post endontic restoration and post and core .pptx

restoration of endodontically treated teeth
this topic touches base on how to proceed after rootcanal therapy

1. RESTORATION OF ENDODONTICALLY TREATED TEETH - Dr. Beverley Themudo

2. WHY DOES A TOOTH NEED A ROOT CANAL TREATMENT ??? DO ALL ROOT CANAL TREATED TEETH NEED A CROWN??? WHAT IS A POST AND CORE ??? WHEN DO WE USE A POST AND CORE ?? HOW TO PERFORM A POST AND CORE TREATMENT ?? INTRODUCTION

3. WHY IS RESTORATION OF A ROOT CANAL TREATED TOOTH DIFFERENT ?

4. Negative influence of RCT on remaining sound tooth structure:

5.   Architectural Changes Loss of tooth Structural integrity (decay, dental procedures and endodontic therapy ) Fracture resistance of the tooth decreases

6. Recent studies have concluded that: access cavity preparation  with 5% reduction in tooth stiffness Loss of 1MR  46% reduction in tooth stiffness Loss of 2 MR  63% reduction in tooth stiffness Circumferential loss in tooth structure is liabiity to # Reduction in the dentin toughness:

7. It has a minimal effect on fracture liability. Reduction in the dentin toughness: It has an insignificant effect on fracture liability. Moisture loss

8. Pre treatment considerations:

9. Pre treatment considerations: Endodontic evaluation Restorative considerations. Periodontal evaluation. Occlusal evaluation. Muscle function considerations. Esthetic considerations.

10. Endodontic evaluation Length, Density (voids) Adequate apical seal Procedural errors (broken instrument or perforation) will compromise the prognosis +/- periapical lesion +/- signs and symptoms in relevance to the quality of ttt Type of root canal filling ,silver points should be replaced

11. Pre treatment considerations: Endodontic evaluation Restorative considerations Periodontal evaluation. Occlusal evaluation. Muscle function considerations. Esthetic considerations.

12. Restorability Strategic importance Last abutment to avoid removable prosthesis. The teeth included as abutments in the fixed or partial dentures absorb more forces and thus need additional retention and protection against fracture and caries due to leakage. Retentive qualities of the remaining tooth structure and the need of added means of retention.

13. Pre treatment considerations: Endodontic evaluation Restorative considerations. Periodontal evaluation. Occlusal evaluation. Muscle function considerations. Esthetic considerations.

14. Periodontal evaluation   Mobility evaluation. (grade III) Proper periodontal treatment to improve the prognosis

15. Gingival biotype (thin visible cervical discoloration) This is of prime importance in anteriors Use of esthetic posts(non metallic posts) glass fiber posts and zirconium posts in mutilated endo treated teeth. Gingival biotype .. e.g thin biotype needs esthetic restoration ( zirconiumpost & all ceramic crowns). Internal discoloration from trauma or previous RCT may need internal bleaching +/- veneers or may need full coverage

16. Pre treatment considerations: Endodontic evaluation Restorative considerations. Periodontal evaluation. Occlusal evaluation. Muscle function considerations. Esthetic considerations.

17. How to proceed …

18. HOW TO KNOW IF A POST AND CORE IS REQUIRED

19. POST AND CORE

20. Post (Dowel): A structure usually made of metal that is fitted into a prepared root canal of a natural tooth. When combined with an artificial crown or core, it provides retention and resistance for the restoration. Core: The center or base of a structure. The core is designed to resemble or become the crown preparation or crown itself. Definition

21. DIAGNOSIS & TREATMENT PLANNING

22. A treatment plan can be formulated based on: Medical and dental history . The clinical and radiographic examination. The patients needs and chief complaint.

23. WHEN SHOULD WE PERFORM A POST AND CORE TREATMENT ??? ANSWER: When there is insufficient tooth structure to provide retention and resistance to the crown to be placed on the tooth. WHAT CONSIDERATIONS SHOULD BE MADE FOR A POST AND CORE TREATMENT ???

24. ENDODONTIC CONSIDERATIONS  quality of the endodontic therapy. Success requires a dense, uniform, three dimensional obturation of the root canal system, 0.5 to 1.0 mm from the radiographic apex of the root or roots. If tooth exhibit signs or symptoms indicating failure, retreatment procedures should be accomplished prior to restoring the tooth.

25. When obturation deficiencies such as incomplete root canal fillings poorly instrumented or condensed canals poorly adapted silver points untreated canals are evident Clinical signs and symptoms of failure

26. PROSTHETIC CONSIDERTIONS Treatment planning is dependent primarily on the AMOUNT OF REMAINING TOOTH STRUCTURE .

27. Additional factors affecting prognosis are the: Tooth type Morphology Arch position Occlusal and prosthetic forces applied to the tooth. Contrary to popular belief, posts do not strengthen the tooth. The primary function of a post is to provide retention for the core.

28. Post & Core Materials Metal : stiffer than tooth Zirconia : Very strong, but brittle and can fracture Ceramic : Also strong but nearly impossible to remove if fracture occurs Resin reinforced with fiber : A good option, but fibers can fray and cause the post to fail Carbon fiber : Very much like original dental material but the dark color can show through teeth Fiberglass : Less brittle than ceramic materials but challenging to manufacture

29. Ideal properties of a post Maximum protection to root Adequate retention within root Maximum retention of the core and the crown. Maximum protection of the crown margin cement seal Pleasing esthetics when indicated High radiographic visibility Retreivability Biocompatibility

30. Classification of posts ( D C N A 2002 ) Metallic Non Metallic Custom cast posts Prefabricated Carbon fiber posts Zirconia posts Woven fiber composite post

31. Multiple cores- in the same arch Small teeth Angle of cores – to be changed - PGP [platinum-gold- palladium] - Nickel –chromium - Cobalt - chromium - Stainless steel - Non oxidizing noble alloys - Titanium Custom cast posts Metallic Posts Indications combinations

32. Pre- fabricated posts Tapered posts :  Mimics natural canal shape  Least amount of retention Parallel posts : provides greater retention Active posts Indicated : in short canal space Passive

33. A - Tapered, smooth-sided posts B – Tapered, serrated posts. C – Tapered, threaded posts D – Parallel, smooth-sided posts E -– Parallel, serrated posts F - Parallel threaded posts. Classification of Prefabricated Posts.

