Rationale of post endodontic restoration /certified fixed orthodontic courses by Indian dental academy

RATIONALE OF POST
ENDODONTIC
RESTORATION

INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
www.indiandentalacademy.com


Contents
 Introduction
 Historical perspective
 Causes of tooth fracture
 Treatment planning
 Post systems
 Evidence based practice
 Principles of tooth preparation
 Core
 Corono-radicular restoration
 Restoration of resected root
 Over dentures
 Conclusion

Why restore endodontically
treated teeth?

Why ask Why?

Historical perspective
 More than 200 years
 1747, Pierre Fauchard: Posts
made of gold or silver and held
in the root canal space with a
heat-softened adhesive called
“mastic.”
 “Pivot crown.” Dubois de
Chemant – 1800, used seasoned
wood
 Prothero reported removing two
central incisor crowns with
wooden pivots that had been
successfully used for 18 years.

Historical perspective
 Metal pivot retention similar to Richman’s
Crown
 Dental Physiology and Surgery, written by Sir John
Tomes in 1849. Tomes’s post length and
diameter conform closely to today’s principles
in fabricating posts
 minimal efforts to clean, shape, and obturate
 Wooden post associated with swelling &pain.
But allowed escape of “morbid humors.”

Causes of tooth fracture
 Altered physical properties of the tooth
 Weakening due o the loss of tooth
structure
Prestressed laminates – Tidmarsh 1974
 Loss of proprioception


Classification of Posts
POSTS

Custom-made Prefabricated

Metallic Non-metallic

Stainless steel Zirconia

Ni-Cr alloy Ceramic

Titanium Fiber


Active Passive
Threaded, engage dentin Retained by luting agent
More retentive, more stress Retention & stress less
Thick but short roots Long slender roots

Parallel Tapered
More retentive Less retentive
Less stress Wedging forces
Less removal, slender & delicate
More dentin removal
roots
Success rate high
www.indiandentalacademy.com Success rate low

Post Design


Metallic Posts
 Rigid except titanium posts
 Round hence lack rotational
resistance
 Metallic posts tend to corrode,
except Ti posts
 Ti posts – not strong & easily
fracture; retrieval difficult
 Flexi-post

Cast Post & Cores
 Used for many years
 Unpopular – 2 appointments, laboratory fee,
temporization
 Advantageous in certain clinical situations:
 multiple teeth requiring posts
 mal-aligned tooth
 slender roots like mandibular incisors
 Requires proper temporization to prevent inter
appointment contamination

Ceramic & Zirconia Posts
 Metal posts & all ceramic crowns
 White or translucent – esthetic posts
 Lack rigidity hence require larger post diameter
 Zirconia posts cannot be etched
 Retrieval is difficult
 Ceramic posts can be ground but procedure is
dangerous
 Zirconium posts are impossible to grind

Fiber Posts
 Carbon posts were first of its kind; mod of
elasticity similar to dentin
 When bonded with resin cement, distribute
stresses evenly
 Retrieval easy – boring through the uniaxial fibers
 Dark – esthetic incompatibility
 Newer fiber posts – quartz fiber, glass fiber,
silicon fiber

Treatment Planning

 Good apical seal
 No sensitivity to pressure
 No exudates
 No sinus
 No apical sensitivity
 No active inflammation


Considerations For Anterior Teeth
 do not always require complete
coverage
 fracture toughness for teeth with
and without endodontic treatment-
SAME (lab)
 strengthen the teeth replacing part
of the root canal filling with a
metal post
 when the tooth is loaded, the
lingual side is under tension and
the buccal side under compression

Considerations For Anterior Teeth
 When there is considerable loss of crown structure or
when the tooth is to serve as an abutment for FPD or
RPD, complete crown becomes mandatory.
 Retention and support then must be derived from
within the root canal because the coronal dentine
remaining after tooth preparation will be thin and
fragile.
 Use of powerful organic solvents
 ZOE sealers and composite resins


Considerations For Posterior Teeth
 Closer to the transverse horizontal axis & cuspal
morphology
 Exceptions to cuspal coverage are mandibular
premolars and first molars - intact marginal
ridges, conservative access preparations, less
load.
 Complete coverage is required on teeth with a
high risk of fracture. This is especially true in
maxillary premolars.

