Abutment & Its Selection In Fixed Partial Denture

Abutment & Its Selection In
FPD
Guided By:-
Dr. Dilip Dhamankar (HOD)
Dr. Ravi Kumar C.M. (Prof.)
Dr. Meenaksi (Prof.)
Dr. DRV Kumar (Reader)
Dr. Arun (Reader)
Dr. Manish Chadha (Senior
Lect.)
Dr. Devendra (Senior Lect.)
Dr. Mayank (Senior Lect.)
Dr. Soham Prajapati
2nd Year PG,
Dept. of Prosthodontics
& Maxillofacial Prosthesis
Including Oral Implantology
22-11-14
1/135

Contents
• Introduction
• Definition
• Assessment of abutment teeth
• Criteria of selection
• Factors governing abutment selection
Crown
Crown to root ratio
Root configuration
Root surface area
• Biomechanical Consideration
– Length of span
– Height of connector
– Double abutment
Abutment & Its Selection In FPD 2/135

Contents
• Types of Abutment
– Questionable Abutment
– Pier Abutments
– Cantilever Fixed Dental Prosthesis
– Spring Cantilever Abutment
– Tilted Molar Abutments
– Canine replacement FDP
– Splinted Abutments
Conclusion
References
3/135Abutment & Its Selection In FPD

Introduction
• Every restoration must be able to withstand the
constant occlusal forces to which it is subjected &
this is of particular significance when designing &
fabricating a fixed dental prosthesis.
• All the forces that would normally be absorbed
by the missing tooth are transmitted, through the
pontic, connectors, & retainers to abutment
teeth.
Shillingburg HT, Hobo S, Whitsett LD, Jacobi R, Brackett SE. Fundamentals of fixed
prosthodontics. 3rd ed. Chicago: Quintessence; 1997.p. 85-103.

Introduction
• Abutment teeth therefore withstand forces
normally directed to the missing teeth, in
addition to those usually applied to the
abutments, so the clinician must evaluate the
abutment teeth carefully.

Definition
• Fixed Partial Denture
– A partial denture that is luted or otherwise securely
retained to natural teeth, tooth roots, and/or
dental implant abutments that furnish the primary
support for the prosthesis.
The Glossary of Prosthodontic Terms, 8th Edition J Prosthet Dent 2005;81:63.

Definition
ABUTMENT –
That part of a structure that directly receives
thrust or pressure; an anchorage .
Or
A tooth, a portion of a tooth, or that portion of a
dental implant that serves to support and/or
retain a prosthesis .

Assessment of Abutment Teeth
• Considerable time and expense are spared, and
loss of a patient’s confidence can be avoided, by
thoroughly investigating each abutment tooth
before proceeding with tooth preparation.
• Radiographs are made, & pulpal health is
assessed by evaluating the response to thermal &
electrical stimulation.

Number and Type of Radiographs
Needed.
• 1 OPG
• If no periapical lesions are present,
– 4 Bitewings Radiographs [2 with each quadrant
(one for premolars and one for molars)]
– 4 IOPA Radiographs (1 for each quadrant covering
incisors and canine)
• If periapical lesions are present,
– 12 IOPA Radiographs
– 2 Occlusal Radiographs

• The primary purpose of roentgenograms is to
disclose hidden areas and structures such as
– Root length and morphology
– Pulp outline
– Periodontal ligament space
– Alveolar bone
– Infrabony defects
– residual roots
– impacted or supernumerary teeth
– The extent of present or past caries
– Evaluate root canal filling

• Existing restorations, cavity liners, & residual
caries are removed & a careful check is made
for possible pulpal exposure.
• In younger adults generally the pulp horns are
high & broad, but as age progresses there is
receding of the pulp horns & also sometimes
calcification occurs

• But when the tooth is non- vital due to reasons like trauma,
periapical pathology, endodontic treatment will have to be
carried out followed by restoration.

• The supporting tissues surrounding the abutment teeth must
be healthy & free from inflammation before any prosthesis
can be contemplated.
• The abutment teeth should not exhibit any mobility, since
they will be carrying an extra load.

