Restoration of endodontically treated teeth

DR. MD. REZAUL KARIM
MS(Resident) Orthodontics
Dhaka Dental College

1. ASSALAMUALIKUM

2. RESTORATION OF ENDODONTICALLY TREATED TEETH

3. Chair person: PROF. UMME KULSUM Head of the department Department of Conservative Dentistry and Endodontics Dhaka Dental College Supervised by: DR. BEGUM ROKEYA AFSAR Assistant professor Department of Conservative Dentistry and Endodontics Dhaka Dental College Presented by: DR.MD. REZAUL KARIM MS (Resident), Orthodontics Dhaka Dental College

4. CONTENTS: Introduction Historical perspective Objectives of final restoration Change of a tooth following endodontic treatment Evaluation of endodontically treated teeth Restorative treatment planning for endodontically treated teeth Restorative options after endodontic treatment

5. Restoration of teeth with minimal remaining tooth structures Post & core Types of post and core Factors to be considered while planning post and core Indications and contraindications of prefabricated and custom made post and core Fabrication of custom made post and core Investing and casting Cementation Conclusion

6. INTRODUCTION Endodontic treatment is largely performed on teeth which are significantly affected by caries, multiple repeat restorations and /or fracture. Already structurally weakened such teeth are often further weakened by the endodontic procedures to provide optimal access. So for long term success skillful integration of both endodontic and restorative procedure is mandatory.

7. HISTORICAL PERSPECTIVE As early as 1728,Pierre Fauchard described the use of “ tenons ” which were metal posts screwed into the roots of teeth to retain bridges. In the mid 1800, wood replaced metal as the post material, and the “pivot crown” a wooden post fitted to an artificial crown and to the canal of the root, was popular among the dentists. Often, these wooden posts would absorb fluids and expand frequently causing root fracture.

8. It was later modified to eliminate the threaded tube and was redesigned as a one piece dowel and crown, which lost its popularity quickly because they were not practical . During the 1930s,the custom cast post and core was developed to replace the one piece post crowns. This procedure required casting a post and core as a separate component from the crown. This two step technique improved marginal adaptation and allowed for a variation in the path of insertion of the crown.

9. In 1869 ,Black introduced the metal posts in which a porcelain faced crown was secured by a screw passing into a gold lined root canal . Clarck in the mid 1800, developed a device that was extremely practical for its time because it includes a tube that allow drainage from the apical area of the canal . The Richmind crown was introduced in 1878, and incorporated a threaded tube in the canal with screw retained crown.

10. OBJECTIVES OF FINAL RESTORATION Maintain coronal and apical seal after endodontic treatment. Protect and preserve the remaining tooth structure. Provide a supportive retention ,foundation for the placement of definitive restoration. Restore the function and aesthetics.

11. ARE ENDODONTICALLY TEETH ARE DIFFERENT?

12. A) Architectural changes: Increase susceptibility to fracture due to.. Decay, Cutting of coronal tooth structure during access cavity preparation Access removal of redicular dentine during canal preparation.

13. B) Change in the dentine physical characteristics/moisture loss: Effects of moisture loss are.. Dehydration Loss of collagen intermolecular cross linking Decrease in 14% strength and toughness of dentine

14. C) Esthetic changes: Non vital teeth show loss of translucency and discolouration and esthetics due to various reasons. Such as.. Pulp necrosis Endodontic procedures Root canal filling materials Loss of tooth structures due to caries fracture .

15. Are endodontically teeth are more brittle?(Modern concept)

16. Contrary to the common belief, endodontically treated teeth are not more brittle. In recent studies no difference in moisture content was found between endodontically treated teeth and a vital tooth. It was found that vital dentine had moisture content of 12.35% whilst dentine from endodontically treated teeth had a moisture content of 12.10 %. (Papa J,et al Moisture content of vital vs endodontically treated teeth ,)

17. The loss of vitality and a proper endodontically treated teeth shows limited extent of changes of biomechanical behavior. The tooth strength reduction is proportional to coronal tissue loss by, carious lesion or restorative procedure.

