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12.Biomechanical Preparation final (2).ppt

Biomechanical Preparation

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Success in endodontic treatment depends almost completely on how well the root canal is shaped and cleaned. Because cleaning and shaping is the most important phase of endodontic treatment. o Cleaning refers to use of antimicrobial agents to remove microorganisms and pulpal debris from the entire root canal system.  Shaping produces a gradual smooth taper in the root canal with its widest part coronally and the narrowest part at the apical constriction, which is normally about 1 mm short of the apex. .
SCHILDER described five MECHANICAL objectives: I. Continuously tapering funnel from the apex to the access cavity. II. Cross-sectional diameter should be narrower at every point apically. III. The root canal preparation should flow with the shape of the original canal. IV. The apical foramen should remain in its original position. V. The apical opening should be kept as small as practical.
I. Confinement of instrumentation to the roots themselves. II. No forcing of necrotic debris beyond the foramen. III. Removal of all tissue and potential irritants from the root canal space. IV. Creation of sufficient space for intra- canal medicaments.
According to Grossman –  Thorough debridement of root canal.  Specific shaping of root canal preparation to receive a specific type of filling. To ensure thorough debridement and proper shaping for obturation certain principles must be followed.
 ENDODONTIC RADICULAR CAVITY PREPARATION A, Radiographic apex. B, Resistance Form,-development of “apical stop” at the CDJ against which filling is to be compacted and to resist extrusion of canal debris and filling material. C, Retention Form, to retain primary filling point. D, Convenience Form, needed to accommodate larger, less flexible instruments. E, Outline Form, basic preparation throughout its length dictated by canal anatomy
 1957- Richman first described a Root canal preparation technique utilizing ultrasonic energy  1961 – Ingle introduced the standardized technique for canal preparation.  1969 – The concept of step back technique first described by Clem and wiene  1971 – Weichman first suggested use of laser for root canal preparation  1974 – Schilder gave a detailed description of the serial step back technique  1980 – Marshall and Pappin described the Crown Down pressureless technique
 1980 – Abou Rass gave the anticurvature filing method for preparation of curved canals.  1982 – Goerig described the stepdown/or the Hybrid technique  1983 – Fava recommended the “ Double Flared” technique  1985 – Roane J.B and Sabal C.L introduced the “Balanced Force” concept  1993 – Lussi et al developed a non instrumented technique for cleaning root canals.  1994 – Mohmoud Torabinejad described passive step back technique
RULES FOR CLEANING AND SHAPING  According to Grossman following rules should be observed –  1. Direct access should be obtained along straight line.  2.Working length of root canal should be accurately determined.  3. Instrument should be used in sequence of size.  4. Barbed broach should be used cautiously and only when the root canal is wide enough to permit their insertion and rotation without binding.
 5. Instrument should be used with a quarter to half turn and withdrawn with a pull stroke.  6. Instrument should be fitted with instrument stop.  7. One must not force an instrument if it bind.
 8. Instrument should be confined to the root canal to prevent trauma to periradicular tissue.  9. Periodic recapitulation helps to prevent the packing of dentin filings and ensure patency of the root canal through to the apical foramen.  10. The apical portion of a root canal, 3 to 4 mm should be enlarged to facilitate the flow of irrigant to the biologically crucial apical third.  11. The remainder of root canal should be enlarged to maintain the original tapered canal configuration.
 12. Debris should not be force through the apical foramen  13. All instrumentation should be done using sterile instrument in a wet canal.  14. Instrument should be checked for deformation and discarded if strain is present.  15.Always precurve the file before instrumentation.
PRE-ENLARGEMENT PRE-ENLARGEMENT sufficient space to introduce files and irrigating solutions deeper the bacterial count in coronal aspects reduced the increased space allows files to fit passively in the canal •inoculation of infected material into the periapical tissues less increasing tactile sense and control when using files in the apical third Working length is more accurate because there is a more direct path to the canal terminus.
1. 1. Manual Manual 2. 2. Automated or rotary Automated or rotary 3. 3. Ultrasonic and sonic preparation Ultrasonic and sonic preparation 4. 4. LASER preparation LASER preparation 5. 5. Non Instrumentation Technique (NIT) Non Instrumentation Technique (NIT)
Hybrid technique Hybrid technique Step back step down combination procedure Step back step down combination procedure Apical coronal preparation technique Apical coronal preparation technique Coronal apical preparation technique Coronal apical preparation technique Apical coronal Apical coronal Standardized preparation Standardized preparation Step back preparation & modifications Step back preparation & modifications Coronal apical Coronal apical Step down tech Step down tech Double flare tech Double flare tech crown down pressureless tech crown down pressureless tech Manual Manual
Passive step back preparation Step back preparation Standardized preparation Apico coronal techniques:
Double flared technique Hybrid technique Step down technique Corono-apical techniques: Crown down pressure less technique
Hand preparation techniques Automated preparation techniques Depending on the Depending on the source of power source of power
 FILING: performed by a push pull action . When the slight curvature is present, the forceful pushing in of a K type file may damage the canal wall. During the inward push, the cutting force is a combination of both resistance to bending and the apically directed hand pressure. These two forces combine at the junctional angle of the instrument tip and perforate the curving canal wall very quickly.
 With Hedstrom type instruments, filing is effective during withdrawal motions as they do not engage during insertion action. A major limitation of filing with a Hedstrom is that it can cut through only the middle of a curvature. Excessive filing can cause strip perforation of the side of the root.
 Reaming: The term ‘ream’ means to enlarge the bore. The cutting edges of endodontic files and reamers are in spiral design around the shaft of the instrument. Due to this configuration, they slide into the canal as the edges rotate clockwise.
As they slide into the canal, more and more of the length of the instrument is engaged into the canal. This in turn increases the strain or working load on the instrument. If it gets stuck, stop any further rotation at once. It should be gradually and gently withdrawn after giving one quarter anti clock wise turn.
 The least aggressive instrument action  Quarter turn using small size #8 and #10 to reach working length
Standardized technique : Ingle (1961) described first formal canal technique. In this technique each instrument was introduced to working length resulting in a canal shape that matched the taper and size of the final instrument. It is also known as “single length technique”
 Currently used with Protaper and MTwo NiTi rotary instruments.  After final shaping of canal with last instrument used in canal, a single matching gutta percha point may then be used for root canal filling.