• Diagnostic Cast
– Dimension of edentulous space.
– Occlusal plane
– Final outcome of propose treatment through
‘diagnositic waxing’
V Rangarajan, Textbook Of Prosthodontics, pg 470

• Diagnostic Cast
– Rotated and malposed teeth can be easily
observed. The form and contour of prospective
abutment teeth and the gingival tissues can be
visualized as well as the alignment and contacts of
opposing teeth.
Reynolds JM. Abutment selection for fixed prosthodontics. J Prosthet Dent 1968;19:483-8.

LOCATION
POSITION
CONDITION
CROWNFORM
TOOTH

LOCATION, POSITION & CONDITION
• Teeth with the following characteristics are
preferred abutments:
– Teeth adjacent to edentulous spaces.
– Teeth with grossly decayed crown that can be
restored with a full veneer crown. (periodontal
support should be uncompromised.)

LOCATION, POSITION & CONDITION
– Modifications like dowel core and pin retained
amalgam restorations may be needed to restore
crown morphology in grossly destructed teeth.
– Vital teeth are preferred, though endodontic
treated teeth can be used.
– Pulp capped teeth should be avoided because
they are under the risk of requiring RCT.

CROWN
• Crown Shape & Length
• Occlusal Anatomy
• Dimensions
– Buccolingual
– Mesiodistal

SHAPE
• Some teeth have tapered crown form that interferes with
the preparation parallelism, necessitating full coverage
crowns to improve esthetics and retention.
• Examples:
• Peg laterals
• Anterior teeth with poorly developed cingula and short
proximal walls
• Mandibular premolars with poorly developed lingual
cusps and short proximal surfaces
• Thin incisors.

Bulbous form Tapered form
Peg form Conical form
SHAPE

CROWN LENGTH
• The abutment teeth must have adequate occlusocervical
crown length to achieve sufficient retention.
• Full coverage restorations and crown lengthening are
considered with short clinical crowns to ensure adequate
retention.
Long Crown Short Crown

DEGREEOF MUTILATIONOF CROWN
• The size, number and location of carious lesions or
restorations in a tooth will influence the type of retainer on
an abutment.
• If the mutilation/fracture is severe, removal of that tooth is
necessary which will alter the design of the original
prosthesis.

Abutment & Its Selection In FPD
• The size, number and location of carious lesions or
restorations in a tooth will influence the type of retainer on
an abutment.
• If the mutilation/fracture is severe, removal of that tooth is
necessary which will alter the design of the original
prosthesis.
• For such tooth, PRINCIPLE OF SUBSTITUTION should be
followed.
DEGREEOF MUTILATIONOF CROWN
26/135

OCCLUSAL ANATOMY
• Has an indirect influence on the loads transmitted.
• The ridges and grooves increase the sharpness and
shearing action of teeth and reduce friction between
opposing surfaces by keeping the contacting area to a
minimum.
• This permits the most efficient mastication of food,
thus reducing the load transmitted.
• According to Stallard, worn-down teeth need more
muscular power and longer and more masticatory
strokes in order to chew food enough .

BUCCOLINGUAL DIMENSION
 The Occlusal surface of pontics should harmonize
with buccolingual dimension of natural
unmutilated teeth, and recreate the normal
buccal and lingual form to the height of contour.
 Reducing the width of the pontics does not
materially reduce the forces transmitted to the
abutments, but merely places heavier per unit
stress on the restoration and produces conditions
in the pontic similar to those of malposed and
improperly contoured teeth.

MESIODISTALDIMENSION
• The total mesiodistal width of the cusps of
abutments should equal or exceed the width
of the cusps of pontics.
• The is relationship assures that the occlusal
load transmitted to the abutment teeth will
not be more than twice the amount normally
supported by these teeth individually.

MESIODISTALDIMENSION
• Most healthy
organs of the body
are considered to
have a reserve
capacity equal, at
least, to their
normal functional
requirements.

