Indication to the type of restoration
O.R.GaneshMurthiM.Sc.D Endo
student
The tooth as a house
Introduction
Teeth that require endodontic treatment are
often severely broken down and can be vulnerable to fracture; they often require extensive (and expensive) restoration following root canal treatment.
A high fracture rate has been found in root-filled teeth that have mesial Occlusal distal (MOD) amalgam restorations, and it is often good practice to place some form of cusp coverage restoration to prevent destructive flexure during mastication.
Fluids No Fluids
Endodontically treated teeth are usually weak
loss of tooth structure
loss of moisture in the dentin
There is good evidence from scientific studies that the quality of coronal seal affects the prognosis of root canal treatment. It takes arelatively short time for the root-filled toothto become reinfected if it is left exposed to theoral cavity.
Sealing the Access Cavity
treatment planning
Existing endodontically treated teeth need to be assessed care fully for the following:
Good apical seal No sensitivity to pressure No exudate No fistula No apical sensitivity No active inflammation
objectives of restoration endodontically treated tooth
Stated as ‘3R’s
Reinforcement
Replacement
Retention
Reinforcement
Reinforcement of the remaining tooth structure is achieved with dowel and coping
DOWEL – post extending approximately 2/3rd the length of the root canal
A - Dowel
Replacement
Replacement of missing tooth structure is achieved with the core
CORE – is the coronal
extension of the dowel
that provide optimal
retention for final
Restoration.
B - CORE
Retention
Is supplied by
1. Dowel for core
2. Core for final restoration
Considerations for anterior teeth
Anterior teeth do not always need complete coverage, except when plastic restorative materials would have limited prognosis in view of the extent of coronal destruction. Many function with composite resin restorations.
when the tooth is loaded, stresses are greatest at the facial and lingual surfaces of the root and an internal post, being only minimally stressed, does not help prevent fracture
protection of anterior teeth?
Coronal coverage does not significantly improve the success of Anterior RCT.
a.Intact marginal ridge
b.Intact cingulum (small access opening)
c.Intact incisal edge
d.1-2 small proximal lesions/restorations
Minimal coronal damage
What is the final restoration of this type of case ?
Restore access opening with a composite resin
significant coronal damage
undermined marginal ridges
loss of incisal edge
coronal fracture/esthetically unacceptable
What is the final restoration of this type of case ?
Post/core-small circular canal acceptable to use prefab post + resin(must have at least 2mm of tooth structure apical to resin core); however, cast post and core best treatment-elliptical/flared canal custom cast post/core
Full coverage crown
do all RCT teeth need “protection”?
Anteriors
Posteriors
YES !!!!!!!!!! (unless not in occlusion)
No, But may need post/core to restore tooth
Considerations for posterior teeth
Endodontically treated posterior teeth are subject to greater loading than anterior teeth are because of their position closer to the insertion of the masticatory mus cles.
Parts of prosthodontic reconstruction compared with chain links
Resin restoration in access opening
Indication Intact anterior tooth with only an access opening or very small class III restoration
ContraindicationsNumerous or large restoration in tooth resulting in extensive desturction most posterior teeth
Resin restoration in access opening
Advantages 1 appointment Cost Preserve tooth structure Esthetics
Disadvantages Potential for microleakage
Amalgam core foundation
IndicationPosterior teeth that are to receive crowns cuspal coverage can be considered for strength as an option to crown
ContraindicationTeeth in which a bulk of amalgam cannot be obtained
TYPES OF POSTS
METALLIC NON-METALLIC
Stainless Steel Titanium Titanium Alloy Gold-Plated
brass
Carbon Fibre Ceramic Glass-fibre
reinforced Composite
Custom cast post and coreAdvantages:
Preservation of maximum tooth structure
Provision of anti-rotational properties
Core retention Less chances of vertical
fractures during preparation High strength
Disadvantages: Less stiff than
wrought Time consuming,
complex procedure
Recommended Use: Elliptical canalsFlared canals
Prefabricated Tapered PostAdvantages: Conserves tooth
structure High strength and
stiffness
Disadvantages: Low retention Longitudinal splitting
of remaining root
Recommended Use:Small circular canals orVery tapered canals
Prefabricated Parallel - Sided Smooth Post
Advantages:
Excellent clinical retention
Minimal stress production within root
Ease of placement Superior rating
Disadvantages: Precious material
post expensive Corrosion of
stainless-steel Less conservative of
tooth structure
Prefabricated Threaded Posts
Advantages:
High retention
Disadvantages: Stresses generated in canal may lead to fracture
Does not conserve coronal and radicular tooth structure
Recommended Use:Only when maximum retention is essential
Fiber Reinforced Post
Advantages: Esthetic
Disadvantages: Low strength High failure rate
Recommended Use:Should not be used where remaining tooth structure is less than ideal or where high occlusal forces are present.
