Direct and indirect retainers in fixed denture prosthodontics

Direct and indirect retainers in fixed partial denture prosthodontics

1. Good mornin
g

2. Retainers in fixed partial
denture

3. definitions
Retainer:
Any type of device used for stabilization or
retention of a prosthesis (GPT-8)
Fixed partial denture retainer:
The part of a fixed dental prosthesis that unites
the abutment(s) to the remainder of the restoration
(GPT-8)
Extra coronal retainers:
That part of a fixed dental prosthesis uniting the
abutment to the other elements of a prosthesis that
surrounds all or part of the prepared crown (GPT-8)

4. Selection of
retainers
DMF rate
Pdl of abutment, length of bridge span & type of
retainer
Retainer selection is usually dictated by:
1) age
2) DMF rate
3) edentulous span
4) Pdl support
5) arch position of the teeth
6) Skeletal relationships
7) Inter occlusal and intra occlusal conditions such as
crown length
8) Existing and projected oral hygiene of the patient
9) Vitality of the potential abutment Ideal retainers

5. Ideal retainers
Prime mechanical function
1
st
attribute, to be constructed for mouth without
injury to pulp & supporting tissues
2
nd
attribute, should protect and maintain the pulp
against thermal and galvanic shock.
3
rd
attribute, ability of the retainer to provide safety
for the tooth during the lifetime of the restoration
4
th
attribute, establishment of self-cleaning
property of the retainer
Retainer with least tooth reduction is more
devisable
Stress should be dispersed to the more receptive
areas of the abutment

6. Extra coronal retainers
Complete crowns:
1) Complete gold crown
2) Complete porcelain crown
3) Complete porcelain fused — to metal crown
4) Complete gold crown with acrylic resin facing
Partial crown:
For anterior teeth:
1) three-quarter crowns
2) pinledges
For posterior teeth:
1) mesial one-half crown
2) three-quarter crown
3) seven-eight crown

7.  other retainers
1) porcelain veneer/laminates
2) resin bonded retainers
Intra coronal retainers
1) inlays
2) onlays

8. Complete cast
crown:
Has the best longevity of all fixed restorations
Advantages

1) Greater retention
2) Greater resistance form
3) Strength
4) Modification of axial tooth contour
-special significance when dealing with malaligned
teeth
-better access to improved oral hygiene

9. 5) special requirements
-when retainers are needed for RPD
6) Easy occlusal modifications
-imp in supra erupted teeth
 Disadvantages
1) Extensive removal of tooth structure
2) Adverse effects on soft tissue
3) Vitality tests not feasible
4) Display of metal

10.  indications
1) Extensive coronal destructive by caries or trauma
2) Endodontically treated teeth
3) More conservative treatment non feasible
4) To provide support to a removable partial denture
5) Correction of occlusal plane
 contraindications
1) When conservative treatment can be carried out
2) If intact buccal or lingual wall exists
3) If less than maximum retention and resistance are
needed
4) High esthetic needs

11. criteria

12. Metal ceramic
crowns
 most widely used
 sufficient tooth reduction is required
 indications
1) esthetics
2) Retainer for FPD
3) Extensive tooth destruction
4) Superior retention and strength
5) Endodontically restored tooth in conjunction with a suitable
supporting structure
 contraindications
1) Active caries, contracted periodontal disease
2) Young patients with large pulp chambers
3) Where a more conservative retainer is feasible unless maximum
retention is needed — as for a long span FPD.