 The shape of the roots also determines the ability
of the root to handle occlusal forces.
Teeth with a wider buccolingual
dimension than mesiodistal have
a greater ability to handle load
than conically shaped roots.
Multi-rooted teeth with separated roots
are better at displacing occlusal load than
teeth with conjoined roots.
Root Configuration

• The tooth with conical roots can be used as an abutment
for a short span fixed partial denture if all the other
factors are optimal.
• Teeth with longer root are stronger abutment than
compared to shorter ones.
• A single rooted tooth with evidence of irregular
configuration or with some curvature in the apical third
of the root is preferable to the tooth that has a nearly
perfect taper.
Root Configuration

• The length of the abutment root is directly proportional
to the stability and strength of the prosthesis.
• Stability : The quality of a prosthesis to be firm, steady,
or constant, to resist displacement by functional
horizontal or rotational stresses
Root Configuration

• Because of the conical shape of most roots, the actual
area of support (A) diminishes more than might be
expected from the height of bone (H). In addition, the
centre of rotation (R) moves more apical (R’) and the
lever arm (L’) increases, magnifying the forces on the
supportive structure.
Rosenstiel SF, Land MF, Fujimoto J. Contemporary fixed prosthodontics. 3rd ed. St. Louis:
Elsevier; 2000. p. 46-64.

Root Proximity
• Must be adequate clearance between the
roots of proposed abutments to permit the
development of physiologic embrasures in the
complete prosthesis.
• Malpositioned anterior teeth and mesiobuccal
roots of maxillary molars often present
unfavourable root proximities.
• Selective extraction or root resection
procedures may be the only solution.

Abutment Evaluation
• Crown-to-Root Ratio
– Ideally, a clinical crown-to-root
ratio of 2:3 is sought after.
Minimally, we’d like to see a 1:1
for a tooth to be considered for
use as an abutment.
– This ratio is determined by a
comparison of the linear
measurement of the portion of
the tooth above the bone to that
within the bone.

Abutment Evaluation
– Hence for the same reason, an abutment teeth with a less
than desirable crown-root ratio is more likely to successfully
support a FPD if
• Opposing Occlusion is a Removable Prosthesis
• Opposing Periodontally Weak teeth
Elsevier; 2000. p. 46-64.

Abutment Evaluation
– Force exerted on FPD depend the opposing dentition,
muscular activity of the patient and parafunctional habits.
– Average values of force exerted against a fixed prosthesis
• RPD – 26 lb
• FPD – 54.5 lb
• Natural teeth 150 lb

Some Facts
– The mean duration of the chewing cycle during which the
teeth are subjected to occlusal forces was 240 ms.
– Masticatory force generated
• Natural dentition -- 120-180 lb
• CD -- 16-22 lb
• RPD -- 22-28 lb
• FPD -- 50-65 lb
• Implant-supported -- 10-100 lb
complete dentures
S Gowri Shankar, Dentest Clinical Sciences, 5th edition, pg 1016
Lundgren D, Laurell L., Occlusal force pattern during chewing and biting in dentitions
restored with fixed bridges of cross extension, J Oral Rehabil. 1986 Jan; 13(1):57-71

• Periodontal Ligament Area
– The periodontal ligament area can be used as a
scale or measurement to determine the potency of
an abutment.
– Tylman stated that the two abutment teeth could
support two pontics.
– Johnston et al improvised Tylman’s Statement amd
proposed the famous ANTE’s Law.
Elsevier; 2000. p. 46-64.

• Periodontal Surface Area (Ante’s Law)
– “The combined pericemental area of the
abutment teeth should be equal to or greater in
pericemental area than the teeth to be replaced”.
– In cases where the periodontal surface area seems
inadequate, the use of multiple teeth for
abutments may be indicated depending on other
biomechanical factors.

The combined root surface area of the second
premolar and the second molar (A2p+A2m) is
greater than that of the first molar being
replaced (A1m).
The combined root surface area of the first
premolar and the second molar abutment
(A1p+A2m) is approximately equal to that of the
teeth being replaced (A2p+A1m)
The combined root surface area of the canine
and the second molar (Ac+A2m) is exceeded by
that of the teeth being replaced (A1p+A2p+A1m

• Jespen (1963) has reported average measurements of
root surface areas that can be used to calculate the
abutment to pontic ratio.