18. Evaluation of endodontically treated teeth A) Endodontic evaluation B) Periodontal evaluation C) Restorative evaluation D) Esthetic evaluation

19. A) Endodontic evaluation Good apical seal. No tenderness on percussion. No apical sensitivity. No exudate. No fistula . No active inflammation. Retreatement should be done if there are signs and symptoms including failure.

20. B) Periodontal evaluation Extent of underlying periodontal disease. Adequate biological width. In case with extensive coronal destruction crown lengthening can be considered. Presence of enough coronal tooth structure to incorporate ferrule into cast restoration

21. C) Restorative evaluation Amount of remaining tooth structure. Tooth type. Morphology of tooth. Occlusal and prosthetic forces. Opposing dentition.

22. D) Esthetic consideration Thin gingiva may transmit a dark shadow of the root through the tissue.

23. Metal or dark carbon fiber placed in the canal can result in unacceptable gingival discolouration from the underlying root.

24. Endodontic and restorative materials in these esthetically critical cases must be selected so as to provide the best health service with the minimum of esthetic compromise .

25. Restorative Treatment Planning for Endodontically Treated teeth

26. Following factors should be taken into consideration . A) Amount of tooth structure present B) Occlusal forces and anatomic position of the tooth C) Restorative requirements . D) Morphology of root canal.

27. A) Amount of tooth structure present: According to “Cohen” choice of post endodontic treatment depends upon the amount of remaining tooth structure . Tooth with minimal loss of structure is inherently stronger and can be restored with only coronal restoration . Tooth with >50% of remaining coronal structure can be restored with crown. Tooth with 25-50% of remaining coronal structure can be restore with non rigid post. Tooth with <25% of remaining coronal structure or <3-4 mm of cervical tooth structure with rigid posts.

28. B) Occlusal forces and anatomic position of the tooth: Anterior tooth with minimum loss of tooth structure can be restored with coronal restoration. If the tooth is discoloured , bleaching and veneer should be considered . Anterior teeth with heavy horizontal forces should be restored withstronger restorative component .

29. Posterior tooth with considerable structure requires restoration with onlay or crown to protect it against fracture. In cases of extensive tooth damage, post/core followed by crown is indicated.

30. C) Restorative requirement : Teeth included as abutments in the fixed or partial dentures undergo more forces and thus need additional retention and protection against fracture and caries due to leakage.

31. D) Esthetic requirement: Loss of translucency and discolouration in the endodontically treated teeth especially in esthetic zone require restorative materials like tooth coloured posts,composites and ceramic cores and ceramic crown.

32. E) Morphology of root canal: In case of structurally compromised teeth where post and core are required ,canal shape ,canal taper, curvature, angulation of canal with the floor of the pulp chamber etc. also guide restoration plan.

33. TREATMENT OPTIONS FOR ENDODONTICALLY TREATED TOOTH

34. Anterior tooth Minor coronal damage Intact marginal damage Intact incisal edge No colour change Esthetically acceptable Complete coverege is not required Conservative treatment bonded resin composite Moderate coronal damage One or two large proximal caries. Average size tooth Full coverage crown is required Significant coronal damage Undermined marginal ridge Loss of incisal edge Coronal fracture or esthetically unacceptable Custom made or, prefabricated post and core Small circular canal Prefabricated post with resin composite core followed by full coverage crown Extremely flared canal Custom made post and core followed by a full coverage crown

35. Posterior tooth Minor coronal damage Low risk of fracture Minimum occlusal fracture Intact buccal and lingual cusp Conservative treatment MOD only No post Moderate coronal damage Amalgam coronal and radicular core or, resin composite core followed by full coverage crown Significant coronal damage Custom made or, prefabricated post and core Canal with circular in cross section Prefabricated post with amalgam or resin composite core followed by full coverage crown Extremely tapered canal Custom made post and core followed by a full coverage crown

36. RESTORATION OF TOOTH WITH MINIMUM REMAINING TOOTH STRUCTURE

37. C HALLENGES These teeth have an increased risk of fracture. They provide decreased retention for restoration. That are in jeopardy for invasion of periodontal attachment.

