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    B  m p/ rotary endodontic courses by indian dental academy B m p/ rotary endodontic courses by indian dental academy Document Transcript

    • RECENT ADVANCES IN BIOMECHANICAL PREPARATION INTRODUCTION: The main objective of the biomechanical preparation is removal of organic substrate and micro organisms from root canal system. 1899 first endodontic hand piece introduced. The problem associated with stainless steal hand instruments are Canal preparation is inconsistent making obturation less predictable Many instruments and steps are needed. Hence it is a tome consuming. Canal transportation occurs when larger stiffer instruments are used. Traditional coronal enlargement instruments remove more dentin. In order to overcome these problems the rotary instruments are evolved. These instruments are made up of 2
    • 54% Nickel 44 % Titanium 2% Cobalt Boran added to improve the surface hardness. The first rotary system which developed is profile system THE PROFILE SYSTEM: The Profile system was developed by Tulsa Dental In 1994. Their first product was Profile 29 Series. The 29 indicates that the rate of increase between file sizes in this series is at a constant rate of 29%. In sometime, some part of Nickel was substituted by 2% cobalt. They are made up of Nickel-titanium i.e. 55% wt nickel and 45wt% titanium. These NiTi files have unique properties of super elasticity and shape memory. Due to these properties, the instruments adapt well in curved canals and maintain canal shape better than stainless steel files. Some unique features of these instruments include: - Strength and flexibility in curved canals. 3
    • - Radial landed U-shaped flutes and cutting edges with 20° negative rake angles which leave the debris coronally and prevent the instruments from screwing into dentin.(fig b) - Bullet shaped nose with rounded transition angle. This design helps the file remain self-centered in the canal and also reduces the chances of canal transportation and procedural errors.(fig c) - Variable taper shafts that reduces the number of instruments( fig a) Fig a fig b fig c Range of instruments: The Profile range comprises 3 instrument types with each type having different length. They can easily identified by the coloured rings on shanks. 4
    • Profile orifice shapers: • 5 to 8% taper. • Available in no. 1-6 (20-80). • Length 19mm • Used to prepare coronary section of canal, removing gutta-percha and sealer before inserting a root post. The Profile 0.5 also can be used for the root canal treatment of deciduous teeth. The handle has 3 rings. 0.06 profile taper: Taper 6% - Available in no. 15-40. Length: 21mm-25mm. 5
    • These files used to prepare middle section of canal. The handle has 2 coloured rings. 0.04 profile: Taper 4%, No. 15-90. It is available in length 25, 21 and 31mm. The handle of 0.04 profile carries single coloured ring. Motor and speeds: For best performance and avoid any breakage the instruments should used at constant speed between 150- 350rpm. For this, independent electric motor can be used. This motor will provide high torque and run quickly allowing comfortable vibration free working. 6
    • These may also used directly on the dental chair unit with a high gear reduction rate contra-angle hand piece. E.g. electrically driven (40,000rpm) with a speed of 300rpm obtained with 120:1 contra angle. Golden Keys: 1) Light pressure: Only light pressure is needed, no heavier than when writing with pencil. Profile instruments, particularly the smaller size should never forced into canal otherwise wind up may occur, possibly to the point of breakage. 2) In and out movement: The high frequency bending caused by high-speed rotation especially in curved canals, leads to stresses in the Ni- Ti alloy used. It can be best avoided by a slight in and out movement (2-3mm) while working. It will help in distributing the fatigue uniformly along the length of instrument. Each instrument is used in the root canal for a period of only 5-10 seconds. 3) Irrigation: Through out entire sequence irrigate as frequently and abundantly with syringe using 2.5% sodium 7
    • hypochlorite. For apical preparation and final preparation NaOCl and EDTA can be used alternatively. For very difficult canals, in an early preparatory stage a lubricant like Glyde may be of advantage. 4) Before canal preparation started with Profile, it is very important to insert stainless steel hand files to the level 2mm deeper than the desired depth. The advantage of these are two-fold: 1) It gives information regarding canal morphology and curvature 2) Creates a patent pathway for rotary instruments. Operational Sequence: 1) Crown-down: Estimate the provisional working length using diagnostic X-ray. The first objective is to pen the root canal as far as minimum estimated working length i.e. for e.g. if your estimated working length is 21mm, 21mm-3mm, 18mm. The stopper on the instrument is adjusted to the 18mm. Then the instruments are used in following sequence: 8
