Endodontics mishaps - Pediatric Dentistry

endodontics mishaps to be expected in pediatric dentistry when you treat the immature and mature teeth

1. ENDODONTIC MISHAPS Presented by: Dr Ramesh R III MDS Dept of Pedodontics

2. REFERENCES Avery & Mcdonald Textbook of pediatric dentistry, 10 th edition Pediatric dentistry infancy through adolescence, cassamassimo , 4 th edition Ingle endodontics, 4 th edition Textbook of Endodontics , Cohen Textbook of Endodontics, Grossman, 10 th edition Textbook of Endodontics, Walton & Torabinajad Cameron & widmer textbook of pediatric dentistry

3. CONTENTS Introduction Definition What to do if it happens? Classification Access related mishaps Instrumentation related Obturation related Conclusion

4. INTRODUCTION Avery and mcdonald textbook of pediatric dentistry, 10 th edition Ingle Textbook of Endodontics, 4 th edidtion

5. What to do when it happens? When an accident occurs during root canal treatment, the patient should be informed about (1) the incident, (2) procedures necessary for correction, (3) alternative treatment modalities, and (4) the effect of this accident on prognosis. Proper medical legal documentation is mandatory

6. How to manage mishaps? Recognition of mishap Correction of mishap Re-evaluation of prognosis of the tooth involved How to prevent the mishaps

7. DEFINITION Unwanted situations faced by clinicians during the root canal treatment which can affect the prognosis of endodontic therapy. These procedural accidents are collectively termed as endodontic mishaps . Walton & Torabinajad Unfortunate circumstances which happen during the owing to the inattention to detail and others totally inpredictable . Ingle

8. CLASSIFICATION

9. CLASSIFICATION

10. FOREGIN BODY IMPACTION

11. most of the authors have opted for the extraction of the primary tooth. The choice is usually guided by the pulpal and periapical status of the tooth in question, the exfoliation timing, and level of difficulty in retrieving the object and on patient factors such as the child’s age and level of cooperation. In the presen

12. ACCESS RELATED MISHAPS

13. TREATING WRONG TOOTH CAUSE Inattention from part of dentist Misdiagnosis RECOGNITION Patient continues to have symptoms after treatment Error may be detected after the rubber dam is removed CORRECTION Appropriate treatment for tooth The one incorrectly opened The one with pulpal problem Ingle, Textbook of endodontics

14. PREVENTION Mistakes avoided by 3 good piece of evidence supporting the diagnosis Obtaining as much information as possible before making diagnosis

15. MISSED CANALS CAUSES ANATOMICAL Some root canals are readily not apparent or easily accesible DENTIST RELATED Lack of thorough knowledge of root canal anatomy along with its variations. Failure to remove cervical ledge Failure to search for additional canals

16. RECOGNITION During canal exploration, if canal is not centered in the root, one should look for presence of extracanal . There are several teeth which have predisposition for extracanal which might be missed if not explored accurately while treatment. For example: – Maxillary premolars have 3 canals ( mesiobuccal , distobuccal and palatal) Upper first molars usually have 4 canals Mandibular premolars often have complex root anatomy Mandibular molars may have extramesial and/or distal canal in some cases.

17. Missed canals can be located by:- • Taking radiographs (SLOB TECHNIC) Explorer pressure: It can help to identify a missed canal. Firm explorer pressure is used to punch through a thin layer of secondary dentin (DG 16 & CK 17)

18. Transillumination: A fiber optic wand either above or below the rubber dam and directing light buccal to lingual. Diagnostics are, at times, improved by turning off the overhead or microscope light source to achieve a different optical effect

19. • Use of magnifying glasses or endomicroscope • Accurate access cavity preparation • Use of piezoelectric ultrasonics: The working ends of specific ultrasonic instruments are 10 times smaller than the smallest manufactured round burs and their abrasive coatings allow them to precisely prepare away dentin when exploring for missed canals.

20. Use of dyes such as methylene blue: can be irrigated into the pulp chambers of teeth to aid in diagnosis. The chamber is subsequently rinsed thoroughly with water, dried and visualized. Frequently the dye will be absorbed into orifices, fins and isthmus areas and serves to “roadmap” the anatomy.