Minimal loss of tooth structure
 GP should be cleared off the access cavity with
hot instruments or GG drills.
 All traces of sealer must be removed to prevent
discoloration of the crown
 Effective use of alcohol
 Posterior teeth can be restored with amalgam or
composite resin
 The core must extend 2-3 mm into the canal
entrances.

Moderate loss of tooth structure
 Anterior teeth - minimal loss of tooth structure.
Treatment options may be simple core restoration or
post and core
 Posterior teeth, loss of one or both marginal ridges
additional to tooth lost in access preparation. Amalgam
or composite cores emanating 2-3 mm from canals,
post and core with compulsory cuspal coverage. Extra
coronal restoration must extend 1-2 mm onto sound
tooth structure
 Interim restoration for cuspal coverage – bonded
amalgam or composite resin.

Extensive loss of tooth structure
 Little or no coronal tooth structure is remaining
 Crown lengthening, forced eruption followed by
cast post & diaphragm with a ferrule. Or pre-
fabricated posts with crown. Metal collar must
extend 2-3mm onto sound tooth structure
 Immature tooth, relined with dentine bonding
composites followed by fiber posts.


Evidence Based Practice

The conscientious, explicit and
judicious use of current BEST
EVIDENCE in making decisions
about the care of individual patients

Sackett DL, et al BMJ 1996;312:71-2

SHOULD CROWNS BE PLACED ON
ENDODONTICALLY TREATED
TEETH?


• 1,273 teeth endodontically treated 1 to 25 years.
Coronal coverage crowns did not significantly improve
the success of endodontically treated anterior teeth
• Structurally weakened or they require significant
form/color changes that cannot be effected by
bleaching, resin bonding, or porcelain laminate veneers
• A significant increase in the clinical success was noted
when cuspal coverage crowns were placed on maxillary
and mandibular molars and premolars. Scurria et al.

• Multiple clinical studies of fixed partial dentures, many
with long spans and cantilevers, have determined that
endodontically treated abutments failed more often
than abutment teeth with vital pulps owing to tooth
fracture
• It has been shown that endodontic procedures reduce
tooth stiffness by 5%, attributed primarily to the access
opening. Also, with aging, greater amounts of
peritubular dentin are formed, which decreases the
amount of organic materials that may contain moisture.
• Dentin from endodontically treated teeth has been
shown to exhibit significantly lower shear strength and
toughness than vital dentin. (Tidmarsh )

• Rivera et al. stated that the effort required to
fracture dentin may be less when teeth are
endodontically treated because of potentially
weaker collagen intermolecular cross-links.
Conclusions:
• Restorations that encompass the cusps of
endodontically treated posterior teeth have been
found to increase the clinical longevity of these
teeth.
• Limited use in anterior teeth

WITH PULPLESS TEETH, DO POSTS
IMPROVE LONG-TERM CLINICAL
PROGNOSIS OR ENHANCE
STRENGTH?


Laboratory Data
 Lovdahl and Nicholls - endodontically treated maxillary
central incisors were stronger when the natural crown
was intact, except for the access opening, than when
they were restored with cast posts and cores or pin-
retained amalgams
 Lu found that posts placed in intact endodontically
treated central incisors did not lead to an increase in the
force required to fracture the tooth or in the position
and angulation of the fracture line
 Trope et al. determined that preparing a post space
weakened endodontically treated teeth compared with
ones in which only an access opening was made but no
post space.

Laboratory Data
 A potential situation in which a post and core could
strengthen a tooth was identified by Hunter et al. using
photoelastic stress analysis. They also determined that
minimal root canal enlargement for a post does not
substantially weaken a tooth, but when excessive root
canal enlargement has occurred, a post strengthens the
tooth.
 When loaded vertically along the long axis, a post
reduced maximal dentin stress by as much as 20%.
However, only a small (3 to 8%) decrease in dentin
stress was found when a tooth with a post was
subjected to masticatory and traumatic loadings at 45
degrees to the incisal edge.

