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Endodontic Retreatment

Endodontic Retreatment

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Endodontic Retreatment

  1. 1. Endodontic Retreatment Dr. Nithin Mathew
  2. 2. Endodontic Retreatment – Dr. Nithin Mathew Contents • Introduction • Definition • Etiology • Evaluation • Indications & Contraindications • Treatment planning • Nonsurgical Endodontic Retreatment • Coronal Access Cavity Preparation • Post removal • Regaining access to periapical area 3 • Removal of separated instruments • Management of canal impediments • Repair of perforations • Heat generation • Conclusion • References
  3. 3. Endodontic Retreatment – Dr. Nithin Mathew 4 Introduction • Friedman stated that “Most patients can relate to the concept of disease-treatment-healing, whereas failure, apart from being a negative and relative term, does not imply the necessity to pursue treatment.” • Suggested using the term posttreatment disease to describe those cases that would previously have been referred to as treatment failures. • RCT : success rates : 86% - 98% (Friedman 2003, 2004)
  4. 4. Endodontic Retreatment – Dr. Nithin Mathew 5 • Success – defined by the following criteria: 1. Patient should be asymptomatic and be able to function equally well on both sides 2. The periodontium should be healthy, including a normal attachment apparatus 3. Radiographs should demonstrate healing or progressive bone fill overtime Principles of restorative excellence should be satisfied. ( C.J.Ruddle )
  5. 5. Endodontic Retreatment – Dr. Nithin Mathew 6 Definition • A procedure to remove root canal filling materials from the tooth, followed by cleaning, shaping and obturating the canals. ( GET – AAE ) • Non surgical retreatment is an endodontic treatment procedure used to remove materials from the root canal space and, if present, address deficiencies or repair defects that are pathologic or iatrogenic in origin. ( C.J.Ruddle )
  6. 6. Endodontic Retreatment – Dr. Nithin Mathew 7 Washington Study • Study carried out at the University of Washington, school of Dentistry to evaluate treated endodontic cases and ascertain their success rate. Results • Periapical repair was frequently not complete for the middle aged and elderly patients within 1 year. • Age of the patients also affected the failure rates. • Higher for patients in the first decade and sixth decade of life. • Lower for patients between second to fifth decade of life. • No significant difference in the success rates of cases treated surgically or non-surgically.
  7. 7. Endodontic Retreatment – Dr. Nithin Mathew 8
  8. 8. Endodontic Retreatment – Dr. Nithin Mathew 9 Toronto Study • The Toronto Study Project, established in 1993, • Was a continuous prospective investigation of the 4 to 6-year outcome of endodontic treatment performed by graduate endodontics students in a university clinic environment. • This modular design provides cumulative data with the completion of each successive phase, with the aim of amassing a sufficient sample to study the prognostic value of various factors.
  9. 9. Endodontic Retreatment – Dr. Nithin Mathew 10 • Strindberg related treatment outcomes to biologic and therapeutic factors. • Some of the factors that influence outcome include the • Presence of apical pathosis • Extension of the obturation (short or long) • Quality and technique of obturation • Observation period • Type of intracanal medication and bacterial status of the canal before obturation
  10. 10. Endodontic Retreatment – Dr. Nithin Mathew 11 Causes for Failure Preoperative causes • Incorrect oral examination & misinterpretation • Sinus tract, pain, vitality test, periodontal problems • Misinterpretation of radiographs • Odontogenic, developmental lesions, anatomic landmarks • Physical injury • Improper case selection • Patient cooperation • Technical difficulties • Patient systemic condition • Grossly destructed teeth • Root resorption • Inadequate sterilization of instruments
  11. 11. Endodontic Retreatment – Dr. Nithin Mathew 12 Operative causes • Failure to obtain Biomechanical objectives • Access preparation • Perforation • Underextended preparation • Overextended preparation • Canal preparation • Perforations • Ledge formation • Canal blockage • Instrument separation & foreign objects
  12. 12. Endodontic Retreatment – Dr. Nithin Mathew 13 • Failure To Obtain Biological Objectives • Removal Of Potential Irritants From • Coronal Portion • Root Canal System • Periapical Tissues • Defective Obturation • Overextended Filling • Underextended Filling • Periodontal Involvement- Lateral And Accessory Canals
  13. 13. Endodontic Retreatment – Dr. Nithin Mathew 14 Post-Operative causes • Trauma & fracture • Impaired periapical healing • Superimposed Non-endodontic involvement • Excessive orthodontic forces, periodontal disease • Poor post-endodontic restoration
  14. 14. Endodontic Retreatment – Dr. Nithin Mathew 15 • In order to plan treatment effectively, the clinician may place the etiologic factors into four groups : • Persistent or reintroduced intraradicular microorganisms • Extraradicular infection • Foreign body reaction • True cysts
  15. 15. Endodontic Retreatment – Dr. Nithin Mathew 16 Persistentor Reintroduced Intraradicular Microorganisms • RC space and dentinal tubules • Contaminated with microorganisms or their by-products • Pathogens are allowed to contact the Periradicular tissues • Persistent or reintroduced microorganisms : Major cause of posttreatment disease • Iatrogenic complications : Ledge/instrument separation : Persistence of bacteria • Previous RCT : Short Obturation : Untreated necrotic infected pulp • Classic “failed” root canal therapy (Sundqvist et al 1998)
  16. 16. Endodontic Retreatment – Dr. Nithin Mathew 17 Persistentor Reintroduced Intraradicular Microorganisms • If the resultant microbial ecosystem is amenable to bacterial survival, a lesion may not heal and root canal treatment would be deemed to have failed. • If the root canal filling fails to provide a complete seal, seepage of tissue fluids could theoretically provide a substrate for bacterial growth. • Relationship between the quality of the coronal restoration and the root canal obturation • No matter what is used to obturate the canals, if the coronal seal is compromised, it may lead to failure.