34. Non-Metallic Posts C arbon fibre Fibre reinforced composite C eramic composite Z irconia post.

35. Desirable features of a core material : CORE Adequate compressive strength Sufficient flexural strength Biocompatibility Resistance to leakage of oral fluids at the core/tooth interface. Ease of manipulation. Ability to bond to remaining tooth structure Thermal co-efficient of expansion and contraction Dimensional stability Minimal potential for water absorption & Inhibition of dental caries.

36. Classification of core materials : Cast core Plastic core materials Metal Ceramic to Zirconia dowels Amalgam Glass ionomer cement Resin modified GIC Dual cure fibre reinforced cores

37. Pissis 1995 proposed a “ Monobloc ” technique for fabrication of a post and core and a crown as a single component made out of glass ceramic material IPS empress. Kantor and pines 1977 teeth little coronal structure the cast gold post and core was superior to a stock post and composite resin core. Cast core Ceramic to Zirconia dowels

38. Amalgam can be used for core build ups Due to its self – sealing proprieties, durability and good working characteristics Amalgam Plastic core materials

39. composite cores show significantly greater marginal leakage compared with amalgam cores. MC lean 1985 GIC can be used where limited loading is anticipated. Resin modified GIC not recommended in high stress situations. Composite Resin GIC

40. Clinical Considerations

41. Apical seal, alveolar bone support, and root morphology are all important considerations when determining post size and depth. Maxillary molars, the PALATAL canal should be used because of its relatively large and straight configuration. Mandibular molars, the DISTAL canal should be used because of the root morphology and size of the canal.

42. POST LENGTH Traditional view of post length have advocated that the post be: Equal to the height of the clinical crown. One and one half times the length of the clinical crown and Two third the length of the remaining root. When ever mechanical preparation of the post hole is required, 4-5 mm of undisturbed apical gutta percha should remain after post preparation.

43. In most instances, the more deeply the post is placed, the more retentive it becomes. Short posts are especially dangerous and have a much higher failure rate. With a post of correct length, a force (F) applied near the incisal edge of the crown will generate a resultant couple (R). When the post is too short, this couple will be greater (R’), leading to increased possibility of root fracture.

44. POST DIAMETER Increasing the diameter of the post does NOT provide a significant increase in the retention of the post. However, it can increase the stiffness of the post at the expense of the remaining dentin and the fracture resistance of the root. Therefore post diameter must be controlled to preserve radicular dentin reduce the potential for perforations permit the tooth to resist fracture

45. Goodacre suggested that post diameters should not exceed one third of the root diameter at any location. Post should be surrounded by at least 1 mm of sound dentin  Particularly important in the apical area where the root narrows & stresses are concentrated.

46. With Ferrule Without Ferrule

47. WHAT IF TOOTH HAS INADEQUATE CORONAL TOOTH STRUCTURE TO CREATE A FERRULE ? SURGICAL : CROWN LENGTHENING Allows ferrule Less favourable crown root ratio Increased leverage on the root during function Consider crown lengthening and or extrusion

48. ORTHODONTIC EXTRUSION

49. Removal of the root canal filling material and enlargement of the canal. 2. Preparation of the coronal tooth structures. 3 .Post & core fabrication 3 STAGE OPERATION.

50. 1.REMOVAL OF THE ENDODONTIC FILLING MATERIAL Chemical Removal Thermal Removal Mechanical Removal Schnell FJ 1978 and Bourgeois R S and Lemon RR (1981) gutta-percha can be removed with a warm condenser immediately after obturation. Dickey DJ et al 1982 Rotary instrument can disturb apical seal if used immediately after obturation.

51. Steps in removal of gutta-percha & Enlargement of the canal IF gutta-percha is old and has lost its thermoplasticity , use a rotary instrument ( Peeso-Reames or Gates Glidden drills) Before enlargement of the canal, the type of post system to be used for fabrication of the post and core must be chosen. Calculate the appropriate length of the post

52. 2.PREPARATION OF THE CORONAL TOOTH STRUCTURE : Remove all internal and external undercuts Complete the preparation by eliminating sharp angles and establishing smooth finish lines. prepared perpendicular to the post, to create a positive stop & to prevent over seating and splitting of the tooth. If insufficient tooth structure remains for this feature, an antirotation groove should be placed in the canal

53. 3.POST & CORE FABRICATION : Prefabricated post : Custom-made posts : Direct procedure : patients mouth Indirect procedure : laboratory

54. Direct method using Pre-fabricated post Post selected Core build up Finishing

55. Basic Procedure for Custom Post & Core Fabrication

56. Basic Procedure for Custom Post & Core Fabrication

57. Indirect procedure : Pieces of orthodontic wire Lubricate the canals syringe in impression material

58. Post-and-cores should be inserted with gentle pressure CEMENTATION : A rotary ( lentulo ) paste filler or cement tube If a parallel-sided post is being used, a groove should be placed along the side of the post

59. Luting agents: Luting agents include Zinc phosphate Polycarboxylate Glass ionomer Filled and unfilled resin cements Studies have indicated that removal of the smear layer and use of unfilled resin cement was significantly more retentive than zinc phosphate cement.

60. CROWNS

61. ONLAYS V/S CROWN