Managment of endodontic teeth / endodontic courses


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Managment of endodontic teeth / endodontic courses

  1. 1. Good morning
  3. 3. Contents  Introduction  History  Changes in tooth when endodontically treatment  Treatment planning  Restorative decision making- factors influencing basic components  Ferrule  Intracoronal posts  Principles of tooth preparation  Techniques of post space preparation  Root reinforcing post  Temporization
  4. 4.  Cementation  Core fabrication  Coronal radicular restoration  Endodontically treated teeth as abutments - factors considered - tooth preparation  Removal of existing posts  Failures in posts  Recent advances  Conclusion  References
  5. 5. Introduction  Teeth that were once considered non restorable and extracted are today treated endodontically and restored of function  Restoration of endo Rx teeth – replaces missing tooth structure maintains esthetics and function protects against fracture prevents from infection
  6. 6. History  Fauchard (1747) used maxillary anterior teeth for anchorage when restoring single and multiple units. He used posts made of gold/silver and a heat softened adhesive “mastic’ to hold them in position.  1830-1870 –Wood replaced metal as the material of choice for posts- swelled and caused roots fracture.  “Pivot crown” – a wooden post fitted to an artificial crown and to root
  7. 7.  G.V Black developed a porcelain faced crown held by a screw inserted into the canal filled with gold foil.  Richmond crown, named after C.M. Richmond (1884) is a dowel-retained crown with porcelain facing.  Davis crown named after Wallace Clydi. Davis is a dowel with in the root canal over, which is, cemented a porcelain tube tooth in direct contact
  8. 8. Changes in tooth when endodontically treated Altered physical characteristics Altered esthetic characteristics. Loss of tooth structure.
  9. 9. Loss of tooth structure Endodontic access cavity destroys the strucutural integrity provided by the coronal dentin of the pulpal ceiling. Tooth stiffness reduction by 5 %. Are endodontically treated teeth brittle? Attributed to loss of tooth structure following trauma, caries, endodontic access, instrumentation. Studies- 9% lower water content of pulpless
  10. 10. Altered physical characteristics Changes in collagen cross linking and dehydration of dentin. 14% reduction in strength and toughness. Altered esthetic characteristics Biochemically altered dentin modifies light refraction through the tooth and correspondingly modifies
  11. 11. Best time to restore endodontically treated teeth Do not wait for extended periods of time after rct Need to seal coronal orifice from contamination Prevent fracture and caries Studies- no diff in leakage of root canal filling material when post space prepared immediately after completing endo Rx
  12. 12. Good apical seal No sensitivity to pressure No exudate No fistula No apical sensitivity No active inflammation
  13. 13. Treatment planning Endodontic consideration Restorative consideration Periodontal consideration
  14. 14. A. Endodontic consideration: Dense, uniform, three dimensional obturation (fluid impervious seal) of the root canal system,0.5 to 1 mm from the radiographic apex of the root/roots is necessary. Unsatisfactory obturation should be re-treated.
  15. 15. B. Restorative consideration: A critical amount of solid coronal dentin is required, which must encase a coronal restoration for structural integrity of the restored tooth. Dentin axial wall height- At least 2 to 3mm Axial walls must be parallel. Restoration should completely encircle the tooth . The margin should rest on sound tooth structure. The crown and the crown preparation should not invade attachment
  16. 16. C. Periodontal consideration: There should be an absolute minimum of 2.5 mm distance between the restoration margin and the crest of bone. Biologic width relates the amount of tooth structure coronal to the osseous crest to the gingival attachment apparatus. As a general rule, a minimum of 3 mm of sound tooth structure coronal to the osseous crest will be necessary to accommodate the connective tissue attachment,
  17. 17. Restorative Decision Making  Anterior teeth:- Minimal to moderate Coronal damage:- Conservative treatment Resin composite, Reinforced GICs Significant Coronal Damage:- Complete crown coverage Custom cast post and core; Prefabricated post and core  Posterior Teeth :- Cuspal coverage required If minimal damage i.e, intact buccal/lingual walls and minimal occlusal load, the conservative treatment of choice will be a MOD Onlay.