  17. 17. Endodontic Retreatment – Dr. Nithin Mathew 18 Extraradicular Infection • Bacteria invade periradicular tissue either by • Direct spread of infection from the root canal space • Extrusion of infected dentin chips • Contamination with overextended, infected endodontic instruments. • Host response : destroy organisms • Some microorganisms : resist the immune defenses and persist in the periradicular tissues • 2 species : Actinomyces israelii and Propionibacterium propionicum • Exist in the periapical tissues and may prevent healing after root canal therapy.
  18. 18. Endodontic Retreatment – Dr. Nithin Mathew 19 True Cysts • Incidence of periapical cysts : 15% to 42% of all periapical lesions • 2 types of periapical cysts : • Periapical true cyst • Periapical pocket cyst. • True cysts • Contained cavity or lumen within a continuous epithelial lining : isolated from the tooth • Pocket cysts • Lumen is open to the root canal of the affected tooth. • True cysts, due to their self-sustaining nature, probably do not heal following nonsurgical endodontic therapy : Usually require surgical enucleation
  19. 19. Endodontic Retreatment – Dr. Nithin Mathew 20 Methods of Evaluation Clinical HistologicRadiographic
  20. 20. Endodontic Retreatment – Dr. Nithin Mathew 21 Clinical Criteria for Success • According to Bender et al • Absence of pain and swelling • Disappearance of sinus tract • No loss of function • No evidence of soft tissue destruction, including probing defects • Persistent findings like (swelling or sinus tract) indicates failures
  21. 21. Endodontic Retreatment – Dr. Nithin Mathew 22 • To make a correct diagnosis, the clinician must • Rule out non-odontogenic etiology • Perform all of the appropriate tests • Properly interpret the patient’s responses to these tests • Derive at a definitive diagnosis • Decide on treatment options
  22. 22. Endodontic Retreatment – Dr. Nithin Mathew 23 • Subjective assessment • Previous treatment : aseptic techniques • Objective assessment • Visual extraoral and intraoral examination • Aided by magnification and illumination • A thorough periodontal evaluation • Comparative : pulpal and Periradicular status. • Percussion, bite, and palpation • Pulp vitality tests : less value in endo treated tooth
  23. 23. Endodontic Retreatment – Dr. Nithin Mathew 24 Radiographic Assessment • Radiographic assessment is obligatory • In cases with previous endodontic therapy, radiographs are useful in • Evaluation of caries, defective restorations, periodontal health • Quality of the obturation • Existence of missed canals • Impediments to instrumentation • Periradicular pathosis • Perforations, fractures, resorptions • Canal anatomy • Multiple angulated films should be used to determine endodontic etiologies • CBCT : Untreated canals, root fractures, resorption
  24. 24. Endodontic Retreatment – Dr. Nithin Mathew 25 • Classified as • Success • Failure • Questionable • Success • Absence of a radiographic resorptive apical lesion. • A lesion present at the time of treatment has resolved or that lesion not present at the time of treatment has not developed. • So success is evident by an eliminated or non-developed area of rarefaction after a post treatment interval of 1 to 4 years.
  25. 25. Endodontic Retreatment – Dr. Nithin Mathew 26 • Failure • Persistence or development of radiographically evident pathosis. • Radiolucent lesion that has enlarged, has persisted or has developed since the treatment. • Questionable • A state of uncertainty • Situation (radiolucent lesion) has neither become worse not significantly improved • A questionable status reverts to failure if the situation (non-resolution) continues, generally after a period of 1 year.
  26. 26. Endodontic Retreatment – Dr. Nithin Mathew 27 Histologic Examination • Evidenced by reconstitution of periapical structures and an absence of inflammation. • Routine histologic evaluation of periapical tissues on patients is impractical. • Thus, clinical findings (signs and symptoms as well as radiographic findings) are the only means of assessing success and failure.