Abutment Evaluation
Order of Abutments concerning
Periodontal Surface Area:
• First Molar
• Second Molar
• Canine
• First Premolar
• Second Premolar
• Central Incisor
• Lateral Incisor
Maxillary Arch

Abutment Evaluation
Order of Abutments
concerning Periodontal
Surface Area:
• First Molar
• Second Molar
• Canine
• Second Premolar
• First Premolar
• Lateral Incisor
• Central Incisor
Mandibular ArchMandibular Arch

• It has been shown that provided periodontal disease is
treated , periodontal health maintained and occlusal
forces evenly distributed, FPD can be successful with as
little as ¼ of the support advocated by Ante.
• Hence, Ante’s Law is a safe and useful guideline for
abutment selection, when employed with other factors
involved in evaluating abutment capabilities.

LONG AXIS RELATIONSHIP
o The long axis relationship of
abutment teeth should be no
more than 25- 30 degree from
the parallel.
oForces are withstood best
when they are directed along
the long axis of the tooth.

o A severely inclined tooth will
not withstand forces as well
as one that is erect.
o Abutment teeth in an FPD
must be prepared with a
common path of insertion for
all retainers when rigid design
is employed.

ARCHCURVATURE
 When pontics lie outside the interabutment axis line,
the pontics act as a lever arm, which can produce a
torquing movement.
This is a common problem in replacing all four maxillary
incisors with a fixed partial denture.

 This can best be accomplished by gaining additional
retention in the opposite direction from the lever
arm and at a distance from the interabutment axis
equal to the length of the lever arm.
 The first premolars sometimes are used as secondary
abutments for a maxillary four-pontic canine-to-
canine fixed partial denture

ARCHCURVATURE

PERIODONTALFACTOR
• Abutment teeth must be
free from
– periodontal diseases,
periodontal pockets,
– osseous defects,
– gingival inflammation,
– and must have an
adequate zone of
attached gingiva.

PERIODONTALFACTOR
• Biologic width is the distance established by the “junctional
epithelium and connective tissue attachment to the root
surface” of a tooth
• Mean Biologic width – 2.04mm

• To avoid encroaching on the biologic width, the tooth
preparation must terminate at least 2mm coronal to
the alveolar crest.
• The presence of caries, fractured root structure, or
previous restorations apical to the gingival crest in
abutment teeth may predispose to violation of biologic
width during tooth preparation.
• A short clinical crown may induce the dentist to
overextend the preparation apically in an attempt to
enhance retention.

Tooth Form
• Two methods of modifying the tooth form to
change the unfavorable crown to root ratio.
– Construction of complete crown.
– Change the occlusal surface of the tooth with an
onlay.
Malone WFP, Koth DL. Tylman’s theory and practice of fixed prosthodontics. 8th ed. St. Louis:
Ishiyaku EuroAmerica; 1989. p. 67-8.

Tooth Form
– Change the occlusal surface of the tooth with an
onlay.
• Lateral and tipping stresses arise during function when
the cuspal inclines are steep or the occlusal topography
is too broad.
• Ideally, forces applied to the tooth fall within the
periphery of the root structure in bone.
• In mandible, this force is transmitted to the root by the
buccal cusps.

Tooth Form
• Hence, the location of the cusp in relation to the roots
in the buccolingual direction influences the direction of
the trasmitted force upon periodontium.
• If the direction of the functional forces fall within the
lateral borders of the clinical root, stress is directed
vertically upon the periodontium.
• If the force is directed beyond the confines of the root,
tipping stresses are induced.

Tooth Form
• Narrowing the buccolingual width of the occlusal
surfaces of the reconstructed crowns encourages a
more desirable location for the mandibular buccal and
maxillary palatal cusps in relation to the root.

Biomechanical Considerations
• Management of Destructive Forces
– The design of the bridge should allow for occlusal
forces and dislodging forces, like torque, flexure,
and tension to be handled.
– Occlusion should be designed to optimize the
distribution of occlusal forces evenly throughout
the envelope of motion over the entire mouth.

Biomechanical Considerations

• Length of Span
(Law of Beams)
– The Law of Beams is an
engineering principle
that states that as the
length of the span
increases, the flexure of
a system will be the
increase in length to the
power of three (cubed).

 Therefore, doubling the length would yield 8 times
the flexure. Tripling the length would yield 27 times
the flexure.