38. As the remaining tooth structure decreases and functional forces increased, greater restorative control is needed. Extensively damaged or missing tooth structure fundamentally alters the use of restorative procedures and the need for adjunctive treatment. In order to increase the resistance and support of the crown in that case dowel core can be used. A dowel core consists of two parts….. 1)Dowel/post 2) Core

39. Dowel core is of two types… 1. Prefabricated post and core 2.Custom made post and core

40. A dowel core provides the necessary amount of retention and acts as a substitute for the lost tooth structure. But studies have shown that the dowel does not take up any masticatory load and that the dowel weaken the tooth structure rather than strengthening it. Therefore dowel preparation should be conservative

41. INDICATIONS FOR POST AND CORE The remaining coronal tooth structure is inadequate for the retention of a restoration. When there is sufficient root length to accommodate the post while maintaining an adequate apical seal.

42. CONTRAINDICATIONS OF PLACING POST Presence of signs of endodontic failures like poor apical seal, active inflammation, presence of fistula or sinus and tenderness on percussion. If adequate retention of core can be achieved by natural undercuts of crown. If there are horizontal cracks in the coronal portion of the teeth. When tooth is subjected to excursive occlusal stresses like lateral stresses bruxism or heavy occlusal guidance

43. DOWEL/POST It is a relatively rigid restorative material placed in the root of nonvital teeth for retention of the core and to transmit forces from core to the root. Purpose of using post… It helps to retain the core. It helps to distribute the stresses through the radicular dentine to the p oor apex.

44. Earlier it was believed that post strengthens or reinforces the tooth but it has been shown by various studies that posts actually weakens the tooth and increase the risk of root fracture. Therefore, a post should be used only when there is insufficient tooth structure remaining to support the final restoration

45. IDEAL REQUIREMENT OF A POST A post should.. Provide maximum protection to the root to resist root fracture. Provide maximum retention to the core and crown. Be easy to place. Be less technique sensitive

46. Have high strength and fatigue resistance. Be visible radio graphically. Be biocompatible. Be esthetic. Be easily available and not expensive

47. CLASSIFICATION OF POSTS

48. CORE Core is the supragingival portion that replaces the missing coronal tooth structure and forms the c entre of new restoration, basically it acts as a miniature crown. Ideal physical properties of core materials… Compressive strength to resist intracoronal forces Biocompatibility. Ease of manipulation. Flexural strength to prevent core dislodgement.

49. Ability to bond to tooth structure and post . Coefficient of thermal expansion similar to dentine Minimal water absorption Dimensionally stable. No reaction with chemicals. Low cost . Easily available . Contrasting colour to tooth structure except when used for anterior teeth.

50. Core build-up materials available are A) DIRECT PLACEMENT: Dental amalgam

51. Glass ionomer Resin modified glass ionomer

52. Composite resin

53. B) Indirect placement Custom made cast post and core

54. ESSENTIAL FACTORS TO BE CONSIDERED DURING DOWEL CORE PREPARATION 1) The canal should be obturated with guttapercha and not with silver cone because, it is easy to remove. Removal of silver cones can lead to lateral perforation.

55. 2) Post length: Greater the post length greater the retention . Ideal post length should be equal to the crown length or, two third of the length of the root of involved tooth . Maintenance of 4-5 mm apical seal is required.

56. 3) Post diameter : - The post diameter should not exceed one third of the diameter of the root . - A minimum of 1mm sound dentine should be maintained circumferentially .

57. 4) Ferrule effect: Ferrule is a 360 degree metal collar of the crown surrounding the parallel walls of the dentine extending coronal to the shoulder of the preparation. It has been seen that ferrule with 1-2 mm of vertical tooth structure doubles the resistance to fracture than in teeth without any ferrule effect. Fig: Ferrule protections the integrity of root by bracing action

58. Types of ferrule … Core ferrule—Core ferrule is part of cast metal . 2)Crown ferrule—Crown ferrule is ferrule created by overlying crown engaging the tooth structure.