21. • Use of sodium hypochlorite: After thorough cleaning and shaping, pulp chamber is filled with sodium hypochlorite. If bubbles appear in, it indicates either there is residual tissue present in a missed canal or residual chelator in the prepared canal. This is called Champagne test .

22. WHITE LINE TEST: During ultrasonic procedures necrotic canals, dentinal dust moves into available anatomical space, such as the isthmus, and forms a visible white line. The white line test is a visible road map that can be followed and diagnostically aid in identifying as an example an MB2 orifice or canal.

23. RED LINE TEST: In vital cases, blood frequently moves into an isthmus area. Like a dye, blood absorbs into orifices, and fins and isthmuses which serves to roadmap and aid in the identification of the underlying anatomy.

24. PERIO-PROBING: Probing the sulcus can provide important information as to the relationship between the long axis of the clinical crown and the underlying root as well as indicate possible root fracture.

25. SYMMETRY: The rules of symmetry suggest that if any given root contains only one canal, then regardless of its anatomical configuration, the orifice should be positioned an equal distance from the external cavosurface of the root.

26. COLOR: Color changes indicate developmental grooves in the pulp chamber floor. Oftentimes, a dark groove on the pulpal floor of a multi-canal tooth can be followed and will lead to another canal orifice. Additionally, orifices frequently appear a darker color than the surrounding dentin in teeth exhibiting mineralizati on. If discovered, missed canals can usually be thoroughly cleaned, shaped and sealed. However, if a missed canal is suspected but cannot be readily identified, then an endodontic referral may be prudent to avoid further complications. Caution should be exercised when contemplating surgery due to the aforementioned concerns, but at times, surgery may be necessary in the hopes of salvaging the tooth.

27. PREVENTION Good radiographs taken at different horizontal angulations Good illumination and magnification ( microscope, magnifying loupes & digital radiography) Adequate coronal access- follow principles of cavity preparation DG 16 explorer/ Microopeners Clinician should always look for an additional canal in every tooth being treated.

28. MICRO-OPENERS: Micro-openers have limited length cutting blades which, in conjunction with their 0.04 and 0.06 tapers , enhance tensile strength, making it easier to locate, penetrate, and perform initial canal enlargement procedures. These instruments provide unobstructed vision when operating in difficult teeth with limited access.

29. PROGNOSIS A missed canal decreases the prognosis and will most likely result in treatment failure. As long as the apical seal adequately seals both canals, it is possible that the bacterial content in a missed canal may not affect the outcome for some time

30. DAMAGE TO EXISTING RESTORATION Endodontic treatment of tooth with porcelain crown in challenging Crown may chip off during the procedure or during rubber dam placement CORRECTION Minor porcelain chips corrected by bonding composite resin to porcelain

31. PREVENTION Avoid placing clamp on margins Remove permanently cemented crown before treatment Specialized crown pliers can be used for crown removal Metalift crown & bridge system Ultrasonics

32. Video metalift

33. An existing porcelain crown presents the dentist with its own unique challenges. In preparing an access cavity through a porcelain or porcelain-bonded crown, the porcelain will sometimes chip, even when the most careful approach using water-cooled diamond stones is followed. There is usually no way to predict such an occurrence. Knowing when to exercise caution can, however, reduce unwanted results. A significant portion of all root canal procedures is performed through existing crowns.

34. CORRECTION Minor porcelain chips can at times be repaired by bonding composite resin to the crown. However, the longevity of such repairs is unpredictable.

35. PREVENTION Placing a rubber dam clamp directly on the margin of a porcelain crown is may result in damage to the crown margin and/or fracture of the porcelain. Even removal of a provisionally cemented new crown prior to endodontic therapy may also pose a problem. These crowns can be difficult to remove, and often a margin will be damaged, or the porcelain may chip.