• Height of Connector (Law of Beams)
– As the height of the span decreases, the
flexure of a system will be the increase in
length to the power of three (cubed).
– Therefore, halving the connector height would
yield 8 times the flexure. A connector only 1/3
as tall would yield 27 times the flexure.

Double Abutment
• This refers to the use of two adjacent teeth at
one or both ends of the FPD as abutments.

Double Abutment
• The abubtment adjacent to edentulous space
is termed as primary abutment and the
adjacent abutment is termed as secondary
abutment.

Double Abutment
• Indications:
– To increase retention of restoration.
– To increase area of supporting periodontal
ligament and bone.
– Unfavourable crown-root ratio.
– Long span FPDs
– Spint and stabilize periodontal compromised
teeth.

Double Abutment
• Secondary abutment must meet the following
criteria:
– It must have as much root surface area, as
favorable a crown root ratio and similar retention
as the primary abutment.
– Sufficient crown length and space should be
present between the adjacent abutments to
prevent impingement of the gingiva under the
connector.

TYPES OF ABUTMENTS

Questionable Abutment
• Definition
– A common dilemma especially when the
abutment is periodontally involved, partially
fractured, polycarious or in poor arch position.

DEVELOPMENTAL ANOMALY

• Disturbances In Size of Teeth
– Microdontia
– Macrodontia
• Disturbances in Number of Teeth
– Anodontia (Complete or Partial)
– Supernumerary Teeth
Swapan Kumar Purkait. Essentials of Oral
Pathology, 2nd Edition, 235-250.

DISTURBANCES IN THE SHAPE OF
TEETH

CROWN AND ROOT
– Gemination (Twinning)
• Developmental anamaly, which refers to the partial
development of two teeth from a single tooth bud
following incomplete division.
• Twinning refers to the complete and equal division of a
single tooth germ that result in the formation of one
normal and one supernumerary tooth.
• Deciduous mandibular incisor and permanent
maxillary incisors.
Swapan Kumar Purkait. Essentials of Oral Pathology, 2nd Edition, 235-250.

CROWN AND ROOT
– Fusion
• Union of two adjacent normal tooth germs at the level
of dentin during development.
• Fusion results in one anomalous large crown in place of
two normal teeth and is having a single enlarged root
or two roots.
• In both dentition and the incisors are frequently
invloved.

• CROWN
– Dens-Evaginatus
• Developmental anomaly of tooth in which a focal area
of the crown projects outward and gives rise to Globe
shaped protruberence on the occlusal surface, which
appears as an extra cusp.
• Does not enounter any problem. Can be used as
abutment.

ROOT
• Concrenscence
• Union of the roots or two or more adjoining teeth due
to deposition of cementum is known as concrescence.
• Acquired defect (erupted or unerupted).
• Permanent maxillary molars

• Root
– Dilaceration
• Refers to the angulation or a sharp bend or a curve
anywhere along the root portion of a tooth.
• Best as abutment tooth
• Seen in both dentition with any tooth.

• CROWN, ROOT & PULP
– Dens-In-Dente (Tooth Within a Tooth)
• A defect in the morphologic of tooth in which a focal
area on the tooth surface is folded or invaginated
pulpally to a variable extend.
• Maxillary Lateral Incisor.

• DISTURBANCES IN THE STRUCTURE OF TEETH

• Enamel
– Amelogenesis imperfecta (hereditary)
– Focal enamel hypoplasia (local factors)
– Acquired
• Nutritional deficiency (vitamin a, c & d)
• Congenital syphilis
• Fluorides

• Dentin
– Dentinogenesis imperfecta (hereditary)
– Dentin dysplasia (local factors)
– Acquired
• Nutritional deficiency (vitamin d)
• Hypophospatasia
• Juvenile hypoparathyroidism.

Classification
• Localized problems associated with
questionable abutment
– Polycarious teeth
– Periodontally involved teeth
– Occlusal plane correction
– Endodontically treated teeth
– Tilted teeth

Carious Teeth
• Determine its amount and distribution.
• Polycarious – usually susceptible to recurrent
caries.
• Full coverage crowns after removal of carious
part and restoring it
• Caries Control Program
– Prophylaxis ----- Fluoride treatment
– Dietary consultation
– Restoration

Carious Teeth
Caries Control Program
– Endo-Perio consultation
– Cast metal restoration after amalgam restoration
– Recall system strictly maintained.