Clinical Data
 Sorenson and Martinoff clinically evaluated
endodontically treated teeth with and without posts and
cores. Posts and cores significantly decreased the
clinical success rate of teeth with single crowns and
improved the clinical success of RPD abutment teeth
but had little influence on the clinical success of FPD
abutments
 A 1994 survey (1,066 practitioners and educators)

10% of the dentist respondents felt that each
endodontically treated tooth should receive a post. 62%
of dentists > 50yrs believed that a post reinforces the
tooth, whereas only 41% of the dentists under age 41
believed in that concept.

Conclusions
 Both laboratory and clinical data fail to provide
definitive support for the concept that posts
strengthen endodontically treated teeth.
Therefore, the purpose of a post is to provide
retention for a core.


WHAT IS THE CLINICAL
FAILURE RATE OF POSTS AND
CORES?


 A 9% overall average for absolute failure was calculated
by averaging the absolute failure percentages from eight
studies (an average study length of 6 years). Range 7 –
14 %
 Kaplan-Meier survival statistics ranged from a high of
99% after 10 years or more of follow-up to a 78%
survival rate after a mean time of 5.2 years. The percent
failure per year has also been calculated and ranged
from 1.56%/year to 4.3%/year.
Conclusions
 Posts and cores had an average absolute rate of failure
of 9% (7 to 14% range) when the data from eight
studies were combined (average study length of 6
years).

WHAT ARE THE MOST COMMON
TYPES OF POST AND CORE
FAILURES?


 Turner reported on 100 failures of post-retained
crowns and indicated that post loosening was the most
common type of failure. 59%
42 - apical abscesses
19 - carious lesions
10 - root fractures
6 - post fractures
 Lewis and Smith presented data regarding 67 post and
core failures after 4 years.
47 (70%) - posts loosening
8 - root fractures
7 - caries
4 -bent or fractured posts

 Sorenson & Martinoff evaluated 420 post &
cores and recorded 36 failures
 8 - restorable tooth fractures

 12 -non-restorable tooth fractures

 13 - loss of retention

 3 - root perforations

 Torbjörner et al. reported on the frequency of 3
technical failures (loss of retention, root fracture,
and post fracture)


Conclusions
 Loss of retention and tooth fracture are the two
most common causes of post and core failure.


WHICH POST DESIGN PRODUCES
THE GREATEST RETENTION?


Laboratory Data
 Threaded posts provide the greatest retention, >by
cemented > parallel-sided posts. Tapered cemented
posts are the least retentive.
 Cemented, parallel-sided posts with serrations are more
retentive than cemented, smooth-sided parallel posts.
Clinical Data
 Torbjörner et al – 7%
 Sorenson and Martinoff - 4%
 Bergman et al. and Mentink et al - 6%
 Weine et al. They found no clinical failures from loss of
retention with cast tapered posts.
 Hatzikyriakos et al. - tapered threaded posts, parallel
cemented posts, and tapered cemented posts.

Conclusions
 Tapered posts are the least retentive and
threaded posts the most retentive in laboratory
studies. Most of the clinical data support the
laboratory findings.


IS THERE A RELATIONSHIP
BETWEEN POST FORM AND THE
POTENTIAL FOR ROOT FRACTURE?


Laboratory Data
 Henry - threaded posts
 Standlee et al - tapered, threaded posts
 Deutsch et al - tapered, threaded posts increased root
fracture by 20 times that of the parallel threaded posts
 Thorsteinsson et al- determined that split-threaded
posts did not reduce stress concentration during
loading
 Henry - parallel- sided posts distribute stress more
evenly to the root
 parallel posts concentrate stress apically and tapered
posts concentrate stress at the post-core junction.
 Assif et al. - tapered posts -equal stress distribution
between the CEJ and the apex compared with parallel
posts (apical pressure).

 Sorenson and Engelman determined that
tapered posts > fractures than parallel-sided
posts, but the load required to create fracture
was significantly higher with tapered posts
 In analyzing the stress distribution of posts,
tapered posts generate the least cementation
stress: thin root walls, are nearly perforated, or have
perforation repairs.