Disadvantages: In small curved root canals Ledging, zipping, elbow formation, perforation and loss of working length owing to compaction of dentin debris Hourglass preparation
STEP BACK PREPARATION  At first CLEM AND WEINE introduced the step back technique. Which relies on stepwise reduction of WL for larger files, typically in 1 or 0.5 mm steps, resulting in flared shapes with 0.05 and 0.10 taper.  Later on MULLANEY described the step back technique effective for fine canals. He divided the step back into two phases.
STEP BACK PREPARATION STEP BACK PREPARATION PHASES Phase I (Apical preparation) Phase II ( Remainder of canal) -Phase IIA -Phase IIB
PHASE I •WL established ,1st active No.8,10, 15 lubricated •Motion- watch winding – 2 to 3 turns clockwise- counter clockwise,retraction •Apical preparation upto the file #25(MAF)to full WL •With recapitulation using prior size
PHASE II •Stepping back in increments with recapitulation using # 25 file to ensure patency to the constriction with irrigation (step back up the canal 1mm and larger instrument at a time)
PHASE II A
• Return to # 25 last file (MAF) • Short of working length to smooth the step back with vertical push- pull strokes (circumferential filing) to perfect the taper. H files used.
Recapitulation. Small files are used often to working length to loosen debris to permit removal by irrigation. A stylized step-back (telescopic) preparation.
Sequencing during preparation. “final prep should be exact replica of original canal configuration ,”
Advantages Advantages  Keeps apical prep small in its original position- gradual taper Keeps apical prep small in its original position- gradual taper avoids apical irritation avoids apical irritation  Greater taper coronally compared to standard prep more dentin Greater taper coronally compared to standard prep more dentin removal and cleaner walls removal and cleaner walls Disadvantages Disadvantages  Chances of pushing debris into peri-radicular tissues Chances of pushing debris into peri-radicular tissues  Working Length likely to change as canal curvatures are Working Length likely to change as canal curvatures are eliminated eliminated  Tendency for canal deviation when large inflexible instrument is Tendency for canal deviation when large inflexible instrument is used. used.
Modified Step-Back Technique  The preparation is completed in the apical area, and then the step-back procedure begins 2 to 3 mm up the canal. This gives a short, almost parallel retention form to receive the primary gutta-percha point when lateral condensation is being used to fill the canal.
4. Passive step back  Developed by Torabinejad uses a combination of hand and rotary instrumentation to develop flared preparation.  Gradual enlargement of root in apical to coronal without application of force ,rotating at 1/8 to one quarter turn  Establish working length with small K-file.  Use passive instrumentation with progressively larger K-files. This step establishes a minimally flared canal before inserting Gates- Glidden burs.  Use Nos. 2, 3, and possibly 4 Gates-Glidden burs to flare the coronal one third.  Prepare the apical stop, and use a step-back apical preparation to blend with the coronal step-back flare. Advantage :  Reduces risk of apical transportation, removal of debris and canal obstruction, gradual passive enlargement  Also advocated for use with ultrasonic instrument
 It was given by Lim and stock in 1987.  It is a movement of file around the circumference of canal while moving it in small vertical movements of 1to 3 mm amplitude.  It is a method of filing whereby K or H file is first placed on the buccal side of the canal, then reinserted and placed mesially, then lingually and then distally until all walls have received planing.  It is used for enhancing flaring, in oval root canals.  Advantages:  It maintains spatial relationship of root canal in root.  Achieves rapid cutting of dentin.
Goerig et al (1982) proposed the concept of first instrumenting the coronal third of the root canal before apical shaping was first advocated. Objectives-  To minimize or eliminate the amount of necrotic debris that could be extruded through the apical foramen during instrumentation.  To prevent post-treatment discomfort, incomplete cleansing, and difficulty in achieving a biocompatible seal at the apical constriction.  By first flaring the coronal two thirds of the canal, the final apical instruments are free through most of their length. This increased access allows greater control and less chance of zipping near the apical constriction.  It “provides a coronal escape way that reduces the “piston in a cylinder effect” responsible for debris extrusion from the apex.
Advantages Permit straight line access to apical region Eliminates coronal interference Elimination of debris and microorganisms from the more coronal parts of the root canal system thereby preventing inoculation of apical tissues with contaminated debris;
 Early movement of large volumes of irrigant and lubricant to the apical part of the canal;  Facilitation of accurate working length determination as coronal curvature is eliminated early in the preparation.  Decreased deviation of instruments in canal curvatures by reducing root wall contact.  Decrease in canal blockages;  Minimization of instrument separation by reducing contact with canal walls;  Faster preparation which may allow one-visit root canal treatment.
PROCEDURE OF CROWN DOWN  Patency with small file  Preparation of coronal two third of canal using H files of size 15,20 and 25 to a point where the file start binding.  Flaring of the coronal segment of the canal with the help of GG drill  Apical instrumentation with a small size 10 or 15 k file followed by WL determination.  Large size file 60 is placed into canal and instrumented using a watch winding motion untill resistance is encounterd.
 The process is repeated with sequentially smaller files until the working length is reached.  Canal should be irrigated with appropriate irrigants in between each change of the instruments to facilitate debridement and cleaning of canals.
 This technique suggested by MARSHALL AND PAPPIN this involves the early coronal flaring with GG drill followed by incremental removal of dentin from coronal to apical direction.  Straight K files are then used in a large to small sequence with a reaming motion with no apical pressure hence called pressureless technique.  After completion of coronal access a provisional WL is determined and a size 35 k file is introduced into the canal with no apical directed pressure.
 GG drill no 2 is used to the depth explored with a size 35 k file followed by no 3 and 4 sequentially shorten the established length.  Use the 60 file to enlarge the canal followed by sequentially smaller file deeper into the canal.
The achievements with this technique of root canal cleaning and shaping may be affected by the following considerations  Clinician desire to learn and skill level developed in application  Use of end-cutting rotary instruments in small or partially calcified canals, possibly predisposing canal to perforation as the instrument moves apically.
Use a Flex-R file, Flex-o-File, or any other flexible triangular file with a modified non-cutting tip. Establish radicular access by step-down or crown-down techniques before preparing the apical one third of the canal.
 Phase I – File Insertion: This is accomplished by reciprocating the handle of the file in a back and forth motion until it feels snug. The handle of the file is turned in 90 degrees. CW rotation to draw the instrument down and move its cutting blades deeper into the canal and engage dentin.