    • Profile 0.5 No. 3 (0.06/40:. It is 19mm relatively and it is easily inserted into the canal. Without any hindrance, from opposing teeth, with # 30.5 already rotating in canal, insert without any excessive pressure and apply simple in and out movement, for about 5-10 seconds. When the progression become difficult do not increase the pressure. 90 for next size file. Profile 0.5 No. 2 (0.06/30): It is smaller than No. 3 0.5 so it moves more apically compared to the previous instrument. Use it in the same way as before; withdraw as soon as progression is difficult. Profile 0.06/25: This Profile has a smaller diameter than the previously used instruments and is more flexible due to greater length of its cutting section used in this instrument same as previous one. Profile 0.06/20: The instrument penetrates more apically than the preceding one .Use in same way as before. Profile 0.04/25: Same as the previous one. 9
    • 2) Determination of working length: By using conventional K-file (No.10, No. 15) with help of radiograph. If preferred, an apex locator is also used to complete the crown-down procedure and determine working length. 3) Apical preparation until the exact working length. Profile 0.04/20: Use this instrument to exact working length. Profile 0.04/25: Use to exact working length. If the canal anatomy is large No. 30, No. 35 can be used each till exact working length. 4) Final flaring: It is by using 0.06 / 20 profile with the profile 0.06/20 inserted into the canal while it is rotating without an apical pressure and is applied in an in and out movement. 10
    • For wide canals: 1. Crown down 0.5 # (.07/50) 0.5 # 3 (.06/40) 0.6/30 0.6/25 0.4/30 0.4/25 2. Determination of working length: Apical preparation .04/25 .04/30 Final flaring (.06/25) profile Advantage of profile 29 series: 1. These files stay centered in canal and maintain canal curvature. 11
    • 2. The instrumentation time required for profile system is less compared to stainless steel files. It reduces the operator and patient fatigue. 3. The instrument is wider at DIG (end of cutting part). Therefore gives necessary coronal flare to root canal automatically. 4. The tip is bullet shaped so that there is less chance of canal transportation and procedural errors. 5. Less debris extrusion compared to step back technique (Hinrich et al). 6. Prepare the root canal with 3-D effect. Disadvantage: 1. Loss of tactile sensation: There is less feed back from rotary instruments regarding direction of curvature and location of apical terminus. 2. Intracanal separation is most often problem while using profile system. Breakage of NiTi instruments can occur without any visible signs of permanent deformation. 3. The Ni-Ti rotary profile system has low cutting efficiency. 12
    • 4. There is chance of corrosion of profile rotary instruments when used along with sodium hypochlorite. It leads to chloride corrosion which leaves micropitting on instruments, surface leading to crack formation and instrument failure. 13
    • PROFILE GREATER TAPER ROTARY INSTRUMENTS (GT ROTARY) Designed by Steve Buchanan. These instruments create funnel shaped root canal more efficiently. The instrument has variable pitched flutes that are closer nearer the tip and further apart toward shank. It allows the instrument to be stronger at tip where stress can be more extensive. The larger spacing of the flutes at the shank provides good flexibility and cutting efficiency. 14
    • Range of instruments: 1) GT rotary files: There are 4 files in this group length 21mm, 25mm. These files have two coloured rings. Each of the file has different taper i.e. G.T. 12% (0.12) GT 10% (0.10) GT 8% (0.08) GT 6% (0.06) Rang e of instruments - 4% taper. - 20-35 no. Available in 21, 25 and 31mm. They have only one ring. They are mainly used to prepare the terminal part of root canal. 15
    • G.T. Accessory files: These are 12 taper available in 35, 50, and 70 size length 21mm and 25mm. • Identified by the three grooves on handle. • Used to refining the final preparation. Operations sequence: 1) Crown down: It can be done using G.T. rotary files. a. Profile G.T. 0.012 taper with tip size 20 take to resistance. b. Profile G.T. 0.10 taper with tip size 20 taken to resistance. c. Profile G.T. 0.08 taper with tip size 20 taken to resistance. d. Profile G.T. 0.06 taper tip size 20 taken to resistance. Before this patency of is canal checked with No. 8 stainless steel file. 2) Determination of working length. 3) Apical preparation. a. Profile 0.04 taper size 20. 16