  18. 18. Classification of remaining tooth structure based on no. of existing axial wallsClass I :- - 4 remaining cavity walls - Thickness greater than 1mm No need for inserting posts Class II & III Loss of one or two cavity walls Remaining hard tissue capable of supporting core-Adhesive system No indication of using a post Class IV 1 remaining cavity wall Post Indicated Class V No remaining cavity wall Post Indicated; Ferrule effect is significant
  19. 19. Should crowns be placed on endodontically treated teeth  Crowns be placed on endo rx posterior teeth having occlusal interdigitation with opposing teeth  Crowns donot enhance clinical success of anterior endo rx teeth  Use limited to esthetic and functional requirements
  20. 20. Factors influencing type of restoration  Amount of remaining tooth structure.  Anatomic position of the tooth.  The occlusal forces on the tooth.  Restorative requirements of the tooth.  The esthetic requirements of the tooth.
  21. 21. Basic components of restoration  Residual coronal and radicular tooth structure  Post located in root- retains core  Core located in pulp chamber and coronal area of tooth- retains crown  Coronal restoration  Adhesive bonding agents/ traditional luting cements
  22. 22. Coronal tooth structure- FERRULE Most important part of restored tooth is tooth itself. Axial walls of crown engage the axial walls of prepared tooth forming the ferrule. Fracture resistance  significantly with  amount of sound tooth structure and ferrule. Ferrule is a band that encircles the external dimension of residual tooth, similar to metal bands around and barrel. Formed by walls and margins of the crown or by cast telescoping coping encasing at least 2-3 mm of sound tooth structure.
  23. 23.
  24. 24. Advantages of Ferrule: reduces the fracture incidence in nonvital teeth by reinforcing tooth at its external surface and dissipating force that concentrates at narrowest circumference of tooth. resists lateral forces from posts and leverages from crown in function and  resistance and retention of
  25. 25. Requirements of ferrule: • Dentine axial wall height must be at least 2-3mm • Axial walls must be parallel • Restoration must completely encircle the tooth • Margin must be on solid tooth structure
  26. 26.  Crown and crown preparation must not invade attachment apparatus. So 4-5mm height and 1mm thick sound, supra bony tooth structure should be available to accommodate both periodontal biologic width and restorative ferrule  Insufficient tooth structure:- Subgingival margin placement Crown lengthening Orthodontic
  27. 27. Also, Crown lengthening- increases crown root ratio increased leverage  In absence of ferrule – dentine bonding agent with an amalgam core and direct stainless steel post - significant increase in fracture resistance
  28. 28. •Pre rx data review •Philosophy and purpose •Post design and shape – various post systems •Post diameter •Post length Intra coronal posts and dowels
  29. 29. Pre treatment data review POST: The dowel is a metal post rigid restoration placed in the radicular portion of a non vital tooth To retain restoration – post is necessary when insufficient tooth structure remains to hold a restoration. To protect remaining tooth structure they are used to direct occlusal, lateral forces more apically. Dowel must be designed in such away that it serves retentive function without endangering the root /coronal integrity
  30. 30. Philosophy and purpose  The Post- restorative dental material placed in the root of a structurally damaged tooth in which additional retention is necessary for the core and the coronal restoration  Donot reinforce endo rx teeth  Not necessary when substantial tooth structure present
  31. 31.  protection from root fracture  retention within root and retrievbility  retention of the core and crown  Protection from coronal leakage
  32. 32.  Pleasing esthetics when needed  High radiographic visibility  Biocompatibility Preservation of remaining tooth structure
  33. 33. Post design and shape (I) Prefabricated and Custom cast dowels Metallic and Non metallic dowels Rigid and Flexible dowels Aesthetic and Non aesthetic dowels (II) 1. Active posts a. Parallel sided post positioned by tapping b. Parallel self threading c. Tapered self threading 2. Passive posts a. Parallel smooth or serrated b. Tapered smooth or serrated
  34. 34. (IV) Ingle’s Classification a. Tapered, smooth, cemented posts b. Parallel sided cemented posts c. Tapered self threading d. Parallel, threaded inserted into prepared channels e. Parallel sided with tapered apical end, cemented in to the channel
  35. 35.