 Phase II – File Cutting: During this phase simultaneous forces are applied on the file handle. The file handle is rotated CCW 120-180while being pushed apically. When rotated CCW, the tendency of the file to back out of the canal is balanced by the force of the file being pushed into the canal. After the first cutting cycle, the instrument is extended slightly deeper into the canal as in Phase I.
The Phase II cutting cycle is then repeated. Phase I and II can be repeated between 2-4 times. Phase III – Flute Loading – The cut dentin lies partially in the inner blade space of the file and partially in the canal just apical to the instrument.
• Step 1: After pressureless insertion of a Flex-R or NiTi Flex Step 1: After pressureless insertion of a Flex-R or NiTi Flex K-file, the instrument is rotated clockwise 90 degrees K-file, the instrument is rotated clockwise 90 degrees using only light apical pressure. using only light apical pressure. • Step 2: The instrument is rotated counterclockwise 180 to Step 2: The instrument is rotated counterclockwise 180 to 270 degrees; sufficient apical pressure is used to keep the 270 degrees; sufficient apical pressure is used to keep the file at the same insertion depth during this step. Dentin file at the same insertion depth during this step. Dentin shavings are removed with a characteristic clicking sound. shavings are removed with a characteristic clicking sound. • Step 3: This step is similar to step 1 and advances the Step 3: This step is similar to step 1 and advances the instrument more apically. instrument more apically. • Step 4: After two or three cycles, the file is loaded with Step 4: After two or three cycles, the file is loaded with dentin shavings and is removed from the canal with a dentin shavings and is removed from the canal with a prolonged clockwise rotation. prolonged clockwise rotation.
The main advantages of the Balanced force technique are  Good apical control of the file tip as the instrument does not cut over the complete length,  good centring of the instrument because of the non-cutting safety tip, and  no need to pre-curve the instrument
8.DOUBLE FLARED TECHNIQUE  Use straight files in a larger-to-smaller sequence, progressively and passively, moving them further into the canal until the apical one third is reached. No binding of instruments should occur.  Use frequent irrigation to remove contents and to aid in cleaning apical one third.  Establish working length with small K-file.  Use larger-to-smaller files until full working length is reached.  Prepare the apical stop, and use a step-back apical preparation to blend with the coronal step-down flare.  Circumferentially file the canal with the master K-file.
It involved preparation into the bulkier parts of the canal wall, that is the buccal, lingual and mesial aspects, avoiding the furcal wall.
 Anti curvature filing is a method of applying instrument pressure so that filing is done to reduce the curvature in the coronal and middle third of a canal.
 Richman (1957) 1st use of ultrasonics in endodontics.  Endosonics is based on a system in which sound as an energy source (at 20- 40kHz) activates an endodontic file resulting in 3D activation of the file in the surrounding medium.  Ultrasonic devices are driven by magnetostriction or piezoelectricity, resulting in oscillation (25–40 kHz) of the inserted file which initiates acoustic microstreaming in the irrigation fluid
difference in ultrasonic vibrations noted in a straight versus a curved canal. Instrument and irrigation patterns may be very active in the straight canal (left). The curve dampens the energy of the file and reduces or eliminates its vibratory action (right).
The major advantage to ultrasonics is the relative ease of operation. If the file can vibrate freely; they can effectively and efficiently remove dentin and debris from the canal walls. Also; there is the potential for increased irrigant action if they vibrate freely.
The disadvantage is that The disadvantage is that the instruments are the instruments are expensive; somewhat expensive; somewhat cumbersome to use. The cumbersome to use. The major technical major technical drawback is the lack of drawback is the lack of vibration when the vibration when the instrument contacts the instrument contacts the canal walls. canal walls.
 Types: special hand pieces are available to which root canal instruments of various designs are attached.  The hand pieces are attached to the high speed airline of the dental unit; and during use; the attached instruments vibrate and whip at a frequency of 1,500 – 8,000 vibrations per second.  Irrigating solution; usually water from the delivery system; passes along the file into the canal.
 Although the vibrations are considerably less than those of the ultrasonic instrument, the sonic hand piece appears to be as or more effective than the ultrasonic system.
Laser stands for Light Amplification by Stimulated Emission of Radiation
 Laser light travels in straight direction therefore specific light emitting probes have been developed to direct laser energy not only straight but also into curved canal.  Kesler et al (2002) observed that enlargement and cleaning of straight canals with an Er;YAG laser was found to be effective and in fact faster than with step back preparation with K files.
 The technique requires widening the root canal by The technique requires widening the root canal by conventional methods before the laser probe can be placed conventional methods before the laser probe can be placed in the canal. The fiber’s diameter, used inside the canal in the canal. The fiber’s diameter, used inside the canal space, ranges from 200 to 400 µm, equivalent to a No. 20- space, ranges from 200 to 400 µm, equivalent to a No. 20- 40 file 40 file
 However, the performance of this equipment, concerning However, the performance of this equipment, concerning safe and effective wavelength and energy levels related to safe and effective wavelength and energy levels related to temperature rise, morphologic changes, and microbial temperature rise, morphologic changes, and microbial reduction, should be well documented before it becomes a reduction, should be well documented before it becomes a current method of treatment. current method of treatment.  Safety precautions used during laser irradiation include Safety precautions used during laser irradiation include safety glasses specific for each wavelength (compatible safety glasses specific for each wavelength (compatible optical density to filtrate that wavelength), warning signs, optical density to filtrate that wavelength), warning signs, and high-volume evacuation close to the treated area (used and high-volume evacuation close to the treated area (used in soft tissue procedures, cavity preparation, etc). in soft tissue procedures, cavity preparation, etc).
 Stabholz and colleagues recently reported the development of a new endodontic tip that can be used with an Er:YAG laser system. The Er:YAG laser is delivered through a hollow tube, making it possible to develop an endodontic tip that allows lateral emission of the irradiation, rather than direct emission through a single opening at its far end.
 This new endodontic side firing spiral tip was designed to fit the shape and volume of root canals prepared by Ni-Ti rotary instruments. It emits the Er:YAG laser irradiation laterally to the walls of the root canal through a spiral slit located all along the tip. The tip is sealed at its far end, preventing the transmission of radiation to and through the apical foramen of the tooth
 Limitations  Not accessible for severely curved canal  Cost of equipment is high  Operator and patient safety are of concern
Based on the premise that “Optimal cleansing of the root canal system is a prime prerequisite for long term success in endodontics,” Lussi and his associates at the University of Bern, Switzerland, introduced devices to cleanse the root canal “without the need of endodontic instrumentation.”