36. Coronal disassembly If the restorative material is deemed inadequate or additional access is required, the restoration should be sacrificed. However on specific occasions it is desirable to preserve and remove the existing restorative dentistry.4 A clinician must obtain a good history, confer with the original treating dentist (if appropriate), consult with the patient and clearly define the risk versus benefit when entertaining the intact removal of an existing restoration. Grasping, Percussive and Active instruments can be used. According to Clark and Khademi12 (2010), cavosurface angle of access cavities differ according to the condition of the tooth, whether non mutilated, mutilated or restored. The 6 types of molar cavosurface and chamber access:

37. INSTRUMENTATION RELATED MISHAPS

38. LEDGE FORMATION Ledge is an internal transportation of the canal which prevents positioning of an instrument to the apex in an otherwise patent canal. Any deviation from original canal curvature without communication with PDL. An artificially created irregularity on the canal surface that prevents placement of instrument to the apex of otherwise patent root canal.

39. CAUSE Caused by forcing uncurved instruments apically short of working length in a curved canal Rotating the file at the working length causes deviation from the natural canal pathway, straightening of the canal, and the creation of a ledge in the dentinal wall Rapid advancement in file sizes or skipping file sizes.

40. RECOGNITION One may get suspicious that ledge has been formed when there is: Loss of tactile sensation at the tip of the instrument Loose feeling instead of binding at the apex. Instrument can no longer reach its estimated working length. When in doubt a radiograph of the tooth with the instrument in place is taken to provide additional information.

41. TREATMENT To negotiate a ledge, choose a smaller number file, usually No. 10 or 15 . Give a small bend at the tip of the instrument and penetrate the file carefully into the canal.

42. Once the tip of the file is apical to the ledge, it is moved in and out of the canal utilizing ultrashort push-pull movements with emphasis on staying apical to the defect. When the file moves freely, it may be turned clockwise upon withdrawal to rasp , reduce, smooth or eliminate the ledge. When the ledge can be predictably bypassed , then efforts are directed towards establishing the apical patency with a No. 10 file . Gently passing 0.02 tapered 10 file 1 mm through the foramen ensures its diameter is atleast 0.12 mm and makes the way for the 15 file .

43. PREVENTION Use of stainless steel patency files to determine canal curvature. Accurate evaluation of radiograph and tooth anatomy. Precurving of instruments for curved canals. Use of flexible NiTi files . Use of safe ended instruments with noncutting tips. Use of sequential filing. Avoids skipping instrument sizes. Frequently irrigation and recapitulation during biomechanical preparation. Preparation of canals in small increments. Modified files:- Flex R file Safety H file Flexofile

44. PROGNOSIS It depends on the amount of debris left in un-instrumented canal Unfilled portion of canal

45. PERFORATION According to glossary of endodontic terms (by AAE) the perforation is defined as “the mechanical or pathological communication between the root canal system and the external tooth surface”. Perforations can occur at any stage while performing endodontic therapy that is during access cavity preparation or during instrumentation procedures leading to canal perforations at cervical, midroot or apical levels.

46. Coronal perforation can occur during access cavity preparation If the perforation is above the periodontal attachment , leakage of saliva into cavity or sodium hypochlorite in mouth is the main sign. But if perforation occurs into the periodontal ligament , bleeding is the hallmark feature.

47. Root canal perforation can occur at three levels: 1. Cervical canal perforation: It commonly occurs while locating the canal orifice and flaring of the coronal third of the root canal. Sudden appearance of blood from canal is the first sign of perforation.

48. Sometimes canal system is improperly shaped which prevents three­dimensional obturation of the root canal space

49. CAUSE Insufficient preparation of the apical dentin matrix . Insufficient use of irrigants to dissolve tissues and debris. Inadequate canal shaping , which prevents depth of spreader or plugger penetration during compaction. Establishing the working length short of the apical constriction. Creation of ledges and blockages that prevent complete cleaning and shaping.

50. PREVENTION Under prepared canals are best managed by strictly following the principles of working length determination and biomechanical preparation. Copious irrigation and recapitulation during instrumentation ensure a properly cleaned canal.

51. CORRECTION OF THE CORONAL THIRD PERFORATIONS Anterior teeth where esthetics is the main concern, calcium sulfate barrier along with composites, glass ionomer cements and white MTA can be used for perforations repair. Posterior teeth where esthetics is not the main criteria, super EBA, amalgam, MTA can be used.

