Custom made post & Core in endodontics
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The document discusses the importance of post and core restorations in endodontically treated teeth, highlighting their role in providing structural support after substantial tooth loss. It covers types of posts, materials, and biomechanical principles that underpin effective restoration practices, as well as advantages and disadvantages of custom cast versus prefabricated systems. The ideal characteristics of post and core systems are outlined, focusing on stability, retention, and the conservation of dental structure.
Custom made post & Core in endodontics
- 1. CUSTOM MADE POST & CORE IN ENDODONTICS Pressented By : Dr. Arpit Viradiya Guided By : Dr. Sandeep Metgud Dr. Prashant Shetty Dr. Deepali Agrawal
- 2. Introduction • The restoration of the endodontically treated tooth is a subject that has been evaluated and discussed widely in the dental literature. • It is complicated by the fact that much or all of the coronal tooth structure which normally would be used in the retention of the restoration has been destroyed by caries, previous restorations, trauma, and the endodontic access preparation itself.
- 3. • All the teeth that have undergone root canal therapy will require some form of restoration to enable them to function again. • Because endodontic treatment removes the vital contents of the canal, which subsequently leads to reduction in elasticity and increased brittleness of remaining tooth structure. • The objective is to return them to full occlusal and cosmetic function.
- 4. • This weakening leads to the need for strong interior as well as exterior support that is achieved by post core system. • Often due to mechanical reasons, the prepared tooth is reinforced by post core systems.
- 5. Post or dowel • It refers to a cylindrical or tapered object that fits into the prepared root canal of a tooth and is synonymous with the term post or endodontic post. • The post is defined as the segment of the restoration inserted into the root canal to aid in retention of a core component.
- 6. • Endodontic post or dowel is usually cemented or threaded into a prepared channel. • It can be fabricated from metal or from other non-metallic substances.
- 7. • Functions: – Retention of core – Protection of remaining tooth structure
- 8. • TYPES OF POSTS • Metallic posts – Custom cast posts – Pre fabricated posts. • Passive. – Tapered. – Parallel. • Active. • Non-metallic posts – Carbon fiber posts – Tooth colored posts – Fiber reinforced posts. – Ceramic and zirconia posts
- 9. • Materials Used: • Metals – Custom-cast posts: » Gold alloys » Chrome-cobalt alloys » Nickel-chromium alloys – Prefabricated posts: » Stainless Steel » Titanium » Brass • Non-metals: – Carbon-fiber – Glass fiber – Quartz fiber – Woven Polyethylene fiber – Ceramic and zirconia
- 10. Core • Refers to a build up restoration, usually amalgam/composite placed in a badly broken down tooth to restore the bulk of the coronal portion of the tooth to facilitate subsequent restoration by means of an indirect extracoronal restoration. • It may serve as either final restoration or as a foundation for a crown.
- 11. • Is defined as properly shaped and well restored substructure which replaces missing coronal structure and retain the final restoration. • Core replaces coronal tooth structure that is lost and forms a bare that has sufficient bulk and retention for final restoration.
- 12. • The core consists of restorative material placed in the coronal area of a tooth. • This material replaces carious, fractured or otherwise missing coronal structure and retains the final crown.
- 13. • Core materials: – Cast core – Amalgam – Composite – Glass ionomer cement – Resin modified glass ionomer cement
- 14. • INDICATIONS : – Where the natural crown of root-filled teeth either has been lost or is extensively damaged. – Where the root-filled tooth is to be used as bridge abutment. – Where a change in axial position greater than 1mm is required. – In a crowned anterior endodontically involved tooth, to reinforce the crown covered tooth at cervical area susceptible to fracture.
- 15. – Loss of two proximal surfaces with a lingual endodontic access opening which weakens the tooth.
- 16. • Contraindications : – Severe curvature of the root-eg: Dilacerations of the root. – Persistent periapical lesion – Poor periodontal health – Poor crown to root ratio – Weak / fragile roots – Teeth with heavy occlusal contacts – Patients with unusual and occupational habits – Economic factors – Inadequate skill.
- 17. IDEAL REQUIREMENTS OF POST CORE: • Posts should have as many of the following clinical features as possible: – Maximum protection of the root – Adequate retention within the root – Maximum protection of the crown marginal cement seal – Pleasing esthetics, when indicated – Radiopacity – Be simple, safe, versatile, and reliable in clinical use. – Not create stresses in the remaining tooth tissues during preparation and cementation. – Allow an even distribution of all functional stress
- 18. – Include provision to ensure appropriate support and retention of the core. – Include features of facilitate removal, if so required, even after prolonged periods of clinical service. – Be made of bioinert material that resist corrosion and other forms of deterioration in the mouth. – Be widely and readily available at reasonable cost. – Resist loosening and displacement due to occlusal and other functional stress.