    • b. Profile 0.04 taper size 25 c. Profile 0.04 taper size 30. d. Profile 0.04 taper size 35 4) Final refining of root canal. This is by using G.T. accessory files. PROTAPER ROTARY SYSTEM: These instruments have following design features: 1. Progressive taper: The protaper has varying tapers within one file ranging from 3.5% to 19% this makes it possible to shape the specific sections of root canal with one file. 2. Modified guiding tip and varying tip diameter: - The modified guiding tip allows one to follow the canal better without any transporation and procedural errors. - The varying tip diameter helps in cutting the specific areas of root canal without stressing the instrument in other sections. 3. New cross-section of instrument: 17
    • - These instruments will have convex triangular cross- section. This design results in a reduced contact are between cutting blade and dentin. It increases the cutting efficiency and decreases the torsional strain of instrument. 4. Varying helicle angle and pitches: 5. New shorter handle: The length of the handle reduced to 15mm to 12.54mm to allow for better access. 18
    • Range of instruments: Available in two sets: - Shaping files (3 files) i.e. SX1, S1 & S2. - Finishing files (3 files) F1, F2 & F3. SX or auxiliary shaping file (SX): Identification by lack of its ring on handle. This instrument has highest increase in taper from D0 to D9 (3.5% to 19%). These files are mainly used for initial preflaring and relocation of canal orifices. S1 or shaping file 1: It has purple identification ring on its handle. S2 or shaping file 2: It has white identification ring on its handle. 19
    • These instruments (S1 & S2) mainly useful in shaping of coronal and middle third of canal. Finishing file: 3 in number: - Finishing file (F1): Tip diameter 0.20 yellow identification ring. - Finishing file 2 (F2): Tip diameter 0.25, red identification ring. - Finishing file 3 (F3): Tip diameter 0.30, blue ring. These instruments has fixed taper from D1 and D3 i.e. F1- 7%, F2-8% and F3-9%. These instruments mainly used in preparation of apical third of canal at full working length. 20
    • Guidelines for use of pro-taper: 1. Establish straight line access. 2. Use instrument in well irrigated and lubricated canal i.e. NaOCl 17% EDTA also can be used. 3. Establish a smooth glide path with No. 10, and no. 15 stainless steel file. 4. Clean the flutes of file frequently and inspect for any signs of distortion. 5. Use torque controlled electric motor with handpiece at 200-300rpm. 6. Force should never be applied to a file; only a light brushing motion should be used. 7. Use the instruments in recommended sequence. 21
    • Operation sequence: 1. Establish straight line access and gliding path, using no. 10 and no. 15 stainless steel file. Determine estimated working length using diagnostic x-ray. 2. Flood the canal with NaOCl and begin shaping with shaper S1 using light brushing motion .Go no. deeper than 3-quarter of estimated length recapitulate and irrigate. 3. Now use SX to improve straight line access and relocate the canals, with same motion. Insert the instrument while it is rotating. If a light resistance is felt it is withdrawn in a brushing motion. Never force instrument once you feel resistance. This instrument will cut more coronal dentin create more flare and thus allow better instrumentation in apical region. 4. Now determine exact working length using stainless steel file (No. 10 or no. 15) with help of well angulated radiograph or electronic apex locator. 5. Now use S1 and S2 to full working length with brushing motion. 22
    • 6. Now with finishing file (F1) passively extend the preparation 0.5mm short of working length withdraw after 1 second. The F1 has tip diameter 0.20mm. If no. 20 hand instruments found to be snug at the apex, preparation is finished. If F1 and no. 20 hand instrument is loose continue preparation with F2. It has tip diameter 0.25mm. Again confirm with no. 25 hand instrument, if it is snug. Irrigate and finish the preparation. If F2 is loose continue preparation with F3 which 0.30mm tip diameter, followed by confirmation with no. 30 hand instrument. If it is snugly fitting finish the preparation. Between each instrument it is very important to irrigate copiously with NaOCl and recaputation with K-file to maintain patency. 23 Straight line axis & gliding path SX-file S2 file – full W.L. F1 file – full W.L. Gauging of apical -file #20) F2 file – full W.L.