  27. 27. Endodontic Retreatment – Dr. Nithin Mathew 28 When to evaluate • Lack of consensus on the criteria for assessing success or failure, the length of time necessary for adequate post-operative follow-up also remains controversial. • Suggested period : 6 months – 4 years
  28. 28. Endodontic Retreatment – Dr. Nithin Mathew 29 Indications • Periapical radiolucencies even after 4 years • Tenderness to percussion • Apical pain to pressure • Fistula formation • Swelling of soft tissue • Incomplete root canal filling – for prosthetic restoration even being asymptomatic
  29. 29. Endodontic Retreatment – Dr. Nithin Mathew 30 Contraindications • Vertical fracture • Poor periodontal status • Non restorable teeth • Access is difficult • Patients with TMJ dislocation problems • Resorption • Anatomical limitations • Non strategic position
  30. 30. Endodontic Retreatment – Dr. Nithin Mathew 31 Treatment Plan • The patient harbouring true endodontic posttreatment disease has four basic options for treatment : • Do nothing • Extract the tooth • Nonsurgical retreatment • Surgical retreatment
  31. 31. Endodontic Retreatment – Dr. Nithin Mathew 32 NONSURGICAL ENDODONTIC RETREATMENT • Primary goal: regain access to the periapical area (endotreated tooth) • Principals of endodontic therapy followed : completion of case • Coronal access needs to be completed • All previous root-filling materials need to be removed • Canal obstructions must be managed • Impediments to achieving full working length must be overcome • Cleaning and shaping procedures : for effective obturation and case completion
  32. 32. Endodontic Retreatment – Dr. Nithin Mathew 33 NonSurgical Endodontic Retreatment : Coronal Disassembly • Retreatment access is called coronal disassembly • Removal of the coronal restoration includes • Full coverage restoration • Core build-up material • Post placed into the canal • Advised to remove the existing coronal restoration if it has • Poor marginal adapatation • Secondary caries • To avoid procedural errors • To maintain form, function and esthetics
  33. 33. Endodontic Retreatment – Dr. Nithin Mathew 34 • Re-access to the pulp chamber through the existing restoration • If it is judged to be functionally designed, well fitting and esthetically pleasing. • Removal is based on whether additional access is required to facilitate disassembly and retreatment. • Preparation type • Restoration design and strength • Restorative material used • Cementing agents • Removal device
  34. 34. Endodontic Retreatment – Dr. Nithin Mathew 35 • Coronal disassembly devices: • Grasping instruments • Percussive instruments • Active instruments
  35. 35. Endodontic Retreatment – Dr. Nithin Mathew 36 Grasping instruments • Appling inward pressure on two opposing handles • Proportionally increases the instrument’s ability to grip a restoration. • Strong purchase while reducing dangerous slippage. • Handle pressure α Instrument ability to grip restoration • E.g.: • Trident crown Placer/ remover • K.Y. Pliers • Wynman Crown Gripper • Removing provisional restorations
  36. 36. Endodontic Retreatment – Dr. Nithin Mathew 37 Percussive instruments • Selective and controlled percussive removal force • Deliver impact directly to restoration or indirectly to another securely engaged prosthetic removal device • Eg: • Ultrasonic Energy • Crown- A-Matic (Peerless) • Coronaflex • Removal or provisional & definitive restoration
  37. 37. Endodontic Retreatment – Dr. Nithin Mathew 38 Active instruments • Actively engage a restoration, enabling a specific dislodgement force to potentially lift off the prosthesis. • Requires a small occlusal window to facilitate mechanical action of the instrument. • Creates a lifting force : separating crown & preparation • E.g: • Metalift • Kline Crown Remover • Higa Bridge Remover
  38. 38. Endodontic Retreatment – Dr. Nithin Mathew 39 Post Removal • Common to encounter a post : increase in frequency • Factors influencing post removal • Operator judgment • Training & Experience • Technique & devices • Post type - parallel/ tapered, active/ passive • Cementing agent
  39. 39. Endodontic Retreatment – Dr. Nithin Mathew 40 • Steps: • Core restorative material is removed • A less aggressive instrument, such as a tapered bur in a slow-speed handpiece or a tapered, midsized ultrasonic tip, should be used to remove the last of the embedding core material. • Magnification and illumination • Minimal restorative material remaining, smaller sized ultrasonic instrument should be used • To minimize the risk of removing unnecessary tooth structure • Thinning of the post. • More post that is left, the more options for removal • More tooth structure that is left, the more options for restoration
  40. 40. Endodontic Retreatment – Dr. Nithin Mathew 41 • Techniques for post removal : • Ultrasonic vibration • Rotosonic vibration • Mechanical devices
  41. 41. Endodontic Retreatment – Dr. Nithin Mathew 42 Ultrasonic vibration • Piezo electric ultrasonic systems in conjuction with specific instruments. • Instrument at the interface between the post and the tooth (the cement line) • Constantly moved around the circumference of the post • Disrupt the cement structure along the post/canal wall interface and decrease post retention • Tip should be removed from the access every 10 to 15 seconds • To allow the use of an air/water syringe • To clean the area of debris • To reduce the temperature produced that could potentially cause damage to the periradicular tissues.
  42. 42. Endodontic Retreatment – Dr. Nithin Mathew 43 Ultrasonic vibration • Area around the post may be flooded with a solvent (chloroform) prior to activating the ultrasonic instrument • Dissolve the cement around the post • Ultrasonic energy produced will set up shock waves in the solvent and make it penetrate deeper into the canal space, exerting a faster solvent action on the cement • One study has shown that heat generation with ultrasonic vibration may help to decrease retention of resin cemented posts. (Garido et al 2004) • But concern for heat generated periodontal ligament damage. (Swartz et al 2004)
  43. 43. Endodontic Retreatment – Dr. Nithin Mathew 44 Rotosonic vibration • Rotosonics is a method to potentially loosen and remove a fully exposed post. • The regular tip Roto-pro Bur (Ellman International, Hewlett, NY) is a high-speed, friction grip bur whose six sides utilize six edges which when rotated in one revolution produce six vibrations per revolution. • Rotated at 200,000 rpm, it produces 1.2 million vibrations per minute.
