Restoration of endodontically treated teeth 1 /certified fixed orthodontic courses by Indian dental academy


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Restoration of endodontically treated teeth 1 /certified fixed orthodontic courses by Indian dental academy

  4. 4. INTRODUCTION The overwhelming success of endodontic therapy has allowed for retention of more number of teeth than ever in the history of dentistry. Following endodontic treatment the restorative dentist is faced with deciding how to restore treated teeth for use as individual units or m
  5. 5. as abutments for fixed or removable restorations. The technique & guideline of how & when to restore endodontic treated teeth have evolved from clinical tradition. Although any number of post designs or no post at all may be used in a m
  6. 6. clinical situation, success can only be achieved when the technique of choice best meets the need of individual clinical diagnosis. m
  7. 7. DEFINITIONS: m
  8. 8. • Dowel : a post, 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 (GPT-8) m
  9. 9. Core : the center or base of a structure Post-core crown: a restoration in which the crown and cast post is one unit m
  10. 10. Ferrule (GPT-8): l: a metal band or ring used to fit the root or crown of a tooth 2: any short tube for making a tight joint m
  11. 11. • Apex (GPT-8): in dentistry, the anatomic end of a tooth root. • Biologic width: the combined width of connective tissue and epithelial attachment superior to the crestal bone m
  12. 12. HISTORY: m
  13. 13. • In 1747, Pierre Fauchard described the process by which roots of maxillary anterior teeth were used for the restoration of single teeth and the replacement of multiple teeth. m
  14. 14. • Posts were fabricated of gold or silver and held in the root canal space with a heat-softened adhesive called “mastic” (prepared by gum, turpentine and white coral powder). m
  15. 15. m
  16. 16. • In Fauchard’s days, replacement crowns were made from bone, ivory, animal teeth, and sound natural tooth crowns. Gradually, the use of these natural substances declined, and were replaced by porcelain. m
  17. 17. • A pivot (what is today termed a post) was used to retain the artificial porcelain crown into a root canal, and the crown-post combination was termed a “pivot crown.” • In the early 1800s Dubois de Clemant described Porcelain pivot crowns. m
  18. 18. • Early pivot crowns used seasoned wood (white hickory) pivots. The pivot was adapted to the inside of an all-ceramic crown and also into the root canal space. Moisture would swell the wood and retain the pivot in place. m
  19. 19. • Subsequently, pivot crowns were fabricated using wood/metal combinations, and then more durable all-metal pivots were used. m
  20. 20. • Richmond crown: • By C.M Richmond, a US dentist in 1879. • It was an artificial crown consisting of a metal base that has a post for insertion & a porcelain facing reinforces the metal backing m
  21. 21. • Metal pivot retention was achieved by various means such as threads, pins, surface roughening, and split designs that provided mechanical spring retention. m
  22. 22. m
  25. 25. ENDODONTIC EVALUATION • In addition to the identification of non-vital teeth and the endodontic evaluation of the vital teeth, the prerestorative evaluation should include an inspection of the quality of the existing endodontic treatment. m
  26. 26. m
  27. 27. • New restorations particularly complex ones ones, should not be placed on abutments with questionable endodontic prognosis. m
  28. 28. m
  29. 29. m
  30. 30. • endodontic retreatment may be indicated for teeth that exhibit radiographic periapical disease . • Restorations that need a dowel need a dowel space which is made by removing GP . m
  31. 31. • Canals obturated with a silver cone should be identified & endodontically retreated. m
  32. 32. PERIODONTAL EVALUATION • Maintainence of periodontal health is critical to the long term success of the endodontically treated & restored teeth. • In addition to the conventional periodontal examination ,the effect of the planned restoration on the attachment apparatus must be considered. m
  33. 33. • Extensive caries, tooth #,previous restoration,perforations,external resorption can destroy the tooth at the level of the periodontal attachment . • Attempts to place the restorative margins on sound tooth structure beyond these defects further invades biologic width. m
  34. 34. the biological attachment zone. m
  35. 35. • A mutilated tooth in which restorative treatment would compromise the junctional epithelium or connective tissue levels should be scheduled for periodontal crown lengthening surgery or orthodontic extrusion. m
  36. 36. m
  37. 37. ESTHETIC EVALUATION: • Potential esthetic complications must be investigated before the initiation of endodontic therapy. • Thin gingiva may transmit a shadow of dark root through the tissue. • The colour & translucency of most uncrowned teeth is adversely affected by opaque substances. m