- 19. • Core materials: Requirements: – Stability in wet environment – Ease of manipulation – Rapid, hard set for immediate crown preparation – Natural tooth color – High compressive strength – High tensile strength – High fracture toughness
- 20. – Low plastic deformation – Inert (no corrosion) – Cariostatic properties – Biocompatibility – Inexpensiveness.
- 21. CLASSIFICATION OF POSTS AND CORES: • According to Ingle – Custom-cast Posts – Prefabricated Posts • Tapered, smooth-sided posts • Parallel-sided posts • Tapered, self-threading screws • Parallel-sided, threaded posts • Parallel-sided, tapered apical end posts
- 22. • According to Weine – Custom-cast Posts – Prefabricated Posts • Tapered, smooth sided post systems • Parallel-sided, serrated and vented posts • Tapered, self-threading post systems • Parallel- sided, threaded post systems – Self-threading – Threaded with use of matched taps • Parallel-sided, threaded, split-shank post systems
- 23. • According to Shillinburg – Custom-cast Posts – Prefabricated posts • Tapered, smooth-sided posts • Tapered, serrated posts • Tapered, threaded posts • Parallel, smooth-sided posts • Parallel, serrated posts • Parallel, threaded posts
- 24. • According to Robbins – Metallic Posts • Custom-cast Posts • Prefabricated Posts – Passive Tapered Posts – Passive Parallel Posts – Active Posts – Non-metallic Posts • Carbon Fiber Posts • Tooth Colored Posts
- 25. CUSTOM CAST POST • Custom cast post has a long history of clinical success • Developed in the 1930’s to replace the one- piece post crowns. • This procedure requires casting a post and core as a separate component from the crown. • It almost always requires minimum tooth structure removal.
- 26. • This method requires two-appointment visits and a laboratory fee. • As it is cast in an alloy with a modulus of elasticity as high as 10 times the natural dentin; this possible incompatibility can create stress concentration in the less rigid root, resulting in post separation or failure.
- 27. • There are, however circumstances in which the custom-cast post is the restoration of choice, including, the following – When multiple cores are being placed in the same arch. It is more cost effective to prepare multiple post spaces, make an impression and fabricate the posts in the laboratory. – When post and cores are being placed in small teeth, such as mandibular incisors. In these circumstances, it is often difficult to retain the core material on the head of the post.
- 28. – When the angle of the core must be changed in relation to the post. Prefabricated posts should not be bent; therefore, the custom post best fulfills this requirement. – The traditional custom cast post core provides a better geometric adaptation to excessively flared or elliptical canals and almost always requires minimum tooth structure removal.
- 29. – Custom-cast post and cores adapt well to extremely tapered canals or those with a non- circular cross-section or irregular shape and roots with minimal remaining coronal tooth structure.
- 30. Advantages of pre-fabricated post-core systems over cast post • They are simple to use. • Require less chair side time. • Can be completed in one appointment. • Are easy to temporize.
- 31. Major disadvantages of pre-fabricated Post-Core systems • The root is designed to accept the post rather than the post being designed to fit the root. • Their application is limited when considerable coronal tooth structure is lost. • Chemical reactions are possible when the post and core materials are made of dissimilar metals. • Attachments for removable prostheses cannot be applied, unless a separate casting is fabricated to place over it.
- 32. Advantages of cast post over Pre- fabricated post-core systems • They are custom fit to the root configuration. • Are adaptable to large irregularly shaped canals and orifices. • Can be adapted to be used with pre fabricated plastic patterns.
- 33. Disadvantages of cast-post • Expensive • Requires two or more appointments. • Temporization between appointments is more difficult. • Risk of casting inaccuracies • May require the removal of additional coronal tooth structure
- 34. BIOMECHANICAL PRINCIPLES • 1. CONSERVATION OF TOOTH STRUCTURE • 2. RETENTION FORM • 3. RESISTANCE FORM
- 35. CONSERVATION OF TOOTH STRUCTURE • Root canal: – When creating post space, the practitioner should use great care to remove only minimal tooth structure from the canal. – Over enlargement can perforate or weaken the root, which then may split during cementation of the post or during subsequent function. – The thickness of the remaining dentin is the prime variable in fracture resistance of the root.