13.  advantages
1) Two in one property
-bcoz it is a combination
-Underlying principle
-Natural appearance
2) Excellent retentive quality
 disadvantages
1) Removal of substantial tooth structure
2) Fracture of porcelain
3) Difficult to select accurate shade & communicate it
to the dental ceramist
4) Expensive
5) Difficult to obtain accurate occlusion in glazed
porcelain

14. criteria

15. Partial veneer
crown
 An extracoronal metal restoration that covers only part
of the clinical crown is considered to be a partial veneer
crown. It can also be referred to as a partial coverage
restoration.
generally includes all tooth surfaces except the buccal
or labial walls in the preparation
preparation is more demanding and is not routinely
provided by practitioners
tends to be less retentive than a complete crown and is
less resistant to displacement

16.  indications
1) Where moderate amount of tooth structure is lost
provided buccal wall is intact and well supported by sound
tooth structure
2) When alteration of the occlusal surface is needed
3) can be used as retainers, to establish anterior guidance
and to splint teeth
4) Teeth that have suitable bulk to accommodate usually
retentive features
 contraindications
1) Short clinical crowns as retention may not be adequate
2) As retainers for long span FPDs
3) Rarely suitable for endodontically treated teeth
4) Endo treatment teeth if buccal walls weakened by access
cavity
5) Active caries or periodontal disease
6) Maligned teeth that have proximal surface bulbous
7) If tooth tilted

17. advantages
1) Conservation of tooth structure
2) Access to supragingival margins is rather easy
3) Access better for oral hygiene
4) less gingival involvement
5) good sealing of restoration
6) permits electric vitality testing
disadvantages
1) Less retention and resistance than complete
coverage crowns
2) Placement of grooves, boxers and pinholes
requires dexterity from the operator
3) Some metal may be displayed

19. Pin ledge
retainer
has the greatest potential for optimal
esthetics
preservation of facial enamel
retention comes from three or more pins
resistance form is provided by
indentations and ledges
involves less than 50% of the coronal area of
the tooth, twisting or rotational forces
pin ledge must be cast from a type IV gold or
an alloy

20.  indications
1) Coronal tooth structure is intact
2) Normal coronal form is present
3) Crown of tooth of average length or longer
4) average or greater labiolingual thickness in the
incisal one half of the crown
 contraindications
1) caries or a restoration extents past the normal
outline
2) if Crown exhibit abnormal form or other
developmental defects
3) if crown of the tooth is thin labiolingually
4) Conditions that cause excessive torsional forces to
be applied to retainer

21.  advantages
1) Minimal tooth structure lost
2) Optimal pdl response because most of finish line
supragingival
3) Optimal esthetic results
 disadvantages
1) Less resistance to distortion than any other
adequately executed retainer.
2) Though a simple design, should be executed with
greater than average skill and care.

23. Porcelain laminate veneers
 A thin bonded ceramic restoration that
restores the facial surface and part of the
proximal surfaces of teeth requiring esthetic
restoration (GPT-8)

These are traditionally been made from
aluminous or reinforced feldspathic porcelains
 Porcelains can also be made from high
strength ceramics.

24.  indications
1) discoloration
2) enamel defects

25. 3) diastemata
4) Malpositioned teeth

26. 5) malocclusion
6) poor restorations
7) aging

27. 8) wear patterns
9) agenesis of the lateral incisor

28.  contraindications

1) available enamel
2) ability to etch enamel
3) oral habits

29.  advantages
1) color
2) bond strength
3) periodontal health
4) resistance to abrasion
5) inherent porcelain strength
6) resistance to fluid absorption
7) esthetics
 disadvantages
1) time
2) repair
3) technique sensitive
4) color
5) tooth preparation
6) fragility
7) cost

30. Resin bonded retainers
 A fixed dental prosthesis that is luted to
tooth structures, primarily enamel, which has
been etched to provide mechanical retention
for the resin cement (GPT-8)

31.  indications
1) Caries free abutment teeth
2) mandibular incisor replacement
3) maxillary incisor replacement
4) periodontal splints
5) single posterior tooth replacements
6) in children
 contraindications
1) extensive caries
2) deep vertical overbite
3) Para functional habits
4) crown surface area
5) quality of enamel

32.  advantages
1) minimal tooth preparation
2) minimal potential for pulpal trauma
3) no anaesthetic needed
4) supragingival margins
5) impression making
6) provisional restorations
7) chair side time
8) reduced cost
9) rebonding possible
 disadvantages
1) uncertain longevity
2) no space correction
3) no alignment correction
4) enamel modification
5) esthetics