    • OPERATION SEQUENCE Advantage: - High cutting efficiency. a. Triangular cross section. b. Balancing pitch and helicle angle. - Fewer instruments to complete the preparation. - Less debris in apical region. - File stress is minimized. Straight line axis & gliding path S1-file (brushing motion) SX-file Determination of W.L. And S1 to full W.L. S2 file – full W.L. F1 file – full W.L. Gauging of apical Foramin (K-file #20) F2 file – full W.L. 24
    • - Modified guiding tip enables file to easily follow a prepared glide path without goughing side walls. - Increased tactile sense due to triangular cross- section. Disadvantage: - Cutting efficiency decrease with use. - Possibility of canal transportation. Therefore instrument is immediately removed once working length has been reached. - Severely curved canal difficult to use so hand Protapers are better option. - 25
    • LIGHT SPEED ROTARY SYSTEM: It was so named because light touch is needed and as the speed of instrumentation is increased. This instrument is specially engineered nickel-titanium Gates-Glidden-like reamers that allows enhanced tactile controls and enhanced apical preparation larger than those created with other rotary systems. The instrument consists of set of ISO sized rotary files i.e. from no. 20 to 140 in length 21, 25, 31mm. Light speed instruments also have half sizes 22.5, 27.5, 32.5. These half sizes are color coded exactly same to that of previous size but also have white or black ring on handle them easy in identification from full size. Some unique design feature of light speed instrument: - Short cutting heads and long non-cutting taper less shafts. - They have radial lands and U-shaped spiral grooves between radial lands. 26
    • - lightly longer non-cutting pilot tip. Guidelines: 1. These instruments should rotate at constant speed between 1500-2000. It should not exceed 2000. This constant speed is very important because Ni-Ti files will not sustain repeated change in torque. 2. Straight-line access to mid-root is very important because they glide the rotating instrument in curves of root canal. 3. Maintain patency of canal using hand-instruments before starting the preparation with light speed instruments. 4. Always use progressively larger instruments in correct sequence from smaller to larger .Never skip a size to gain time. 5. Irrigate copiously with sodium hypochlorite and EDTA alternatively between each instrument. 6. Once the instrument reached to W.L. do not linger at that point and immediately withdraw while rotating. Technique: 27
    • Zurich Light speed technique: 1. Initial apical rotary (IAR): First light speed instrument which begins to cut canal wall at W.L. 2. Master apical rotary (MAR): It is the last instrument to form the apical preparation. This is G-12 light speed larger than IAR. 3. Final rotary (FR): The last step back instrument which completes the preparation. It has 4 steps: Access and coronal pre-flaring: Once the orifices are located they are enlarged using Gates- Glidden drills (No. 12). Determination of working length and IAR: W.L. should determined using 15 No. stainless steel file and verified radiographically or electronically. Now start using light-speed instruments (No. 20) to W.L. The first few instruments are may not ream the canal wall because canals are too large these instruments are called non-binding instruments. Always begins with No. 20 28
    • never skip the size. Eventually one instrument will begin to cut at W.L. It is called initial apical rotary (IAR). Determine MAR: All light speed instruments used after IAR are called binding instruments. These instruments are used in controlled forward and backward movement (3-4mm) it is called pecking movement. This forward movement reams the canal and backward motion tends to clean the head. Now use the instrument sequentially with pecking movement. The last instrument which used to prepare the apical portion is depending on many factors like: - Degree and angle of curvature. - Presence of secondary or tertiary curves. - Diameter of root apices. Usually the size of MAR: - For anterior 60-70 no. - For posterior teeth 40-50. Step back and recapitulation: 29
    • Light speed instruments are stepped back after selecting the MAR. The step-back is 1mm from previous instrument. Finally all canals are recapitulated with respective to their MARS and irrigation should be done. Manufacture recommended technique: Here the initial apical rotary (IAR): file is identified by gauging the apical canal diameter. To gauge the light speed instruments must used by hand advancing apically by advancing apically using moderate pressure but never rotated. The initial smaller size instrument easily goes to working length. One instrument which is not going to full working length, it is called first light speed size to bind (FLSB). From this instrument we should begin rotary instrumentation. Determining the apical preparation size: Start instrumenting with FLSB with slow continuous movement until it engages the canal wall. From this point give slowly controlled forward and backward movements (pecking movement). This pecking movement translates downward cut of the dentin count the no. of pecks it takes FLSB to reach the working length. Repeat the counting of pecks for each sequentially larger instruments. 30