  36. 36. Prefabricated posts Advantages  They are simple to use  Less time consuming  Can be completed in one appointment  Cost effective  Remarkably strong Disadvantages  root is designed to accept a post rather than post being designed to fit the root  application is limited when considerable coronal tooth structure is lost  chemical reactions are possible when posts and core are made of dissimilar metals.
  38. 38.  Indicated when there is increased need for retention when the preparation of the parallel canal space will not jeopardize the root integrity in the apical one third Passive tapered posts: Maintains natural pericanal tooth structure Mimics natural canal shape Tapered shaped provide least retention When there is adequate canal length for axial retention (8 to 9 mm) Maxillary premolars- tapered root form .
  39. 39. Passive parallel posts: Greater retention. Clinically successful history. Pericanal tooth structure has to be removed.
  40. 40. Tapered post  Kerr endopost  Ellman nuband  Mooser Parallel post  Parapost  Boston post  Parkell parallel post (CI Kit) Parallel side with tapered apical end  Deggusa  Unilek
  41. 41. Tapered smooth sided post They are oldesing most widely used design. Systems employing this configuration are Kerr endopost, Ellmaninubond and Mooser post. They are least retentive of all post designs. used in teeth not subjected to high functional loads.
  42. 42. Parallel posts- PARA POST SYSTEM Passive, parallel, vented posts made of stainless steel or Titanium. Has a vertical groove cut through the length of its serrations, allowing axial venting. The transfer of occlusal forces of the tooth occurs through the cement layer.
  43. 43. BOSTON POST SYSTEM (Goldsman and Nathanson) It resembles parapost system without the vertical venting channel. 99.6% Titanium It is a passive post, depends upon horizontal serrations and cementing medium for retention. PARKELL PARALLEL POST SYSTEM Stainless steel passive, vented serrated post. It has an anti rotational lock which fits on to the seat produced on the root. It has a plastic core burn out pattern available for cast pattern
  44. 44. Parallel sided post with tapered apical end provide greater retention than parallel posts confine to tapered apical position of deggusa , unitek Because of taper, these posts are venting and easily cemented acts as wedges, the effect of wedging is related to flare of post channel; greater the flare greater
  46. 46. The active posts engage the root dentine with threads they must always be cemented with a luting cement.  Self threaded- Tapered- Dentatus Flexi post Parallel sided- V lock Radix anchor system  Pretapped posts- Kurer anchor post
  47. 47. Self-threading posts have a shank (shaft) that is fractionally narrower than the post channel. a) Dentatus Screw Post
  48. 48.  (b) Flexi Post  Split end design- collapses when screwed – less stress
  49. 49. (c)Radix Anchor System Twist drill , gauge to check fit ,root facer to produce flat surface for post head, post mounted on driver clockwise then quarter turn anti
  50. 50. Pretapped posts- KURER POST SYSTEM High frequency thread around a parallel-sided shank. After post space preparation counter-thread on the internal aspect of the post hole is prepared with a thread cutter. Root Facer which flattens the root face onto which the head of the post seats. This unfortunately removes coronal tissue, which is important in creating a
  51. 51. Drill, root facer, tapping device, threaded post with driver
  52. 52. which post design produces the greatest retention?  Tapered cemented posts are the least retentive.  Cemented, parallel-sided posts with serrations are more retentive than cemented, smoothsided parallel posts.  Threaded posts are most retentive
  53. 53. post form and the potential for root fracture  All types of threaded posts produce the greatest potential for root fracture(7%)  tapered cemented posts (3%)  parallel cemented posts (1%).
  54. 54. Rigid post systems Traditionally rigid post systems were metal and were either Custom cast or prefabricated. Properties:- Titanium, Gold and Zirconium posts are biocompatible. Stainless steel contains nickel which is an allergen. Cast gold, stainless steel are all radio opaque and easily distinguished on a radiograph. Titanium and a well condensed gutta purcha share almost similar radio
  55. 55. Non rigid posts  Carbon fibres- Endo post Carbonite system Mirafit carbon  Silica Fibres - Glass Fibre- Fibre white Mirafit white Quartz Fibre - Aestheti post Style post  Polyethylene - Ribbond Construct
  56. 56. CARBON FIBRE POSTS:- Introduced by Duret and associates(1990) in France. They consist of continuous, unidirectional, pyrolytic carbon / graphite fibres reinforced in an epoxy resin matrix with 64% carbon.
