cast post & core

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Fabrication of a cast post and

core by direct technique

Parul Agarwal, B.D.S., M.S.

Michael Linebaugh, D.D.S., M.S.Scott Joslin, R.D.H.

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Cast Post and Core

 The cast post and core is utilized in situations when inadequate coronal tooth structureremains to support a crown. The cast post and

core utilizes the retention available in the canalspace remaining post endodontic treatment. Asthe retention of the CPC is achieved through

cement contact to internal canal surface area, itis still necessary to have adequate ferrule of3mm to support the crown.

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 Armamentarium

Crown and Bridge cassette

Including GC Pattern Resin

Endo cassette Including Gates Glidden setup

High and Low speed handpieces

Parapost™ Kit  Torch

NaOCl and Syringe

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Cast post and core

Canal Preparation

 The tooth was prepared for a crown, note that all of the unsupported tooth

structure and coronal undercuts were removed.

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Cast post and core:

Canal Preparation

 A pre-operative radiograph isneeded to determine thelength of the canal

Remember that it isimperative to allow 4-5mmof remaining Gutta Perchaapically

 Also look for canal

curvatures as they will not beable to be negotiated in thepost preparation

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Cast post and core:

Canal preparation

Once the length of postpreparation is determined,canal preparation is needed

Several methods exist forpreparation

 Warm Instrument Searing

Peeso Reamers

Gates Glidden

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Cast Post and Core

Canal Preparation  Warm Instrument Searing

Mark desired depth with andendodontic stopper

 An endodontic plugger is heateduntil it is glowing red

 The plugger is inserted into thecanal with apical pressure

 When resistance is achieved theplugger should be rotated fromside to side, to prevent pulling out

all of the remaining gutta percha,and removed

 This should be performed untilineffective and followed withrotary instrumentation

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Cast post and core:

Canal preparation Gates – Glidden drill Mark depth with endo

stopper Place a drop of NaOCl

in the canal forlubrication Begin preparation with

bur spinning prior tocanal entry

DO NOT FORCE THE BUR, yield toresistance andreevaluate

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Cast post and core:

Canal preparation

Gates Gliddentaken to length

Remember the

minimum widthacceptable is ayellow post whichcorresponds to a

#4 Gates Glidden

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Cast post and core:

Canal Preparation

Post preparation after removal of Gates Glidden

Flush with NaOCl, take care if no isolation is in placeas NaOCl is caustic

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Cast post and core:

Resin pattern fabrication Following space preparation,

Fabrication of the resin patternoccurs

 A SERRATED plastic post ormetal post can be used.

 When a plastic post is used, thepattern completely burns out, andthe post is formed entirely in thecasting alloy.

 When a metal post is used, moltenalloy is cast around the post,

 which mechanically interlocks withpreviously developed notches toproduce a rigid structure.

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Cast post and core:

Resin pattern fabrication

 The metal post is notched occlusally so that goodinterlocking with the core material can be achieved.

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Cast post and core:

Resin pattern fabrication

In this post and core fabrication a plastic post

has been used. Note that the posts in both instances are the

SERRATED variety, do not use the smooth

posts

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Cast post and core:

Resin pattern fabrication

  Plastic post

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Cast post and core:

Resin pattern fabrication

 When adding theGC Resin to theplastic or metal

post, a salt andpepper technique isutilized

For finer additions,the brush can becut to a point withsharp scissors

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Cast post and core:

Resin pattern fabrication

Cutting the brush to a point

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Cast post and core

Resin pattern fabrication

Note the finer tip on the cut brush on the right

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Cast post and core

Resin pattern fabrication

 Trying in the plastic post

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Cast post and core

Resin pattern fabrication

Once the post is in place, grab it at the coronal most extent of the preparation with the cotton pliers, remove it and re-measure to confirm the post is fullyseated

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Cast post and core

Resin pattern fabrication

 The preparation is cleaned and dried with air and paper points

It is then lightly lubricated with petroleum jelly to prevent adhesion

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Cast post and core:

Resin pattern fabrication

GC Pattern Resin application using the “Salt and Pepper”

 Technique

C t p t nd r

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Cast post and core:

Resin pattern fabrication

Resin is added by the “Salt and Pepper” technique, dipping asmall brush in a monomer and then into polymer and applying itto the post. Before it fully hardens, it is loosened and reseated

several times.  This is why it is important to leave the remainingcoronal extent of the post.