    • The instrument which takes atleast 12 pecks to reach working length is the MAR. This is called the “12 peck’s rule”. Complete apical instrumentation: After determining the MAR use next instrument 4mm shorter than the W.L. This enables the SimpliFill G.P. Plug to closely match the size and shape of canal preparation. If you are obturating with standardized GP step back should start from 4mm so that each instrument length is 1mm shorter than previous one. Instrument middle root: Instrument with sequentially larger size instrument the 4-5mm of canal with only full size instruments (skip half size instrument). These instruments should not enter the apical 5mm of canal. Instrument with larger size instrument until the size which will not pass easily the apical extent of coronal third of canal. Recapitulate: Recapitulate to working length with MAR of each canal. Light speed technique taper technique: 31
    • It is also called hybrid technique. In this technique canals are cleaned and shaped in a crown-down fashion by using tapered instruments. The apical portion of canal cleaned by using light speed instruments. The master apical rotary files are selected using 12 pecks rule. Advantages: 1. The light speed instruments produce larger apical preparation, because of their tip design. Due to this there is better removal of necrotic material and micro-organism in apical area, with larger canal space more disinfecting solutions reach apical area and ensure a better disinfection. 2. There is no or little transportation when canal prepared with light speed instruments. (Glossen et al JOE 1995). Disadvantage: Time consuming because of too many instruments used in the system. 32
    • K3 ROTARY NICKEL TITANIUM FILE SYSTEM Designed by Dr. John McSpadden in 2002. It has following design features: 1. Positive rake angle: The profile and most of the other instruments has negative rake angle which result in scraping rather than cutting action. The slight positive rake angle as in the case of K3 results in digging and plowing of dentin. It will improve the cutting efficiency. 2. Variable flute angle: The flute angle is variable i.e. taper increases from tip to handle. So more debris removal from the canal. 3. Wide radial land: In K3 has increased mass of metal in peripheral area near the blade. It has good mass of metal behind the cutting blade. It makes the K3 resistant to torsional or rotary stress. 33
    • Design of K3 Rotary system 34
    • 4. Access handle: The K3 files has short handle so that it can be used easily in posterior region of the mouth. 5. Variable core diameter or flute depth: The flute depth is less in the tip of the instrument where the strength is more important. It gradually increases as it moves up. It results in more flexibility and increased debris removal. 6. Simplified color coding: The K3 system has only two tapers 0.04 (green) and 0.06 (orange). The instrument handle has two colour bands on handle. The top band signifies taper and bottom band conforms ISO sizing. 7. Safe ended tip: It avoids ledging, perforations zipping and other nasty surprises. 35
    • Range of Instruments: Body shapers: They have enhanced taper of 0.08, 0.10 and 0.12 with tip size no. 25 and in length 17, 21 and 25mm length. They are mainly used for coronal shaping. Files are which are used for apical preparation 0.02 taper files, tip size 15-40 in length 21mm, 25mm and 30mm. 0.04 taper files, 0.06 taper file} tip size 15-60, and in length 21mm, 25mm, 30mm. Guidelines: 1. Never force an instrument apically. 2. Frequent irrigation with sodium hypochlorite with EDTA is desirable. 3. Patency should maintained during preparation. Patency can be maintained using small K-file (6-15) after every rotary file. 4. Check the flutes of K3 files for bend, or stretch, shiny spot, if found discard immediately. In the case where root canals are linked the files are discarded after single use. 36
    • 5. Use electric torque control motor with auto reverse to rotate the files in proper rpm (300-350rpm). The instrument should not use more than 5-7 seconds. Technique: - If the canals are severely curved, scouting of middle third and coronal third with hand files before advancing into rotary file is important. - Crown down instrumentation is desirable. It implies cleaning of coronal third is done first then middle third and finally apical third. - First obtain straight line access. - Locate canal orifice and obtain canal patency using hand files. - Begin crown down by taking 0.12 taper K3 body shaper to resistance (3-4mm down the canal). It should be done with EDTA gel followed by flushing with NaOCl. - Take next 0.10 taper K3 shaper to resistance. 37
    • - Recapitulation and irrigation can be done to clear the debris from coronal and middle third of canal. - Before rotary instrumentation in apical area it is important to explore with hand instruments (K-file 10-15). It helps to determine any curvature calcification or patency. After achieving this goal operator should passively introduce no. 10 or 15 K file to estimated working length. - The working length is confirmed by the use of a well angulated radiograph or electronic apex locator. - Once the true working length is established the K3-rotary files are introduced in a canal in a crown down fashion. It can be done by two ways: a. With sequence (from longer tip size to smaller with fixed taper). b. With varying taper (mixing the taper as tip size diminishes). 38