- 36. • Coronal tissue: – As much of the coronal tooth structure should be conserved as possible because this helps reduce stress concentration at the gingival margin. – The amount of remaining tooth structure is probably the single most important predictor of clinical success. – It has been shown experimentally that if more than 2mm of coronal tooth structure remains, the post and design plays little role in the fracture resistance of the restored tooth. J Prosthet Dent 1990;64:515-19.
- 37. – Incorporation of this tooth structure within the final restoration provides the ferrule. – In extensively damaged tooth creating a ferrule with orthodontic extrusion may be preferred to surgical crown lengthening as, although the root is effectively shortened, the crown is not lengthened.
- 38. RETENTION FORM • Post retention is defined as the ability of a post to resist vertical dislodging forces. • Retention of a post is affected by: – Preparation geometry and post design. – Post length. – Post diameter. – Surface texture. – Luting agent. – Number of posts.
- 39. • Post design and preparation geometry: • Circular canals can be prepared with drills or reamers to give parallel walls or minimum taper, allowing use of parallel-prefabricated post. • Elliptical or excessively flared canals cannot be prepared to give parallel walls and require custom cast posts or tapered prefabricated posts. • Laboratory testing has confirmed that – Parallel sided posts are more retentive than tapered posts. – Threaded posts are the more retentive than smooth posts. J Prosthet Dent 1995;73:139-44.
- 40. • Post length: • Retention increases with increase in post length. • One study shows that retention increases by more than 97% when post length equals or is greater than crown length. • However, this length must be well within constraints of tooth length, canal morphology and root diameter in the apical area.
- 41. • Various criteria for post length are: – Post length should be equal the incisocervical or occlusocervical dimension of the crown – The post should be longer than the crown – The post should be one and one-third the crown length – The post should be half the root length – The post should be 2/3rd of root length – The post should be 4/5th the root length – The post should terminate half way between crestal bone and root apex – The post should be as long as possible without disturbing the apical seal.
- 42. • Post diameter • Whether posts are cemented or threaded, diameter makes little difference in retentive ability. • Instead, if the post diameter is increased, the amount of remaining dentin between the post and the external surface of the root is decreased. • This diminished remaining dentin becomes an area of high stress concentration under load and, consequently, an area with a high potential for failure.
- 43. • Therefore, increasing the diameter in an attempt to increase retention is not recommended. • The smallest diameter post that is practical should be used for a given clinical situation. • Deusch et al determined that there was a six fold increase in the potential for root fracture with every millimeter the tooth’s diameter was decreased.
- 44. • There are three schools of thoughts regarding the post diameter – Conservationist (Advocated by Mattison) : Post diameter should be as narrow as possible – Proportionist (Advocated by Stern and Hirschfeld) : Diameter should not exceed 1/3rd root diameter – Preservationist (Advocated by Halle) – Leaving at least 1mm of sound dentin around post
- 45. Post space preparation width (Shillingburg) Reamer Number Diameter Teeth 1 0.7mm Mandibular incisor 2 0.9mm Maxillary first premolar Maxillary second molar (DF) Mandibular first molar (ML) Mandibular second molar (MF, ML) 3 1.1mm 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 1.5mm Canine 6 1.7 mm Maxillary central incisor.
- 46. • Surface texture: • A serrated or roughened post is more retentive than a smooth post. • Roughening can be done with sandblasting.
- 47. • Luting agent: • Any of the current luting cements can be successfully used with a post if the proper principles are followed. • The most commonly used luting agents are: zinc phosphate, resin cement, glass-ionomer and resin-modified glass ionomer. • However, Resin-modified glass ionomer cements should be avoided as they expand on water absorption and may cause root fracture.
- 48. • Generally, in the past, zinc phosphate was the cement of choice, but, recent trend has been toward resin cements because they: – Increase retention. – Tend to leak less than other cements.
- 49. • Number of posts: – It is possible to place more than one post in teeth with multiple roots. – Additional posts may be used, where feasible, to increase retention and retain core material, especially in severely broken down teeth.
- 50. RESISTANCE FORM • Resistance is defined as the ability of the post and tooth to withstand lateral and rotational forces. • One of the functions of a post and core restoration is to improve resistance to laterally directed forces by distributing them over as large an area as possible. • However, excessive preparation of the root weakens it and increases the probability of failure. • The post design should distribute stresses as evenly as possible.