Zirconia Ceramic Post
Advantages: Esthetics High stiffness High modulus of
elasticity
Disadvantages: Expensive Uncertain clinical
performances
Recommended Use:High esthetic demands
Cast metal post and core
IndicationTeeth in which minimal tooth structure remains a tooth that is to be used as an abutment for fixed partial denture.
ContraindicationsTeeth requiring some types of very translucent all ceramic crowns
Cast metal post and core
AdvantagesStrength post and core one unit
Relative easy to incorporate anti rotation feature
DisadvantagesNumerous appointments
Cost
More tooth removal
Ceramic post and core
IndicationTeeth requiring some type of very translucent all ceramic crowns
ContraindicationTeeth for which a metal ceramic crown is planned
Ceramic post and core
AdvantagesEsthetics
DisadvantagesNumerous appointment
Cost
Long term data are limited
Ceramic materials may have a tendency to fracture
Crown placement
IndicationEnhancement of esthetic outcome situation in which existing restoration combined with the endodontic access under mine the structure if crown
ContraindicationAnterior teeth that have only a conservative endodontic access opening
Crown placement
AdvantagesProtection of reaming tooth structure by encirclement
DisadvantagesRemoval of more tooth structure
cost
Crown placement
IndicationEnhancement of esthetics out come situation in which existing restorations combined with the endodontic access undermine the structure integrity of the natural crown
ContraindicationsAnterior teeth that have only a conservative endodontic access opening
metal-ceramic crowns
Metal-ceramic crowns are very strong and resist occlusal loads well. Minimal preparation (0.5 mm) is required on the palatal and approximal surfaces. This may be beneficial in a root-filled tooth with little remaining coronal tooth substance
metal-composite crowns
Metal-composite crowns are often used as
long-term provisional restorations. The composite discolours with time
metal-free crowns -porcelain jacket crown
Porcelain jacket crowns require a buccal tooth
reduction of between 0.8 and 1.3 mm, and can
therefore be more conservative on tooth substance than a metal-ceramic crown. Stained
dentine and metal posts affect the aesthetic
appearance of a porcelain jacket crown. Excessive occlusal loading may be a problem and can result in unpredictable fracture.
Mesio-occlusal cavities
Plastic Restorative TechniquesThe best method of restoring a root-treated
tooth with an existing proximal box depends
on the size and depth of the box and on the
occlusal stresses that are applied during mastication. In a case with a shallow box and no evidence of occlusal loading, an amalgam
restoration could be used
conservative cuspal coveragerestorations
A bevelled margin of I mm depth is prepared
around the circumference of the tooth.
Base metal alloys can be bonded to the etched
occlusal surface of the tooth using a silane
bonding system. Extra retention will be provided
by the internal contours of the access
cavity, the majority of which is packed with
IRM.
Plastic restoration
The cusps are reduced in height and the entire
occlusal surface is rebuilt in amalgam. The technique is technically demanding since the correct occlusal contacts are difficult to achieve, and the material must be thick enough to withstand occlusal forces (2-3 mm). Direct light cured composite materials are not really suitable for use in this situation, and indirect composite or porcelain restorations
Cast restorations
If a metal-ceramic crown is required, significantly more tooth substance will need to
be removed (at least 1-1.5 mm). The clinician
needs to be sure that sufficient tooth substance
will remain after preparation for retention of the restoration to avoid an unnecessarily weakened tooth.