    • - With sequence: Here start instrumentation with tip size 35 (0.06 taper) or large to tip size no. 20 or 15, until full working length is achieved. In the case where canals are narrow 0.04 taper series are also used in similar fashion. - - Variable taper sequence: 0.06 K3 + 40 to resistance. 0.04 K3 + 35 to resistance. 0.06 K3 + 30 to resistance. 0.04 K3 + 25 to resistance. 0.06 K3 + 20 to W.L. 0.04 K3 + 25 to W.L. 0.06 K3 + 25 to W.L. Combination of K3 and light speed technique: Hence shaping of coronal and middle third of canal done by using K3 rotary system. The apical shaping can be done using light speed instruments. 39
    • Advantages: 1. Excellent cutting ability. 2. Moves smoothly in canal and give robust sense of tactile control. 3. Excellent fracture resistance. 4. More flexible. 5. Due to their access handle they can be use efficiently in posterior teeth or patient with limited mouth opening (shortening of handle by 5mm without affecting the working length of file). 6. Less screwing in effect in K3 compared to other brands of NiTi files (because of variable flute pitch). 40
    • REAL WORLD ENDO-SEQUENCE FILE: Developed by Brassler USA. It has following design features. 1. It has alternate contact point design. - Improves cutting efficiency. - Prevents screwing into dentin. - Enhances debris removal. - Centres the file within the canal. 2. Electro-polished surface. - Eliminates surface imperfections. - Increases file sharpness. 3. Precision tip: It has a nonactive tip, fully active precisely at 1mm (D1). The file has good self-centring capacity in canal with less transportation. 4. No radial lands and with variable pitch and helicle angle. - Flexibility is maximized. - Torque is minimized. 41
    • - Sharp cutting edge. - Good controls over procedure. DESIGN OF REAL WORLD ENDO-SEQUENCE FILE Range of instruments: 42
    • The real word end sequence file available in both 0.04 and 0.06 tapers. The kit consists of following files. Expeditor file: it is 0.04 taper, no. 27, 21mm used to estimating the canal size. 0.06 taper file: with size extra small, small, medium, and large. 0.04 taper file: with size extra small, small, medium, and large. i.e. small (no. 15-30). Medium (25-40) Large (35-50). Speed: It run in portable hand piece with speed of 450- 600rpm. This portable handpiece has several advantages. - It is light in weight and good tactile controls. - It has torque controls and autoreverse feature. - Nine-speed options are available (200-1000rpm) thus deliver a outstanding power). 43
    • Technique: 1. After access opening confirm / establish patency by moving a no. 10 or 15 stainless steel K-file with help of no. 15 stainless K-file creating a glide path. After obtaining the glide path working length should determined with help of x-ray / Apex locator. 2. Using an endo-sequence expeditor rotary file penetrate the canal until significant resistance (i.e. progress is no longer easy). Now remove expeditor rotary file. Now we should choose the next size file by information gained by. - Preoperative radiograph. - Resistance of # 10 hand file. - Depth of penetration of expeditor. If E-file is goes down half away it means canal is small. If E-file goes more than half away it means canal is medium. If E-file is loose that means canal is large. 3. Now according to the size determined by expeditor file choose appropriate size of file. Use these files in a crown down fashion i.e. (30, 25, 20, 15 for small 44
    • canal). Use each file until resistance is encountered .Usually no. 70 file with will go to full working length with resistance. RACE (REAMER WITH ALTERNATING CUTTING EDGES) Design feature: 45
    • 1. Triangular cross section. - Sharper cutting edges with good cutting efficiency. - Less torque required. 2. Electrochemical polishing: - Removes microsurface imperfections produced during manufacture, it reduces the fracture of instrument. - Result in smooth cutting edge with less stresses in the canal. - Improved resistance to metal fatigue. 3. Alternate helix angle of instrument. The cutting edges of instrument has alternate helix angle as it rotates in the canal. - Reduces the torque by 75% so there is no screwing in effect. - It reduces the cutting length of instrument. - Enhanced debris removal. 46
    • - Guard against binding, grabbing file followup. 4. Softex tip: - Ensure excellent centring in the canal. - Decreases risk of deviation. 47
    • DESIGN OF RACE (REAMER WITH ALTERNATING CUTTING EDGES) Range of instrument available: 48
    • These are available in different tapers: 0.2 taper (15-40 no.). 0.4 taper (25-35) 0.6 taper (25-40) 0.8 taper; 0.10 taper } (35-40). These instruments have ISO sizing color coding . Available in length 21, 25, 31 mms. These are available in two kits i.e. 12mm handle and 15mm handle. Speed: Cordless single micromotor can be used at a speed (125-625rpm). These hand pieces:. Are compact light weight, comfortable and have time torque control with autoreverse feature. Technique: Five instrument technique: Step 1: Establishing glide path using 10 no. hand K-file (Schotlander and canal finder # 10 0.02 taper). Step 2: Insert a 10, # 40 into canal in light in and out painting motion, while moving circumferentially around the canal. Then use next 0.08 taper in a same manner. These instruments are restricted to 4/3rd portion of canal only. 49