Periodontally Involved teeth
Prior to or concomitant carious control program.
- Excessive mobility – no FPD.
- Splinting may be tried.
Treatment
- Early interception
- elimination of those periodontally involved
teeth beyond the dignity of a restoration.

Periodontally Involved teeth
Treatment
- Termination of finishing line at or above the
soft tissue(except for esthetics and retention).
- quadrant splinting if and when single units
are impossible.
- telescopic type full arch splinting for
terminal cases.

• Disadvantage of Splinting
– Severely limits ability to perform oral hygiene
procedures.
– Crucial decision – especially sound terminal
abutment to stabilize healthy teeth.

Resected Teeth
• Clinical evidence shows selected usage is
acceptable.
• Surgery should be so performed that cleanable
gingival termination is possible.
• Bicuspid/molars are most suitable.
• Resected maxillary molars- use only if it’s a must-
as a pier abutment.
• Patient should be informed of the risk and the
dentist must be confident to do the procedure.

Resected Teeth
• Treatment
– Core and Dowel
– Crown and contour to prevent tissue stagnation.
– Splinting

Attrition and Abrasion
• Short teeth
• Problem encountered are:-
– Vertical height is less so less retention.
– FPD may not be possible.
– Plan out for Overdentures or Telescopic Crown.

Eroded Teeth
• The gingival finish line is placed beyond the
eroded area/ restoration.
• It arrests the process.
• Has the pulpal recession proceeded at the
same rate as erosion – not usually related.
• If bone support is adequate – restoration and
full coverage are usually recommended.

Pier Abutment/Intermediate Abutment
• It is a natural tooth located
between terminal
abutments that serve to
support a fixed or
removable prosthesis.
• Because they lie in the
middle of the span, they can
act as a fulcrum for
destructive forces.

• A common clinical situation , either in maxillary or
mandibular arch is of missing first premolar & first
molar, resulting in FDP design where –
 First premolar & first molar are terminal abutments
& second premolar serves as a pier abutment.

• Parfitt GJ (1960), have shown that the faciolingual
movement ranges between 56-108 µm, and intrusion of
28 µm. Teeth in different segments of the arch move in
different directions. Because of the curvature of the
arch, the faciolingual movement of an anterior tooth
occurs at a considerable angle to the faciolingual
movement of molar.

• These movements of measurable magnitude and in
divergent directions can create stresses in a long span
prosthesis that will be transferred to the abutments.
• Because of the distance through which it occurs, the
independent direction and magnitude of movements of
the abutment teeth, and the tendency of the prosthesis
to flex, stress can be concentrated around the
abutment teeth as well as between retainers and
abutment preparations.

• It has been postulated that the tendency of the
terminal abutments to intrude during function results
in a teetering movement, where the pier acts as a
fulcrum.
• This movement will eventually result in debonding of
the less retentive terminal retainer i.e canine &
inevitably the failure of the prosthesis.

• In order to overcome this potential risk, the use of
non-rigid connector has been advised.
• Shillinburg et al ( 1973 ) determined that the patrix of
non-rigid connector ( either a precision or
semiprecision attachment) should be placed at the
distal aspect of the pier retainer & matrix in the distal
pontic.

Precision Attachment
• Synonym : Parallel Attachment
• a retainer consisting of a metal receptacle
(matrix) and a closely fitting part (patrix); the
matrix is usually contained within the normal
or expanded contours of the crown on the
abutment tooth and the patrix is attached to a
pontic or the removable partial denture
framework
---- GPT, 8th Edition

SemiPrecision Attachment
• Synonym : Semiprecision rest
• A rigid metallic extension of a fixed or
removable partial denture that fits into an
intracoronal preparation in a cast restoration
---- GPT, 8th Edition

• He assumed that this would nullify the fulcrum effect,
& that the matrix portion of the attachment would be
seated firmly in place when pressure was applied
distally to the pier, due to mesial movement of distal
abutment.