52. MID ROOT PERFORATION: CAUSE It commonly occurs in the curved canal when a ledge is formed during instrumentation along inside the curvature of root canal, as it is straightened out, i.e. strip perforation may result Usually it is caused by overinstrumentation and over­preparation of the thin wall of root or concave side of the curved canals . Sudden appearance of bleeding is the pathognomonic feature.

53. TECHNIQUE OF PLACEMENT OF MATRIX Attain the hemostasis and place files , silver cones or guttapercha points in the canals to maintain their patency. The hydroxyapatite (HA) particles are wetted with saline and clumped together for their easy transportation. The HA is deposited into perforation and condensed with pluggers. This will stop bleeding

54. Like this, completely fill the defect with HA Excess material is removed with excavator to the level of periodontal ligament. After that, a bur is used to prepare the perforation site to receive the material. Using a flat instrument, apply restorative material like amalgam or GIC to repair the perforation

55. CORRECTION OF PERFORATION IN MID ROOT LEVEL In these cases, the success of perforation repair depends on the hemostasis, accessibility and visibility, use of microinstrumentation techniques and selection the material for repair . If the defect is small and hemostasis can be achieved, perforation can be sealed and repaired during three dimensional obturation of the root canal. In case the perforation defect is large and moisture control is difficult, then one should prepare the canal before going for perforation repair.

56. Lemon in 1992 gave the internal matrix concept for the repair of inaccessible strip perforations using microsurgical technique. The rationale behind this concept was that a matrix was needed to control the material and thus preventing overfilling of the repair material into the periradicular tissues. Lemon suggested use of hydroxyapatite for this purpose. A material to be used as internal matrix should Be biocompatible Be sterile Be easy to manipulate Stimulate osteogenesis.

57. INDICATIONS OF MATRIX PLACEMENT Accessible perforations. Larger perforations in middle or apical thirds of the roots with straight canals. CONTRAINDICATIONS Inaccessible defects. Perforations on external root surface or above the level of crestal bone.

58. DISADVANTAGES OF MATRIX PLACEMENT TECHNIQUE Internal matrix cannot be used in all the cases. Radiographic evaluation of bone fill is difficult especially if radiodensities of materials and bone are same. Special device for placement of matrix, i.e. fiberoptic imaging technology is required.

59. APICAL ROOT PERFORATION: ­ CAUSE When instrument goes into periradicular tissue, i.e. beyond the confines of the root canal By overuse of chelating agents along with straight and stiffer large sized instruments to negotiate ledging, canal blockage or zipping , etc.

60. RECOGNITION Placing an instrument into the opening and taking a radiograph. Using paper point. Sudden appearance of bleeding. Complain of pain by patient when instrument touches periodontal tissue.

61. These types of perforations can be repaired both surgically as well as nonsurgically . But one should attempt nonsurgical repair before going for surgery. MTA is choice of material for perforation repair

62. CORRECTION Apply rubber dam and debride the root canal system. Dry the canal system with paper points and isolate the perforation site. Prepare the MTA material according to manufacturer’s instructions. Using the carrier provided, dispense the material into perforation site. Condense the material using pluggers or paper points.

63. While placing MTA, instrument is placed into the canal to maintain its patency and moved up and down in short strokes till the MTA sets. It is done to avoid file getting frozen in the MTA. Place the temporary restoration to seal chamber. In next appointment, one sees the hard set MTA against which obturation can be done.

64. PREVENTION Evaluation of the anatomy of the tooth before starting the endodontic therapy. Using the smaller, flexible files for curved canals. Do not skip the file sizes. Recapitulation with smaller files between sizes. Confirming the working length and maintaining the instruments within the confines of working length. Using anticurvature filling techniques in curved canals to selectively remove the dentin.

65. Minimizing the overuse of Gates-Glidden too deep or too large especially in curved canals. Avoiding overuse of chelating agents, larger stiff files in order to negotiate procedural errors like ledges, canal blockages, etc. Copious irrigation of the canal to prevent the canal blockage by dentin chips or tissue debris.

66. FACTORS AFFECTING PROGNOSIS OF PERFORATION REPAIR Location Size Visibility, accessibility also affects the perforation repair. Time Associated periodontal condition and strategic importance of tooth.