- 51. • The influence of post design on stress distribution has been tested and from these laboratory studies, the following conclusions have been drawn – The greatest stress concentrations are found at the shoulder, particularly inter-proximally and at the apex. Dentin should be conserved in these areas. – Stress is reduced as post length increases. But excessive length reduces the thickness of dentin at the apical area and hence the fracture resistance decreases.
- 52. – Parallel-sided posts distribute stresses more evenly than tapered posts, which can have a wedging effect. However, parallel posts generate high stresses at the apex. – Sharp angles should be avoided as they produce high stresses during loading. – High stress can be generated during insertions of smooth parallel-sided posts that have no vent for escape of cements.
- 53. • Therefore, in these posts, longitudinal grooves (vents) running along the length of the post should be provided to allow escape of cement thus reducing the hydrostatic pressure and generation of stress. • Tapered posts are self-venting and generally do not require vents. • Threaded posts can produce high stresses during insertion and loading, but they have been shown to distribute stress evenly if the posts are backed off a half-turn.
- 54. • Rotational Resistance: – It is important that a post with a circular cross section not rotate during function. – Where sufficient coronal tooth structure remains, this should not present a problem because the axial wall then prevents rotation. – When coronal dentin has been completely lost, a small groove placed in the canal can serve as an anti-rotational element.
- 55. • The groove is normally placed where the root is bulkiest, usually on the lingual aspect.
- 56. • The Ferrule • Rosen in 1961 described the extracoronal brace (ferrule) and defined it as “….a subgingival collar or apron of gold which extends as far as possible beyond the gingival seat of the core and completely surrounds the perimeter of the cervical part of the tooth. It is an extension of the restored crown which, by its hugging action, prevents vertical shattering of the root”.
- 57. • More recently, Sorensen and Engelman (1990) defined Ferrule Effect as “…..a 360° metal collar of the crown surrounding the parallel walls of the dentin extending coronal to the shoulder of the preparation. The result is an elevation in resistance form of the crown from the extension of dentinal tooth structure”
- 58. • The walls and margins of the crown covers 2mm of the axial walls of the preparation form the ferrule.
- 59. • A properly executed ferrule significantly reduces the incidence of fracture in the non- vital tooth by reinforcing the root at its external surface and also by dissipating force that concentrates at the narrowest circumference of tooth.
- 60. Clinical Technique • Removal of the Endodontic Filling Material – It is recommended that the root canal system should first be completely obturated and then space made for a post. – A post cannot be placed if the canal is filled with a full length silver point, so these must be removed and the tooth re-treated with gutta-percha. • The two commonly used methods for gutta- percha removal are: – With a heated endodontic plugger. – With a rotary instrument.
- 61. • Though previously it was thought that rotary instruments would disturb the apical seal, recent research has shown that both methods can be safely used to remove gutta-percha without disturbing the apical seal when 5mm of gutta-percha is retained apically. • Controversy exists regarding the timing of removal of gutta-percha after endodontic treatment. • It was believed that removal should be delayed by 1 week, as intermediate removal should disturb the apical seal.
- 62. • Now, it has been shown that adequately condensed gutta-percha can be safely removed immediately after endodontic treatment. • If doubt exists about the endodontic treatment, removal should be done after 1 week. J Endod 1996;22:583-5.
- 63. Removal with rotary instruments: • Gutta-percha can be removed with GG drills, Peeso reamers, Parapost-drills and other commercially available burs. • When rotary instruments like burs or drills (B & C) are used, it should be ensured that the instrument follows the gutta-percha and does not engage the dentin otherwise perforation can occur.
- 64. • For this reason GG drills and Peeso reamers (A) are preferred as their non-cutting tips keep them centered on the gutta-percha (the path of least resistance). • Technique: – Choose a Peeso reamer slightly narrower than the canal. – The depth of insertion is determined by superimposing the Peeso reamer over the radiograph of the tooth being restored.
- 65. – Set the stopper at the level of incisal edge of adjacent teeth. – Carefully remove the gutta-percha and avoid cutting the root dentin. – Often only a part of the root canal fill need be removed with a rotary instrument, and the remainder can be removed with the heated condenser. – Once removal reaches the appropriate depth shape the canal as needed.
- 66. Removal with a heated endodontic condenser • In this method a heated endodontic plugger or an electronic device is used to remove the gutta-percha. • This method is commonly used when gutta- percha is to be removed right after obturation as there are minimal chances of disturbing the apical seal.