  44. 44. Endodontic Retreatment – Dr. Nithin Mathew 45 Mechanical Devices • If retention reduction does not remove the post, some form of vice is needed to pull the post from its preparation. • Gonon post removing system (Thomas Extracteur De Pivots, Ffdmpneumat, Bourge, France) • Effective instrument for removing parallel or tapered, nonactive preformed posts • Kit utilizes a hollow trephine bur aligned with the long axis of the post and placed over its exposed end
  45. 45. Endodontic Retreatment – Dr. Nithin Mathew 46 Ultrasonic exposure of the post Fractured post in a lower incisor Domer bur creating a shape that the trephine bur can engage Trephine bur milling the post Extraction device tapping a thread onto the post Vice applied. Turning the screw on the vice opens the jaws, creating the extraction force.
  46. 46. Endodontic Retreatment – Dr. Nithin Mathew 47 • Drawbacks: • Size of the vice that can make access in the molar region and between crowded lower incisors difficult. • If the extraction force applied is not directed in the long axis of the root, root fracture may occur • This method is effective because • All the force is applied to the bond between the tooth and the post, ideally in the long axis of the root.
  47. 47. Endodontic Retreatment – Dr. Nithin Mathew 48 • Other Post Removal Systems (PRS) : • Thomas Screw Post Removal Kit • Ruddle Post Removal System • Universal Post Remover • JS Post Extractor • Post Puller (Eggler Post Remover)
  48. 48. Endodontic Retreatment – Dr. Nithin Mathew 49 Removal Of Fibre Posts • Ultrasonic / gonon kit : none works for fibre post removal • Use of a high-speed bur to channel down through the post may result in a high rate of root perforation. • A new bur Gyrotip has been designed for the specific purpose of removing fiber-reinforced composite posts. • Drills consist of a heat generating tip designed to soften the matrix that binds the fibers within the fiber-reinforced post.
  49. 49. Endodontic Retreatment – Dr. Nithin Mathew 50 • Fibers within the post are parallel, which assists the axial travel of the drill through the center of the post. • Fluted zone of the drill allows the fibers to be safely removed, creating access to the root canal filling. • Above the fluted zone, a layer of plasma bonded silica carbide reduces the heat generation • This abrasive zone also provides for a straight-line access preparation and facilitates the placement of a new post
  50. 50. Endodontic Retreatment – Dr. Nithin Mathew 51 • Ceramic and Zirconium posts : Impossible to retrieve. • They are more fragile than metal posts, and though ceramic posts may be removed by grinding them away with a bur. • High risk of root perforation • Zirconium has a hardness approaching that of diamond and cannot be removed by this method. • Removal of a fractured zirconia post by ultrasonic vibration has been found to cause temperature rise of the post and on the root surface • Great white Z bur (SS White) : For Zirconia Posts
  51. 51. Endodontic Retreatment – Dr. Nithin Mathew 52 Potential Complications of Post Removal • Fracture of the tooth, leaving the tooth nonrestorable • Toot perforation • Post breakage • Inability to remove the post • An additional concern is ultrasonically generated heat damage to the periodontium.
  52. 52. Endodontic Retreatment – Dr. Nithin Mathew 53 Gutta Percha Removal • Initially removed from the canal in the coronal one third, then the middle one third and finally eliminated from apical one third. • Following methods or combination of methods are used. • K-files or H-files • Gutta-percha solvent • Combination of paper points and gutta-percha solvent • Rotary instruments • Specialized rotary instruments designed for retreatment • Heat transfer devices • Soft tissue laser
  53. 53. Endodontic Retreatment – Dr. Nithin Mathew 54 • K & H files • Allows for a gross removal of gutta-percha especially from large canals, which are poorly compacted allowing files to bypass the obturating material and ‘bite’ into the mass • Micro-debriders (Dentsply Maillefer) are small files having 90-degree bend at the working end and an attached handle. • It may also be used to substitute standard K-files and H-files.
  54. 54. Endodontic Retreatment – Dr. Nithin Mathew 55 Solvents • Chloroform • Methyl chloroform • Eucalyptol oil • Halothane • Turpentine • Xylene • Orange wood oil • Chloroform • Proven to be most successful • Evaporates rapidly • Potential carcinogenicity
  55. 55. Endodontic Retreatment – Dr. Nithin Mathew 56 • Eucalyptol: • Less irritating than chloroform • Antibacterial • Least effective GP solvent • Xylene: • Highly toxic • Evaporates too slowly • Dissolving effect less than chloroform • Orange wood oil: • Contraindicated – over extended fillings • Halothane: • Longer time for dissolving than chloroform
  56. 56. Endodontic Retreatment – Dr. Nithin Mathew 57 Rotary Removal • Gates Glidden Drill and Peeso Reamer • GPX Gutta-percha Remover (Prestige Dental) • Specially designed file • Slowspeed handpiece. • Plasticizes by frictional heat and facilitates its removal by its H-file like flute design. • ISO 25–50 • Recently introduced NiTi GPX -curved canals
  57. 57. Endodontic Retreatment – Dr. Nithin Mathew 58
  58. 58. Endodontic Retreatment – Dr. Nithin Mathew 59 • NiTi Rotary instruments • Advantage of removing gutta-percha as well as shaping the root canals in an under-prepared tooth, simultaneously. • Several studies carried out for comparing the gutta-percha removal efficacy of rotary with the hand instrumentation, have shown both techniques to be almost equally effective • The use of rotary devices in retreatment should be followed by hand instrumentation.
