restoration of endodontically treated teeth ready post
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restoration of endodontically treated teeth cast post
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restoration of endodontically treated teeth ready post
- 1. Restoration of the Endodontically Treated Tooth 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 1
- 2. PROCEDURES • three-stage operation: 1. Removal of the root canal filling material to the appropriate depth 2. Enlargement of the canal 3. Preparation of the coronal tooth structure 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 2
- 3. Canal enlargement • Before the canal is enlarged, the type of post system that will be used for fabrication of the post and core restoration must be chosen. • Indications of ready made posts -prefabricated posts are recommended for conservatively prepared root canals in teeth with roots of circular cross section. 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 3
- 4. classification of ready made post • According to nature of fit • Passive or Active • According design or shape • Parrallel Tapered Parrallel tapered • According to surface configuration •Smooth Serrated Threaded • According material •Metal non metal 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 4
- 8. Why we should know these types 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 8 Because no system is universally applicable, familiarity with more than one technique is a significant advantage. Prefabricated posts range widely in shape and size with varying radiopacity that may assist in their identification on radiographs
- 9. How to select ready made post 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 9 Prefabricated posts are available in kits that include rotary instruments (twist drills) for post space preparation that correspond in size to the posts. These posts are manufactured to match standard sizes of endodontic files.
- 11. steps 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 11 1. Enlarge the canal with a drill that matches the configuration of the post. alternate between the Peeso Reamer drills and twist drills that correspond in size. Gain length with the Peeso Reamer drill, and then make the walls parallel with the twist drill. 2. A tapered post conforms better to the canal than does a parallel-sided post and requires less removal of dentin to achieve an adequate fit. However, it is slightly less retentive and results in greater stress concentrations, although retention may be improved by controlled grooving. 3. Be especially careful not to remove more dentin at the apical extent of the post space than is necessary . if measurements have been made carefully, radiographs are not normally necessary to verify the post space preparation.
- 12. Post Fabrication 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 12 it is an easy process , A post is selected to match the dimensions of the canal, and only minimum adjustment is needed to seat it to the full depth of the post space. The coronal part of the post may have an inadequate fit because the root canal has been flared. This the dentist can correct by adding material when the core is made.
- 14. Core Fabrication 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 14 The core of a post and core restoration replaces missing coronal tooth structure and, in combination with the remaining coronal tissue, forms the shape of the optimal tooth preparation. It can be shaped in resin or wax and added to the post pattern before the assembly is cast in one piece. It is fabricated directly onto a prefabricated post.
- 16. Interim Restorations 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 16 To reduce the need for endodontic re-treatment, endodontically treated teeth should be restored as soon as practical after completion of the endodontic procedure. Thus if definitive restoration of the tooth is delayed, it is appropriate to etch and seal the access cavity with an adhesive resin to reduce the risk of microleakage. teeth in the esthetic zone often require a well-adapted interim restoration
- 18. Investing and Casting 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 18 A cast post and core restoration should be slightly undersized in relation to the prepared post space in order to ensure full seating. However, the fit should not be so loose that light finger pressure causes rocking, rotation . On the other hand, a tight fit may cause root fracture. The casting should be slightly undersized, which the dentist can accomplish by appropriately restricting expansion of the investment (e.g., by omitting the usual ring liner or by casting at a lower mold temperature).
- 19. Evaluation 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 19 The practitioner must be particularly careful that casting defects such as small nodules do not interfere with seating of the post; otherwise, root fracture can result. Post and core restorations should be inserted with gentle pressure. Should any resistance be encountered, the practitioner must remove the casting and determine what prevents full seating before proceeding. Once the casting is seated, however, the marginal fit of a cast foundation is not as crucial as that of extracoronal restorations because the margins will be covered by the final crown. Air-abrading the surface to a matte finish may help detect interferences at try-in.
- 20. Cementation 10/21/2019 Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 20 The luting agent must fill all space within the root canal system . Voids may be a cause of periodontal inflammation via lateral canals. rotary (Lentulo) spiral filler is used to fill the canal with cement. The post and core restoration is inserted gently to reduce hydrostatic pressure, which could cause root fracture.
- 23. The influence of post design on stress distribution • Post design should enable stresses to be distributed as evenly as possible. • • Stresses are reduced as post length increases. • • Parallel-sided posts may distribute stress more evenly than do tapered posts, which may have a wedging effect. However, parallel-sided posts heighten stresses at the apex. • • High stress can be generated during insertion, particularly with smooth, parallel-sided posts that have no vent for cement escape. • • The cement layer results in a more even stress distribution to the root with lower stress concentrations. Dr.Sherif sultan,BDS,MSc,PhD,Fixed prosthodontics 2310/21/2019