59. 5) The restoration should not completely encroach on the “Biological width”. A minimum of 4-5 mm of supra bony tooth structure should be available to accommodate for the restoration and attachment apparatus.

60. Fabrication of custom made post and core The steps in the fabrication of post and core are.. A) Tooth preparation B) Canal preparation C) Canal pattern fabrication D) Casting E) Finishing and cementation

61. A) Tooth preparation: The tooth is prepared as usually. Unsupported enamel is removed . Only weak enamel is removed and it is not necessary to remove all the coronal tooth structure . The tooth should be evaluated for residual caries to assess its strength. Any weak enamel wall or restoration should be removed.

62. B) Canal preparation : Pesso reamer is the instrument of choice for removing gutta percha and for enlarging the canal because they have non cutting tips, which follow the path of least resistance (i.e. the reamer will try move along the length of the canal instead of walls and perforating it ) A hot condenser can be used to remove GP remnants.

63. After removing the GP, the pesso reamer should again be inserted to the require depth and used to enlarge the canal . A test radiograph should be taken to decide the amount of canal enlargement .

64. The diameter of the canal should be at least 1/3 rd of the width of the tooth. A No. 170 bur is used to prepare a keyway in the tooth along the length of the canal for a distance of 4mm.The keyway should be equal to the width of the bur . A contrabevel is placed around the occlusal axial line angle so that a metal coller is formed during casting which will embrace the remaining coronal tooth structure and protect it from fracture.

65. The canal and the post are coated with petroleum jelly .

66. C) Resin pattern fabrication: A 14 gauge plastic post is trimmed so that is slides easily in and out of the canal. A notch is cut on the facial side of the post so that it can be easily oriented.

67. The external bevel(on the tooth) should be covered wit resin before the resin in the canal is set . Next the canal is filled with fluid pattern resin. Now the plastic post should be inserted into the canal

68. After the resin become doughy ,the pattern should be pumped in and out so that it does not lock into any undercut. Once the resin polymerizes , it should be removed from the canal and inspected for voids.

69. A second mix of acrylic is used for core build up. The core should be moulded with the hand to resemble a prepared tooth.

70. Green stone and garnet disks should be used to smoothen and shape the coronal pattern.

71. D) Casting : The dowel core pattern should be wiped with alcohol to remove all the lubricant. The pattern should be sprued at the cingulum . One to two cubic centimeter of extra water should be added to the investment and a casting liner should not be used. So that there is shrinkage of the dowel. A smaller dowel is preferred because it will not bind to the canal.

72. Burnout should be done for an additional 30mins to ensure complete elimination of wax.

73. E) Finishing : After casting , the sprue is cut off using a carbundum disk. The dowel should be checked for proper fit. If it binds to the canal, air abrasion should be done till the shiny spots are removed. The coronal portion should be polished to a statin finish using a burlow wheel. A groove should be cut along the length of the dowel from the apical end to the contrabevel to act as escape way for the luting cement.

74. F) Cementation: The luting agent must fill all dead space within the root canal system. Voids may be a cause of periodontal inflammation via lateral canals. The cement is loaded into the canal using lentulospiral .

75. The post and core is inserted gently to reduce hydrostatic pressure, which could cause root fracture . Final impression is made after cementation of the dowel and the temporary crown is prepared . Permanent crown is cemented later.

76. CONCLUSION Although restoration of endodontically treated teeth has been rationalized, information from controlled long term clinical trials is still needed. As much tooth structure must be preserved as possible and post and core is basically used to provide retention and support for a cast restoration. There is not one post, core or final restoration that can be used in all clinical situations. So we have to learn with these variable and understand the basic concepts of how to use them to maximum advantage.

77. BIBLIOGRAPHY Textbook of endodontics;4 th edition ( Nisha Garg and Amit Garg ) Grossman’s ENDODONTIC PRACTICE ;13 th edition Textbook of Prosthodontics; 2 nd edition(Deepak Nallaswamy Veeraiyan ) Also from different websites