NON INSTRUMENTATION NON INSTRUMENTATION TECHNIQUE TECHNIQUE ( NIT ) ( NIT )  Lussi and his associates at the University of Bern, Switzerland, introduced devices to cleanse the root canal “without the need of endodontic instrumentation.  The first device, reported in 1993,  Consisted of a “pump” that inserted an irrigant into the canal, creating “bubbles” and cavitation that loosened the debris.  This pressure action was followed by a negative pressure (suction) that removed the debris: “
Loss of Working Length  It is a very common and frustrating error usually noted on a master cone radiograph.  It is actually secondary to the other procedural errors. Maintaining Proper Working Length During Canal Cleaning and Shaping  Sound reproducible reference points should be used.  Firm or secure rubber stops should be placed at right angles to the shaft of the instruments.  All instruments should be curved with sterile 2 x 2-inch gauze, over curving them in the apical one third will compensate for some loss of curvature once in the canal. .  The instrument stops should be continually observed as they approach the reference points.
 Directional instrument stops should be used. The direction of the stop must be observed constantly to maintain files in their proper relationship to the canal anatomy  Consistent radiographic angles should be used when radiographically verifying the instrument position.  The original preoperative shape of the canal should be maintained and cleaning and shaping should be done within these confines.  Copious irrigation and recapitulation should be used throughout cleaning and shaping procedures.  Sequential file sizes should be used
Blockage of the Canal System Blockage of the Canal System A blockage is an obstruction in a previously patent canal A blockage is an obstruction in a previously patent canal system that prevents access to the apical constriction or system that prevents access to the apical constriction or apical stop. apical stop. The packing of dentin chips, tissue debris, restorative The packing of dentin chips, tissue debris, restorative materials, cotton pellets, paper points, or a fractured materials, cotton pellets, paper points, or a fractured instrument in the canal are common causes of blockages. instrument in the canal are common causes of blockages.
To avoid canal blockage-  Always use the smaller sized instruments first.  Use instruments in sequential order.  Always precurve stainless steel hand instruments.  Use reproducible reference points and silicon stopper on instruments while cleaning and shaping.
 Use copious amounts of irrigants and always work in a wet canal.  Recapitulate repeatedly.  Disposed off used instruments.
Ledging A ledge is 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. Ledging is caused by the insertion of uncurved instruments short of the working length with excessive amounts of apical pressure.
 Common causes for ledging-  Incorrect assessment of root canal curvature.  Erroneous root canal length determination.  Forcing the instrument into the canal.  Inadequate irrigation and lubrication during instrumentation.  Over relying on chelating agents  Attempt to retrieve broken instruments  Attempting to prepare calcified canals.
 Prevention of ledge formation-  Assess the usual root curvature by preoperative radiograph.  Maintained the patency of canal  Periodic recapitulation  Work passively without forcing the instrument  Work sequentially increasing the size of instrument.
 Ledge management  Early recognition of ledge  Precurve the apical 3-4 mm of the file with the same curvature as seen in radiograph and tease the file until it able to bypass the ledge.  If the ledge is closer to apical terminus complete the canal cleaning and obturate with an injectable thermoplasticize obturation technique.
Breakage of Instruments in the Canal Separated (broken) instruments within the root canal system are a potential hazard during root canal treatment. The possibility of instrument separation is enhanced remarkably when the instrument is used incorrectly. In most clinical situations, the instrument fractures that occur in the apical one third of the canal are almost impossible to remove or bypass, especially in cases of small, tight canals.
 An artificial opening in a tooth or its root , created by boring, piercing , cutting or pathologic resorption, which results in a communication between the pulp space and the periodontal tissues  Causes - Caries - Resorptive defects - Iatrogenic events
This type of perforation occurs through the apical foramen or through the body of the root. Etiology: Instrumentation of canal beyond the apical foramen. Incorrect WL or inability to maintain proper WL causes blowing out of the apical foramen Treatment: establish a new WL, creating an apical seat and obturating the canal to its new length. The new WL should be established 1-2mm short of the point of perforation.
Zipping refers to transposition or transportation of the apical portion of the canal. A normally curved canal that has been straightened, especially in the apical one third. The main reasons for zipping are (1) a failure to precurve files, (2) rotation of instruments in curved canals, and (3) the use of large, stiff instruments to bore out a curved canal. DEVIATIONS FROM THE NORMAL CANAL ANATOMY DEVIATIONS FROM THE NORMAL CANAL ANATOMY In these situations, the In these situations, the apical foramen will tend to apical foramen will tend to become teardrop shaped or become teardrop shaped or elliptical and be elliptical and be transported from the curve transported from the curve of the canal. of the canal.
Stripping or lateral perforation Stripping refers to a thinning of the lateral root wall with eventual perforation. Stripping is primarily caused by overzealous instrumentation in the midroot areas of certain teeth, usually molars that have curved roots and canals.
Mechanical preparation of the root canal may result in a Mechanical preparation of the root canal may result in a significant reduction of bacteria but will not significant reduction of bacteria but will not reproducibly leave bacteria-free root canals. reproducibly leave bacteria-free root canals. Mechanical preparation of the root canal must be Mechanical preparation of the root canal must be assisted and completed by intense disinfection assisted and completed by intense disinfection protocols using appropriate irrigants and intracanal protocols using appropriate irrigants and intracanal medicaments. medicaments.
 Ingle Endodontics 6  Pathways of pulp 10th edition  Endodontic practice 12th edition  Castalluci vol 2  Endodontic theraphy 5th edition  DCNA modern endodntic practice 2004
12.Biomechanical Preparation final (2).ppt

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12.Biomechanical Preparation final (2).ppt

  • 2.
    Success in endodontictreatment depends almost completely on how well the root canal is shaped and cleaned. Because cleaning and shaping is the most important phase of endodontic treatment. o Cleaning refers to use of antimicrobial agents to remove microorganisms and pulpal debris from the entire root canal system.  Shaping produces a gradual smooth taper in the root canal with its widest part coronally and the narrowest part at the apical constriction, which is normally about 1 mm short of the apex. .
  • 3.
    SCHILDER described fiveMECHANICAL objectives: I. Continuously tapering funnel from the apex to the access cavity. II. Cross-sectional diameter should be narrower at every point apically. III. The root canal preparation should flow with the shape of the original canal. IV. The apical foramen should remain in its original position. V. The apical opening should be kept as small as practical.