Core Materials - Amalgam
It is strong and easy to use. Added retention can be gained by packing the amalgam into irregularities and undercuts in the pulp chamber and by using grooves, slots and pits in the cavity walls. Self-tapping dentine pins are rarely needed, and they may impart
unwanted stresses within the dentine.
The Nayyar core
The Nayyar core is a useful means of restoring
a molar tooth after root treatment when there is sufficient remaining tooth substance to support the core. Amalgam is packed into the root canals to a depth of approximately 3 mm and into the pulp chamber to give mechanical retention. An adhesive can be used to give extra retention
Composite
Composite cores have the advantage that they can be built up and prepared at the same visit. Chemically activated materials such as Ti Core, have been shown to perform well.
There is some concern in the literature
that there may be risk of microleakage
between the composite core and dentine
Cermets
Although cermets have been recommended as core materials they are not as durable as amalgam or composite. Cermets are easy to use and bond to tooth substance. They should not be used when strength is required, but they could be used as a space filler to reduce the amount of alloy required in a cast restoration
Crowns for Posterior Teeth
Cast Metal CrownsHigh noble metal alloys are considered to be
best since they have the greatest resistance to
corrosion and tarnishing and are easy to work
with. Metal crowns are excellent in situations
where the patient is not concerned with
the appearance of metal. Significantly less
reduction in the tooth is required
Partial Cast Metal Crowns
Partial cast metal crowns may be used when
the buccal surface of the tooth is intact. They
are more conservative of tooth tissue than
complete crowns, but they are more demanding
technically both for clinician and in the
laboratory
Full Cast Metal Crowns
The preparation for a full cast metal crown
is more conservative than for a metal ceramic
crown (0.5-1.0 mm compared with
1.0-2.0 mm).
Metal-Ceramic Crowns
Metal-ceramic crowns are generally used
when a patient requires a more aesthetic
restoration. Porcelain can be used on the visible surfaces, such as the buccal and occlusal surfaces of mandibular teeth. If the clinical crown height is small, then retention grooves are cut in the core to provide added retention
Ceramic Crowns
Occasionally it is reasonable to use a castable or high-strength ceramic crown on a posterior tooth, if occlusal factors are not inhibitive. The amount of tooth reduction is more than with a metal-ceramic crown (occlusal reduction of 2 mm) and may compromise retention, especially in teeth with a short crown height
Temporary crowns
For anterior Polycarbonate and acrylic temporary crown forms Custom-cast temporaries.
For posterior teethMetal shell crown forms
• Custom-cast temporaries
• Long-term temporaries, metal-acrylic and
metal-composite crowns
Full metal veneer crown
Advantages
1. Strong, rigid and wear resistant
2. High resistance & retention
3. Fairly conservative prep
4. Uncomplicated preparation & margins
5. High degree of occlusal accuracy in casting
Disadvantages
Esthetics– Some patients dislike and will strongly
object to the full metal cover– May be limited to upper and lower
molars and lower premolarsGalvanic action
– With other opposing metals (rare)
Advantages of composite fiber post
Can bonded to the tooth with resin cement Modulus of elasticity similar to dentin Ease of removal for retreatment Excellent esthetics Non corrosive
The Role of Posts in the Restorationof Endodontically Treated Teeth
The primary purpose for a post is to retain a core that can be used to support the final restoration.
Posts do not reinforce endodontically treated teeth, and a post is not necessary when substantial tooth structure is present after a tooth has been prepared.
INDICATIONS
Post placement is indicated if both of the following clinical conditions exist: The remaining coronal tooth structure is
inadequate for the retention of a restoration.
When there is sufficient root length to accommodate the post while maintaining an adequate apical seal.
Ideal tooth preparation for post placement
Ferrule Effect
The ferrule is the circumferential ring of sound tooth structure that is enveloped by the cervical portion of the crown restoration. A minimum sound dentine height of 1.5-2 mm is required between the core and crown margins.
ANY QUESTION ?
Thank you all