- 67. • Technique: – Before removing gutta-percha calculate the appropriate length of the post. – As a guide, the post length should be equal to the height of the anatomic crown or two-thirds the length of the root, whichever is greater, but 5mm of apical gutta-percha should be left. – In short teeth, compromises must be made. An absolute minimum of 3mm of apical fill is needed. – If this cannot be achieved without having a very short post, then prognosis of the tooth is impaired.
- 68. – Avoid the apical 5mm if possible as curvatures and lateral canals are found in this segment. – The instrument is gauged for length against a preoperative radiograph and the stopper is set at the level of incisal edge of adjacent teeth. – Apply rubber dam to prevent aspiration of instrument. – Select an endodontic condenser large enough to hold heat well but not so large that it binds against the canal walls. – The instrument is heated till it is red hot, inserted into the gutta-percha and is quickly withdrawn.
- 69. – This sears off the gutta-percha. – If condenser it kept for a longer time or is not heated well the gutta-percha will stick to the instrument resulting in its being pulled out when the condenser is withdrawn, thus disturbing the endodontic seal. – If the gutta-percha is old and has lost its thermoplasticity, use a rotary instrument.
- 70. Enlargement of the Canal • This is accomplished with, Peeso reamers or a low speed drill. • The purpose is to remove undercuts and prepare the canal to receive an appropriately sized post without excessively enlarging the canal.
- 71. • Before starting canal preparation, remove any existing restorations, caries, bases and thin or unsupported walls of tooth structure while, preserving as much tooth structure as possible. • Often very little preparation will be needed for a custom-made post. • However, undercuts within the canal should be removed and some additional spacing is usually necessary. • Set the stopper on the instrument to the predetermined length.
- 72. • Gradually enlarge the canal (in 0.2mm increments) to the size that has been determined for that tooth. • Enlargement should not be greater than one-third the diameter of the root at the CEJ (A) and there should be a minimum thickness of 1.0mm of tooth structure around the post at mid-root and beyond (B).
- 73. • If anti-rotational resistance is required use a no. 170 bur to make a key way or groove in the orifice of the canal. • Place it in the area of greatest bulk. It should be cut to the depth of the bur (approx. 0.6mm) and up the canal to the length of the cutting blades of the bur (approx. 4mm)
- 74. Preparation of Coronal Tooth Structure • Ignore any missing tooth structure and prepare the remaining tooth as though it was undamaged. • The facial surface (in anteriors) should be adequately reduced for good esthetics. • Remove all undercuts that will prevent removal of pattern. • Preserve as much tooth structure as possible.
- 75. • Prepare the finish line at least 2mm gingival to the core. • This establishes the ferrule. • For custom-made post and core restorations, place a contra bevel with a flame-shaped diamond at the junction of the core and tooth structure.
- 76. • The bevel provides a metal collar around the occlusal circumference of the preparation (in addition to the ferrule) in bracing the tooth against fracture. • It also provides a vertical stop to prevent over-seating and wedging effect of the post. • Complete the preparations by eliminating sharp angles and establishing a smooth finish line.
- 77. Post Fabrication • A custom-made post can be cast from a direct pattern or an indirect one. • A direct pattern utilizing autopolymerizing resin is recommended for single canals whereas an indirect procedure is more appropriate for multiple canals.
- 78. Direct procedure • Trim a 14-gauge solid plastic sprue so that it slides easily into the canal to the apical end of the post preparation without binding. • Cut a small notch on the facial portion to aid in orientation during subsequent steps. • Mix acrylic resin monomer and polymer to a runny consistency. • Lubricate canal with petroleum or any other lubricating agent, on cotton wrapped on a Peeso reamer.
- 79. • Fill the orifice of the canal as full as possible with acrylic resin applied with a plastic filling instrument. • Alternatively: – In the doughy stage, roll the resin into a thin cylinder, introduce it in the canal and push it to place with the monomer-softened sprue. • Seat the monomer coated sprue completely into the canal. • Make sure the external bevel is completely covered with resin at this time.
- 80. • Trying to cover it later may disturb the fit of the post. • When acrylic resin becomes tough and doughy, pump the pattern in and out to insure that it will not lock into undercuts. • As the resin polymerizes, remove post from canal and make sure it extends till the apical end. • If required, additional resin can be placed at the apical end and the post is reseated and removed. • Any voids can be filled with soft dead wax e.g. utilizing wax Reinsert and remove to ensure smooth withdrawal.