67. LOCATION: If perforation is located at alveolar crest or coronal to it, prognosis is poor because of epithelial migration and periodontal pocket formation. Perforation in the furcation area has the poor prognosis. Perforation occurring in midroot and apical part of root does not have communication with oral cavity and thus has good prognosis.

68. SIZE: A smaller perforation has less tissue destruction and inflammation, thus having better prognosis than larger sized perforation. Visibility, accessibility also affects the perforation repair

69. TIME The perforation should be repaired as soon as possible to discourage further loss of attachment and prevent sulcular breakdown.

70. Associated periodontal condition and strategic importance of tooth also influence the treatment plan of the perforation. If attachment apparatus is intact without pocket formation, nonsurgical repair is recommended where as in case of loss of attachment, surgical treatment should be planned

71. Esthetics influences the perforation repair and material to be used for repair of the perforation.

72. An ideal material for perforation repair should:- Adhere to preparation walls of the cavity and seal the root canal system. Be nontoxic Be easy to handle Be radiopaque Be dimensionally stable Be well tolerated by periradicular tissue Be nonabsorbable Not corrode Not to be affected by moisture Not stain periradicular tissues.

73. Commonly used materials for perforation repair include:- Amalgam, Calcium hydroxide, IRM, Super EBA, gutta-percha, MTA, and other materials include dentin chips hydroxyapatite, Glass ionomer cements and Plaster of Paris

74. For perforation repair, hemostatis are needed to control the hemorrhage and make the area dry so that optimal placement of restorative material can be accomplished. Materials which can be used as hemostatics include calcium hydroxide, calcium sulfate, freeze dried bone and/or MTA. Whichever is the material used, the ultimate goal is to seal the defect with a biocompatible material and maintain an intact periodontal attachment apparatus.

75. INSTRUMENT SEPARATION Instrument breakage is a common and frustrating problem in endodontic treatment which occurs by improper or overuse of instruments especially while working in curved, narrow or tortuous canals. CAUSES Variation from normal root canal anatomy Over use of damaged instruments Over use of dull instruments Inadequate irrigation Use of excessive pressure while inserting in canal Improper access cavity preparation.

76. Grossman, “A dentist who has not separated a tip of a file, reamer, or broach has not done enough root canals.” The incidence of instrument separation in permanent dentition was reported to be 0.25%–14%. Another study reported the incidence as 0.25% and 1.68% for hand and rotary instruments, respectively Grossman LI. Guidelines for the prevention of fracture of root canal instruments. Oral Surg Oral Med Oral Pathol 1969;28:746-52. Cheung GS, Liu CS. A retrospective study of endodontic treatment outcome between nickel-titanium rotary and stainless steel hand fi ling techniques. J Endod 2009;35:938-43.

77. RECOGNITION When an instrument fracture occurs, take a radiograph to evaluate Curvature and length of canal Accessibility of instrument Location of separated instrument Type of broken instrument that is whether stainless steel or NiTi Amount of dentin present around the instrument.

78. FILE BYPASS TECHNIQUE The key to bypass a file is establishing straight line access and patency with small instruments

79. The mechanism of instrument separation is different for stainless steel and NiTi files. Stainless steel instruments undergo separation due to the excessive amounts of torque and separation results from instrument overuse or the preexisting distortion of the instrument. For NiTi rotary files, it is a combined action of torsional stress and cyclic loading. Prajapati, et al.: Instrument separation in primary teeth Indian journal of Dentistry, 2018

80. The initial attempts should be made with number 6 or 8 file. In order to get past the broken instrument fragment, a small sharp bend should be given at the end of the instrument . Insert the file slowly and carefully into the canal. When the negotiation occurs past the fragment, one will find a catch . Do not remove file at this point. Use a small in and out movements along with copious irrigation of the root canal. While doing these movements, sometimes file may kink , and one may not be able to place the file in the canal to the same length.

