Retainers- FPD
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Transcript Retainers- FPD
RETAINERS
DEFINITION:
Any type of device used for
stabilization or retention of
prosthesis -- GPT
Retainer
That
for an FPD…
component of an FPD which
takes support from the abutment
tooth and provides retention to
the prosthesis
SELECTION OF RETAINERS
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Retainer selection for abutment is critical
and is dictated by the followings:
Age
DMF rate
Edentulous space-Partial veneer crown
contraindicated in long span FPD
Periodontal support
Arch position of the tooth
Skeletal relationship
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Inter occlusal & intraocclusal
condition such as crown length
Oral hygiene of the patient
Vitality of the abutment teeth--endodontically treated teeth may
have to be restored with core &
post before designing the
retainer
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Condition of the abutment teeth
Cost
Preservation of the tooth
structure----Buccal surface
should be conserved. Partial
veneer crown is more
conservative than full crown . All
ceramic crowns are least
conservative
Types of retainers
I.
Classified as:
Based on tooth coverage
Full veneer crown
Partial veneer crown
Conservative (minimal prep.)
retainers
II.
Based on material used
All metal retainers
Metal ceramic retainers
All ceramic retainers
All acrylic retainers
Full veneer crowns
Covers all 5 surfaces of abutment
Most retentive of the veneer preparations
Compared to partial veneer designs,full
veneer crown exhibits superior resistance
nd retention
Used on those teeth whose restoration
demands max. retention.
Variations—Metal ceramic crowns and all
ceramic crowns used in situations that
requires a good cosmetic results
The full veneer crown should be used
when less extensive and less destructive
design have been considered and found
lacking in retention ,resistance ,coverage
or esthetics to properly restore the tooth
Partial veneer crown
Preferred than full veneer crown because
they requires less tooth reduction
Crown does not cover the entire abutment
Facial surface is left intact for superior
esthetics
Used when minimal retention is sufficient
and when abutment tooth is healthy
Contra indications
In
long span FPDs
Endodontically treated tooth
Dentition with active caries or
periodontal disease
Poorly aligned abutment tooth
Advantages
Conservation
of tooth structure
Reduced pulpal and periodontal
insult during tooth prep
Improved access for finishing by
dentist & oral hygiene by patient
Less
of margin approximate soft
tissues subgingivally and hence
less gingival involvement than
complete coverage
Remaining
intact facial or buccal
tooth surface permits electric
vitality test
Disadvantages
Less retention & resistance than
complete crowns
Some metal displayed in completed
restoration—unaesthetic
Tooth prep is difficult because only
limited
adjustments can be made in the
path of placement
Resin bonded retainers
(Maryland bridges)
Require
minimal tooth preparation
Acid etched
Esthetically appealing
Economical , conservative ,
functional & do not irritate soft or
hard tissues
Indication
As
retainers of FPD for abutment
with sufficient enamel to etch
Splinting of periodontally
compromised teeth
Stabilizing dentition after
orthodontic treatment
Contraindication
In
patients with sensitivity to base
metal alloys
When facial esthetic of abutment
require improvement
Inadequate enamel surface to
bond eg;caries,existing
restoration
Incisor with extremely thin faciolingual dimension
Advantages
Non invasive to dentin with lingual
and proximal tooth preparation
including occlusal rest
Conservative with undeniable patient
appearance
Tissue tolerant because of
Supragingival margin,without pulpal
irritation
Reduced cost and less chair side time
Disadvantage
Demanding
technique and tooth
prep.
Plaque accumulation
Bulky contour
Restricted to single pontic
placement
Graying out of teeth that are thin
labiolingually
Based on material used
All
metal retainers
Metal ceramic retainers
All ceramic retainers
All metal retainers
Partial
or full veneer crown
Require minimal tooth
reduction
Strong even in thin sections
Metal ceramic retainers
Indicated on teeth that require
complete coverage & esthetic
demand
Can accommodate cast or soldered
connectors
Can afford high force—metal
Require more teeth reduction
Indication
Extensive tooth destruction as a
result of caries or trauma
Existing previous restoration that
precludes the use of a more
conservative restoration
Need for superior retention and
strength
Endodontically treated tooth
Contraindication
Whenever
a more
conservative retainer is
feasible
All ceramic
Primary
purpose ---to achieve
best possible esthetic results
Risk of reduced restoration
longevity—potential for fracture
,inferior marginal adaptation than
PFM retainer
Telescopic retainers
Used when path of insertion of FPD does
not coincide with long axis of abutment
Design involves fabricatin of two copings
one over the other
Internal or primary coping function to
modify the morphology of tooth –path pf
insrtn changed
Secondary coping designed to fit over
primary
REFERENCES
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4.
Fundamentals of Fixed Prosthodontics
Herber T.Shillingburg
Contemporary Fixed Prosthodontics
Rosenstiel,Land,Fujimoto
Tylmans Theory and Practice of Fixed
Prosthodontics
Textbook of Prosthodontics-Deepak
Nallaswamy
Thanking you…..