  57. 57. (a) ENDOPOST:- Narrow parallel sided cylindrical posts(1 to 1.2mm) used for retention of core materials in narrow-diameter roots such as molars or mandibular incisors. (b) CARBONITE SYSTEM :-Parallel sided with a 3 mm conical tip. Available in three diameters- 1.2mm, 1.35 mm and 1.5mm, with a single bur for each size.
  58. 58. GLASS FIBRE QUARTZ FIBRE Silica fibre posts-
  59. 59. GLASS FIBER POSTS Glass fibers have a lower elastic modulus than carbon / graphite fibers. These posts can be made of different types of glasses. a) snow post :- It is composed of 60% longitudinally arranged Silica Zirconium glass fibres in an epoxy resin matrix. It is cylindrical in shape with a 3 degrees taper. The taper is 4-6 mm long. Available in 1, 1.2, 1.4, and 1.6 mm diameters along with matching burs.
  60. 60. b) Parapost fibre white :- Designed to complement and extend the existing parapost system, fiber white has longitudinally arranged glass fibers. Post is parallel has a removable colour coded ring around the head for identification. Available in four diameters – 1.14, 1.25, 1.4 & 1.5 mm.
  61. 61. QUARTZ FIBRE:- I. AESTHETI POST:- These posts retain the central core of carbon fibre bundle surrounded by quartz fibers arranged longitudinally. II. AESTHETI PLUS POST: - Belong to the next generation of aesthetic posts and is composed entirely of quartz fibers.
  62. 62. III. LIGHT POST: - A translucent quartz fibre post designed to permit light curing materials to be used for leading curing light in to the canal. IV. STYLE POST: - Parallel sided, tapered end quartz fibre post system.
  63. 63. Woven-fibre composite materials/ polyethylene fibre materials: They are cold gas plasma treated, polyethylene woven fibres embedded in conventional resin composite, they are advocated for corono radicular stabilization of pulpless teeth. Disadvantage similar to those of fibre reinforced epoxy resin post system-Inferior strength combined with undesirable
  64. 64. Post diameter  THE CONSERVATIONIST The instrumentation is limited to removal of undercuts that prevent withdrawal of dowel patterns  THE PROPORTIONIST Optimal diameter of the dowel was one-third the diameter of the root(Goodacre)  THE PRESERVATIONIST 1 mm of sound dentin be maintained around the entire circumference.
  65. 65.  As the post diameter increased - stress increased in the tooth  Mesial roots of mand molars and buccal roots of max molars not to be used – perforation in furcation area  Molar posts should not be larger than 7 mm  Mand incisors- 0.6-0.7 mm  Max central incisors, palatal root of max molars- 1.0 mm  Rest of teeth – 0.8-0.9 mm
  66. 66.
  67. 67. Post length (1) Make the post approximately three-quarters the length of the root when treating long-rooted teeth. (2) When average root length is encountered, then post length is dictated by retaining 5 mm of apical gutta- percha and extending the post to the gutta-percha. (3) Whenever possible, posts should extend at least 4 mm apical to the bone crest to decrease dentin stress. (4) Molar posts should not be extended more than 7 mm into the root canal apical to the base of the pulp chamber.
  68. 68. Average Crown Length Average Root length 2/3 Root length 4 mm from Apex. Maxillary Teeth Central Incisor 10.8 12.5 8.3 8.5 Lateral Incisor 9.5 13.1 8.7 9.1 Canine 10.2 15.8 10.5 11.8 First Premolar 8.6 12.7 8.5 8.7 Second Premolar 7.5 13.5 9.0 9.5 First Molar 7.4 MF DF L 12.5 12.0 13.2 MF DF L 8.3 8.0 8.8 MF DF L 8.5 8.0 9.2 Second Molar 7.4 12.8 12.0 13.4 8.5 8.0 8.9 8.5 8.0 9.4 Mandibular Teeth Central Incisor 9.1 12.4 8.3 8.4 Lateral incisor 9.4 13.0 8.7 9.0 Canine 10.9 14.3 9.5 10.3 First premolar 8.7 13.4 8.9 9.4 Second premolar 7.8 13.6 9.1 9.6 First Molar 7.4 M D 13.5 13.4 M D 9.0 8.9 M D 9.5 9.4 Second Molar 7.5 13.4 13.3 8.9 8.9 9.4 9.3
  69. 69. Principles of tooth preparation
  70. 70. 1. Conservation of the tooth structure:- Preparation of the canal:- The thickness of the remaining dentin is the prime variable in fracture resistance. The root canal should be enlarged only enough to enable the post to fit acuurately yet passively.
