Indication to the Type of Restoration

Indication to the type of restoration

O.R.GaneshMurthi M.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, 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

Sealing

the Access Cavity Cav ity There is good evidence from scientific studies that the quality of coronal seal affects the prognosis of root canal treatment. It takes a relatively short time for the root-filled tooth to beco become me reinf reinfect ected ed if it is left exposed to the oral 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



Reinforcement



Replacement



Retention

as µ3R¶s

einforcement R ei 

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 - Do Dow wel

eplacement R eplaceme Replacement of missing tooth structure is achieved with the core CORE ± is th the e cor coron onal al extension of the dowel that provide optimal retention for final Restoration.

B - CORE

etention R ete 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 would have limited prognosis in view of the extent of coronal destruction. Many function with composite resin restoration restorations. s. 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. RCT.

Minimal a.I tact

coronal damage

ar i al ri

What is the final r es est r ati n f this ty e f  .I tact ci case l ? ( all access ening) Rest r e access ening with a composite c. Intact incir  sa edge es eslin d. - small r imal lesi ns/r es est r ati ns

significant coronal damage What is the final restoration of this type of case ? 

undermined marginal ridges

Post/core -small circular canal  acceptable to use prefab post + resin(must at least incisal edge2mm of tooth  loss ofhave structure apical to resin core); however, cast post and core best treatment fracture/esthetically  coronal -elliptical/flared -elliptical/flare d canal  custom cast post/core

unacceptable Full

coverage crown

do all R CT CT teeth need ³protection´? Anteriors

No, But may need post/core to restore r estore tooth Posteriors YES

!!!!!!!!!! (unless not in occlusion)

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

R esi esin

restoration in access opening

Indication Intact anterior tooth with only an access opening or very small class III restoration

Contraindications Numerous or large restoration in tooth resulting resul ting in exten extensive sive desturct desturction ion most posterior teeth

R esi esin

restoration in access opening

 Advantages 

1 appointment



Cost



Preserve tooth structure



Esthetics

Disadvantages 

Potential for microleakage mic roleakage

Amalgam core foundation Indication Posterior teeth that are to receive crowns cuspal coverage can be considered for strength as an option to crown

Contraindication Teeth in which a bulk of amalgam am algam cannot be obtained

TYPES OF POSTS METALLIC  Stainless Steel  Titanium  Titanium Alloy  Gold-Plated

 brass

NON-METALLIC 

Carbon Fibre  Ceramic  Glass-fibre reinforced  Composite

Custom cast post and core Advantages:

Disadvantages:



Preservation of maximum tooth structure



Less



Provision of anti-rotational properties



Time consuming, complex procedure



Core retention



Less



chances of vertical fractures during preparation High strength

stiff than wrought

Recommended Use:

Elliptical canals Flared

canals

Prefab refabricat ricated ed

Advantages: 



Conserves tooth structure High strength and stiffness

Tapered Post Tapered Disadvantages: 

Low

retention



Longitudinal

splitting of remaining root

Recommended Use:

Small

circular canals or  Very tapered canals

Prefabricated Parallel

- Sided

Smooth Post

Advantages: 

Excellent

clinical

Disadvantages: 

Precious material post expensive



Corrosion of  stainless-steel



Less

retention 

Minimal stress production within root



Ease



Superior

of placement rating

conservative of  tooth structure

Prefabricated

Threaded Posts Disadvantages:

Advantages: 

High retention



Stresses

generated in canal may lead to fracture

Does not conserve coronal and radicular  Recommended Use: Only when maximum tooth structure retention is essential 

Fiber R ei einforced Post

Advantages: 

Esthetic

Disadvantages: 

Low

strength



High failure rate

Recommended Use:

Should

not be used where remai r emaining tooth structure is less than ideal or where high occlusal forces are present.

Zirconia

Advantages:

Ceramic Post Disadvantages:



Esthetics



Expensive



High stiffness





High modulus of  elasticity

Uncertain clinical performances

Recommended Use: High

esthetic demands

Cast metal post and core Indication Teeth in which minimal tooth structure remains a tooth that is to be used as an abutment for  fixed partial denture.