- 81. • Slightly overbuild the core and allow it to fully polymerize. • Shape the core with carbide finishing burs. • Correct any small defects with wax. • A direct pattern can also be made using inlay wax in a similar manner. • Add more resin or wax to form the core. • Shape it in the form of the final preparation.
- 82. Indirect Procedure: • Any elastomeric material will make an accurate impression of the root canal if wire reinforcement is placed to prevent distortion. • Cut pieces of orthodontic wire to length and shape them like the letter J. • Verify the fit in each canal. It should fit loosely and extend to the full depth of the post space. • Coat the wire and tray with adhesive; gingival retraction would be needed for subgingival margins.
- 83. • Use a die lubricant to lubricate canals and facilitate removal. • Using a lentulospiral, fill the canals with elastic impression material. • Seat the wire to full depth, syringe in more impression material around the prepared teeth and insert the impression tray. • Remove the impression, evaluate it, and pour the final cast.
- 84. • In the cast, trim a loose fitting plastic post or sprue to fit the preparation till the apical end without binding, make a notch for orientation. • Use the impression as a guide to aid in orientation. • Apply a thin coat of sticky wax to the plastic post and add soft inlay wax in increments. • It is best to start at the most apical end and make sure that the post is correctly oriented as it is seated to adapt the wax.
- 85. • When post pattern is made, add wax to form the core. • Use the impressions as a guide to evaluate whether the wax pattern is completely adapted to the post space.
- 86. Investing and casting: • The post-core pattern is sprued on the incisal or occlusal end. • 1.0 to 2.0cc of extra water is added to the investment and a liner is omitted to increase the casting shrinkage. • This results in a slightly smaller post that does not bind in the canal, and it also provides space for the cement.
- 87. • A tight fit may cause root fracture. • When resin is used, the pattern should remain for 30 minutes longer in the burnout oven to ensure complete elimination of the resin.
- 88. Provisional Restorations • After endodontic treatment, if a cast post and core is planned, a provisional crown with attached temporary post can be fabricated for the teeth with limited supragingival structure. • A provisional restoration is also needed while the post and core is being fabricated to prevent drift of adjacent and opposing teeth.
- 89. • Fitting a wire paper clip (e.g. or orthodontic wire) into the prepared canal or using a temporary post available with proprietary post systems can do this. • Restoration is then conveniently fabricated with autopolymerizing resin; after that temporary crown can be given.
- 90. • The final post, core and crown should be fabricated as soon as possible, because microleakage can contaminate the post space and endodontic fill.
- 91. Try-In and Cementation • Check the fit of the post-core in the tooth by seating it with light pressure. • If it binds in canal or will not seat completely, air abrade the post and reinsert it in the canal. Relieve any shiny spots. • The core portion of the casting should be polished.
- 92. • If required, a vertical groove, from apical end to contrabevel, can be cut in the post to provide an escape vent for the cement. • The canal should be cleaned with a cavity cleaner to remove lubricant / temporary cement which may inhibit set of resin cements and decrease retention.
- 93. • Cement the post as for prefabricated posts. • Modify the core if necessary. • Make an impression for the final restoration.
- 94. FAILURE AND RETREATMENT • Vire classified failure of endodontically treated teeth are: – Prosthetic failures. – Periodontic failures. – Endodontic failures. • Of these, prosthetic failures occurred 59.4% of the times, thus emphasizing the need to properly restore endodontically treated teeth to increase their longevity.
- 95. • For post and core restorations, failure rates between 7% and 15% have been reported in the literature (Torbjorner). • The main factors that make endodontically treated teeth more disposed to technical failure are: – Thin-walled, weakened roots unable to withstand high stress. – Reduced retentive surfaces resulting in high stress levels in the cement.
- 96. • The main causes of post and core restoration failure are: – Dislodgement of post (loss of retention). – Root fracture. – Fracture of post. – Caries. – Periodontal disease. • Careful, case selection, adherence to biomechanical principles of post and core restoration, appropriate post selection and meticulous maintenance of oral hygiene on the part of the patient can prevent this.
- 97. Conclusion • Restoring the endodontically treated tooth remains one of the most challenging problems facing the restorative dentist. • An uncomplicated and systematic decision making process, based on universally accepted philosophy and techniques, is necessary to maximize chances for a successful restorative outcome.
- 98. References