  38. 38. m
  39. 39. • Endodontic & restorative materials in these aesthetically critical cases must be selected to provide best possible service. m
  40. 40. Effects of endodontics on tooth m
  41. 41. *Pathways of the Pulp,Stephen Cohen,6th edn,Mosby • The tooth structure that remains after endodontic treatment has been undermined & weakened by all of the previous episodes of- caries, fracture, tooth preparation & restoration. • Endodontic manipulation further removes important intracoronal & intraradicular dentin. m
  42. 42. • Finally endodontic treatment changes the actual composition of the remaining tooth. • The combined result of these changes is the increased # susceptibility & decreased translucency in non-vital teeth. m
  43. 43. • Endodontic procedures have been shown to reduce tooth stiffness by only 5%, whereas an MOD preparation reduces stiffness by 60%.* * J Endodont 16,512,1989 m
  44. 44. • Endodontic access into the pulp chamber destroys the structural integrity provided by the coronal dentin of the pulpal roof & allows greater flexing of tooth under function.* * JPD 67;458;1992 m
  45. 45. m
  46. 46. Altered physical characteristics• Changes in the collagen cross-linking & dehydration of dentin results in 14% reduction in strength & toughness. m
  48. 48. • Tooth structure loss can range from very minimal access preparation to very extensive damage. • Before restoration existing endodontic tooth needs to be assessed for• Good apical seal • No sensitivity • No exudate m
  49. 49. • No fistula • No apical sensitivity • No active inflammation m
  50. 50. • Restorative treatment decision depends on the: • Amount of remaining tooth structure • Functional demand • Need for the tooth as abutment for large restorations. m
  51. 51. • If coronal structures are largely intact & loading is favorable as on anterior teeth that are farther removed from the fulcrum line a simple filling can be placed in the access cavity. m
  52. 52. • If a substantial amount of tooth structure is missing, a cast post & core is indicated. • Molars are often restored with amalgam or a combination of 1 or more cemented posts & amalgam or composite resin. m
  53. 53. • Prefabricated metal, cabon fibre, ceramic & glass fibre posts are available. • They are used in conjunction with a plastic material such as- composite resin,amalgam or glass ionomer. m
  54. 54. Considerations for anterior teeth: • Endodontically anterior tooth do not always need complete coverage by placing a crown • Unless tooth has a large proximal composite restoration & unsupported tooth structure. m
  55. 55. m
  56. 56. • Cementing a post in an endodontically treated teeth is a fairly clinical practice despite paucity of data to support it. • A study determined that there was no significant reinforcement .* * JPD 62,166,1989 m
  57. 57. • When the tooth is loaded, stresses are greatest at the facial & lingual surfaces of the root & an internal post, being only minimally stressed does not prevent #. m
  58. 58. m
  59. 59. Disadvantage of routine use of cemented post in intact anterior teeth: • Requires additional operative procedure • Removes additional tooth structure for post space preparation. m
  60. 60. • May be difficult to restore the teeth later when crown is needed, because this post may fail to provide adequate retention for the core material. • Post can complicate or prevent further endodontic re treatment if it becomes necessary. m
  61. 61. Discoloration: • In the absence of significant tooth str loss treated by bleaching. • In the presence of tooth str loss complete crown. • If tooth is abutment for RPD or FPD complete crown mandatory. m
  62. 62. Considerations for posterior teeth: • Endo treated posterior teeth are subject to greater occlusal loading than anterior teeth because of their close proximity to the transverse horizontal axis. m
  63. 63. • This combined with their morphological characteristics [having cusps that can be wedged apart]makes them more susceptible. • Endodonticaly treated posterior teeth should receive cuspal to prevent biting forces from causing #. m
  64. 64. m
  65. 65. • Complete coverage is recommended on teeth with high risk of # • Maxillary Premolar m
  66. 66. • Possible exceptions are • Mandibular premolars & 1st molars. m
  67. 67. • When significant tooth structure loss has occurred, a cast post & core or an amalgam foundation restoration is needed. m
  68. 68. m
  69. 69. NEED FOR POSTS:* • THE MANIPULATION OF the pulp chamber leads to the greatest weakness of a treated teeth. *Endodontoc therapy,Franklin Weine,6th edn,Mosby m
  70. 70. Access into the pulp chamber- • There is a need for stronger interior as well exterior support. m
  71. 71. Canal enlargement- m
  72. 72. • So the motivation for placing a post should not be for reinforcement. Studies of posts used to reinforce teeth offer mixed results. m
