Endodontic Instruments basic and hand

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Endodontic Instruments: Basic & Hand instruments: 

Endodontic Instruments: Basic & Hand instruments By Dr Sajid Ali JR 2 Under guidance of Prof R K T ewari Co guided by Dr S K M ishra Dr Z A Dental College, AMU, Aligarh.

introduction: 

introduction In considering the endodontic instruments those that are hand operated are the most important. However other specialised instruments such as explorers & excavators have been designed to adapt to the root canal treatment requirement. Originally instrument for root canal treatment were few in number and crude in design. The earliest hand operative devices had long handles that were best suited for anterior teeth. As RCT diversified, small “finger” instruments were developed for posterior teeth. New designs in endodontics instruments have been introduced and will continue to evolve.

GENERAL INSTRUMENTS: 

GENERAL INSTRUMENTS 1) Front surface mouth mirror

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2) Periodontal probe

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3 ) Explorer

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4 ) Cotton forceps

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5) Endodontic explorers DG 16 DG 16/23

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6) Endodontic excavator

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7) Endodontic ruler

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8) Instrument organizer (endodontic kit ) used for arrangement of reamers and files according to the size and length. provides holes for the files to be place vertically in a sponge which is saturated with disinfectant to maintain its sterility.

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9) Endodontic syringe tip of the instrument is flat to prevent penetration of the needle to the small canals; also it has a groove in its tip to permit the irrigation which might be under pressure to flow coronally rather than forcing it to the apical foramen causing post operative pain.

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10) Transfer sponge

Alloy used for manufacturing:: 

Alloy used for manufacturing: A-Carbon steel- contain less than 2.1% of carbon Have high hardness than SS instruments. Prone to corrosion, so cant be re- sterilised . Prone to rust. Example: barbed broch B-Stainless steel instruments- contain 18% chromium, 8-10% nickel, 0.12% carbon Corrosion resistant Stiff nature Prone to fracture Prone to distortion

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C-Nickel titanium - contain 55% Ni and 45% Ti Shape memory Super elasticity Low modulus of elasticity Corrosion resisitant Softer Good resilience Biocompatibility Poor cutting efficiency Don’t show signs of fatigue before they fracture Poor resistance to fracture.

INTRACANAL INSTRUMENTS: 

INTRACANAL INSTRUMENTS 1-Broaches & Rasps: Made from round stainless steel wire blank. Working edges are created by cutting into the wire at an angle to its long axis. The depth angle and number of cuts ( barbs) will determine how the instrument is used

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2- K Files & reamers: Designed in 1904 by Kerr Manufacturing Co. Are the most widely copied and extensively manufactured endodontic instruments worldwide . Previously made of Carbon Steel Presently made of Stainless Steel. K File and Reamer are the oldest instruments used to machine dentin. Produced by grinding graduated sizes of round Piano wire into either a square or triangular configuration These instruments are useful for penetrating and enlarging root canals. These instruments works primarily by compression and release destruction of the dentin surrounding the canal.

Reamers: : 

Reamers : Design & structure Made from triangular blanks. More flexible. The helix angle is small, therefore effective only in rotating motion Has cutting tip 0.5-1 flute/mm .

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Reamer: Sizes & Codes comes in sizes 06 - 140, all with a taper of 0.02 . design is identified by the triangle symbol on the handle.

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Reamer: Recommended use It is used by continuous rotation when the resistance is small or moderate and by balanced force when the resistance is greater . In curved canals ledging easily occurs with even small reamer sizes if instruments are not pre-curved.

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Reamer: Safety tips Reamers can be rotated only using moderate pressure. Use of force, particularly with smaller sized instruments, may result in distortion of the helical structure and ultimately in fracture. Each instrument should be checked for symmetry by rotating it against an even background before introducing it into the canal .

K-FILE : 

K-FILE K-file : Design & Structure Made from rectangular blanks Helix angle is greater than in a reamer, and therefore preparation by a K-file is effective both in rotary and filing motion. The tip of the instrument is cutting less flexible than reamers but are more effective in cutting . 1.5-2.25 flute/mm .

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K-file: Sizes & Codes K-files are produced in sizes 06 - 140, all with a taper of 0.02. K-file design is identified by the square symbol on the handle .

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K- file: Recommended use It prepares both in filing motion (up and down) and when rotated. In slightly curved canals -continuous rotation when the resistance is small and balanced force against greater resistance . Compared to reamers, the use of continuous rotation is limited because of the screwing effect typical of K-file.

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K-file: Safety tips K-files can be rotated only using moderate pressure. Use of force, particularly with smaller sized instruments may result in distortion of the helical structure and ultimately in fracture. Balanced force technique and filing instead of continuous rotation should be used with sizes 06 - 15 to minimize fracture risk. Each instrument should be checked for symmetry by rotating it against an even background before introducing it into the canal

FLEXOREAMER : 

FLEXOREAMER Flexoreamer : Design & Structure manufactured from a triangular steel wire that is twisted to give the typical shape of a reamer. The helix angle is small , and therefore effective only in rotatory motion . The tip of the instrument is non-cutting (bat-tip/inactive tip) making flexoreamer well suited for the preparation of evenly curved canals without risk of ledging .