  71. 71. 2. Retention form of a Post (a) Preparation geometry:- Preparation walls desire parallelism or minimal taper, elliptical canal (6 to 8 degrees) (b) Post surface texture (c) Luting agent:- It is of great importance if the post is lose in the canal, Adhesive resin have the potential to improve the performance of the post and core. Zinc phosphate and Glass ionomer cement have similar retentive properties. Composite resin and zinc polycarboxylate cements have slightly less.
  72. 72. 3. Resistance form of a Post a) Stress distribution The greatest stress distribution is at the shoulder, particularly interproximally, Dentin should be conserved in these areas. Parallel sided posts may distribute stress more evenly than tapered posts. Sharp angles should be avoided. High stresses are generated during insertion, particularly with smooth, parallel sided posts that have no vent for cement escape. Threaded posts distribute stresses more evenly if the posts are backed off half a
  73. 73. b) Rotational thickness post with a circular cross section should not rotate during function. Pins Pins are used either alone or in combination with a post Retention for the core material Increase the resistance Maximum of 3 pins in anterior teeth if no coronal tooth structure exists
  74. 74. groove If sufficient coronal structure is present rotation is prevented by a vertical coronal wall. If coronal dentin is absent then a small vertical groove in the canal serves as an anti rotational element. Located in the bulkiest area of the root, usually lingual
  75. 75.
  76. 76. •Prefabricated cemented post •Prefabricated threaded post •Custom cast post and core •Glass fibre snow post Techniques in post space preparation
  77. 77. Acc. to Rosenstiel Removal of the root canal filling material to the appropriate depth. Enlargement of the Canal. Preparation of the coronal tooth structure.
  78. 78. Acc to Ingle Coronal tooth preparation Root canal preparation Pulp chamber preparation
  79. 79. Coronal tooth preparation  Amount of tooth structure that needs to be removed- type of crown to be placed extent of core fabrication  Thin tooth structure- remove that part of dentine
  80. 80. Pulp chamber preparation  Cleaned of any filling material  If prefabricated post- undercuts and irregularities aid in retention of core material  If custom cast post- undercuts should be eliminated
  81. 81. Root canal preparation  Prudent to isolate tooth with a rubber dam  Periodontal probe- measure preparation depth The root canal should be completely obturated in the first place so as the lateral canals get sealed. Full length silver point- removed and the canal should be retreated with gutta percha.
  82. 82. Removal of the root canal filling material to the appropriate depth. Q1.)How much gutta-percha should be retained to preserve the apical seal? Ans.) 4 to 5 mm should be retained apically to ensure an adequate seal. Stopping precisely at 4 mm is difficult, and radiographic angulation errors could lead to retention of less than 4 mm.Therefore, 5 mm of gutta-percha should be retained apically
  83. 83. Methods to remove Gutta Percha  Use of heated hand pluggers  Use of Chemical solvents  Use of rotary instruments
  84. 84. Use of heated hand pluggers A heated instrument such as a lateral compactor can be inserted in to the canal up to desired depth. In narrow canals system B spreader is ideal for removal. The hot instrument is carried in to canal and allowed to cool in the canal for up to 7-10 seconds
  85. 85. Use of Chemical Solvents Organic solvents such as Chloroform , Eucalyptol or Xylol Disadvantage:- - Solvent evaporate from the softened Gutta percha and the latter material shrinks - It is difficult to control the depth of softening of the gutta percha and potential leakage of the solvents in to the periradicular tissues.
  86. 86. Use of rotary instruments Systems such as Peeso reamers, Gates Glidden drills are advocated for gutta percha removal. Advantages of Peeso reamer:- Non cutting tip and Ability to remain centered in the canal The frictional heat generated during the mechanical elimination of the gutta percha aids in its removal by softening it. Softened mass is transported coronally by the direction of the flutes, slight apical pressure will condense it apically, thus improving the apical seal.