  73. 73. • These studies lend credence to the contention that the strength of the remaining dentin around the post provide strength & resistance to # rather than the post itself. m
  74. 74. Primary function of post• To aid in retaining a core to restore lost tooth structure & not provide strength or resistance to #. m
  75. 75. Factors affecting Post selection: *Pathways of the Pulp,Stephen Cohen,6th edn,Mosby *Endodontoc therapy,Franklin Weine,6th edn,Mosby m
  76. 76. Non-threatening role of post • Occlusal forces are transmitted through the core to the dowel & ultimately along the length of root. • The remaining dentin & dowel together must have adequate rigidity to withstand functional load. m
  77. 77. • Dowels should be retained by cementation to the dentin walls of the root; active engagement of dowel space by screw threads is contraindicated. m
  78. 78. • 40% of self-threaded dowels failed by angular # & vertical root #; whereas 98% of cemented parallel posts were successful.* * JPD 52;28;1984. m
  79. 79. Dowel design: • The non threatening & retentive capacity of the dowel depends on the appropriate combination of mechanical design features- Dowel length - Taper - Diameter - Surface configuration m
  80. 80. • The basic post design may be tapered or parallel sided. m
  81. 81. 3 types of threaded posts:* Dentin spreading screw Tapped screw Self-threading screw * Felton et al JPD 1991;65:179 m
  82. 82. • Parallel sided posts are more retentive .As the angle of convergence exceeds 3.5 degree, surface area of post & resistance to displacement decreases. < m
  83. 83. • Parallel-sided dowels are 2 to 4 times as retentive as tapered ones.* • Tapered dowel is generally reserved for the significantly tapered canal system. * JPD 1978;40;645 m
  84. 84. Dowel classification: • Preformed dowel system • Custom cast dowel system • Preformed dowel system include various sizes of ready made metallic dowels. m
  85. 85. • Matching instrumentation- m
  86. 86. • Custom cast dowel system- utilize a casting procedure to fabricate a 1piece metal dowel & core. m
  87. 87. • By using instrumentation that is paired with castable plastic patterns the dowel space is shaped. m
  89. 89. Contemporary Fixed Prosthodontics,Rosenstiel,3rd edn • Prefabricated post • Tapered smooth sided posts • Tapered serrated posts • Tapered Threaded posts • Parallel smooth sided • Parallel serrated posts • Parallel Threaded posts m
  90. 90. • Custom made post • Direct technique • Indirect technique m
  91. 91. Endodontoc therapy,Franklin Weine,6th edn,Mosby • A. Tapered smooth sided • B Parallel, serrated and vented • C. Parallel threaded posts • D. Parallel threaded split shank. m
  92. 92. BDJ 2005;198: 533 1 . Active Posts • A. Pre tapped posts • B. Self threading 2.Passive Posts • A. Custom made or prefabricated • B. Parallel smooth or serrated • C. Tapered smooth or serrated m
  93. 93. Dowel length: • Dowel retention is proportional to dowel length. • Increase in dowel length from 5 to 8mm increases retention by47%.* • The dowel should be long enough without jeopardizing the root integrity. * JPD 1979;41;163 m
  94. 94. • The standard parameters for dowel length- 2/3rd length of canal m
  95. 95. • Coronal length of the tooth m
  96. 96. • Approx.. Half the bone supported length of the root. m
  97. 97. • The final length of the root is limited by 2 variables1. Root morphology 2. Need for sufficient apical seal m
  98. 98. • Root morphology• At least 1mm of dentin around post in all direction to resist perforation.* * DCNA 1976;20;299 m
  99. 99. • Short post • Long post in tapered root in parallel-sided root m
  100. 100. • Root curvature: • Greater the curve shorter the dowel. • Deep concavities:* - Maxillary 1st molar-94% MB roots - Mand 1st molar- all M & 99% D roots *JPD 1992;67;458 m
  101. 101. JPD 1991;65:179 • Most of the root # resulting from dowel insertion occurred on mesial & distal root surfaces as a result of the presence of flutes [external depressions] . m
  102. 102. At CEJ 2mm Max 1st premolar 4mm 6mm m
  103. 103. • Need for apical seal• Retaining the last 3-5m of filling material at the apex is sufficient for endodontic seal m
  104. 104. Dowel diameter: • The dowel must be of sufficient dia to resist fonctional forces. • A large dia gives little or no improvement in the dowel-to-root retention reduces resistance to # . m
  105. 105. • Preservation of dentin should take precedence over larger dia dowel m
  106. 106. JPD 1991,65:179 • The amount of remaining dentin & existing root morphology may be a determining factor for endo treated teeth to resist fracture. m
  107. 107. Surface configuration: • 1. 2. 3. 4. Can be: Smooth Serrated Threaded Sand blasted & silica coated m
  108. 108. • Serrated surface provide mechanical undercut for cement & increase retention over that of smooth surface. m
  109. 109. • Greatest retention from-increased legth,llel sides,serrated surface* • Ability to resist forces-increased length, llel sides, mod dia.* * JPD 1984;51;780m