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Flexoreamer : Sizes & Codes come in sizes 15 – 40 . all with a taper of 0.02. Flexoreamers are best distinguished from normal reamers by the size code at the top of the instrument: in flexoreamers the colour of the number is the same as the colour of the handle.

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Flexoreamer : Recommended use The flexoreamer is well suited both for straight canals and slightly curved canals. It prepares dentin in rotation but not if used as a file. The cutting efficiency and usability of flexoreamers are excellent . In slightly curved canals the recommended technique sare continuous rotation when the resistance is small and balanced force against greater resistance.

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Flexoreamer : Safety tips Flexoreamers can be rotated only using moderate pressure. Use of force, particularly with smaller sized instruments, may result in distortion of the helical structure and ultimately in fracture. Every instrument should be checked for symmetry by rotating itagainst an even background before introducing it into the canal

FLEXOFILE : 

FLEXOFILE FlexoFile : Design & Structure

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FlexoFile : Sizes & Codes

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FlexoFile : Recommended use Flexofile is suited for both straight canals and slightly curved canals. Effective both in filing motion(up and down) and when rotated. In slightly curved canals the recommended techniques are continuous rotation when the resistance is small and balanced force against greater resistance. Use of continuous rotation is limited as compared to reamers because of the screwing effect typical of K-files

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FlexoFile : Safety tips Flexofiles can be rotated (balanced force) only using moderate pressure. Use of force, particularly with smaller sized instruments, may result in distortion of the helical structure and ultimately in fracture. Every instrument should be checked for symmetry by rotating it against an even background before introducing it into the canal

HEDSTROM FILE : 

HEDSTROM FILE Hedstrom File: Design & Structure Manufactured from round steel wire by grinding. The helix angle is close to right angle, which is therefore preparation by H files is effective only when using a filing motion (up and down movement ). More positive rake angle. blade with a cutting rather than a scraping angle

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Hedstrom File: Sizes & Codes come in sizes 08 – 140. all with a taper of 0.02 . H-file design is identified by the circle symbol on the handle.

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Hedstrom File: Recommended use can be used both in straight canals and curved canals. Cut only in retraction. In curved canals , files (sizes 20/25 and bigger) must be pre-curved to correspond to the shape of the curve. H-files must always fit loosely in the canal to avoid risk for fracture . Small sizes up to #25 can be used down into full preparation length while bigger sizes are often used 1 - 3 mm short.

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Hedstroem File: Safety tips Hedstrom files show a greater risk for fracture than reamers and K-files if used in a wrong way. Hedstrom must always fit loosely in the canal and they must never be rotated. In curved canals Hedstrom -files are pre-curved to correspond to the shape of the canal. Before introducing them into the canal, all Hedstrom files must be inspected for possible earlier damage to the instrument and discarded immediately if an asymmetry in the cutting area is found

K flex file: : 

K flex file: Rhomboidal or Diamond shaped This new cross-section presents significant changes in instrument flexibility and cutting characteristics The cutting edges of the high flutes are formed by the two acute angles of the rhombus and present increased sharpness and cutting efficiency The alternating low flutes formed by the obtuse angles of the rhombus are meant to act as an auger, providing more area for increased debris removal

Triple Flex File : 

Triple Flex File They are made up of SS A hybrid instrument. More flutes than reamer but fewer than K-file. Made from triangular stainless steel blank by twisting, not ground. More aggressive & flexible than regular K-style instrument.

Flex-R-files/Roane Files : 

Flex-R-files/Roane Files Made by removing the sharp cutting edges from the tip of instrument. Have non cutting tip, so less chances of ledge formation, canal transportation when used with balance force technique. Triangular cross section which provides it flexibility Made up of NiTi and cut during anticlockwise rotary motion.

Safety Hedstrom File : 

Safety Hedstrom File Has noncutting safety side along the length of the blade which reduces the chances of perforation. The noncutting side is directed to the side of canal where cutting is not required. Therefore prevents ledging of the canals

S-File : 

S-File It is called S because of its cross-sectional shape. Produced by grinding, which makes it stiffer than H file. The file is designed with 2 spirals for cutting blades, forming double helix design. It has good cutting efficiency in either filing or reaming action, thus file can also be classified as hybrid design.

C+ Files : 

C + Files Used for difficult and calcified canals. Have better buckling resistance than k files. Available in size 8, 10, 15 of length 18, 21 and 25 mm.

Golden Medium Files : 

Golden Medium Files Were described by Weine . Comes under intermediate files provided with half sizes between conventional instruments. Available in sizes from 12-37 like 12, 17, 22, 27, 32, 37. Used for narrow canals. They are formed by cutting 1 mm from tip of instrument.