  59. 59. Endodontic Retreatment – Dr. Nithin Mathew 60 • NiTi Rotary Instruments • Rotary : Reach the whole working length easily • Plasticize through frictional heat. • Hand instruments : refine and complete the removal. • Recommended to be used at rotational speed of 3-4 times more than that for routine cleaning and shaping.
  60. 60. Endodontic Retreatment – Dr. Nithin Mathew Specialized Rotary Instruments Designed for Retreatment • ProTaperUniversal Retreatment Kit (Dentsply) • D1 File : 30/0.09 NiTi file (one white ring) of 16 mm : Coronal third • D2 File : 25/0.08 NiTi file (two white rings) of 18 mm : Middle third • D3 File : 20/0.07 NiTi file (three white rings) of 22 mm : Apical third • R-Endo (Micro-Mega) • Made up from a round blank • Cross-section is characterized by three equally spaced cutting edges. • Speed of 300-400 rpm along with gutta percha solvent. • Series of six files named as Rm, Re, R1, R2, R3 and Rs 61
  61. 61. Endodontic Retreatment – Dr. Nithin Mathew • Mtwo Retreatment Kit (Sweden and Martina) • S-shaped cross-section • 2 instruments with cutting tips designed to reach the apex. • Mtwo R 15/.05 • Mtwo R 25/.05 • Advantage of shaping the root canal in an under-prepared tooth, simultaneously. 62
  62. 62. Endodontic Retreatment – Dr. Nithin Mathew Heat Transfer Devices • Heat Carrier Tips • System B • Endotec • EndoTwinn • Touch’NHeat • DownPak • Heat generated on the tip : soften guttapercha mass. • More effective in well prepared canals. • Alternatively, the hand spreaders can also be used in the similar manner, however, the amount of heat transferred to these instruments is not consistent. 63
  63. 63. Endodontic Retreatment – Dr. Nithin Mathew • Ultrasonics • Piezoelectic ultrasonic system, produces heat that thermo softens GP • It will float coronally into the pulp chamber • Tips available for ultrasonic • Condensation of GP or specialized re-treatment tips 64
  64. 64. Endodontic Retreatment – Dr. Nithin Mathew • Soft Tissue Lasers • The studies, conducted on effectiveness of the Nd: YAG laser for removal of gutta- percha, have shown that it is capable of softening gutta-percha. • Lower settings (100 mJ, 15 Hz, 1.5 W) • Fairly clean root canals, but an incomplete elimination of gutta-percha from dentinal walls. • Increased power levels (100 mJ, 20 Hz, 2 W) • More effective on the canal walls, cleaning them better • The addition of solvents have not shown any improvement in their efficiency in terms of time required for removal of GP. 65
  65. 65. Endodontic Retreatment – Dr. Nithin Mathew • Paper point and chemical removal • Drying solvent filled canals with paper points is known as “wicking” • It is always the final step of gutta percha removal. • Wicking action removes residual gutta percha end sealer out of fins, cul de sac and aberrations of the root canal. • Wicking takes place by pulling dissolved materials from periapical to central. 66
  66. 66. Endodontic Retreatment – Dr. Nithin Mathew Carrier Based gutta percha removal • After careful access and complete circumferential exposure of the carrier a suitable grasping pliers is selected and a purchase is obtained on the carrier. • Carrier is grasped with the pliers and extrication is attempted using fulcrum mechanics, rather than a straight pull out of tooth. • If enough canal space exists, a 4 or 5 ultrasonic instrument can be used along side carrier to produce heat and thermosoften the G.P. 67
  67. 67. Endodontic Retreatment – Dr. Nithin Mathew 68 Silver Point Removal • Easily removed : chronic leakage greatly reduces the seal and hence lateral retention. • The coronal heads of silver points are within pulp chambers and are entombed in cements, composites or amalgam cores. • Initial access with high speed surgical-length cutting tools. • Subsequently, ultrasonic instruments may be carefully used within the pulp chamber to brush cut away restorative materials and progressively expose the silver point.
  68. 68. Endodontic Retreatment – Dr. Nithin Mathew 69 • Pliers removal • Stieglitz Plier used gently pull to confirm its relative tightness. • When grasping a silver point, rather than trying to pull it straight out of the canal the plier is rotated using fulcrum mechanics and levered against the restoration or tooth structure to enhance removal efforts. • Indirect Ultra Sonic • Used when a segment of silver point is encountered below the orifice and space is restricted.
  69. 69. Endodontic Retreatment – Dr. Nithin Mathew 70 • Indirect Ultra Sonic • Care must be used so that ultrasonic instruments are not used directly on silver points because elemental silver is soft and rapidly erodes during mechanical manipulation. • Once the surrounding material is removed, ultrasonic energy then may be transmitted on a grasping plier to synergistically enhance the retrieval efforts.
  70. 70. Endodontic Retreatment – Dr. Nithin Mathew 71 • Braided file technique • Using Hedstrom files • Sealer is dissolved • Files are negotiated as apically as possibly in two to three areas around the silver point. • The spaces surrounding the silver point are carefully instrumented to size 15. • Then small Hedstrom files are gently screwed in as far as possible apically. • The flute design of Hedstrom file allows for better engagement into the silver point. • Files are then twisted together and pulled out through the access.