  • 4.
    I. Confinement ofinstrumentation to the roots themselves. II. No forcing of necrotic debris beyond the foramen. III. Removal of all tissue and potential irritants from the root canal space. IV. Creation of sufficient space for intra- canal medicaments.
  • 5.
    According to Grossman–  Thorough debridement of root canal.  Specific shaping of root canal preparation to receive a specific type of filling. To ensure thorough debridement and proper shaping for obturation certain principles must be followed.
  • 6.
     ENDODONTIC RADICULARCAVITY PREPARATION A, Radiographic apex. B, Resistance Form,-development of “apical stop” at the CDJ against which filling is to be compacted and to resist extrusion of canal debris and filling material. C, Retention Form, to retain primary filling point. D, Convenience Form, needed to accommodate larger, less flexible instruments. E, Outline Form, basic preparation throughout its length dictated by canal anatomy
  • 7.
     1957- Richmanfirst described a Root canal preparation technique utilizing ultrasonic energy  1961 – Ingle introduced the standardized technique for canal preparation.  1969 – The concept of step back technique first described by Clem and wiene  1971 – Weichman first suggested use of laser for root canal preparation  1974 – Schilder gave a detailed description of the serial step back technique  1980 – Marshall and Pappin described the Crown Down pressureless technique
  • 8.
     1980 –Abou Rass gave the anticurvature filing method for preparation of curved canals.  1982 – Goerig described the stepdown/or the Hybrid technique  1983 – Fava recommended the “ Double Flared” technique  1985 – Roane J.B and Sabal C.L introduced the “Balanced Force” concept  1993 – Lussi et al developed a non instrumented technique for cleaning root canals.  1994 – Mohmoud Torabinejad described passive step back technique
  • 9.
    RULES FOR CLEANINGAND SHAPING  According to Grossman following rules should be observed –  1. Direct access should be obtained along straight line.  2.Working length of root canal should be accurately determined.  3. Instrument should be used in sequence of size.  4. Barbed broach should be used cautiously and only when the root canal is wide enough to permit their insertion and rotation without binding.
  • 10.
     5. Instrumentshould be used with a quarter to half turn and withdrawn with a pull stroke.  6. Instrument should be fitted with instrument stop.  7. One must not force an instrument if it bind.
  • 11.
     8. Instrumentshould be confined to the root canal to prevent trauma to periradicular tissue.  9. Periodic recapitulation helps to prevent the packing of dentin filings and ensure patency of the root canal through to the apical foramen.  10. The apical portion of a root canal, 3 to 4 mm should be enlarged to facilitate the flow of irrigant to the biologically crucial apical third.  11. The remainder of root canal should be enlarged to maintain the original tapered canal configuration.
  • 12.
     12. Debrisshould not be force through the apical foramen  13. All instrumentation should be done using sterile instrument in a wet canal.  14. Instrument should be checked for deformation and discarded if strain is present.  15.Always precurve the file before instrumentation.
  • 13.
    PRE-ENLARGEMENT PRE-ENLARGEMENT sufficient space tointroduce files and irrigating solutions deeper the bacterial count in coronal aspects reduced the increased space allows files to fit passively in the canal •inoculation of infected material into the periapical tissues less increasing tactile sense and control when using files in the apical third Working length is more accurate because there is a more direct path to the canal terminus.
  • 14.
    1. 1. Manual Manual 2. 2. Automatedor rotary Automated or rotary 3. 3. Ultrasonic and sonic preparation Ultrasonic and sonic preparation 4. 4. LASER preparation LASER preparation 5. 5. Non Instrumentation Technique (NIT) Non Instrumentation Technique (NIT)
  • 15.
    Hybrid technique Hybrid technique Stepback step down combination procedure Step back step down combination procedure Apical coronal preparation technique Apical coronal preparation technique Coronal apical preparation technique Coronal apical preparation technique Apical coronal Apical coronal Standardized preparation Standardized preparation Step back preparation & modifications Step back preparation & modifications Coronal apical Coronal apical Step down tech Step down tech Double flare tech Double flare tech crown down pressureless tech crown down pressureless tech Manual Manual
  • 16.
    Passive step back preparation Stepback preparation Standardized preparation Apico coronal techniques:
  • 17.
  • 18.
    Hand preparation techniques Automated preparation techniques Depending onthe Depending on the source of power source of power
  • 19.
     FILING: performed bya push pull action . When the slight curvature is present, the forceful pushing in of a K type file may damage the canal wall. During the inward push, the cutting force is a combination of both resistance to bending and the apically directed hand pressure. These two forces combine at the junctional angle of the instrument tip and perforate the curving canal wall very quickly.
  • 20.
     With Hedstromtype instruments, filing is effective during withdrawal motions as they do not engage during insertion action. A major limitation of filing with a Hedstrom is that it can cut through only the middle of a curvature. Excessive filing can cause strip perforation of the side of the root.
  • 21.
     Reaming: The term‘ream’ means to enlarge the bore. The cutting edges of endodontic files and reamers are in spiral design around the shaft of the instrument. Due to this configuration, they slide into the canal as the edges rotate clockwise.
  • 22.
    As they slideinto the canal, more and more of the length of the instrument is engaged into the canal. This in turn increases the strain or working load on the instrument. If it gets stuck, stop any further rotation at once. It should be gradually and gently withdrawn after giving one quarter anti clock wise turn.
  • 23.
     The leastaggressive instrument action  Quarter turn using small size #8 and #10 to reach working length
  • 24.
    Standardized technique : Ingle(1961) described first formal canal technique. In this technique each instrument was introduced to working length resulting in a canal shape that matched the taper and size of the final instrument. It is also known as “single length technique”
  • 26.
     Currently usedwith Protaper and MTwo NiTi rotary instruments.  After final shaping of canal with last instrument used in canal, a single matching gutta percha point may then be used for root canal filling.
  • 27.
    Disadvantages: In small curvedroot canals Ledging, zipping, elbow formation, perforation and loss of working length owing to compaction of dentin debris Hourglass preparation
  • 28.
    STEP BACK PREPARATION At first CLEM AND WEINE introduced the step back technique. Which relies on stepwise reduction of WL for larger files, typically in 1 or 0.5 mm steps, resulting in flared shapes with 0.05 and 0.10 taper.  Later on MULLANEY described the step back technique effective for fine canals. He divided the step back into two phases.