Clinical Data
 threaded posts - mean fracture rate of 7%

(5 studies)
 parallel-sided cemented posts - 1% (4 studies)

 tapered posts - 3% ( 7 studies)

 Creugers et al. - 91% tooth survival rate for cemented
cast posts and cores & 81% survival rate for threaded
posts with resin cores
 In comparing fracture rates - parallel and tapered
posts
 Hatzikyriakos et al, Ross & 2 other studies – no
difference in fracture rates bet parallel & tapered posts

Conclusions
 Threaded posts ↑ root fracture – lab & clinical

 Stress analysis & fracture rates - Tapered and
parallel cemented posts
 Further research to study designs of posts


WHAT IS THE PROPER LENGTH
FOR A POST?


Various recommendations……
 equal the incisocervical or occlusocervical dimension of
the crown
 longer than the crown

 one and one-third the crown length

 half the root length

 two-thirds the root length

 four-fifths the root length

 terminated halfway between the crestal bone and root
apex
 as long as possible without disturbing the apical seal.


 Radiographic study of 217 posts - only 5% of the posts
were 2/3 to ¾ the root length
 Sorensen and Martinoff - clinical success was markedly
improved when the post was equal to or greater than
the crown length
 Ideal root length – 2/3rds post length, but hampered
apical seal in short roots.
 Abou-Rass et al. 150 molar teeth. They determined
that molar posts should not be extended more than 7
mm apical to the root canal orifice ( risk of root
perforation)
 diminished bone support, ↑ stresses are concentrated in
the dentin near the post apex. To ↓ stress in the dentin
& in the post, the post should extend > 4 mm apical
to the bone

Conclusions
Reasonable clinical guidelines for length include
the following:
(1) three-quarters - long-rooted teeth
(2) When average root length - retain 5 mm of
apical gutta-percha
(3) Whenever possible, posts should extend at
least 4 mm apical to the bone crest to
decrease dentin stress
(4) Molar posts should not be extended more than
7 mm into the root canal apical to the base of
the pulp chamber

HOW MUCH GUTTA-PERCHA
SHOULD BE RETAINED TO
PRESERVE THE APICAL SEAL?


Apical seal….
 4 mm of GP - only 1 of 89 specimens showed
leakage
 Mattison et al. 3, 5, and 7 mm
 Nixon et al. 3, 4, 5, 6, and 7 mm
 Kvist et al. radiographic examination of 424
posts. Teeth with 3mm seal leaked the most
Conclusions
 Greater leakage - 2 to 3 mm
 4 to 5 mm should be retained apically to ensure
an adequate seal.

DOES POST DIAMETER AFFECT
RETENTION AND THE
POTENTIAL FOR TOOTH
FRACTURE?


 Krupp et al - retention - post diameter was a
secondary factor
 Mattison - stress - increased diameter

 Deutsch et al - six fold increase in the potential
for root fracture with every millimeter the
tooth’s diameter was decreased.
Conclusions
 Laboratory studies on retention - mixed results,

 definitive relationship between root fracture and
large-diameter posts.

Large diameter causing root fracture and failure


WHAT IS THE RELATIONSHIP
BETWEEN POST DIAMETER AND
THE POTENTIAL FOR ROOT
PERFORATIONS?


Lloyd and Palik – 3 distinct philosophies of post
space prep.
 the conservationists
 the proportionists
 the preservationists

Tilk et al 1,500 roots based on the proportionist
 0.6 to 0.7 mm – small teeth
 Large-diameter roots - 1.0 mm
 Remaining teeth - 0.8 to 0.9 mm.


Shillingburg et al- 700 root dimensions - minimize
the risk of perforation
 mandibular incisors- 0.7 mm
 maxillary central incisors or other large roots, 1.7
mm (max)
 post tip diameter, at least 1.5 mm less than root
diameter at that point
 post diameter at the middle of the root length,
2.0 mm less than the root diameter.


 mesial roots of mandibular molars & buccal roots of
maxillary molars
 For the principal roots not more than 7 mm into the
root canal
 Instrument size - No. 2 Peeso instrument safe. but
perforations are more likely when the larger No. 3 and
4 Peeso instruments were used.
 Raiden et al. 0.7 mm or less for maxillary I pre-molars
with single canals (mesial and distal developmental root
depressions). Dual canals, as large as 1.1 mm because
the canals are located buccally and lingually into thicker
areas of the roots.

CAN GUTTA-PERCHA BE REMOVED
IMMEDIATELY AFTER ENDODONTIC
TREATMENT AND A POST SPACE
PREPARED?