  71. 71. Endodontic Retreatment – Dr. Nithin Mathew 72 • Caufield silver point retrievers • When not much of the silver point exposed in the chamber, the clinician can attempt to remove it using the Caufield silver point retrievers (Integra Miltex). • Instrument is a spoon with a groove in the tip that can engage the exposed end of the silver point so it may be elevated from the canal or possibly elevated to the point where it may be grasped by forceps. • Available in three sizes: • 25, 35 and 50
  72. 72. Endodontic Retreatment – Dr. Nithin Mathew 73 Paste Removal • When evaluating a paste case for retreatment, it is useful to clinically understand that the coronal portion of the paste in the canal is most dense (the material is progressively less dense moving apically). • Ultrasonic energy • Ultrasonic instruments in conjunction with the microscope, afford excellent control in removing paste from the straight portions of a canal. • To remove paste apical to a canal curvature, precurved file is attached to a specially designed adapter that mounts on and is activated by the ultrasonic hand piece.
  73. 73. Endodontic Retreatment – Dr. Nithin Mathew 74 • Rotary instruments • Stainless steel O.O2 tapered hand files to negotiate through paste fillers. • These files can potentially create a pilot hole for safe ended, Ni Ti rotary instruments to follow. • Solvents and Hand Files • Reagents like Endosolv ‘R’ and Endoslov ‘E’ can be helpful in chemically softening hard paste. • These reagents can be placed interappointment.
  74. 74. Endodontic Retreatment – Dr. Nithin Mathew 75 • Micro debriders • To precisely remove residual paste materials • Offset handles, 0.02 tapers with 16mm of efficient hedstrom type cutting blades. • Solvents and paper points • After paste removal, paper point wicking in the presence of specific paste solvents is important
  75. 75. Endodontic Retreatment – Dr. Nithin Mathew 76 Broken Instrument Removal • Incidence of hand instrument separation has been reported to be 0.25% and for rotary instruments it ranges from 1.68% to 2.4%. (Iqbal et al 2006) • A common cause for instrument separation is improper use. • Overuse and not discarding an instrument and replacing it with a new one when needed.
  76. 76. Endodontic Retreatment – Dr. Nithin Mathew 77 List of guidelines for when to discard and replace instruments : 1. Flaws, such as shiny areas or unwinding, are detected on the flutes 2. Excessive use has caused instrument bending or crimping • NiTi instruments : tend to fracture without warning • Constant monitoring of usage is critical 3. Excessive bending or precurving has been necessary 4. Accidental bending occurs during file use. 5. Corrosion is noted on the instrument. 6. Compacting instruments have defective tips or have been excessively heated.
  77. 77. Endodontic Retreatment – Dr. Nithin Mathew 78 Factors influencing broken instrument removal: 1. Cross sectional diameter of the canal 2. Length of the canal 3. Root morphology – thickness of dentin and the depth of external concavities. 4. Curvature of the canal • Straight portion of canal : removed usually. • Around canal curvature : removal is possible if the access if established to its most coronal extent. • Apical to curvature : removal may not be possible. 5. Type of material that obstructs the canal • SS files do not fracture during removal • NiTi breaks again because of heat build up caused by ultrasonic devices.
  78. 78. Endodontic Retreatment – Dr. Nithin Mathew 79 Technique for broken instruments removal • Steps: 1. Coronal access • Done with high speed, friction grip surgical length burs 2. Radicular access • Hand files, and GG drills used • GG drills maximize visibility coronal to the obstruction 3. Create staging platform • Modified GG is used. • Cutting the bud of GG perpendicular to its long axis at its maximum C-S diameter. • This creates a small staging platform that facilitates the introduction of ultrasonic instruments.
  79. 79. Endodontic Retreatment – Dr. Nithin Mathew 80 • Ultrasonic instrument moved lightly in a CCW direction around the obstruction • This will remove the dentin and trephines around the obstruction • Gently, wedging the energized tip between the file and canal wall will remove the instrument • Deeper in the canal the obstruction is, the longer and thinner an ultrasonic tip must be. • Thin tips must be used on very low power settings to prevent tip breakage
  80. 80. Endodontic Retreatment – Dr. Nithin Mathew 81 MICROTUBE DEVICES • Instrument Retrieval System (IRS) • Small staging platform : Further reduced by ultrasonics until enough of the separated instrument is exposed to retrieve. • Microtube is inserted into the canal and the long part of its beveled end is oriented to the outer wall of the canal to scoop up the head of the broken instrument.
  81. 81. Endodontic Retreatment – Dr. Nithin Mathew 82 • The insert wedge is placed through open end of microtube and passed down its internal lumen until it contacts the broken obstruction. • The broken instrument is secured by turning the insert wedges handle screw in a clockwise rotation.
  82. 82. Endodontic Retreatment – Dr. Nithin Mathew 83 • Wire Loop & Tube Removal Method : • 25-gauge dental injection needle • 0.14-mm-diameter steel ligature wire. • Needle is cut to remove the beveled end • Both ends of the wire are then passed through the needle from the injection end until they slide out of the hub end, creating a wire loop • Once the loop has passed around the object to be retrieved, a small hemostat is used to pull the wire loop up and tighten it around the obstruction • Complete assembly is withdrawn from the canal.
