Prosthodontics

1. RESTORATION OF
ENDODONTICALLY TREATED
TEETH
DR SHRIMANT RAMAN
DEPARTMENT OF PROSTHODONTICS

2. INTRODUCTION
 During the past 20 -30 years there has been an increased interest
in restoring endodontically treated teeth
 This mode of treatment is complicated by the fact that much or all
of the coronal tooth structure which normally would be used in
the retention of the restoration has been destroyed by :
• Caries
• Previous restoration
• Trauma
• Endodontic access itself

3. • The complete coverage crown is the most ideal
restoration to protect the remaining natural teeth in
endodontically treated teeth.
• As coronal tooth structure is mostly damaged, the
crown requires a core or a post and core for
retention, depending on the extent of damage and
location of the tooth

4. DEFINITIONS
According to GPT 2005
Post (Dowel): A structure usually
made of metal that is fitted into a
prepared root canal of a natural tooth.
When combined with an artificial
crown or core, it provides retention
and resistance for the restoration.
Core: The center or base of a structure

5. Principles of restoration of endodontically treated teeth :
• Provide good coronal seal
• Protect/conserve remaining tooth structure.
• Satisfy functional and aesthetic needs.
• Reduction of stresses with favorable distribution within
remaining tooth structure.

6. DIAGNOSIS &
TREATMENT
PLANNING

7. ENDODONTIC CONSIDERATIONS
• Attention must be given to the quality of the
endodontic therapy.
• Predictable success in endodontic therapy requires a
dense, uniform, three dimensional obturation of the
root canal system, 0.5 to 1.0 mm from the
radiographic apex of the root or roots.

8. PROSTHETIC CONSIDERTIONS
• The extent of coronal destruction is an important determinant in
deciding on the restorative technique and materials to be used in
returning the tooth to normal form and function.
• Contrary to popular belief, posts do not strengthen the tooth. The
primary function of a post is to provide retention for the core.

9. • Posts are indicated when there is inadequate tooth
structure to retain a core for a coronal structure.
• It is evident now that care should be taken to
preserve as much sound dentin during endodontic
therapy and subsequent restorative procedures.

10. PERIODONTAL CONSIDERATIONS
• Periodontal disease should be treated prior to placement of
definitive restorations.
• A healthy periodontium provides the best prognosis for the
tooth and will make procedures such as placement of margins
and making of an impression easier and more accurate.

11. TREATMENT OPTIONS
Anterior teeth
• Intact coronal tooth structure except for prepared access opening
– access opening is restored with composite resin if no
discoloration is present.
• Less than 25% coronal tooth structure is damaged – a complete
coverage crown is required.
• More than 25% coronal tooth structure is damaged – a post and
core with crown is required.

12. Posterior teeth
• Less than 50% coronal tooth structure is damaged – core and
crown are required.
• More than 50% coronal tooth structure is damaged – post, core
and crown are required.

13. CLASSIFICATION
• All posts can be classified as rigid and non-rigid, which can be sub-
classified according to the post material, shape and surface
configuration.
• Posts can be classified according to the following features:
 Shape – parallel, tapered
 Stiffness – rigid, non-rigid
 Surface – smooth, serrated, threaded
 Colour – aesthetic, non-aesthetic
 Pressure on root – active, passive
 Fabrication – prefabricated, custom-made (cast posts).

14. Parallel sided, threaded post Parallel sided post with tapered end
Parallel sided, vented post Parallel sided, passive posts

16. Parallel and tapered post :
• Parallel-sided posts direct the occlusal forces apically while tapered
posts direct the forces laterally by producing a wedging effect.
• Hence, occlusal forces are better directed by parallel posts.
• They are also more retentive than tapered posts. Tapered posts are
more conservative of tooth structure.