 Bourgeois and Lemon- immediate & 1 week later
when 4 mm of GP were retained
 Madison & Zakariasen; Zmener – imme & 48 hrs
 Harrington - immediate GP removal - warm and
rotary instruments.
 Karapanou et al- immediate and delayed removal
of two sealers (ZOE & resin sealer)
 Portell et al - removal after 2 weeks > leakage
than immediate removal when only 3 mm of
gutta-percha were retained apically.
 Fan et al. found more leakage from delayed
removal of gutta-percha.

Conclusion
Adequately condensed gutta-percha can be
safely removed immediately after endodontic
treatment.


WHAT INSTRUMENTS REMOVE
GUTTA-PERCHA WITHOUT
DISTURBING THE APICAL
SEAL?


 Suchina & Ludington and Mattison et al. found
no difference between hot instrument removal
and removal with GG burs
 Camp & Todd found no difference between
Peeso reamers, GG burs, and hot instruments
 Haddix et al. a heated plugger < a GPX
instrument or GG drills


Conclusion
Both rotary instruments and hot hand
instruments can safely be used to remove
adequately condensed gutta-percha when 5 mm
are retained apically.


CAN A PORTION OF A SILVER
POINT BE REMOVED AND STILL
MAINTAIN THE APICAL SEAL?


 In one study, all of the specimens leaked when 1
mm of a 5mm long silver point was removed
using a round bur.
 Neagley found that removal of the filling
material coronal to the silver point with a Peeso
reamer caused no leakage. However, when all of
the filling material and 1 mm of the silver point
were removed, complete dye penetration
occurred in 8 of 9 specimens.


DOES THE USE OF A CERVICAL
FERRULE THAT ENGAGES TOOTH
STRUCTURE HELP PREVENT TOOTH
FRACTURE?


Studies to investigate…
1. Core Vs crown ferrule
2. Manner of engaging the tooth ( beveled Vs parallel)
3. Amount of tooth engaged
 Assif et al. found no difference in the tooth fracture
patterns with different types of posts when they were
covered by a crown that grasped 2 mm of tooth
structure
 Isidor et al. compared no ferrule with 1.25 and 2.55
mm crown ferrules. Ferrule length was more
important than post length in increasing a tooth’s
resistance to fracture under cyclic loading.


 Libman & Nicholas- improved resistance to
fatigue failure with crown ferrule extending
1.5mm apical to core margin
 Loney et al – higher mean stress in core ferrule
than crown ferrule


Conclusions
 Crown ferrule > core ferrule
 Length of ferrule more important than length
of post
 More effective when the crown encompasses
relatively parallel prepared tooth structure than
when it engages beveled/sloping tooth
surfaces.


Principles of Tooth Preparation
Conservation of tooth structure
Preparation of the canal
 Minimal preparation
 Teeth with posts thicker than 1.8mm fractured more
easily than those with thinner posts(1.3mm)
 Strength of the root = R4 – r4
 one or two additional files than the largest size


Preparation of coronal tissue
 Amount of remaining tooth
structure is the most important
predictor of clinical success

Cast post-core will require
reduction to accommodate a
complete crown and to remove
undercuts from the chamber
and internal walls
 Extension of the axial wall of
the crown apical to the missing
tooth structure is known as the
ferrule



ferrule may not be possible in short clinical
crowns

surgical crown lengthening procedure or
orthodontic extrusion


Ferrule


Retention Form
Anterior Teeth
Preparation geometry
 Round canal configuration can be prepared
with minimal taper to accommodate
prefabricated post
 Elliptical canals – minimal taper(6-8 degrees)
 Threaded posts improve retention

Post length
 Longer the post better the retention & stress
distribution

minimum length of root filling -3 to 7mm

Root morphology also influences the length
 Post length
• In teeth with loss of periodontal support the post
should extend apical to the alveolar bone.

The required length of the post must be weighed
against the occlusal loading. If loading is minimal;
long posts will become unnecessary.

Post length
 In any case post length less than that of crown
height is least retentive and also increases the
chances of root fracture( Fuss et al). The latter
occurs because stress is distributed over a small
surface area.