  • 29.
    STEP BACK PREPARATION STEPBACK PREPARATION PHASES Phase I (Apical preparation) Phase II ( Remainder of canal) -Phase IIA -Phase IIB
  • 30.
    PHASE I •WL established,1st active No.8,10, 15 lubricated •Motion- watch winding – 2 to 3 turns clockwise- counter clockwise,retraction •Apical preparation upto the file #25(MAF)to full WL •With recapitulation using prior size
  • 31.
    PHASE II •Stepping backin increments with recapitulation using # 25 file to ensure patency to the constriction with irrigation (step back up the canal 1mm and larger instrument at a time)
  • 32.
  • 33.
    • Return to# 25 last file (MAF) • Short of working length to smooth the step back with vertical push- pull strokes (circumferential filing) to perfect the taper. H files used.
  • 34.
    Recapitulation. Small filesare used often to working length to loosen debris to permit removal by irrigation. A stylized step-back (telescopic) preparation.
  • 35.
    Sequencing during preparation. “finalprep should be exact replica of original canal configuration ,”
  • 37.
    Advantages Advantages  Keeps apicalprep small in its original position- gradual taper Keeps apical prep small in its original position- gradual taper avoids apical irritation avoids apical irritation  Greater taper coronally compared to standard prep more dentin Greater taper coronally compared to standard prep more dentin removal and cleaner walls removal and cleaner walls Disadvantages Disadvantages  Chances of pushing debris into peri-radicular tissues Chances of pushing debris into peri-radicular tissues  Working Length likely to change as canal curvatures are Working Length likely to change as canal curvatures are eliminated eliminated  Tendency for canal deviation when large inflexible instrument is Tendency for canal deviation when large inflexible instrument is used. used.
  • 38.
    Modified Step-Back Technique The preparation is completed in the apical area, and then the step-back procedure begins 2 to 3 mm up the canal. This gives a short, almost parallel retention form to receive the primary gutta-percha point when lateral condensation is being used to fill the canal.
  • 39.
    4. Passive stepback  Developed by Torabinejad uses a combination of hand and rotary instrumentation to develop flared preparation.  Gradual enlargement of root in apical to coronal without application of force ,rotating at 1/8 to one quarter turn  Establish working length with small K-file.  Use passive instrumentation with progressively larger K-files. This step establishes a minimally flared canal before inserting Gates- Glidden burs.  Use Nos. 2, 3, and possibly 4 Gates-Glidden burs to flare the coronal one third.  Prepare the apical stop, and use a step-back apical preparation to blend with the coronal step-back flare. Advantage :  Reduces risk of apical transportation, removal of debris and canal obstruction, gradual passive enlargement  Also advocated for use with ultrasonic instrument
  • 40.
     It wasgiven by Lim and stock in 1987.  It is a movement of file around the circumference of canal while moving it in small vertical movements of 1to 3 mm amplitude.  It is a method of filing whereby K or H file is first placed on the buccal side of the canal, then reinserted and placed mesially, then lingually and then distally until all walls have received planing.  It is used for enhancing flaring, in oval root canals.  Advantages:  It maintains spatial relationship of root canal in root.  Achieves rapid cutting of dentin.
  • 41.
    Goerig et al(1982) proposed the concept of first instrumenting the coronal third of the root canal before apical shaping was first advocated. Objectives-  To minimize or eliminate the amount of necrotic debris that could be extruded through the apical foramen during instrumentation.  To prevent post-treatment discomfort, incomplete cleansing, and difficulty in achieving a biocompatible seal at the apical constriction.  By first flaring the coronal two thirds of the canal, the final apical instruments are free through most of their length. This increased access allows greater control and less chance of zipping near the apical constriction.  It “provides a coronal escape way that reduces the “piston in a cylinder effect” responsible for debris extrusion from the apex.
  • 42.
    Advantages Permit straight lineaccess to apical region Eliminates coronal interference Elimination of debris and microorganisms from the more coronal parts of the root canal system thereby preventing inoculation of apical tissues with contaminated debris;
  • 43.
     Early movementof large volumes of irrigant and lubricant to the apical part of the canal;  Facilitation of accurate working length determination as coronal curvature is eliminated early in the preparation.  Decreased deviation of instruments in canal curvatures by reducing root wall contact.  Decrease in canal blockages;  Minimization of instrument separation by reducing contact with canal walls;  Faster preparation which may allow one-visit root canal treatment.
  • 44.
    PROCEDURE OF CROWNDOWN  Patency with small file  Preparation of coronal two third of canal using H files of size 15,20 and 25 to a point where the file start binding.  Flaring of the coronal segment of the canal with the help of GG drill  Apical instrumentation with a small size 10 or 15 k file followed by WL determination.  Large size file 60 is placed into canal and instrumented using a watch winding motion untill resistance is encounterd.
  • 48.
     The processis repeated with sequentially smaller files until the working length is reached.  Canal should be irrigated with appropriate irrigants in between each change of the instruments to facilitate debridement and cleaning of canals.
  • 49.
     This techniquesuggested by MARSHALL AND PAPPIN this involves the early coronal flaring with GG drill followed by incremental removal of dentin from coronal to apical direction.  Straight K files are then used in a large to small sequence with a reaming motion with no apical pressure hence called pressureless technique.  After completion of coronal access a provisional WL is determined and a size 35 k file is introduced into the canal with no apical directed pressure.
  • 50.
     GG drillno 2 is used to the depth explored with a size 35 k file followed by no 3 and 4 sequentially shorten the established length.  Use the 60 file to enlarge the canal followed by sequentially smaller file deeper into the canal.
  • 56.
    The achievements withthis technique of root canal cleaning and shaping may be affected by the following considerations  Clinician desire to learn and skill level developed in application  Use of end-cutting rotary instruments in small or partially calcified canals, possibly predisposing canal to perforation as the instrument moves apically.
  • 57.
    Use a Flex-Rfile, Flex-o-File, or any other flexible triangular file with a modified non-cutting tip. Establish radicular access by step-down or crown-down techniques before preparing the apical one third of the canal.
  • 58.
     Phase I– File Insertion: This is accomplished by reciprocating the handle of the file in a back and forth motion until it feels snug. The handle of the file is turned in 90 degrees. CW rotation to draw the instrument down and move its cutting blades deeper into the canal and engage dentin.