17. Rigid and Non-rigid :
The post should be resilient enough to cushion an impact and strong
enough to resist permanent deformation.
Rigid Post
• Can be made of crown and bridge alloys (cast posts), stainless steel,
titanium, zirconia (prefabricated posts).
• Zirconia has greatest stiffness followed by steel and titanium alloy.
• More chance of root fracture than non-rigid.
• Indicated for teeth with less than 3–4 mm vertical height or less than
25% tooth remains

18. Non- Rigid Post
• Made of glass, quartz or carbon fibres embedded in a resin matrix, also
called ‘fibre-reinforced composite’ posts (FRC).
• They have to be adhesively bonded to the root canal space.
• Can reinforce weak teeth with flared canals.
• Require less preparation – preserve integrity and strength of dentine.
• Less root fracture.
• Indicated in teeth with more than 25% remaining tooth structure.

19. Custom-made and prefabricated posts :
• The only custom-made post is the ‘cast post’.
• It is also called ‘one-piece’ post, as the post and core are not
separable.
• The use of this post is declining.

20. Cast post and core
A one-piece foundation restoration for an endodontically treated
tooth that comprises a post within the root canal and a core replacing
missing coronal structure to form the tooth preparation (GPT8).
Advantages of cast post :
• Conservative of tooth structure.
• High strength.

21. Disadvantages of cast post :
• Time – requires two appointments.
• Wedging effect – because they can only be made tapering and
high rigidity.
• Porosity – problem and casting procedure.
• Fit – may not be very accurate because of indirect method.
• Unaesthetic – as it can be made only of crown and bridge
alloys. Hence, it cannot be used with all-ceramic restorations.
• Cost – lab costs will be incurred.

22. Prefabricated posts:
• They are versatile. They are available in different configurations
and can be selected as per the given clinical situation.
• They are also available in different diameters corresponding to
the size of the drill. Hence, the fit is accurate.
• Though post and core is inserted in two separate procedures, it
requires only one appointment with no laboratory costs.

23. SELECTION OF POST
The following parameters govern post selection:
• Length
• Diameter
• Shape
• Surface configuration
• Location

24. Guidelines for determining post length are :
• Equal to half the remaining length of the tooth.
• Equal to two-thirds the root length of the root.
• Equal to the length of the remaining crown.
• Half the length of root contained in bone.
• Have minimum of 4 mm of gutta-percha apically to provide
adequate seal.
LENGTH

25. DIAMETER
Post diameter should not exceed one-third
mesio-distal root diameter.
1 mm dentine should surround the post
preparation.

26. SHAPE
• Parallel-sided posts are preferred as they have better retention
and more favourable stress distribution.
• Tapered posts are indicated for the significantly tapered canal
system, where use of a parallel-sided dowel would involve
vigorous preparation of the radicular dentine walls.
• To minimize the splitting potential of a tapered dowel, there
should be flat seat at the occlusal end of the preparation to resist
apically directed forces and prevent wedging.

27. SURFACE CONFIGURATION
• Parallel-sided serrated posts are generally
indicated.
• If root length is less, threaded posts offer better
retention.

28. LOCATION
• Posts should be placed in roots that are round straight
and long
• In the anterior teeth, roots are seen mostly with circular
cross-section.
• Root anatomy of multi-rooted teeth is most suitable in
the palatal roots of maxillary molars, palatal roots of
maxillary premolars and distal roots of mandibular
molars.

29. TOOTH PREPARATION FOR POST
• Coronal tooth structure is prepared
according to the type of extra
coronal restoration planned.
• All existing caries, restorations,
cements, bases and unsupported
tooth structures are removed.
• Preserve as much of intact coronal
tooth structure as possible to
externally brace the tooth.

30. Ferrule:
• Minimum of 1.5 mm of sound tooth structure 360° around the
tooth should be present, apical to the core.
• It improves structural integrity of the tooth and prevents fracture

31. PREPARATION OF POST SPACE
Peso reamers Gates Glidden Drill (GG Drill)

32. • The procedure is begun with the largest Peso or Gates that will fit into the
canal.
• Once the root filling is removed, successively larger Peso or Gates is used to
enlarge the canal to desired dimensions.
Radiograph with reamer in position is used as
a guide to determine length and diameter.
Peso reamer in use is placed and
radiograph taken

33. • Appropriate length and diameter of the post are determined
using a radiograph as a guide and following the guidelines
• The dimensions of the previous endodontic filling, if
available, can also be a good guide to determine length and
diameter.
• An endodontic stopper is placed in the shank of reamer or
drill to ensure appropriate length.