• Markley (1951) suggested that non-rigid connector
should be placed on one of the terminal retainers, &
emphasized that it should not be placed at the pier
abutment because this would subject the relatively
weak premolar abutment to the extreme loads.
• Gill (1952) recommended placing non-rigid connectors
at one side or both sides of pier abutment.
• Adams ( 1956) advised placing one non-rigid connector
at the distal side of the pier, & if desired adding one
more at the distal of the anterior retainer.

• However use of non-rigid connector in a posterior 5
unit FDP with a pier is contraindicated in some
situations ( SCHILLINBURG ET AL )
Abutment teeth with significant mobility.
Span between abutments is longer than 1 tooth.
If the distal retainer & pontic are opposed by a
removable partial denture or an edentulous ridge,
while the 2 anterior retainers are opposed by
natural dentition, possibly allowing the distal
terminal abutment to supraerupt.

Cantilever Fixed Dental Prosthesis
• Terms Used are:- Swing On or free-end
• A fixed dental prosthesis in which the pontic is
cantilevered i.e. is retained and supported only on one
end by one or more abutments ( GPT-8)
Joseph E. Ewing, Fixed Parial Prosthesis, 2nd Edition, 270.

Cantilever Fixed Dental Prosthesis
• Long term prognosis of single abutment cantilever is
poor.
• Forces applied to a cantilever FDP are resisted on only
one side, leading to imbalance.
• Endodontic treated tooth are contraindicated as
abutment.

• Vertical forces can cause tipping,
and horizontal forces, rotation of
abutment teeth.
• A Cantilever induces lateral forces
on the supporting tissues, which
may be harmful and lead to tipping,
rotation, or drifting of the
abutment.

• Prospective abutment teeth for cantilever FDP should
be evaluated with an eye toward lengthy roots with a
favourable configuration, long clinical crowns, good
crown-root ratio, & healthy peridontium.
• Generally, a cantilever should replace only one tooth &
have atleast two abutments.

• Rigid bridge design is always preferred for
cantilever principle.
• Cantilever principle when properly applied,
will serve as an excellent compromise to meet
clinical conditions.
Joseph E. Ewing, Fixed Parial Prosthesis, 2nd Edition, 270.

SPRINGCANTILEVER ABUTMENT
• Abutment is not located
adjacent to edentulous
space and pontic recieves
support from one side only.
• A posterior abutment,
generally, premolar is used
to replace an anterior tooth
and a bar is used to connect
the abutment and pontic.

SPRINGCANTILEVER ABUTMENT
• Indication
– Replacement of missing central incisor when diastema is to
be maintained.
• Contraindication
– Mandibular arch as bar causes tongue interferences.
• Disadvantages
– Bar interferes with speech and can cause food entrapment.

TILTED MOLAR ABUTMENTS
 Loss of permanent mandibular
first molars to caries early in life
is still relatively common.
 If this space is ignored, the
second molar will tilt mesially
with eruption of the third molar.

• It then becomes difficult or impossible to make a
satisfactory FDP, because the positional relationship
no longer allows for parallel paths of insertion with
out interferences from adjacent teeth.

Treatment Options
PROXIMAL HALF CROWN ON MOLAR
ORTHODONTIC TREATMENT –
Uprighting the tilted molar

TELESCOPIC CROWN & COPING NONRIGID CONNECTOR

Canine replacement fixed partial dentures
• Fixed partial dentures replacing canines can be
difficult because the canine often lies outside the
interabutment axis.
• The prospective abutments are the lateral incisors,
usually the weakest tooth in the entire arch, and the
premolar, the weakest posterior tooth.

• A fixed partial denture replacing a
maxillary canine is subjected to more
stresses than that replacing a
mandibular canine, since forces are
transmitted outward (labially) on the
maxillary arch, against the inside of the
curve (its weakest point).
• On the mandibular canine, the forces
are directed inward (lingually), against
the outside of the curve (its strongest
point)..

SPILNTED ABUTMENT
It is the abutment which is used in addition to the
primary abutments in case of a long edentulous span, or
if the primary abutment is weak.

SPILNTED ABUTMENT
Splinting is done by:-
- Splinting by Bonding (Composite)
- Provisional splinting with full coverage acrylics.