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Cast post and core

 The core is slightly overbuild and is let to polymerize fully. Theshape of the pattern should resemble an ideal preparation andshould be completely sealed at the apical margins.

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Cast post and core:

Resin pattern fabrication

 The resin pattern is removed and the excess plasticsprue is cut off

Replace the Pattern to confirm all margins are closed

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Cast post and core:

Resin pattern fabrication

Resin pattern is then sent to the laboratory for sprueing andcasting in the desired alloy.

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Laboratory Wait Time

 As the Cast post and Core is a Laboratorydependent procedure, a wait time is necessary while the lab fabricates the alloy core from the

pattern

Be sure to ask your lab how long they want forfabrication time.

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Cast post and core:

Finishing of the post and core

Cast Post and Core returned from the lab

Be sure to check for flashing and bubbles in the finished product

as these may inhibit the CPC from fully seating

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Cast post and core:

Finishing of the post and core

 Try in the CPC

Check for Draw

 There should be no adhesions with insertion

Marginal Fit

 Adjust as necessary until desired fit is achieved

It is important that you make a mental note of the fitso that when you are cementing the CPC you have areference to be sure it is adequately and completelyseated

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Cast post and core:

Cementation of the post and core

Lentulospiral rotary pastefillers are used to fill the postspace completely.

It is important to fill all thedead space within the rootcanal system.

 Voids may be a cause ofperiodontal inflammation viathe lateral canals. 

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Cast post and core:

Cementation of the post and core

Required components for cementation

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Cast post and core:

Cementation of the post and core

Choose the cement to be used for seating the CPC

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Cast Post Core Cementation

 After assembling all of the cementationcomponents, be sure to isolate the tooth andprepare/dry the canal as prescribed depending

upon the type of cement you are using

Be sure all of the temporary cement is removedfrom the canal and preparation as it may inhibit

seating of the CPC or setting of the cement

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Cast post and core:

Cementation of the post and core

 The canal is dried with a paper point prior to cementation.

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Cast post and core:

Cementation of the post and core

Placement of the cement on the Lentulospiral

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Cast post and core:

Cementation of the post and core

Place the CPC in the post space and apply apical pressure

Clear the excess cement from the margin and check to make sureit is completely seated

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Cast post and core:

Clearing cement from the margin after cement setting

Be sure not to disturb the post when the cement is setting as this

may weaken the cement bond

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Cast post and core:

Finished CPC

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Cast post and core:

Often, minor preparation may be needed after seating the CPC

BE SURE the cement is completely set before doing this

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Cast post and core:

Final restoration

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Cast post and core:

Cementation of the final restoration

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References

Trope M, Maltz DO, Tronstad L Endod Dent TraumatoGoodacre CJ,Spoolnik KJ

Goodacre CJ, Spoolnik KJ J Prosthodont 1995;4:51 l. 1985 Jun;1(3):108-11

Standlee JP, Caputo AA et al J Prosthet Dent 1980;44:398-404   Barkhordar RA, Radke R, Abbasi J J Prosthet Dent. 1989

 Jun;61(6):676-8.

Gargiulo et al J Periodontol 1961;32:261

Sorensen JA, Engelman MJ. J Prosthet Dent. 1990 May;63(5):529-36.

Reinhardt RA et al J Dent Res 1983;63:1002-1008

 Morgano SM J Prosthet Dent 1996;75:375-80