Surface texture

Dramatic effect on retention and stress distribution
 Retention decreases as one progresses from
threaded to serrated to smooth surface
configurations

Radicular stress is greatest with threaded posts to
smooth-tapered post followed by parallel-serrated
posts
 Of the threaded designs, the tapered screw creates
greatest wedging effect and highest stress
concentration.

Surface texture
 Threaded posts with countersink also generate very
high stresses when the countersink is fully engaged.
These stresses can be reduced by counter-rotation of
the post by half a turn. Placing a split in the shank of
tapered threaded posts create stresses comparable to
parallel-sided serrated posts


Luting agent
 Adhesive resin luting agents have improved the
performance of post and core restorations
 Resin cements are affected by eugenol containing
sealers. This should be removed by irrigation with
ethanol or etching with 37% ortho phosphoric acid
or alcohol
 Zinc phosphate and glass ionomer have similar
retentive properties. Polycarboxylate and composite
resins have slightly less.

RMGIC – hydrophilic resins

Posterior teeth:
 Long posts are not indicated in posterior teeth
which often have curved roots and elliptical or
ribbon shaped root canals. For these teeth retention
is better provided by two or more relatively short
posts in divergent canals.
 If more than 3-4 mm of coronal tooth structure
remains, use of post is unnecessary. Core build-ups
in molars with one or more missing cusps will
benefit from cemented posts and amalgam
condensed around it.

Resistance form: laterally directed forces
 The greatest stress concentrations are found at the
shoulder, particularly at the inter-proximal region
and the apex. Dentin should be conserved in these
areas whenever possible.
 stresses are reduced as post length increases
 Parallel sided posts distribute stresses more evenly
than tapered posts, which tend to have a wedging
effect. However, parallel post concentrate stresses at
the apex

Resistance form:
 Sharp angles should be avoided
 Increased stress can be generated during post
insertion, especially with smooth- parallel
sided posts that have no vent.
 Threaded posts produce stresses during
insertion and loading but distribute stresses
evenly if backed off.
 The cement layer tends to distribute stresses
more evenly.

Rotational resistance
 circular cross-section
 In areas where coronal dentin has
been completely lost, a small
groove is placed in the canal can
serve as an anti-rotational element.
 The groove is place in the bulkiest,
usually on the lingual aspect.
 Alternatively, rotation can be
prevented by placing a pin in the
root surface.

Hydrostatic Forces
 Post cementation – retention, stress distribution,
sealing irregularities
 During cementation – development of hydrostatic
pressure
 This pressure causes problems with seating & also
causes root fracture
 Provision of cement vent
 Viscosity of cement – Zn PO4 cement
 Auto-polymerizing resin cement may polymerize
prematurely – Dual cure cements

CORE
 It consists of the restorative material placed in
the coronal area of the tooth that replaces
carious, fractured or otherwise missing tooth
structure.
 Retained by the post
Desirable properties of a core include:
 High compressive strength
 Dimensional stability
 Ease of manipulation
 Short setting time
 An ability to bond to both tooth and dowel

Cast core:
 integral part of the restoration and does not
depend on mechanical means of retention.
Noble metals are non-corrosive. Ceramic cores
can also be fused to zirconia posts in the
laboratory.
Disadvantages:
 Cast dowels and cores have shown to have a
higher incidence of root fracture.
 laboratory technique sensitive


Amalgam core:
 High compressive strength and modulus of
elasticity.
 Stable to thermal and functional stress and
therefore transmits minimal stress to the residual
tooth and to the crown and cement margins.
 Amalgam cores are highly retentive when used
as a corono-radicular core. It requires more
force to dislodge than a cast-post metal core.
 The disadvantage is the potential for corrosion
and subsequent discoloration of the gingival.

Composite resin core:
 Ease of manipulation, very rapid set and strong
compressive strength
 Composite microleakage and retention to
tooth structure are dependant on dentin
bonding. Hence coronal build up with
composite resins requires 2mm of sound tooth
structure at the margins


Glass ionomer core:
Glass ionomer and glass ionomer silver are adhesive
materials for small build ups or to fill undercuts. The
major benefit is its property of anticariogenecity.
Adhesive failure can result from contamination of the
tooth structure by saliva, blood, cutting debris or
protein. It is not indicated as a core for an abutment
tooth.
It is indicated in posterior tooth when:
 a bulk of core material is possible
 significant crown dentin remains
 additional retention is available with pins and dentin
preparations
 caries control is indicated

Resin-modified glass ionomer core:
 It exhibits moderate strength and water
solubility between GIC and composite resins.
 Its bond is close to that of composite resins
and significantly reduces microleakage.
 The property of fluoride release is equal to that
of GIC. It is indicated in moderate core build
ups.