  87. 87.
  88. 88. PEESO REAMER SIZES Reamer Number Diameter Teeth 1. 0.7 mm Mandibular incisor 2 0.9 mm Maxillary first premolar Maxillary second molar (DF) Mandibular first molar (ML) Mandibular second molar (MF, ML) 3 1.1 mm Maxillary Second premolar Maxillary first molar (MF, DF) Maxillary second molar (MF) Mandibular first molar (MF, D) Mandibular second molar (D) 4 1.3 mm Maxillary lateral incisor Mandibular premolar Maxillary molar (L) 5 1.5 mm Canine 6 1.7 mm Maxillary central incisor
  89. 89. Prefabricated cemented/bonded post
  90. 90. Coronal Tooth Preparation a) Post and core fabrication can often best be done after the coronal tooth preparation has been completed. b) Type of single crown or retainer (all-metal, all-ceramic, metal ceramic) i.e., the definitive restoration decides the reduction depths and form recommended for each type of crown/retainer.
  91. 91. 5. When metal posts are used, they can be bent coronally,if necessary, to align them within the core material . Post bending is done outside the mouth with orthodontic pliers. 6. If there is little or no remaining coronal tooth structure to provide resistance to core rotation, an auxiliary threaded pin (TMS pins, minimum or regular) should be placed into the remaining tooth structure
  92. 92. Prefabricated threaded post
  93. 93. Custom cast post and core Direct method
  94. 94. Direct method for multirooted teeth
  95. 95. Indirect method
  96. 96.
  97. 97.
  98. 98. Indirect method for multirooted teeth
  99. 99. Glass fibre snow post system
  100. 100. Root reinforcing post Composite resin reinforce internal walls of roots thinned by caries Composite Injected into primed and bonded dentine canal, light transmitting post used to shape and set composite Post removed , metal post of same dimension cemented
  101. 101. Temporization
  102. 102. Cementation  Zinc phosphate cement  Polycarboxylate cement  Glass ionomer cement  Resin Composite cements  Resin modified Glass Ionomer Once mixed, the cement is delivered to the dowel space with a lentulo spiral, to ensure that all walls are coated. At the same time, the dowel and core are coated with a thin layer of cement. The restoration should slide slowly and easily into place with light finger pressure. Excess cement must escape coronally as the dowel nearly fills the dowel space.
  103. 103. Core fabrication restorative material placed in the coronal area of tooth. This material replaces carious, fractured or otherwise missing coronal structure and retains final coronal restoration anchored to the tooth by extending into the coronal aspect of the canal or through the endodontic dowel Pins, grooves can be placed in dentin in a position remote from dowel space & keways help to provide anitirotational
  104. 104. Desirable physical properties  High compressive strength  Dimensional stability  Ease of manipulation  Short setting time  An ability to bond to dowel & tooth
  105. 105. Optimal core build up materials Cast metal Amalgam Composite Glass Ionomer
  106. 106. (1) Cast Metal A cast dowel and core are a traditional & proven method to restore endodonticaly treated tooth. cast core does not depend on mechanical means for retention to dowel. This construction avoids dislodgement of core & crown from dowel & root when minimal tooth structure remains. Disadvantage :  Cost is high  Two appointments are needed  Laboratory phase may be technique sensitive  Casting large core with small dowel can result in porosity at dowel core interface
  107. 107. (2) Amalgam core: It is strong, economic, easy to use, very stable to thermal, functional stresses, high compressive and tensile strength and high modoulus of elasticity. Amalgam cores are highly retentive when used with a preformed dowel in posterior teeth . Disadvantage :  Dark colour potentially lowers the value of all ceramic restorations.  Causes a grey halo at the gingival margin.  Low early strength (15-20 minutes wait before core preparation.)  Messy to prepare.