  83. 83. Endodontic Retreatment – Dr. Nithin Mathew 84 • Other Methods: • Endo Extractor (Brasseler USA) • Masserann Kit (Medidenta International) • Extractor System (Roydent) • Separated Instrument Retrieval System (SIRS)
  84. 84. Endodontic Retreatment – Dr. Nithin Mathew 85 • Specifically for use with Microscopes : • Cancellier instrument (Sybron Endo) • Mounce extractor (Sybron Endo)
  85. 85. Endodontic Retreatment – Dr. Nithin Mathew 86 Management of Canal Impediments • Iatrogenic mishaps resulting from • Vigorous instrumentation short of the appropriate working length • Failure to confirm apical patency regularly during instrumentation. • Includes: • Blocked canals • Ledge Formation
  86. 86. Endodontic Retreatment – Dr. Nithin Mathew 87 Managing Blocked canals • Well-angulated radiographs • Coronal portion of the canal should be enlarged • To enhance tactile sensation • Remove cervical and middle third obstructions in the canal space • Canal should be flooded with irrigant, and instrumentation to the level of the impediment should be accomplished using non-end-cutting instruments • Precurved #8 or #10 file used in pecking motion • Determine if there are any “sticky” spots that could be the entrance to a blocked canal.
  87. 87. Endodontic Retreatment – Dr. Nithin Mathew 88 • Directional rubber stop should be used • Very short amplitude, light pecking strokes to be used • Short amplitudes - ensure safety, carry irrigant deeper, and increase the possibility of canal negotiation • File's handle whose tip is engaged, should never be excessively rotated. • Frequent evacuation of the irrigant and using a lubricant, such as RC prep. • Risk of deviating from the original canal path, creating a ledge, and ultimately a false canal leading to zip perforation. • Working radiograph taken when some apical progress made
  88. 88. Endodontic Retreatment – Dr. Nithin Mathew 89 • Occasionally, clinical situations arise where the aforementioned techniques have been carefully attempted, but either the file is not progressing apically or is not maintaining the true pathway of the canal. • If the tooth is asymptomatic and symptoms are not masked by a pharmaceutical agent, and if the periodontium is healthy and there are no lesions of endodontic origin, then the preparation may be finished to the level of the obstruction and obturated.
  89. 89. Endodontic Retreatment – Dr. Nithin Mathew 90 Ledge Formation • An artificially created irregularity on the surface of the root canal wall that prevents the placement of instruments to the apex of an otherwise patent canal. • A deviation from the original canal curvature without communication with the PDL, resulting in a procedural error is termed ledge formation or ledging. (JOE, 33, 2007)
  90. 90. Endodontic Retreatment – Dr. Nithin Mathew 91 Recognition of a Ledge : • Root canal instrument can no longer be inserted into the canal to full working length. • Loss of tactile sensation of the tip of the instrument binding in the lumen. • Instrument point hitting against a solid wall • Radiograph with instrument in place.
  91. 91. Endodontic Retreatment – Dr. Nithin Mathew 92 Management : • Locating the ledge • Irrigate, smaller instruments are preferred. • No. 10 or 15 with a distal curve at the tip can be used • Pointed towards the wall opposite to the ledge • “Tear shaped” silicone stops can be used. • Watch-winding motion • If resistance is felt, retract slightly, rotate and advance again, until it bypasses and reach apically. • Confirmed with a radiograph • If ledge cannot be bypassed, then clean, shape and obturate till obstruction.
  92. 92. Endodontic Retreatment – Dr. Nithin Mathew 93 Prevention of Ledge : • Proper examination of the diagnostic radiographs. • Awareness of canal morphology • Frequent recapitulation and irrigation • Precurving the instrument and not forcing it. • Using instruments with not cutting tip • Using NiTi files in case of curved canals • Modified instruments: • Flex R files • Safety Hedstrom files • Flexofile
  93. 93. Endodontic Retreatment – Dr. Nithin Mathew 94 Endodontic Perforation • Perforations in all locations can be caused by 2 main errors: 1. Creating a ledge in the canal wall during initial preparation and perforating through the side of the root at the point of obstructions / root curvature. 2. Using too large or too long an instrument and either perforating directly through the apical foramen or wearing a hole in the lateral surface of the root by over instrumentation.