  • 59.
     Phase II– File Cutting: During this phase simultaneous forces are applied on the file handle. The file handle is rotated CCW 120-180while being pushed apically. When rotated CCW, the tendency of the file to back out of the canal is balanced by the force of the file being pushed into the canal. After the first cutting cycle, the instrument is extended slightly deeper into the canal as in Phase I.
  • 60.
    The Phase IIcutting cycle is then repeated. Phase I and II can be repeated between 2-4 times. Phase III – Flute Loading – The cut dentin lies partially in the inner blade space of the file and partially in the canal just apical to the instrument.
  • 61.
    • Step 1:After pressureless insertion of a Flex-R or NiTi Flex Step 1: After pressureless insertion of a Flex-R or NiTi Flex K-file, the instrument is rotated clockwise 90 degrees K-file, the instrument is rotated clockwise 90 degrees using only light apical pressure. using only light apical pressure. • Step 2: The instrument is rotated counterclockwise 180 to Step 2: The instrument is rotated counterclockwise 180 to 270 degrees; sufficient apical pressure is used to keep the 270 degrees; sufficient apical pressure is used to keep the file at the same insertion depth during this step. Dentin file at the same insertion depth during this step. Dentin shavings are removed with a characteristic clicking sound. shavings are removed with a characteristic clicking sound. • Step 3: This step is similar to step 1 and advances the Step 3: This step is similar to step 1 and advances the instrument more apically. instrument more apically. • Step 4: After two or three cycles, the file is loaded with Step 4: After two or three cycles, the file is loaded with dentin shavings and is removed from the canal with a dentin shavings and is removed from the canal with a prolonged clockwise rotation. prolonged clockwise rotation.
  • 64.
    The main advantagesof the Balanced force technique are  Good apical control of the file tip as the instrument does not cut over the complete length,  good centring of the instrument because of the non-cutting safety tip, and  no need to pre-curve the instrument
  • 65.
    8.DOUBLE FLARED TECHNIQUE Use straight files in a larger-to-smaller sequence, progressively and passively, moving them further into the canal until the apical one third is reached. No binding of instruments should occur.  Use frequent irrigation to remove contents and to aid in cleaning apical one third.  Establish working length with small K-file.  Use larger-to-smaller files until full working length is reached.  Prepare the apical stop, and use a step-back apical preparation to blend with the coronal step-down flare.  Circumferentially file the canal with the master K-file.
  • 68.
    It involved preparationinto the bulkier parts of the canal wall, that is the buccal, lingual and mesial aspects, avoiding the furcal wall.
  • 69.
     Anti curvaturefiling is a method of applying instrument pressure so that filing is done to reduce the curvature in the coronal and middle third of a canal.
  • 71.
     Richman (1957)1st use of ultrasonics in endodontics.  Endosonics is based on a system in which sound as an energy source (at 20- 40kHz) activates an endodontic file resulting in 3D activation of the file in the surrounding medium.  Ultrasonic devices are driven by magnetostriction or piezoelectricity, resulting in oscillation (25–40 kHz) of the inserted file which initiates acoustic microstreaming in the irrigation fluid
  • 72.
    difference in ultrasonicvibrations noted in a straight versus a curved canal. Instrument and irrigation patterns may be very active in the straight canal (left). The curve dampens the energy of the file and reduces or eliminates its vibratory action (right).
  • 73.
    The major advantageto ultrasonics is the relative ease of operation. If the file can vibrate freely; they can effectively and efficiently remove dentin and debris from the canal walls. Also; there is the potential for increased irrigant action if they vibrate freely.
  • 74.
    The disadvantage isthat The disadvantage is that the instruments are the instruments are expensive; somewhat expensive; somewhat cumbersome to use. The cumbersome to use. The major technical major technical drawback is the lack of drawback is the lack of vibration when the vibration when the instrument contacts the instrument contacts the canal walls. canal walls.
  • 75.
     Types: specialhand pieces are available to which root canal instruments of various designs are attached.  The hand pieces are attached to the high speed airline of the dental unit; and during use; the attached instruments vibrate and whip at a frequency of 1,500 – 8,000 vibrations per second.  Irrigating solution; usually water from the delivery system; passes along the file into the canal.
  • 76.
     Although the vibrationsare considerably less than those of the ultrasonic instrument, the sonic hand piece appears to be as or more effective than the ultrasonic system.
  • 78.
    Laser stands forLight Amplification by Stimulated Emission of Radiation
  • 79.
     Laser lighttravels in straight direction therefore specific light emitting probes have been developed to direct laser energy not only straight but also into curved canal.  Kesler et al (2002) observed that enlargement and cleaning of straight canals with an Er;YAG laser was found to be effective and in fact faster than with step back preparation with K files.
  • 80.
     The techniquerequires widening the root canal by The technique requires widening the root canal by conventional methods before the laser probe can be placed conventional methods before the laser probe can be placed in the canal. The fiber’s diameter, used inside the canal in the canal. The fiber’s diameter, used inside the canal space, ranges from 200 to 400 µm, equivalent to a No. 20- space, ranges from 200 to 400 µm, equivalent to a No. 20- 40 file 40 file
  • 82.
     However, theperformance of this equipment, concerning However, the performance of this equipment, concerning safe and effective wavelength and energy levels related to safe and effective wavelength and energy levels related to temperature rise, morphologic changes, and microbial temperature rise, morphologic changes, and microbial reduction, should be well documented before it becomes a reduction, should be well documented before it becomes a current method of treatment. current method of treatment.  Safety precautions used during laser irradiation include Safety precautions used during laser irradiation include safety glasses specific for each wavelength (compatible safety glasses specific for each wavelength (compatible optical density to filtrate that wavelength), warning signs, optical density to filtrate that wavelength), warning signs, and high-volume evacuation close to the treated area (used and high-volume evacuation close to the treated area (used in soft tissue procedures, cavity preparation, etc). in soft tissue procedures, cavity preparation, etc).
  • 83.
     Stabholz andcolleagues recently reported the development of a new endodontic tip that can be used with an Er:YAG laser system. The Er:YAG laser is delivered through a hollow tube, making it possible to develop an endodontic tip that allows lateral emission of the irradiation, rather than direct emission through a single opening at its far end.
  • 84.