81. In such cases, use new file with similar bend and repeat the above procedure. Once the patency with a No. 15 instrument is achieved, go to K reamers Waterhouse P, Whitworth J. Pediatric endodontics: endodontic treatment for the primary and young permanent dentition. In cohen’s pathways of the pulp. Kenneth Hargreaves, Stephen Cohen. 10th ed., St. Louis: Mosby; 2011. pp. 808–857

82. Use a “ place-pull/rotate/withdrawal ” movement rather than a filing motion. By this motion two things may occur: – The reamer will be deflected by the fragment and then there is need to find a consistent path of instrument insertion that is probably different than the initial path. – Every time one rotates the reamer, there will be a “clicking” sound as the flutes brush up against the file fragment. This is normal.

83. One must avoid placing an instrument directly on top of the broken file. This can push it deeper resulting in loss of patency. If the file is visible at this point, it is possible to use a small tipped ultrasonic instrument or 1/4 turn withdrawal ­type handpiece to dislodge and remove it.

84. INSTRUMENT RETRIEVAL In order to attempt file removal, exposure of fragment is mandatory. Modified Gates-Glidden can also be used to expose the instrument. Gates-Glidden is modified by removing their bottom half and thus creating a flat surface. The crown down technique using Gates-Glidden burs is carried out.

85. Once it is accomplished, use modified Gates-Glidden to enlarge the canal to a point where instrument is located; this way a platform is created which enable to visualize the broken fragment Lambrianidis T. Therapeutic options for the management of fractured instruments. In: Lambrianidis T. Management of Fractured Endodontic Instruments. 1st ed., Springer, Cham 2018. 75–195.

86. It creates a flat area of dentin surrounding the file fragment. Thereafter, small tipped ultrasonic instruments can be used around the instrument and eventually vibrate the file out of the canal The tip is used in a counter clockwise motion to loosen the file. Irrigation combined with ultrasonics can frequently flush it out at this point. If sufficient file is exposed, an instrument removal system can be used.

87. Special instruments used for retrieval of separated instrument are: Wire-loop technique Masserann kit Endo-extractor Instrument removal system Nonsurgical mechanical removal system Surgical removal of broken instrument.

88. MASSERANN KIT In masserann kit, an extractor is present into which the instrument to be retrieved is locked. It has assorted end cutting trepan burs which are large and rigid meant to be used only in coronal portion of straight canals.

89. Steps for retrieving instruments using masserann kit Enlarge the canal orifice using a round bur. Gain a straight line access to fractured instrument using Gates-Glidden drills. Move end cutting trepan burs slowly in anticlockwise direction so as to free 4 mm of the fragment. These burs can be used by hand or with reduction gear contra­angle handpiece at the speed of 300 to 600 rpm . Take extractor and slide it over free end of the fragment. Firmly hold the extractor in place and rotate the screw head until the fragment as gripped. Once gripped tightly, move extractor in anticlockwise direction for removal of all cutting root canal instruments and in clockwise direction for removing filling instruments.

90. USE OF ENDO-EXTRACTOR In endo-extractor, cyanoacrylate adhesive is place on it so as to lock the object into the extractor. Technique for removal is same as that for Masserman extractor.

91. INSTRUMENT REMOVAL SYSTEM Instrument removal system consists of different size of microtubes , and inserts wedges which fit into separated instrument. Microtube has 45° bevelled end and a handle..

92. Technique of using IRS Gain straight line access to the canal. Select a microtube and insert it into the canal. After this guide the head of the broken instruments into the lumen of the microtube. Place an insert wedge through the open end of microtube till it comes in contact with separated instrument. Turn the insert wedge clockwise to engage the instrument. Finally move the microtube out of canal to retrieve the separated instrument

93. If it is very difficult to remove the fractured instrument, incorporate the instrument fragment in the final obturation.

94. NONSURGICAL MECHANICAL REMOVAL SYSTEM It consists of burs, ultrasonic tips and loop device for removal of broken instrument

95. Before removal of fractured instrument, the canal should be enlarged and so as to gain straight line access and exposure of the instrument. For this Gates-Glidden drills or greater taper files can be used Once the file is exposed, remove it using loop device

96. Surgical treatment for removal of broken fragment is indicated when:- Broken file is behind the curve. File fragment is not visible because of the curved root. Instrument is in the apical part of the canal and is difficult to retrieve Much of dentin has to be removed to allow file removal.