34. • Some prefabricated post systems are provided with specific drills
corresponding to the diameter of the posts.
• These drills are used to enlarge the canals to the required diameter,
when available.
Prefabricated posts of varying widths with
their corresponding drills.

35. Custom-Made Posts (Cast Posts)
• Custom-made posts are categorized as rigid,
metal, tapered, smooth, in the classification
for posts.
• They can be fabricated:
1. Direct method
2. Indirect method

36. Direct Method
A pattern of the post and core is fabricated
directly in the patient’s mouth and then cast in
the laboratory.
Disadvantages :
• Consumes a lot of clinical time.
• Any problem in casting, procedure has to be
repeated intra-orally.

37. Procedure:
• A 14-gauge plastic sprue (a plastic
toothpick or stainless steel wire
can also be used) is trimmed to
check the fit in canal.
• Grooves are cut on the surface for
retention of the pattern material.
• A mark or notch is made facially to
allow re-orientation subsequently.

38. • Canal and surrounding areas are lubricated with
petroleum jelly.
• Autopolymerizing acrylic resin is mixed to a running
consistency, coated on sprue and inserted in the canal.
• As the resin becomes doughy, move the pattern up and
down to ensure it is relieved from any undercuts.
• Any voids can also be filled with new resin, pattern
reseated and finally allowed to set outside the mouth.

39. • After the resin in the post
portion sets, the core is
built up with the same
material and moulded with
fingers (Fig.1)
• After setting, it is prepared
to the appropriate shape of
core
(Fig.2)
Fig.1
Fig.2

40. Indirect method
• In this technique, an impression is made of the canal space using
a putty and light body wash, and the pattern is fabricated
indirectly on a model and cast.
• This is indicated for multiple posts and posts in multi-rooted
teeth.
Putty impression is made of
prepared tooth along with the
entire arch
Light body material injected into
post space and placed on the putty
impression

41. Advantages :-
• There is less usage of chair-side time and as a cast is available, any
problems in casting can be easily repeated.
A second impression is made.
Following removal of final
impression – cast can be
poured where the post can be
fabricated

42. Fabrication of Cast Post in Molar
• Post can be made in one-piece if the canals
are convergent or parallel.
Upper molar palatal and
disto-buccal canal
prepared for cast post
One piece cast post
fabricated
Cemented cast post and
core

43. • Post for posterior teeth may need to be made
in two parts if canals are divergent.
Post space in mesio-buccal,
disto-buccal and distal canals
in mandibular molar with
divergent canals
Post space impression made
with putty and light body
wash

44. Cast is poured and cast post to
fit distal canal (overextended
occlusally) is fabricated first
Wax pattern with distal post Wax pattern minus the distal
post
Wax pattern fabricated for the
remaining posts along with the core
is fabricated around the distal post

45. The pattern is cast and distal
post is fitted
Larger casting (buccal posts
with core)
Distal post is cemented

46. After the cement sets
overextension in distal post is
trimmed
Cemented two piece cast
post

47. Core Materials :
• Cast core
• Amalgam
• Glass ionomers
• Composite resin
Cements:
• Zinc Phosphate
• GIC
• Resin Cement

48. POST CROWN
• This is a one-piece post crown.
• It is also called ‘Richmond crown’.
• Indicated in patients with deep incisal overbite where it is difficult
to provide space for a core and crown separately
Fracture maxillary central incisor
(tooth no: 11) with lack of occlusal
clearance
Coronal tooth preparation

49. Preparation of canal space Post crown fabricated by indirect
method
Cemented post crown