  94. 94. Endodontic Retreatment – Dr. Nithin Mathew 95 Factors influencing repair Considerations influencing perforation repair: 1. Level 2. Location 3. Extend of perforation 4. Potential for successful management • Level: • Coronal / furcation perforation : threaten sulcular epithelium • In general, more apical the perforation, more favourable the prognosis
  95. 95. Endodontic Retreatment – Dr. Nithin Mathew • Location: • Can occur circumferentially on the buccal, lingual, mesial and distal aspects of roots. • Location of the perforation is not so important when non-surgical treatment is selected. • Position is critical and may preclude surgical access if this approach is considered. • Extend & Size of Perforation: • Size greatly affects the clinician’s ability to establish a hermetic seal. • The area of a circular shaped perforation can be mathematically described as πr2. • Therefore doubling the perforation size with any bur or instrument increases the surface area to seal four-fold. 96
  96. 96. Endodontic Retreatment – Dr. Nithin Mathew • Time: • Regardless of the cause, a perforation should be repaired as soon as possible to discourage further loss of attachment and prevent sulcular breakdown. • Esthetics: • Perforations in the anterior region can definitely impact esthetics. • Tooth colored restoratives are chosen and selected from the best materials currently available in adhesive dentistry. 97
  97. 97. Endodontic Retreatment – Dr. Nithin Mathew • Periodontal condition : • If the attachment apparatus is intact without pocketing, timing is critical and the treatment is ideally directed toward non-surgically repairing the defect. • Decision should be made for periodontal breakdown teeth, to go for surgical or non- surgical or both together. • Longstanding defect with periodontal lesion: surgery with guided tissue regeneration • Most cases, nonsurgical retreatment and internal perforation repair prior to surgery will be beneficial to the treatment outcome. 98
  98. 98. Endodontic Retreatment – Dr. Nithin Mathew 99 Management • Difficulty of the repair : Level of perforation • Furcal floor of a multirooted tooth or in the coronal one third of a straight canal (access) • Considered to be easily accessible • Middle one third (strip or post perforations) : Difficulty increases • Apical one third (instrumentation errors) • Predictable repair • Frequently, apical surgery will be needed.
  99. 99. Endodontic Retreatment – Dr. Nithin Mathew 100 Barrier Materials For Perforation Repair • Barriers help produce a ‘‘dry field’’ and also provide an internal matrix or ‘‘back stop’’ against which to condense restorative materials. • Absorbable • Collagen materials (colla cote) • Calcium sulfate (cap set) • Non-Absorbable • MTA • Other restoratives (amalgam, super EBA resin cement, composite restoratives, calcium phosphate cement)
  100. 100. Endodontic Retreatment – Dr. Nithin Mathew • Hemostatics to control bleeding. • Small area : sealed from inside the tooth • Large area : seal from inside, then surgical repair • Where esthetics is a concern, a calcium sulfate barrier along with composite restoration is generally used. • Super EBA have been used when esthetics not an issue. • Presently MTA is restorative of choice because of its many desirable attributes. 101 Management of Coronal Third
  101. 101. Endodontic Retreatment – Dr. Nithin Mathew • By nature of occurrence, these defects are ovoid in shape and typically represent relatively large surface area to seal. • Access to midroot perforation is most often difficult, and repair is not predictable. • Successful repair depends upon the adequacy of the seal established by the repair material. • The repair should be immediate, to protect the perforated site from saliva and other contaminants. • Barrier material of choice is MTA. 102 Management of Middle Third
  102. 102. Endodontic Retreatment – Dr. Nithin Mathew • Overinstumentation : • Re-establish the WL and enlarge with larger instrument. • Apical barrier: Ca(OH)2, MTA, Dentin Chips, Hydroxyapatite • Apical Perforation : • Negotiate • Perforation site as the new apical opening and obturation is done to seal of the foramen • Surgery is necessary, if a lesion present apically 103 Management of Apical Third
  103. 103. Endodontic Retreatment – Dr. Nithin Mathew • Surgical Approach: • A combined intracoronal and surgical approach involves repairing the defect intracoronally, then reflecting a surgical flap to remove the inevitable overextension of the repair material from the periodontal space. • In case of failing furcation repairs, • Bicuspidation • Hemi-Section • Intentional Replantation can be considered as treatment options. 104 Management of Apical Third
  104. 104. Endodontic Retreatment – Dr. Nithin Mathew 105 Heat generation during treatment procedures • Several procedures in endodontic therapy that generate heat • Greatest risk with Non-surgical retreatment • Use of heat to soften canal filling materials • Use of ultrasonics to dislodge posts and separated instruments • Can potentially generate enough heat to raise the temperature of the external root surface by 10° C or more. • Temperature elevations of the periodontal ligament in excess of 10° C can cause damage to the attachment apparatus. (Eriksson et al 1983, Saunders et al 1989,1990)
  105. 105. Endodontic Retreatment – Dr. Nithin Mathew 106 • Accepted that the heat-induced damage to periradicular tissues during the usage of ultrasound energy for post removal is Time Dependent. • Study has showed that ultrasonic vibration for post removal without coolant can cause root surface temperature increases approaching 10° C in as little as 15 seconds. (Dominici et al 2005)
  106. 106. Endodontic Retreatment – Dr. Nithin Mathew 107 Recommendations for the use of ultrasound energy during the removal of canal obstructions : • Use ultrasonic tips with water ports whenever possible • If ultrasound device does not have tips with waterports, have your assistant use a continuous water/saline irrigation during usage. • Take frequent breaks to let the tooth cool down. • Avoid using the ultrasound on the high power setting.
  107. 107. Endodontic Retreatment – Dr. Nithin Mathew 108 Conclusion • Posttreatment endodontic disease does not preclude saving the involved tooth. • In fact, the majority of these teeth can be returned to health and long-term function by current retreatment procedures. • In most instances the retreatment option provides the greatest advantage to the patient because there is no replacement that functions as well as a natural tooth. • Armed with the information in the preceding section, appropriate armamentaria, and the desire to do what is best for the patient, the clinician will provide the foundation for long- term restorative success.
  108. 108. Endodontic Retreatment – Dr. Nithin Mathew 109 References • Pathways of the Pulp – Cohen • Textbook of Endodontics – Ingle • Endodontic practice - Grossman
  109. 109. Endodontic Retreatment – Dr. Nithin Mathew 110

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