Restoration Of Endodontically Treated Tooth
Rationale For Use Of Post
If the coronal tooth structure is lost due to fracture or severe carious lesion and remaining tooth structure is not suficient to provide enough support to prosthesis then the post is used to achieve additional support from root.
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Post is inserted into root canal to get support from root and restorative material is supported on coronal part of the post which is known as “core”. The main function of the post is to support the core material. If more than 25% of anterior tooth structure and 50% of posterior tooth structure is lost then post and core with crown prosthesis is recommended treatment.
Classification Of Post
Various types of posts are available to match different treatment needs. Broadly they can be classified as under.
Procedure For Post And Core Treatment
Evaluation of Endodontically Treated Tooth:
Once the root canal treatment is completed, the operator should observe the endodontically treated tooth for sometime. The tooth should be asymptomatic after root canal treatment. There should be no pain or sensitivity during chewing or any other function.
Read and Learn More: Preclinical Prosthodontics Notes
Selection of Post and Core System:
If the tooth root diameter and canal diameter is small and use of prefabricated post needs more widening of canals then it results in additional loss of tooth structure. In such cases custom made post and core is used. Where wider canals are available prefabricated posts are used.
Preparation of Post Space:
After endodontic treatment, the root canals are filled with restorative materials, most commonly the gutta-percha. For post space preparation, the gutta-percha is removed from the filled canals using Peeso Reamers or Gates Glidden drills. The apical seal of filled root canals should be kept intact. Minimum 5 mm of gutta-percha are kept in the root canals to maintain apical seal. Post space is modified after removal of gutta-percha from the canals.
- Use of prefabricated post: Prefabricated post is used when root canal diameter is wider and needs less canal preparation to accommodate prefabricated post.
- Use of custom post: When canal diameter is smaller and needs more canal preparation for receiving prefabricated post, in such cases custom post is fabricated after making impression of narrow post space (canal space). In such cases usually post and core is single unit.
Ferrule:
When part of coronal tooth structure is lost, the remaining tooth structure is encircled with part of crown prosthesis. This remaining natural crown structure encircled by crown prosthesis is known as “ferrule”. Minimum 2 mm of ferrule is indicated for longevity of prosthesis.
Procedure And Pictorial Representation Of Post And Core Treatment
Fractured tooth or grossly carious tooth with more than 25% tooth structure loss is recommended for post and core treatment. Endodontic treatment is recommended in such cases where pulp is exposed due to fracture of tooth structure or carious lesion. After removing the pulp tissue, the root canals are widens and shaped to receive the inert restorative material in place of pulpal tissue.
The coronal gutta-percha is removed keeping the apical seal intact to prevent infection. Apical gutta-percha of 3–5 mm is kept in the root canal to preserve the apical seal. Appropriate inlay wax or pattern resin is inserted into root canal and wax pattern/resin pattern is made of the canal. The same material is extended on crown portion to
shape it like prepared tooth. The extended material forming crown-like portion is called as core. The post and core wax pattern is casted and converted to custom post and core
and cemented into post space. Impression is made after cementation and crown prosthesis is prepared. Prepared crown prosthesis is cemented over core to restore the fractured tooth.
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