ABSTRACT: Post and cores can be fabricated either intraorally on the tooth or indirectly on the

die. Indirect techniques for the fabrication of posts and cores provide some advantages over

direct techniques. Fabricating the resin pattern in vivo by the bead brush technique may lose time

and effort for both the dentist and the patient. In the described technique , a vinyl polysiloxane

matrix is used for indirect fabrication of custom post and core wax pattern without the preparation

of a die. The final instrument used to prepare the post space corresponds to the size and shape of

the final post. Hence an index of the same is made with vinyl poly siloxane impression material

and used to fabricate a wax pattern. Using an indirect technique, posts prepared with acrylic resin

may become locked into the cast undercuts. Use of wax for the post fabrication reduces this

problem however insertion and removal of wax may cause distortion or breakage of the pattern.

The material used in the technique is inlay wax. The advantages of this technique include the

precise fit of the post into the post space along with less chairside time, as the wax pattern is not

fabricated inside the patient's mouth.

1 2Seema Sajood Mufti, Achyut Sinha1.Consultant Prosthodontist at Family Health Dental Centre, Srinagar, Jammu and Kashmir.2.Post Graduate Student, Dept. of Prosthodontics, Rama Dental College Hospital And Research

Centre , Kanpur, Uttar Pradesh.

INTRODUCTION : The successful treatment of a badly

broken down tooth with pulpal disease depends not only upon

a good endodontic therapy, but also on a good prosthetic

reconstruction following endodontic therapy. The purpose of

the post is to retain a core that can be used to retain definitive

prosthesis. When a substantial amount of coronal structure is

lost , a cast post and core is indicated.

Canal configuration aids in making a choice between a

custom designed post and a prefabricated post . If the selected

post closely fits or conforms to the canal shape and size , it

may be a more conservative option because less dentin

removal is required, thus enhancing fracture resistance of the

tooth, as well as retention of the post. It has been reported that

if a canal requires extensive preparation , a well adapted cast

post and core will be more retentive than a prefabricated post

that does not match the canal configuration. The cast post and

core is custom fitted to the prepared root canal space and

designed to resist tortional forces. The quick fabrication and

exact fitting of custom –made posts is the aim of fixed

prosthodontic clinicians.

CASE REPORT : A 35 year old female patient with root

canal treated maxillary left lateral incisor (22) reported to the

prosthodontic clinic with grossly decayed coronal structure.

The treatment options figured out were:

Restoration of the fractured tooth with a custom made metal

post and core with fabrication of PFM crown.

Amalgam coronal radicular dowel post

Composite restoration

Amalgam restoration

It was planned to rehabilitate the tooth with a custom made

metal post and core using an indirect technique. Other

A MODIFIED INDIRECT TECHNIQUE FOR FABRICATION OF A POST AND CORE WAX PATTERN USING A VINYL POLY SILOXANE MATRIX.

Key Words:

post, post space,

wax pattern,

indirect technique.

Source of support : Nil

Conflict of interest: None

Journal of Dental Sciences

University

University Journal of Dental Sciences, An Official Publication of Aligarh Muslim University, Aligarh. India 85

University J Dent Scie 2017; No. 3, Vol. 1

Case Report

treatment options were ruled out due to their unreliability

regarding this particular case.

As the coronal structure of the tooth was grossly decayed

amalgam coronal radicular pour and restoring with admix was

ruled out, due to their reduced tolerance to functional stresses

and diminished strength to retain a core. Composite and

amalgam restorations were also ruled out for the same reason.

In the following case report indirect technique for fabrication

of post and core has been discussed. The material used for

fabrication of the post and core wax pattern was inlay wax.

Further the patterns are casted using the conventional lost wax

technique in base metal alloy and adjusted on the cast. After

the adjustment , the cementation of the post has been done

with GIC cement. The technique is particularly useful for

short post preparations where precise fit is necessary for

retention.

PROCEDURE : Using a long flat and tapered diamond bur

prepare the post space by removing gutta percha from the

coronal two thirds of the root leaving the apical 4-5 mm of the

canal as in the usual procedure.

Shape the canal as needed in such a manner that the post space

has almost the same configuration as that of the diamond bur

that is used to prepare and shape it. Mark the length of the post

space on the bur with a red pencil.

Now , mix a small amount of vinyl polysiloxane impression

material (putty) into a small block and before it sets make an

impression of the flat and tapered bur , which corresponds to

the prepared post space of the endodontically treated tooth by

sliding it into the putty block, upto the red pencil mark.

Remove the bur from the putty once it is set. Now take a thin

orthodontic wire of (21guage) and place it into the post space

impression created inside the putty block. The wire will

loosely fit into this hole.

Apply vaseline over the wire as well as on the space created

inside the putty block and fabricate a wax pattern over it using

the putty block as the index. Continue core build up. Once the

pattern is completed it is removed from the putty index and

casted in the usual manner.

DISCUSSION : The technique is particularly useful for short

post preparations where precise fit is necessary for retention.

Advantages of this technique include:

1. Patient comfort as no tedious wax pattern fabrication

inside patient's mouth.

2. Less chairside time.

3. Elimination of pouring a cast.

4. Superior adaptation to the root canal.

5. Eliminates the need for developing full contoured

patters and their removal from the working cast for

investment.

6. Disadvantages of distortion of wax pattern while

removing from either patient's mouth or working

cast are eliminated.

IMPRESSION OF FLAT AND TAPERED BUR USING

POLYVINY SILOXANE

ORTHODONTIC WIRE THINNED TO LOOSELY FIT

INTO THE PUTTY INDEX

O R T H O D O N T I C W I R E A N D P O S T S P A C E

IMPRESSION GREASED WITH VASELINE FOR EASY

RETRIEVAL OF WAX PATTERN.

ORTHODONTIC WIRE FITTING LOOSELY INTO POST

SPACE PUTTY IMPRESSION WAX PATTERN

FABRICATED USING INLAY WAX

University Journal of Dental Sciences, An Official Publication of Aligarh Muslim University, Aligarh. India 86

University J Dent Scie 2017; No. 3, Vol. 1

WAX PATTERN RETRIVED FROM PUTTY INDEX FOR

CASTING.

REFERENCES

1. Rosensteil SF, Land MF, Holloway JA. Custom -

cast post fabrication with a thermoplastic material. J

Prosthet Dent. 1997; 77: 209-11.

2. Rosensteil SF, Land MF, Fujimoto J. Contemporary

fixed prosthodontics. in: 3rd ed: CV Mosby, St.

Louis; 2001:300.

3. Kanoy BE , Brantley CF, J Prosthet Dent;

1995:54;6757-9.

4. Gavelis JR, Hope DM, J Prosthet Dent;

1984:51;1:55-9.

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