     This newendodontic side firing spiral tip was designed to fit the shape and volume of root canals prepared by Ni-Ti rotary instruments. It emits the Er:YAG laser irradiation laterally to the walls of the root canal through a spiral slit located all along the tip. The tip is sealed at its far end, preventing the transmission of radiation to and through the apical foramen of the tooth
  • 85.
     Limitations  Notaccessible for severely curved canal  Cost of equipment is high  Operator and patient safety are of concern
  • 86.
    Based on thepremise that “Optimal cleansing of the root canal system is a prime prerequisite for long term success in endodontics,” Lussi and his associates at the University of Bern, Switzerland, introduced devices to cleanse the root canal “without the need of endodontic instrumentation.”
  • 87.
    NON INSTRUMENTATION NON INSTRUMENTATION TECHNIQUE TECHNIQUE (NIT ) ( NIT )  Lussi and his associates at the University of Bern, Switzerland, introduced devices to cleanse the root canal “without the need of endodontic instrumentation.  The first device, reported in 1993,  Consisted of a “pump” that inserted an irrigant into the canal, creating “bubbles” and cavitation that loosened the debris.  This pressure action was followed by a negative pressure (suction) that removed the debris: “
  • 89.
    Loss of WorkingLength  It is a very common and frustrating error usually noted on a master cone radiograph.  It is actually secondary to the other procedural errors. Maintaining Proper Working Length During Canal Cleaning and Shaping  Sound reproducible reference points should be used.  Firm or secure rubber stops should be placed at right angles to the shaft of the instruments.  All instruments should be curved with sterile 2 x 2-inch gauze, over curving them in the apical one third will compensate for some loss of curvature once in the canal. .  The instrument stops should be continually observed as they approach the reference points.
  • 90.
     Directional instrumentstops should be used. The direction of the stop must be observed constantly to maintain files in their proper relationship to the canal anatomy  Consistent radiographic angles should be used when radiographically verifying the instrument position.  The original preoperative shape of the canal should be maintained and cleaning and shaping should be done within these confines.  Copious irrigation and recapitulation should be used throughout cleaning and shaping procedures.  Sequential file sizes should be used
  • 91.
    Blockage of theCanal System Blockage of the Canal System A blockage is an obstruction in a previously patent canal A blockage is an obstruction in a previously patent canal system that prevents access to the apical constriction or system that prevents access to the apical constriction or apical stop. apical stop. The packing of dentin chips, tissue debris, restorative The packing of dentin chips, tissue debris, restorative materials, cotton pellets, paper points, or a fractured materials, cotton pellets, paper points, or a fractured instrument in the canal are common causes of blockages. instrument in the canal are common causes of blockages.
  • 92.
    To avoid canalblockage-  Always use the smaller sized instruments first.  Use instruments in sequential order.  Always precurve stainless steel hand instruments.  Use reproducible reference points and silicon stopper on instruments while cleaning and shaping.
  • 93.
     Use copiousamounts of irrigants and always work in a wet canal.  Recapitulate repeatedly.  Disposed off used instruments.
  • 94.
    Ledging A ledge isan 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. Ledging is caused by the insertion of uncurved instruments short of the working length with excessive amounts of apical pressure.
  • 95.
     Common causesfor ledging-  Incorrect assessment of root canal curvature.  Erroneous root canal length determination.  Forcing the instrument into the canal.  Inadequate irrigation and lubrication during instrumentation.  Over relying on chelating agents  Attempt to retrieve broken instruments  Attempting to prepare calcified canals.
  • 96.
     Prevention ofledge formation-  Assess the usual root curvature by preoperative radiograph.  Maintained the patency of canal  Periodic recapitulation  Work passively without forcing the instrument  Work sequentially increasing the size of instrument.
  • 97.
     Ledge management Early recognition of ledge  Precurve the apical 3-4 mm of the file with the same curvature as seen in radiograph and tease the file until it able to bypass the ledge.  If the ledge is closer to apical terminus complete the canal cleaning and obturate with an injectable thermoplasticize obturation technique.
  • 98.
    Breakage of Instrumentsin the Canal Separated (broken) instruments within the root canal system are a potential hazard during root canal treatment. The possibility of instrument separation is enhanced remarkably when the instrument is used incorrectly. In most clinical situations, the instrument fractures that occur in the apical one third of the canal are almost impossible to remove or bypass, especially in cases of small, tight canals.
  • 99.
     An artificialopening in a tooth or its root , created by boring, piercing , cutting or pathologic resorption, which results in a communication between the pulp space and the periodontal tissues  Causes - Caries - Resorptive defects - Iatrogenic events
  • 100.
    This type ofperforation occurs through the apical foramen or through the body of the root. Etiology: Instrumentation of canal beyond the apical foramen. Incorrect WL or inability to maintain proper WL causes blowing out of the apical foramen Treatment: establish a new WL, creating an apical seat and obturating the canal to its new length. The new WL should be established 1-2mm short of the point of perforation.
  • 101.
    Zipping refers totransposition or transportation of the apical portion of the canal. A normally curved canal that has been straightened, especially in the apical one third. The main reasons for zipping are (1) a failure to precurve files, (2) rotation of instruments in curved canals, and (3) the use of large, stiff instruments to bore out a curved canal. DEVIATIONS FROM THE NORMAL CANAL ANATOMY DEVIATIONS FROM THE NORMAL CANAL ANATOMY In these situations, the In these situations, the apical foramen will tend to apical foramen will tend to become teardrop shaped or become teardrop shaped or elliptical and be elliptical and be transported from the curve transported from the curve of the canal. of the canal.
  • 102.
    Stripping or lateralperforation Stripping refers to a thinning of the lateral root wall with eventual perforation. Stripping is primarily caused by overzealous instrumentation in the midroot areas of certain teeth, usually molars that have curved roots and canals.
  • 103.
    Mechanical preparation ofthe root canal may result in a Mechanical preparation of the root canal may result in a significant reduction of bacteria but will not significant reduction of bacteria but will not reproducibly leave bacteria-free root canals. reproducibly leave bacteria-free root canals. Mechanical preparation of the root canal must be Mechanical preparation of the root canal must be assisted and completed by intense disinfection assisted and completed by intense disinfection protocols using appropriate irrigants and intracanal protocols using appropriate irrigants and intracanal medicaments. medicaments.
  • 104.
     Ingle Endodontics6  Pathways of pulp 10th edition  Endodontic practice 12th edition  Castalluci vol 2  Endodontic theraphy 5th edition  DCNA modern endodntic practice 2004