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Cleaning and shaping 2
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Cleaning and shaping 2

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Introduction to Endodontics

Introduction to Endodontics
Forth Year

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Cleaning and shaping 2 Cleaning and shaping 2 Presentation Transcript

  • CLEANING AND SHAPING 2
  • STEP DOWN/ CROWN DOWN PRESSURELESS TECHNIQUE  In this technique Gates- Glidden drills and larger size files are first used in the coronal 2/3rds of the root canal and progressively smaller files are used until the desired working length is achieved.  Main disadvantage of Step Back technique was extrusion of debris apically. This was prevented by this technique.  This technique provides a coronal escapeway that reduces the piston in a cylinder effect responsible for the extrusion from the apex. debris
  • CORONAL THIRD MIDDLE THIRD APICAL THIRD
  • TECHNIQUE: The canal is explored with a small instrument to assess patency and morphology Working length established The coronal third is flared with a Gates-glidden drill #2 or #3 [depending upon the initial anatomy of the root canal] A large file is introduced into the canal till resistance is felt [ using a watch winding motion] example size #35
  •  Now a smaller file [#30] is introduced into the canal to a depth greater than the initial file, till a resistance is felt.  Sequentially smaller files are introduced until the apical portion is reached  Lubricants and copious irrigation is necessary throughout these steps.  Final smoothening of the walls is accomplished with a a headstorm file [a size larger than the master file] used circumferentially
  • Clinical benefits of Crown-Down technique 1. Ease of removal of obstacles that prevent access to the root apex. 2. Enhanced tactile feed back with all instruments by removal of coronal interferences. 3. Increased space for Irrigant penetration and debridement 4. Rapid removal of dental pulpal tissue that is located in the coronal 1/3rd. 5. Straight line access to root curves and canal junctions. 6. Decrease in canal blockages
  • Biological benefits of the Crown-Down technique 1. Rapid removal of contaminated, infected tissue from the root canal system. 2. Removal of tissue debris coronally, thereby minimizing the pushing of debris apically. 3. Enhanced disinfection of canal irregularities due to increased irrigant penetration
  • PASSIVE STEP BACK TECHNIQUE A modification of the step back technique After determination of the apical diameter [example #30], next higher file [#35] is inserted until it makes contact [binding point] It is the rotated a half turn and withdrawn The process is repeated with larger and larger instruments. #30 → #35 → #40 → #45 → #50 → …..
  •  The entire sequence is then repeated .  Each time the instrument goes deeper than the previous time .  This creates a tapered preparation.
  • Advantage : The canal morphology dictates the preparation shape. Does not require a standardized measurement of incremental step back. Removal of debris and minor obstructions Gradual and passive enlargement of the canal in apical to coronal direction
  • ANTI CURVATURE FILING •Advocated during the coronal flaring of canals to prevent strip perforations •The walls on the opposite side from the curve are instrumented more than the inner walls resulting in a decrease of the overall degree of canal curvature. •Anti curvature approach can preserve dentinal thickness near the furcation •It also gives a more straight line access deeper into the canal
  • DANGER ZONE
  • BALANCED FORCE TECHNIQUE [ROANES TECHNIQUE] Introduced by ROANE Based on the fact that the canal walls guide the instruments An instrument normally cuts in both clock wise and counter clock wise motion. Technique consists of placing the instrument as apically as it can go and then rotating it clockwise [ less than 180 motion engages the dentin 0 ]. This
  •  This is followed by a counter clockwise rotation [of at least 120 0 ] with slight apical pressure to break the engaged dentin and enlarge the canal.  Small instruments --------- apical pressure is less  The clock wise rotation pulls the file apically while counter clock wise motion pulls it coronally.  There fore chances of the file getting screwed apically during the counter clock wise position is less.  This is repeated till the desired working length is obtained
  • Technique is carried out with modified K-files like Flex-R files A. K-FILE B. MODIFIED K-FILE
  • NICKEL TITANIUM [NiTi] ROTARY PREPARATION These instruments utilize the CROWN DOWN [STEP DOWN] technique Instruments of various tapers. Coronal third → 0.10/ 0.08 Middle third → 0.08/0.06 Apical third → 0.06/0.04
  • 0.06 / 6 % 0.04 / 4% 0.02 / 2% CONSTANT TIP DIAMETER
  • FINAL APICAL ENLARGEMENT AND APICAL CLEARING The canals are enlarged to a minimum of three sizes more than the first file that binds at the apex at full working length [ initial apical file (IAF) ]. The last file used for the preparation at the apex is called the Master Apical File [MAF]. After the MAF is reached the apex is cleared of all the debris by using the master file at the working length in a reaming action in the presence of an irrigant
  • RECAPTULATION:  Performed inbetween each successive enlarging file irrespective of the technique used. Involves the use of a small file to the whole working length. This helps in clearing the apical portion and removing the debris which gets collected there. Patency filing
  • COMBINATION TECHNIQUE: 1.Canal negotiation 2.Working length determination 3.Straight line access [enlarging the coronal third] 4.Initial apical file determination 5.Rotary preparation on the middle third of the root 6.Apical step back preparation 7.Apical clearing and establishing a MAF
  • ERRORS DURING INSTRUMENTATION
  • Transportation Moving the position of canal's normal anatomic foramen to a new location surface. on the external root
  •  Occurs mainly due to failing to precurve files, using large instruments.  When the instrument is overused - the elastic memory of the instrument may create the teardrop and tearing of the apical foramen  another form of external transportation is direct perforation. • begins with a ledge or apical blockage. • continues its misdirection until it perforates the root surface.
  • LEDGING Caused by – forcing uncurved instrument in a curved canal. – Rapid advancement in file size. • Identified by Loss of tactile sensation on instrument - loose feeling instead of binding at the apex.
  • STRIP PERFORATION
  • ELBOW