  110. 110. Principles of tooth preparation*Contemporary Fixed Prosthodontics,Rosenstiel,3rd edn m
  111. 111. 1. Conservation of tooth structure 2. Preparation of coronal tooth structure 3. Retention form 4. Resistance form m
  112. 112. Conservation of tooth structure: • Preparation of the canal• Caution advised- Great care in removing only minimal tooth str from the canal - Avoid excessive enlargement - Thickness of remaining dentin – prime variable in # resistance of root. m
  113. 113. • Reasons- Perforate or weaken the tooth - Root may split during cementation or function. m
  114. 114. Photo elastic study* • Internal stresses are reduced with thinner posts. • Therefore the strength of the prepared root comes from its periphery & not interior. m
  115. 115. m
  116. 116. • Most roots are narrower MD than FL & often have proximal concavities m
  117. 117. • Along the length of the post space, enlargement seldom needs to exceed what would have been accomplished with 1 or 2 additional size files beyond the largest size used for endo treatment. m
  118. 118. m
  119. 119. *Endodontoc therapy,Franklin m Weine,6th edn,Mosby
  120. 120. Preparation of the coronal tissues: • Endo treated teeth often have lost much coronal tooth structure as a result of caries, previous restn,endo preparation. m
  121. 121. • If a cast core is used further tooth structure is needed to accommodate a complete crown & to remove undercuts m
  122. 122. • This may leave very little dentin. Every effort must be made to conserve as much coronal tooth structure as possible. • Extension of the axial walls of the crown apical to missing tooth structure- to save tooth structure. [FERRULE EFFECT] m
  123. 123. FERRULE• Def*- a ferrule is defined as a metal ring or cap placed around the end of a cane or a tool. * Endodontic Therapy-Franklin Weine m
  124. 124. • GPT-8 defl: a metal band or ring used to fit the root or crown of a tooth 2: any short tube for making a tight joint m
  125. 125. m
  126. 126. m
  127. 127. m
  128. 128. m
  129. 129. • When the post is in position, and receiving lateral forces, the ferrule ensures the dentine is under compression (which it is good). • If there is no ferrule, the dentine would be under tension (which is poor), and would fracture. m
  130. 130. Purpose of ferrule ( JPD 1990) improve the structural integrity of pulpless tooth by counteracting • 1. the functional lever forces • 2. the wedging effect of tapered dowels • 3. the lateral forces exerted during insertion of dowel Thus prevents root fracture. m
  131. 131. Core ferrule-* • ferrule is a part of cast metal core. *endodontics,5th edn,John.Ingle,B.C.Decker m
  132. 132. • Ferrule formed as a part of core are less effective than ferrule as a part of crown • Ferrule effect at both the levels did not increase fracture resistance as compared to ferrule only at crown level. m
  133. 133. m
  134. 134. • Libman et al (IJP 1995;8:155) found that 0.5-1 mm crown ferrule are ineffective , whereas 1.5-2mm crown ferrule is effective. • Isidor et al (IJP 1999;12:78) increasing crown ferrule length increases fracture resistance (1.25 & 1.55 mm) • Concluded : ferrule length was more important than post length in increasing tooth’s fracture resistance. m
  135. 135. • the tooth’s resistance to fracture was increased when a substantive amount of tooth structure was engaged • 2 mm in the core ferrule • 1 to 2 mm in the crown ferrule m
  136. 136. *Endodontics,5th edn,John.Ingle,B.C.Decker m
  137. 137. Extensively damaged teeth* • Ferrule effect can be accommodated by- Surgical crown lengthening - Orthodontic extrusion. *Contemporary Fixed Prosthodontics,Rosenstiel,3 rd edn m
  138. 138. ^ Orthodontic extrusion Surgical CL m
  139. 139. RETENTION FORM: • Is affected by- Preparation geometry - Post length - Post dia - Surface texture - Luting agent m
  140. 140. Preparation Geometry• For circular canals• Instrumentation- twist drills & reamers • Preparation – parallel canal with minimum taper • Indicated- prefabricated parallel post m
  141. 141. m
  142. 142. • For elliptical canals• Preparation-with tapered walls[6-8 degree] • Indicated- for tapered prefabricated or custom cast post. m
  143. 143. Retention study* • Parallel post are more retentive than tapered post & that threaded posts are most retentive. • However these studies are relevant only when post fits the canal space. * JPD 1977,38,515 m
  144. 144. • Parallel posts- only effective in most apical portion of the post space m
  145. 145. • Parallel post not effective in tapered canals m
  146. 146. • Post length• As post length increases so does retention. m
  147. 147. m
  148. 148. • Post diameter• Increase in post diameter weakens the tooth m
  149. 149. • Surface texture• Serrated or roughened post>smooth post • Controlled grooving of the post & canal considerably increases the retention. m
  150. 150. Thank you For more details please visit m