97. PROGNOSIS Prognosis of separated instrument depends upon following factors: • Timing of separation Status of pulp tissue Position of separated instrument Ability to retrieve or by pass the instrument. Spili P, Parashos P, Messer HH. The impact of instrument fracture on outcome of endodontic treatment. J Endod 2005;31(12):845–850. DOI: 10.1097/01.don.0000164127.62864.7c.

98. Separated instrument are not the prime cause of endodontic failure but separated instruments impede mechanical instrumentation of the canal, which may cause endodontic failure. Studies have shown that instrument separation in root filled teeth with necrotic pulps results in a poorer prognosis. Also if instrument separates at later stages of instrumentation and close to apex, prognosis is better than if it separates in undebrided canals, short of the apex or beyond apical foramen.

99. PREVENTION Examine each instrument before placing it into the canal. Instead of using carbon steel, use stainless steel files. Use smaller number of instruments only once. Parashos P, Messer H. Rotary NiTi instrument fracture and its consequences. J Endod 2006;32(11):1031–1043. DOI: 10.1016/j. joen.2006.06.008.

100. Always use the instruments in sequential order . Never force the instrument into the canal. Canals should be copiously irrigated during cleaning and shaping procedure. Never use instruments in dry canals . Always clean the instrument before placing it into the canal. Debris collected between the flutes retard the cutting efficiency and increase the frictional torque between the instrument and canal wall. Do not give excessive rotation to instrument while working with it.

101. Parashos P, Gordon I, Messer H. Factors influencing defects of rotary nickel titanium endodontic instruments after clinical use. J Endod 2004;30(10):722–725. DOI: 10.1097/01.don.0000129963.42882.c9.

102. Extraction of primary teeth was usually the most frequently followed treatment modality in case of instrument separation. Retention of the primary tooth can be done in case of intraradicular instrument separation if strict radiographic and clinical follow-up can be ascertained. Immediate extraction can be performed in following scenarios: Part of the separated instrument was extra radicular Necrotic teeth Questionable patient compliance with follow-up Contraindicated in certain medical conditions - e.g., known nickel allergy Musale PK, Kataria SC, Soni AS. Broken instrument retrieval with indirect ultrasonic in a primary molar. Eur Arch Paediatr Dent. doi : 10.1007/s40368-015-0203-y

103. GUIDELINES following guidelines can help a clinician decide when to discard an instrument during reuse: Flaws – shiny areas or unwinding of flutes Instrument bent or crimped Excessive precurving done Corrosion File kinks when an attempt is made to bend it. Excessively heating of instrument Dulling of NiTi instrument.

104. OBTURATION RELATED MISHAPS

105. UNDER FILLING/INCOMPLETELY FILLED ROOT CANALS UNDER FILLING, i.e. more than 2 mm short of radiographic apex occurs commonly because of procedural errors like Ledge formation, Blockage or Incomplete instrumentation of the root canal.

106. CAUSE Inaccurate working length determination. Inadequate irrigation and recapitulation during biomechanical preparation which can lead to accumulation of dentin chips and tissue debris, and thus canal blockage. If ledge is there which can be due to Large stiff files in curved canals. Inadequate straight line access to canals apices Inadequate irrigation . Skipping the file sizes during biomechanical preparation. Packing dentin chips, tissue debris in apical portion of the canal

107. SIGNIFICANCE Inadequate removal of infected necrotic tissue in the apical portion of the root canal results in persistent bacterial infection and thus initiation or perpetuation of existing periapical pathosis .

108. Thus fillings short of apex have shown poorer prognosis, especially in cases with necrotic pulp and periradicular pathosis .

109. PREVENTION Obtaining straight line access to canal orifices to apex. Precurving the files before using in curved canals. Copious irrigation and recapitulation of the canal

110. OVERFILLING Attaining apical patency. Using EDTA in vital cases especially to emulsify the pulp and remove it completely. Using the files sequentially. Clinician should feel the tensional binding of the file which exists at minor constriction of the apical foramen. Overfilling of the Root Canals is filling more than 2 mm beyond the radiographic apex