    • Step 3: Measure working length. Step 4: For preparation of apical portion of canal, start with 0.02 taper no. 25 gradually inserted to working length. If this file is not going to the working length, instrument with hand file (k-file no. 15) .When working length has reached, continue with 0.02 (no. 25), change to 0.04 ± 25 and 0.06 ± 25 proceed to W.L. Three instrument technique: After some experience in wide canals we can use this technique. Here first 3 steps are same as above in step 4 go directly to 0.06 taper ± 25 to full working length. Advantages: - Less work torque (75%). - More debris removal. - Optimum controls. - Reduced risk of metal fatigue. - Improved resistance to instrument fracture. 50
    • TECHINQUE Technique 51
    • LIBERATOR Design: 1. Straight flute design: Most of the other rotary file systems helically fluted like appearance. They act like a wood screw, so natural tendency to self thread. The liberator is a straight flute design so there is 0% self threading. 2. Lack of radial lands so less friction. Liberator rotary files have no land area so not friction. 3. Higher rpmm reduces torque. The liberator file rotates at high rpm 1000 to 2000. So less torque generated and less file separation. 4. Roane softex tip that keeps file centred and minimizes ledging and file separation. 5. Efficient dentin removal – Liberator NiTi files quickly and more efficiently removes dentin because of their sharp cutting blades moving at high velocity. So there is more kinetic energy generated. (Liberator delivers 32 times more kinetic energy than conventional file system). 52
    • 6. Less transverse micro-cracks. The pattern of grinding is parallel with axis of file. This compare to conventional file where grinding pattern is perpendicular to axis is resulting in transverse micro- cracks in file. Range of instruments: The liberator files available in different tapers: 0.02, (25-70). 0.04 (30-70) 0.06 (35-80) They available 21, 25, and 31 length. Guidelines: 1. Complex canal systems may require. - Reduced rotational speed. - Use 0.2 taper files. - Hand filing. 2. Be sure that straight line access is there for canal orifices. 3. Operate liberator at 1000-2000 rpm. 53
    • 4. Advance each liberator slowly (no-packing movement). 5. Irrigate between each liberator file. 54
    • Straight flute design Straight flute Helicle flute 55
    • Less transverse micro-cracks Conventional file Liberator file Technique: For small root diameter: Access opening and determine working length using small flex file. Establish gliding path using 10 no. file for select file tip size according to root diameter. 70 no. liberator place rotating file into the canal and apply sufficient pressure to advance to depth 5mm short of working length. 60 no. liberator advance 4mm short of working length. 56
    • 55 no. liberator advance 3mm short of working length. 50 no. liberator advance 2mm short of working length. 45 no. liberator advance 1mm short of working length. 35 no. liberator advance 0.5mm short of working length. 25 no. liberator advance slightly beyond the foramen. Shaping is completed irrigate dry and fill the canal. For medium sized root diameter: No. 70 liberator rotating file into the canal with slight apical pressure advance to depth 2mm short of working length. No. 60 advance to depth 1mm short of working length. No. 45 advance to depth 0.5mm short of working length. 57
    • No. 30 advance to depth slightly through apical foramen. Shaping is completed. File tip size for large root diameter: 80 no. liberator rotating file introduced into the canal and 55 liberator file is advanced to a depth 0.5mm short of foramen. 35 no. Liberator file advanced to a depth slightly through foramen. Shaping is completed. 58
    • V-TAPER ROTARY SYSTEM Design feature: 1. Safe core, variable pitch and neutral rake angle. Safe core – Reduces chances of instrument fracture, variable pitch – Decrease screw in effect. Neutral rake angle: eliminates gouging, and grabbing of positive rake angle and inefficiency and heat build of negative rake angle 2. No radial lands: Thus no dragging, friction heat build and inefficiency which can cause fracture. 3. Non-cutting tip prevents ledging and transportation. 4. Variable taper: Natural root canal has variable taper. So these variable taper files shape effectively 59
    • especially in apical third area. (Deep apical preparation and eliminates taper lock), natural shape of canal maintained. 5. Parabolic cross section: It is most efficient cross- sectional design especially for deep hole reaming action in root canal. 6. Endonol: It uses a specially formulated NiTi-alloy for manufacturing of V-taper files. This metal has superior mechanical features. 7. Easy color coding for identification. 8. Short handle. Guidelines: - Straight line access and establish glide path (# 10 V hand file). - Do not over prepare the working length. - Do not over heat NiTi files. Super elastic and shape memory properties may be lost. - 1 second rule: Cut the dentin only for 1 second. 60