ENDODONTIC INSTRUMENT STANDARDIZATION: 

ENDODONTIC INSTRUMENT STANDARDIZATION In 1959, a new line of standardized instruments and filling material was introduced by ingle and levine A formula for the diameter and taper in each size of instrument and filling material was agreed on . A formula for a graduated increment in size from one instrument to the next was developed. A new instrument numbering system based on instrument metric diameter was established.

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After the introduction of standardized instruments, about the only changes made were the universal use of stainless rather than carbon steel the addition of smaller (Nos. 6 and 8) and larger (Nos. 110-150) sizes as well as color coding. It was not until 1976 that the first approved specification for root canal instruments was published (ADA Specification No. 28)

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The numbering system, last revised in 2002 , using numbers from 6 to 140, is based on the diameter of the instruments in hundredths of a millimeter at the beginning of the tip of the blades, a point called D0 (diameter 1 mm) , and extending up the blades to the most coronal part of the cutting edge at D16 (diameter 2-16 mm in length). Additional revisions are under way to cover instruments constructed with new materials, designs, and tapers greater than 0.02 mm/m

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Instruments with a taper greater than the ISO (International Standards Organization) standard of 0.02 mm/mm have become popular: 0.04, 0.06, 0.08, 0.10, and 0.12. This means that for every millimeter gain in the length of the cutting blade, the width (taper) of the instrument increases in size by 0.04, 0.06, 0.08, 0.10, or 0.12 of a millimeter rather than the ISO standard of 0.02 mm/mm. These new instruments allow for greater coronal flaring than the 0.02 instrument

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comes in three lengths: standard , 25 mm; long , 31 mm; and short , 21 mm.

Parts of file:: 

Parts of file: T aper usually is expressed as the amount the file diameter increases each millimeter along its working surface from the tip toward the file handle. Flute It is the groove in the working surface used to collect soft tissue and debris

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L eading (cutting) edge The surface with the greatest diameter that follows the groove (where the flute and land intersect) as it rotates. .

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land (marginal width ) If a surface projects axially from the central axis as far as the cutting edge between flutes

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Relief To reduce frictional resistance , some of the surface area of the land that rotates against the canal wall may be reduced to form the relief.

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Helix angle The angle the cutting edge forms with the long axis of the file

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Rake angle angle formed by the leading edge and the radius of the file.

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cutting angle/effective rake angle is a better indication of a file’s cutting ability determined by measuring the angle formed by the cutting (leading) edge and the radius when the file is sectioned perpendicular to the cutting edge If the flutes of the file are symmetric, the rake angle and the cutting angle are essentially the same.

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Pitch T he distance between a point on the leading edge and the corresponding point on the adjacent leading edge, or it may be the distance between corresponding points within which the pattern is not repeated

3) Spreader & Plugger: 

3) Spreader & P lugger long , tapered and pointed end instrument, -compress gutta percha into the apex and periphery of the prepared canal and also towards the irregularity of canals leaving a space for insertion of auxiliary root canal filling material cones. Pluggers have blunt or flat ended tips.

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M series plugger -spreaders double-ended long-handled instruments Handles colour coded Corresponds to standard sizing and taper of K-type files Finger held spreaders and condensers similar to K-type files with plastic or metal handles.

Micro-instruments: 

Micro-instruments Instruments have been designed to take full advantage of the increased visibility obtained with dental operating microscopes, endoscopes, and orascopes . Better visualization of the surgical site would have limited value without microsurgical instruments such as ultrasonic tips for root-end preparation and micro-mirrors for inspecting the root end.

Surgical instruments: 

Surgical instruments 1- micro-mirrors Small round Medium oval

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2-Retractor Care must be taken to rest the retractors only on bone, not on the reflected soft-tissue flap or on the neurovascular bundle

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3-Elevator 4-Curette Jacquette spoon Rubinstein Mini-Molt

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5-Scaler 6-Surgical forceps

Root end filling & suturing: 

Root end filling & suturing 1-Castroviejo needle holder 2-Castroviejo scissor

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3- microcondenser & plugger

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4-Messing gun type syringe

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5-Plugger with teflon sleeve

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6- Another delivery system designed specifically for MTA placement. Kit includes a variety of tips for use in different areas of the mouth and a single-use Teflon plunger.

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7- Hard plastic block with notches of varying shapes and sizes MTA is mixed on a glass slab to the consistency of wet sand and then packed into a notch. The applicator instrument is used to transfer the preformed plug of MTA from the block to the root end.

conclusion: 

conclusion Current NiTi hand preparation procedures that use files with a greater or variable taper are a substantial improvement over instrumentation with 0.02 tapered stainless steel files particularly when used in curved root canals. These newer instruments should produce canals with a better shape, using fewer instruments in a shorter time . M icrosurgical instruments such as ultrasonic tips for root-end preparation and micro-mirrors for inspecting the root end enhances better visualization and contributed to rapid development of peri -radicular surgery.

Thank you: 

Thank you