  108. 108. (3) Composite resin core Easy to build up and sets very rapidly. Preparation for final restoration is readily accompanied during core placement session. Auxillary pins and dentin bonding agents are used for auxillary retention.  Polymerization shrinkage and contraction away from tooth structure can result in core or tooth marginal openings, microcracks and microleakage. More than 2mm sound tooth structure should remain at margin and dentin walls should be present for optimal composite core
  109. 109. (4) Glass Ionomer core High viscosity glass ionomer employ adhesion to dentin. This chemical union improves retention of restoration and reduces marginal leakage over that of unbonded amalgam, and composite resin cores. The anticariogenic effect derived from presence of flouride Disadvantages  GIC cores are sensitive to moisture.  GIC cores have low strength  Brittle because of low fracture toughness. Indicated in posterior teeth where bulk of core is possible significant sound dentin remains moisture control is assured. Resin moidfied GIC
  110. 110. Coronal radicular restoration Nayyar technique (1980) Coronal-Radicular restoration. Amalgam core build up, where retention is gained from pulp chamber and coronal part (2-4mm) of root canals. As posts and pins are not used, perforations and cracking are unlikely. Bonding of core by Panavia or other 4-META containing agents and in retention and decrease coronal leakage Composite core in Nayyar technique- pulpal floor is sealed with resin modified glass ionomer, as composite is difficult to remove, should the root canals be
  111. 111. Endodontically treated teeth serving as abutments
  112. 112. Factors considered  Use of post or no post  Type of post anticipated based on root anatomy  Methods of post placement and cementation  Distribution of forces on the abutment teeth  Use of ferrule effect  Status and soundness of coronal margins on sound tooth structure
  113. 113. Overdenture abutment preparation  Crowns amputated 3 to 4 mm above the gingival level.  The coronal 3 to 5 mm of the gutta-percha filling are then removed, the preparation is undercut, and a well- condensed amalgam filling is placed to cap the canal obturation.  The abutments should rise 2 to 3 mm above the tissue and rounded or bullet shaped with a slope back from the labial surface to accommodate the denture tooth to be set above it. They should then be highly polished
  114. 114. Removal of existing posts for retreatment of a failed root canal filling. risky process- radicular fracture. If sufficient length of post is exposed coronally, the post can be retrieved with thin-beaked forceps. Vibrating the post firstwith an ultrasonic sealer will weaken brittle cement and facilitate removal. A thin sealer tip or special post removal tip
  115. 115. Masserann technique An embedded fractured post- Masserann in 1966 Use special hollow end-cutting tubes (or trephines) to prepare a thin trench around the post Retrieval can be facilitated by using an adhesive to attach a hollow tube extractor or by using a threaded extractor
  116. 116.
  117. 117. Thomas Gonon system for post removal
  118. 118. A post that has fractured within the root canal cannot be removed with a post puller or forceps. The post can be drilled out, but great care is needed to avoid perforation. The technique is best limited to relatively short fractured posts.
  119. 119. Failures in post and core restorations  Post loosening – 60 to 70% of all failures  Root fracture  Post fracture  Delamination of core from post – loss of crown retention
  120. 120. Recent advances Core material – pressed ceramic Ceramic Posts Castable glass posts and cores, glass infiltrated alminous porcelain post and cores produced conventionaly or machined from computer linked systems have been developed.
  121. 121. The introduction of zirconium oxide ceramics have provided a material with over twice the flexure strength of aluminous ceramic system. Eg: Cosmo post It is cylindrically shaped with a conical tip. It is available in two relatively wide diameters (1.4mm, 1.7mm). It is suitable if 1/3 of coronal tooth structure remains.
  122. 122. Conclusion A pulpless tooth has commonly lost substantial tooth structure. Restoration conserves and protects the remaining tooth structure Application of sound biomechanical principles Long term clinical success - skilled integration of restorative and endodontic disciplines.
  123. 123. References • Contemporary fixed prosthodontics- Rosenstiel , Land and Fujimoto. 4th edition. • Fundamentals of fixed prosthodontics- shillingburg,et al. 3rd edition. • Endodontics:- Ingle, Bakland, 5th Edition • Pathways of the pulp :- Cohen S,8th Edition • Problem solving in endodontics- Gutmann • IJP 2008 vol 21:4;328-336 • Dental update 2008 35; 222-228
  124. 124. • DCNA 36:3;631-650 • DCNA 45:1;103-116 • DCNA 46:2;367-384 • BDJ 2005 198:8;463-541
  125. 125. Thank you For more details please visit