Restoration of RCT part 2

3. Which is more important; an adequate
endodontic treatment or an adequate
coronal restoration? Could they be
equally important?

4. Is there an expected rate of unfavourable
outcome associated With prosthodontic
failure?

5. •Vire(1991) classified failures of endodontically treated
teeth according to
•Prosthodontic
•Periodontic
•Endodontic
•Teeth that had been crowned had a greater longevity (87
months) than uncrowned teeth (50 months) of the 116
endodontically treated teeth, of 59.4 % were prosthetic
failures, primarily due to crown fracture.

6. When and Why Do Endodontically
Treated Teeth Require Full
Coverage?

7. The need for a full-coverage restoration after
endodontic therapy is largely determined by:
• Tooth type
• Amount of tooth structure loss
• The amount of occlusal stress on the tooth.

8. Anterior Teeth
•Not always need complete coverage by placing a
complete crown
•Extensive loss of coronal tooth structure or tooth will
be serving as an FPD or RPD abutment crown or post
&crown

9. Posterior Teeth
•Subject to greater loading of cusps can be wedged
apart (Cuspal deflection)
•Complete coverage is recommended on teeth with
high risk of fracture

11. Quantifying Tooth Loss Peroz et al. ( 2005 )
•Based on the number of remaining axial walls:
•Class I 4 walls present ( occlusal cavity )
•Class II mesio-occlusal (MO) or disto-occlusal (DO)
cavity in which one cavity wall is missing
•Class III MOD cavity with two remaining axial walls.
•Class IV category, a single axial wall either buccal or
lingual remains
•Class V crownless tooth with no remaining axial walls

16. Tilk et al 1979 , teeth with and without posts had the
same longevity outcome,
Raiden et al 1999 , teeth with posts exhibited significantly
more apical periodontitis
Another study, post compromise the apical
endodontic seal.

17. Disadvantages to the Routine Use of a Cemented Post
•Placing the post requires an additional operative
procedure.
•Preparing a tooth to accommodate the post entails
removal of additional tooth structure.
•The post can complicate or preclude future
endodontic re-treatment that may be necessary.

18. Clinical Complications of Post and Core Restorations
• Post loosening
• Influence of post form
• Influence of post length
• Root fracture and Root perforation
• Influence of threaded posts
• Influence of post length
• Influence of residual dentin thickness (P. Diameter)
• Influence of instrument diameter(Drill, GG)

20. Principles for Restoration of
Endodontically Treated
Teeth

21. • Several factors affect the outcome when
endodontically treated teeth are
restored.
Ø Post Length
Ø Post Diameter
Ø Canal Preparation
Ø Ferrule Effect
Ø Anatomical and Structural Limitations

22. Post Length
• Recommendations have been made regarding post Length,
including the following:
1. Post length should equal the incisocervical or occlusocervical
dimension of the crown
2. Post should be longer than the crown
3. Post should be one and one-third times the crown length
4. Post should be one-half the root length

23. Several studies have demonstrated that short posts are
associated with higher root stresses and greater tendency
for root fracture to occur

24. Post Diameter
• Deutsch et al, when large diameter posts (1.5 mm or
more) were placed, root fracture increased six-fold
for every mm of decreased root diameter
• Post diameter not exceed 1/3 the root diameter
• Preserve at least 1.0 mm of root wall thickness

26. Guidelines for pulp chamber preparation
• Prefabricated post ; morphologic pulp chamber
undercuts should be retained for core retention
• Custom cast post and core; pulp chamber
undercuts should be blocked out with a definitive
cement or restorative material that is bonded to
the tooth, or the undercut should be eliminated by
removal of tooth structure

27. Immediate versus delayed removal of gutta-percha
and post space preparation
•Several studies have indicated that there is no
difference in the leakage of the root canal filling
material
•Abramovitz et al compared immediate gutta-
percha removal and delayed gutta-percha removal
(after 2 weeks). They found no difference
between the two methods.

28. Ferrule Effect
ØWhen possible, maintenance of
1.5 to 2.0 mm of intact tooth
structure around the entire
circumference of a core
Ø When preparation margin is
partially or entirely seated on
core material,
ØForces of occlusion may be
transmitted to core & in case
of a post and core, between
the internal aspect of the
root and the post.

30. • Ingber et al , biologic width,
approximately 2 mm. They
suggested that an additional 1
mm be added coronal to the 2-
mm dentogingival junction as an
optimal distance between the
bone crest and the restorative
margin
Components of the biologic width (~ 2.04 mm): EA
epithelial attachment (~ 1.00 mm); CTA connective
tissue attachment (~ 1.00 mm). S sulcus (~ 0.75 mm).

32. Management of Severely Damaged
Endodontically Treated Teeth

33. •Crown Lengthening
•Allowing longer clinical crowns and reestablishment
of the biologic width
•Crown lengthening surgery has been categorized as
esthetic or functional

34. Preprosthetic Orthodontic Tooth Eruption
Orthodontic tooth extrusion not used in:
Posterior teeth where the furcation would
be exposed on tooth extrusion,
Teeth with moderate to severe bone loss
from periodontal disease where the
procedure would also compromise the
optimal crown-root ratio.