Corono-radicular Restoration
 In this restoration, the core extends 2-4mm into the
coronal portions of the canal.
 Retained by the divergence of the canal, the undercuts
in the pulp chamber and adhesion with dentin-
bonding agents
 This type of restoration is indicated for posterior
teeth with large pulp chambers and multiple canals for
retention
 It requires a minimum of 50% of tooth structure to
be presentwww.indiandentalacademy.com

CORONAL COVERAGE
It serves the function of isolating the endodontic filling
and dentin from microleakage. They also distribute the
stresses and protect the tooth against fracture. This can
be achieved with cast metal crowns and high strength
ceramic onlays.
The crown and crown preparation must achieve the
following requirements:
 A minimum of 2mm dentin axial wall height
 Parallel axial walls
 The metal must encircle the tooth
 Finish line must be on solid tooth structure
 It must not invade the attachment apparatus

Canal Rehabilitation
 Done in immature and
hollowed-out roots
 Makes use of dentin
bonding composites to
reinforce the canal
 Key for success is the
remaining tooth
structure and length of
ferrule.
 Endodontic Obturator

Restoration of tooth with
Resected Root
 Mandibular mesial root resection
 Mandibular distal root resection
 Maxillary distobuccal or mesiobuccal root
resection
 Hemisection


Over Dentures
 As long as the root remains, the
bone remains
 Support, stability and retention
 The abutment selected must
have ↓ mobility, ↓ sulcus depth
& band of attached gingiva
 Canines and premolars are ideal
abutment candidates
 Diagonal cross-arch arrangement

Crown Cementation
 Functional forces cause strain against the crown margins,
resulting in bond failure. This results in microleakage and
secondary caries.
 RMGIC has shown to expand hygroscopically causing cracking
or fracture of low strength all ceramic crowns.
 Crowns cemented with light cured resin cement are more
resistant to fracture than when compared with RMGIC, GIC or
zinc phosphate cement. However removal of excess resin cement
after setting will be difficult.
 Dual cure cement can be used. This allows the removal of excess
cement, while the internal cement sets chemically.

….. Success can only be achieved when the technique
choice best meets the needs of the individual clinical
diagnosis – specifically, the needs of the individual
diseased tooth and the clinical use for which it is
indicated.
- Weine

Now say Why!

References
 Endodontics – Ingle & Bakland; 5th edn
 Pathways of Pulp – Stephan Cohen; 8th edn
 Endodontic Therapy – Weine; 5th edn
 Contemporary Fixed Denture Prosthodontics –
Rossensteil; 3rd edn
 Restoration of endodontically treated teeth –
DCNA, 2004, 48; 397-416
 Crowns & Extracoronal restoration: Endodontic
considerations – BDJ, Mar 2002 192; 6, 315-327

References
 Post placement & restoration of endodontically
treated teeth – JOE, 2004; 30, 5: 289-301
 Ferrule design & Fracture resistance of
endodontically treated teeth – JDP 1990; 63,
529-36
 Clinically significant factors in Dowel Design –
JPD; 1984, 52(1), 28-34
 JPD – 1990, 63(6), 1984 51(5), 1985 53(5)
 Color Atlas of endodontics – Christopher Stock

Rationale of post endodontic restoration /certified fixed orthodontic courses by Indian dental academy

Recomendados

Recomendados

Más contenido relacionado

La actualidad más candente

La actualidad más candente (20)

Destacado

Destacado (20)

Similar a Rationale of post endodontic restoration /certified fixed orthodontic courses by Indian dental academy

Similar a Rationale of post endodontic restoration /certified fixed orthodontic courses by Indian dental academy (20)

Más de Indian dental academy

Más de Indian dental academy (20)

Último

Último (20)

Rationale of post endodontic restoration /certified fixed orthodontic courses by Indian dental academy