Contraindications Teeth requiring some types of very translucent all ceramic crowns

Cast metal post and core  Advantages Strength

post and core one unit

Relative easy to incorporate anti rotation feature

Disadvantages Numerous appoint appointments ments Cost More tooth removal

Ceramic post and core Indication Teeth requiring some type of very translucent all ceramic crowns

Contraindication Teeth for which a metal ceramic crown is planned

Ceramic post and core  Advantages Esthetics

Disadvantages Numerous appoint appointment ment Cost Long

term data are limited

Ceramic materials may have a tendency to fracture

Crown placement Indication Enhancement

of esthetic outcome situation in which existing restoration combined with the endodontic endodo ntic access under mine the structure if  crown

Contraindication  Anterior teeth that have only a conservative endodontic access opening

Crown placement  Advantages Protection of reaming tooth structure by encirclement

Disadvantages Removal of more tooth structure cost

Crown placement Indication Enhancement

off esthetics out come o c ome situation in which existing restorations combined with the endodontic endod ontic access undermine the structure integrity of the natural crown

Contraindications  Anterior teeth that have only a conservative endodontic access opening

metal--ceramic metal -ceramic crowns Metal-ceramic crowns are very strong and resist occlusal loads well. Minimal preparation preparat ion (0.5 mm) mm ) is required on the palatal pala tal and and approx approximal imal surfa surfaces. ces. This may may be beneficial in a root-filled tooth with little remaining coronal tooth substance

metal--composite metal -composite crowns Metal-composite crowns are often used as long-term provisional restorations. The composi comp osite te disco discolou lours rs wi with th time

metal--free metal -free crowns -porcelai - porcelai 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 m etal-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 esio--occlusal -occlusal

cavities

Plastic Restorative Tech niques The 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 coverage restorations  A bevelled margin of I mm m m 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. am algam. The technique is technically demanding since the correct occlusal contacts are difficult to achieve, and the material must be thick enough to withstand withstan d occlusal forces (2-3 mm). mm ). Direct light cured composite materials are not really suitable for use in this situation, and indirect composite or porcelain restorations

Cast restorations Cast If a metal-ceramic crown is required required,, significantly more tooth substance will need to be removed (at least 1-1.5 mm). 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 - Amal 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 N Nayyar  ayy ay yar core cor oree The Nayy Nayyar ar core is a usefu usefull means of of restoring 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 m aterials such as Ti Core, have been shown to perform well. There is some concern in the literature that there may be risk of microleakage m icroleakage between the composite core and dentine

Cermets  Although  Althoug h cermet cermets s have bee been n recommended recommen ded as core materi materials als they they are are not as durable as amalgam or composite. Cermets Cermet s are easy to use and bond bond to 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 Crowns

High 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

reduction in the tooth is required

less

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 preparation for a full cast metal crown is more conservative than for a metal m etal ceramic crown (0.5-1.0 mm compared with 1.0-2.0 mm).

etal-Ceramic -Ceramic Metal-

Crowns

Metal-ceramic Metal-cera mic crowns c rowns 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 casta ble or high-stre high-strengt ngth h ceramic crown crown on 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 reduction of 2 mm) and may m ay compromise retention, retention, especially in teeth with a short crown height

Temporary crowns For

anterior 

Polycarbonate and acrylic temporary crown forms Custom-cast temporaries. For

posterior teeth

Metal shell crown forms  Custom-cast Custom-c ast 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

4.

Uncomplicated preparation preparation & margins

5.

High degree of occlusal accuracy in casting

conservative prep

Disadvantages



Esthetics

 ± Some patients patients dislike and will strongly object to the full metal cover   ± May be be limited limited to upp upper er and lower  lower  molars and lower premolars 

Galvanic action  ± With oth other er opposing opposing metals metals (rare) (rare)

 Advantages  Advantage  A dvantages dvantage s of composite fiber post     

Can bonded to the tooth with resin cement Modulus Modulu s of elasticity similar to dentin Ease of removal for retreatment Excellent esthetics Non corrosive

The R ole ole of Posts in the R estoratio estoration of Endodontica tically lly Treate Treated d Teet Teeth h 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.

CAT TIO NS I NDICA 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 prepar preparatio ation 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.