35. ■ Effect of apical preparation on crown-to-root ratio. A, Schematic of extensively damaged
premolar tooth. Apical extension of the gingival margin would encroach on the biologic width .This
preparation has no ferrule. C, crown length; R, root length. B, Creating a ferrule with orthodontic
extrusion reduces root length (Rʹ), whereas crown length remains unchanged. C, Surgical crown
lengthening also reduces root length (Rʹ) but increases crown length (Cʹ). This results in a much
less favorable crown-to-root ratio, which may, in fact, weaken the restoration.

36. Supracrestal fiberotomy
Indicated when the bone is extruded with the tooth,
requiring its removal for two reasons: bone levelling with
the adjacent teeth and exposure of sufficient tooth
substance for crown restoration.
Fiberotomy. The surgical blade (blue) is inserted
to the depth of the gingival sulcus, through the
biologic width (BW), and severs all fibrous
attachments around the tooth, almost beyond the
supracrestal fibers (SF), to a depth of nearly 2 to 3
mm apical to the alveolar crest (dashed line).
(Adapted from Edwards7 with permission.)

37. Intra-alveolar Transplantation
• Atraumatic extraction with a
Power tome.
• Interproximal interrupted
sutures.
• Completed RCT at 5 weeks.
• Periapical radiograph at 13
weeks.
• Core build-up and tooth
preparation.

39. •Gingival margins do not stabilize completely until
at least 5 months after surgery
•In areas of no esthetic concern, it is this author’s
opinion that restorative treatment can be
commenced after at least a 6- to 8-week healing
period without aberrant healing issues.

44. •The luting agent must fill all dead space within the
root canal system
•A rotary (lentulo) paste filler or cement tube is used to
fill the canal with cement
•Inserted gently to reduce hydrostatic pressure Voids
may be a cause of periodontal inflammation via
lateral canals.

45. If cement is placed only on the post, as it is seated (large arrow) the air trapped within
the post preparation travels through the liquid cement (small arrows), producing
multiple voids. (Reprinted from Morgano and Brackett3 with permission.)

48. Core Build-up Materials

49. Amalgam
Ø It has physical properties
Ø Relatively dimensionally stable
Ø Resistance to leakage of amalgam improves with
time because of its corrosion products
Ø It is a relatively inexpensive material compared
with others
Advantages:

50. Disadvantages:
§ Lack of bonding to dentin,
§ Poor color under an all-ceramic crown,
§ Formation of amalgam tattoo during tooth
preparation.
§ At initial setting, the strength of amalgam is
low. Hence, it cannot be prepared right away

52. Composite resin
Advantage
• Easy to use and satisfies esthetic demands
• More flexible than amalgam
• It adheres to tooth structure
• May be prepared and finished immediately
• Acceptable core material when coronal tooth
structure remains

53. Disadvantage
• Poor choice when a significant amount of tooth
structure is missing
• Instability of material in oral fluids (water sorption)
• Hygroscopic expansion of composite can generate
stresses that may cause extensive cracking in the
overlying ceramic layer
• Shrinkage during polymerization causes stress on the
adhesive bond resulting in gap formation

54. Glass ionomer
• It adheres to tooth structure by chemical bond
• Has a low coefficient of thermal expansion
• Low polymerization shrinkage
• Has the ability to release fluoride
• Weakest core build up material when compared
with others.
• Used primarily to block minor undercuts in a
tooth preparation

56. Removal of Posts

57. Risks of Post Removal Procedures
•May cause cracks, vertical root fracture, or
perforation as a result of direct mechanical
action from the transfer of ultrasonic energy

58. Removal of Posts TECNIQUES
•Post removal :
ØMechanical post removal devices
ØHigh-speed rotary instruments
ØUltrasonic devices.
• Threaded posts are best removed by grasping the exposed
and flattened head of the post and gently turning it,
usually in counter-clockwise direction

62. Endodontic Treatment of a Tooth with a Prosthetic
Crown

63. Retrofitting a Post to an Existing Crown

68. References
Contemporary Fixed Prosthodontics; Fifth edition; Restoration of the
Endodontically Treated Tooth, 278
Restoration of Root Canal-Treated Teeth- An Adhesive Dentistry
Perspective, Jorge Perdigão , © Springer International Publishing Switzerland
2016
The Dental Reference Manual , A Daily Guide for Students and
Practitioners, Geraldine M. Weinstein Mitchell T. Zientz Editors© Springer
International Publishing Switzerland 2017
Contemporary Restoration of Endodontically Treated Teeth Evidence-Based
Diagnosis and Treatment Planning/[edited by] Nadim Z. Baba. © 2013
Quintessence Publishing Co Inc