SPILNTED ABUTMENT
Splinting is done by:-
- Experience has shown that splinting can create more
problems than it solves.
-Splinting is arduous, expensive and time
consuming, the completed restoration is difficult for
the patient to clean.

• Conditions where increase in number of abutments is
considered ( TYLMAN )
 Bone loss from periodontal disease.
 Mesial or distal tipping or changes in axial inclination.
 Less than favourable opposing arch relationships
producing increased occlusal load.
 Endodontically restored abutment teeth with root
resections.
 Arch form situations creating greater leverage factors.
 Tooth mobility created after osseous surgery.

CONCLUSION

• Every restoration must be able to withstand the constant
occlusal forces to which it is subjected. This of a
particular significance when designing and fabricating a
FPD.
• Since the forces that would normally be absorbed by the
missing teeth are transmitted through pontic, connectors
and retainers to the abutment tooth.
• If success is to be attained, the prosthodontist must take
into account the abutment mobility, alveolar bone
support, root configuration and angulation, opposing
occlusion, pulpal condition, presence of endodontic
treatment, and the remaining tooth structure.

REFERENCES
• Rosenstiel SF, Land MF, Fujimoto J. Contemporary fixed
prosthodontics. 3rd ed. St. Louis: Elsevier; 2000. p. 46-64.
• Shillingburg HT, Hobo S, Whitsett LD, Jacobi R, Brackett SE.
Fundamentals of fixed prosthodontics. 3rd ed. Chicago:
Quintessence; 1997.p. 85-103, 191-2.
• Malone WFP, Koth DL. Tylman’s theory and practice of fixed
prosthodontics. 8th ed. St. Louis: Ishiyaku EuroAmerica; 1989. p.
67-8.
• Swapan Kumar Purkait. Essentials of Oral Pathology, 2nd Edition,
235-250.

REFERENCES
• S Gowri Shankar, Dentest Clinical Sciences, 5th edition, pg 1016
• V Rangarajan, Textbook Of Prosthodontics, pg 470
• Joseph E. Ewing, Fixed Parial Prosthesis, 2nd Edition, 14-20.
• The Glossary of Prosthodontic Terms, 8th Edition J Prosthet Dent
2005;81:63.
• Reynolds JM. Abutment selection for fixed prosthodontics. J
Prosthet Dent 1968;19:483-8.

• Yoav Grossmann, Avishai Sadan : The prosthodontic concept of
crown-to-root ratio: A review of the literature ; J Prosthet Dent
2005;93:559-62.
• Jerome.M.S and Robert.D.S Free end pontics used on fixed partia;
denture J.Prosthet.Dent 1968;20;121-138
• Igal Savion, Chris L. Saucier, Stefan Reus. The Pier Abutment :
Review of literature & suggested mathematical model,
Quintessence Int 2006 ; 37 : 345-352.
• Jepsen A: Root Surface Measurement and a Method for X-ray
Determination of Root Surface Area. Acta Odont. scandinav. 21:
35-46, 1963.

• Lundgren D, Laurell L., Occlusal force pattern during chewing and
biting in dentitions restored with fixed bridges of cross extension,
J Oral Rehabil. 1986 Jan; 13(1):57-71
• William E Wright : Success with the Cantilever Fixed partial
denture. J Prosthet Dent ; May 1986, vol 55, 537-39.
• Richard Jacobi, Herbert Schillinburg Jr. Effect of abutment
mobility, site, and angle of impact on retention of fixed partial
dentures. J Prosthet Dent ; aug 1985, vol 54, 178-83.
• Jon P. Standlee, Angelo A. Caputo : Load transfer by fixed partial
dentures with three abutments : Quintessence Int; 1988.vol 19,
no.6, 403-9.

Abutment & Its Selection In Fixed Partial Denture

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Andere mochten auch

Andere mochten auch (20)

Ähnlich wie Abutment & Its Selection In Fixed Partial Denture

Ähnlich wie Abutment & Its Selection In Fixed Partial Denture (20)

Mehr von Self employed

Mehr von Self employed (10)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Abutment & Its Selection In Fixed Partial Denture

Hinweis der Redaktion