    • - Always use a lubricant. - Set electric motor between 250- 400rpm. - Use light apical pressure. - Consider 21mm length whenever possible for better access. - Do not over use the file. The file should be used for 3-4 individual canals. If file damaged discard immediately. - When apical third of canal has abrupt curvature use hand files for preparation. Range of instruments: It is 3 file systems: 0.10 taper tip diameter 30 0.08 taper tip diameter 25 0.06 taper tip diameter 20 61
    • Technique: 1. Glide path: #10 V-hand files. 10 (VO2) - # 10 (VO4) - # 10 (VO6). Determine working length. 2. Coronal shaping: 25(V08) – 30 (V09) to the point of resistance. 3. Apical shaping: 30 (V10) – 25 (V08) – 20 (V06) to the point of resistance. 4. Final shaping 30 (V10) to working length for large canal. 25 (V08) to working length for medium canal. 20 (V06) to working length for small canals. 62
    • HERO-642 Introduced by Daryl Green – manufactured by Micromega instrument Co, from NiTi. Features and benefits: 1. Three cutting edges for a positive cutting in curette effect. 2. Bigger inner core provides better resistance to fracture. 3. Progressive fluting present, so less screwing in effect. 4. Three variable tapers which peel the canal wall on small contact point. 5. Tip which stays centred in the canal. 6. Versatile it can be used along with sonics and hand files. 7. Economical as it requires few instruments. 63
    • Speed: these files can be run in contraangle handpiece at a speed of 300-600rpm. Instruments: Available in 3 tapers. 2% taper # 20-45, in 21, 25, 29mm in length, 4% taper – 20-30 in 21, 25, 29mm 6% taper # 20-30 21mm, 25mm. Technique: For easy canals: - Locate canal orifice and determine working length. - Use 0.06 taper # 30 to 2/3 of working length by slow in and out 64
    • movement with circumferential filling. 0.04 taper # 30 to 2mm short of working length. - 0.02 # 30 taper to full working length. Recapitulate with hand file and irrigate. For easy canals Difficult canals For canals with Average difficulty 65
    • For canals with average difficulty Same technique but the sequence begins with # 25 For difficult canals use the same procedure but sequence begins with # 20. 66
    • QUANTEC ROTARY SYSTEM Design: Features and benefits: - Positive rake angle with active cutting action. - Wider radial lands which provides blade support while providing peripheral strength to resist torsional and rotary stress. - The third radial land stabilizes and keeps the instrument centered in canal and minimizes over engagement. 67
    • - Radial land relief reduces the friction on the walls. - Safe ended tip: Safe cutting; non cutting. - Short handle: So easy posterior access. Range of instrument: These instruments are available in different taper. It consists of range of instruments with identical tip size # 25 17, 21, 25mm length. 0.12 taper. 0.10 taper 0.08 taper 0.06 taper 0.05 taper 0.04 taper 0.03 taper 0.02 taper } # 15-40, 17, 21, 25mm length. 68
    • This instrument run in high torque gear reduction slow speed hand piece. Technique: Crown down starting with larger taper file first and progressing with file with lesser taper. - Straight line access and check for patency of canal. - Determination of working length. - Establishment of glide path. - Use light pecking movement – now start instrument with 0.12 taper instrument advances till you meet resistance. - Then follow the frequency instrument till # 0.03 taper. - Apical preparation with 0.02 taper Quantec file from 15-40 to working length. 69
    • MITY ROTO 360° Design: - Unique 4-file design with flat edged flutes prevents instrument from getting caught on canal walls. - It works in reaming motion provides uniform canal preparation. - Reduces preparation time. Available in: - 15-80 tip sizes in 21 and 25mm length. NAVI-FLEX ROTARY SYSTEM: - Precision grounded flutes. - Self-centering bullet tip. - 18mm length for easy use in initial flaring. 70
    • - ISO colour coded easy for identification. Range of instruments available in: - 0.8 Taper (tip size 60, 45). - 0.6 Taper (tip size 35, 25). - 0.4 taper from no. 15-55. 71
    • Techniques: Establishment of straight line access and patency. Instrument in a crown down fashion. - Navi-Flex 0.08/60 till significant resistance. - Naviflex 0.08/45 till significant resistance. - Naviflex 0.6/35 - Naviflex 0.6/25 Determine working length: - NF 0.04 / 45 till resistance. - 0.04 / 35 till resistance. - 0.04/30 till resistance. - 0.04 / 25 till resistance. This sequence should repeated until the 0.04/25 taper reaches to full working length. 72
    • Irrigate and recapitulate. CONCLUSION Proper biomechanical cleaning and shaping of root canal system is the basis of endodontic therapy. Since the introduction of first rotary instrument, various new systems have been established in the market, the benefits of which are apparent in their perfect preparation of the root canal system. Their widespread use in regular practice is being looked upon with skepticism because of overzealous tooth removal and a highly mechanical approach. Nevertheless, the combination of anatomic, biologic and pathophysiologic knowledge of the tooth and skill of the operator play a large role in optimizing the quality of root canal treatment. 73