from
the cavity margin and is impregenatedthe cavity margin and is impregenated
with a- chemical for hemostasis aswith a- chemical for hemostasis as
impression are made.impression are made.

3. Surgical3. Surgical - a ribbon of gingival tissue is- a ribbon of gingival tissue is
removed from the sulcus around the cavityremoved from the sulcus around the cavity
margin with dental electrosurgery. Themargin with dental electrosurgery. The
procedure creates a space in the tissueprocedure creates a space in the tissue
surrounding the tooth, control seepage, andsurrounding the tooth, control seepage, and
provides a trough for the impression material.provides a trough for the impression material.
Another method is gingitage-the literature hasAnother method is gingitage-the literature has
indicated successful exposure of the cavityindicated successful exposure of the cavity
margin with healing comparable to dentalmargin with healing comparable to dental
electrosurgery. In this technique, specialelectrosurgery. In this technique, special
diamond stones remove the sulcus epitheliumdiamond stones remove the sulcus epithelium
as the margins are finished beneath the crest ofas the margins are finished beneath the crest of
the gingiva.the gingiva.
The cast metal preparation is constructed toThe cast metal preparation is constructed to
minimize tissue laceration with sub gingivalminimize tissue laceration with sub gingival
margins. Tissue laceration can be reduced bymargins. Tissue laceration can be reduced by
avoiding sub gingival margins and creating aavoiding sub gingival margins and creating a
sulcus space by dilation with a mechanical orsulcus space by dilation with a mechanical or
mechanical -chemical method.mechanical -chemical method.www.indiandentalacademy.comwww.indiandentalacademy.com

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

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

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

Mechanical Chemical DilationMechanical Chemical Dilation
Mechanical chemical dilation consists ofMechanical chemical dilation consists of
cords impregnated with chemical that arecords impregnated with chemical that are
eased into the intracrevicular spaceeased into the intracrevicular space
beneath the preparation margin withoutbeneath the preparation margin without
force. The area must be kept dry but notforce. The area must be kept dry but not
dessicated if the hemostatic chemical indessicated if the hemostatic chemical in
the cord is to have maximumthe cord is to have maximum
affectiveness .After 5 to 10 minutes, theaffectiveness .After 5 to 10 minutes, the
cord is gently removed and the sulcuscord is gently removed and the sulcus
surrounding the preparation margin issurrounding the preparation margin is
exposed and hemostasis maintained.exposed and hemostasis maintained.
If bleeding is still evident, the crevice isIf bleeding is still evident, the crevice is
repacked for an additional 5 minutes.repacked for an additional 5 minutes.www.indiandentalacademy.comwww.indiandentalacademy.com

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

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

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

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

The depth of tissue removal is determined byThe depth of tissue removal is determined by
the morphology of the tissue and the biologicthe morphology of the tissue and the biologic
width. The tissue should extend about 0.3 towidth. The tissue should extend about 0.3 to
0.5 mm below the margin of the cast0.5 mm below the margin of the cast
restoration for definite margin detection in therestoration for definite margin detection in the
impression and on the master dies. When usingimpression and on the master dies. When using
a continuous loop there is usually a smalla continuous loop there is usually a small
amount of tissue left beneath of the marginamount of tissue left beneath of the margin
because of the shape of the loop. This tissuebecause of the shape of the loop. This tissue
tag is removed using a single-wire or variable-tag is removed using a single-wire or variable-
tip electrode wire. The variable-tip electrodetip electrode wire. The variable-tip electrode
wire can be adjusted to the desired length. Thewire can be adjusted to the desired length. The
troughting procedure is pressureless, and iftroughting procedure is pressureless, and if
additional tissue refinement is required, a timeadditional tissue refinement is required, a time
laps of at least 5 second is needed to dissipatelaps of at least 5 second is needed to dissipate
heat.heat.

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

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

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

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

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

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

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

TEMPORARY AND PROVISIONAL CROWNS:TEMPORARY AND PROVISIONAL CROWNS:
Temporary and provisional crowns withTemporary and provisional crowns with
intracrevicular margins are usuallyintracrevicular margins are usually
associated with gingival recession. Theassociated with gingival recession. The
gingiva recovers its original position aftergingiva recovers its original position after
the permanent crown is in place, but thethe permanent crown is in place, but the
possibility of permanent recessionpossibility of permanent recession
increases the longer the temporaryincreases the longer the temporary
restoration is in place. Gingival recessionrestoration is in place. Gingival recession
is avoided around temporary crowns byis avoided around temporary crowns by
careful preparations and by makingcareful preparations and by making
contours of the treatment restorationcontours of the treatment restoration
resemble those of the natural teeth.resemble those of the natural teeth.www.indiandentalacademy.comwww.indiandentalacademy.com

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Under some circumstances a beveledUnder some circumstances a beveled
margin is more suitable for castmargin is more suitable for cast
restorations, particularly if a ledge orrestorations, particularly if a ledge or
shoulder already exists, possibly fromshoulder already exists, possibly from
dental caries, cervical erosion or adental caries, cervical erosion or a
previous restoration. The objective inprevious restoration. The objective in
beveling is three foldbeveling is three fold
• To allow the cast metal margin to be bentTo allow the cast metal margin to be bent
or burnished against the prepared toothor burnished against the prepared tooth
structure.structure.
• To minimize the marginal discrepancyTo minimize the marginal discrepancy
caused by the complete crown that fails tocaused by the complete crown that fails to
seat completely andseat completely and
• To protect the unprepared tooth structureTo protect the unprepared tooth structure
from chipping.from chipping.www.indiandentalacademy.comwww.indiandentalacademy.com

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

To conclude, the margin is one of theTo conclude, the margin is one of the
components of the cast restoration mostcomponents of the cast restoration most
susceptible to failure, both biologically andsusceptible to failure, both biologically and
mechanically. Most of the investigative proofmechanically. Most of the investigative proof
shows that supragingival margins are kinder toshows that supragingival margins are kinder to
the gingival than are subgingival margins.the gingival than are subgingival margins.
However, practicality dictates that supragingivalHowever, practicality dictates that supragingival
margins are not always usable. There is somemargins are not always usable. There is some
indication that quality of the margin may be ofindication that quality of the margin may be of
as much importance to gingival health asas much importance to gingival health as
location. Research on the configuration oflocation. Research on the configuration of
margins seems to agree with the majority ofmargins seems to agree with the majority of
authors writing technical articles. Most agreeauthors writing technical articles. Most agree
that feather edge or knife edge margins are notthat feather edge or knife edge margins are not
always the most acceptable. Apparently bulkyalways the most acceptable. Apparently bulky
margins with rounded internal line angles aremargins with rounded internal line angles are
best.best. www.indiandentalacademy.comwww.indiandentalacademy.com

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

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

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