Endodontic Instruments

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Endodontic Instruments (Material & Design ) :

Endodontic Instruments (Material & Design ) SubmittedBy : Alka Arora PG Student Department of Conservative Dentistry and Endodontics

Contents:

Introduction Classification Contents

Introduction:

Introduction

CLASSIFICATION OF ENDODONTIC INSTRUMENTS:

BASED ON FUNCTION GROSSMAN 11 th ed . A) EXPLORING – to locate canal orifice and to assist in obtaining patency of root canal B) DEBRIDING – to extirpate pulp and remove debris C) CLEANING AND SHAPING – clean and shape root canals laterally and apically . D) OBTURATING- To pack filling material into root canal CLASSIFICATION OF ENDODONTIC INSTRUMENTS

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BASED ON FUNCTION GROSSMAN 12th ed : Group I : Hand operated endodontic instruments , broaches , files , reamers Group II : Non Rotary endodontic instruments Group III : Rotary endodontic instruments used with a handpeice

ISO GROUPING:

A) GROUP I – hand use only B) GROUP II- engine driven latch type C) GROUP III- engine driven latch type drills or reamers D) GROUP IV- root canal points ISO GROUPING

COHEN CLASSIFICATION:

Group I : Manually operated instruments. Group II : Low Speed Instruments with a latch attachment . Group III : Engine Driven Nickel Titanium Rotary instruments. Group IV : Engine Driven instruments that adapt themselves to shape of root canal. Group V : Engine Driven Reciprocating instruments Group V I : Ultrasonic Instruments COHEN CLASSIFICATION

EXAMINING INSTRUMENTS:

Instruments used in examination are 1) front surface mouth mirror- overcomes the problem of associated with double image . 2) periodontal probe 3) explorer 4) cotton forceps EXAMINING INSTRUMENTS

DEBRIDING INSTRUMENTS ENDODONTIC EXCAVATOR::

Longer offset – better reach Excise pulp tissue from pulp chamber DEBRIDING INSTRUMENTS ENDODONTIC EXCAVATOR:

BARBED BROACH, RASP AND APPLICATORS:

(ANSI sp. No : 63 ) The length of working portion of shaft is 10mm . Taper – 0.007 mm/mm (Broach ) 0.015 mm/mm (rasp ) Difference between broach and rasp- depth and angle of cut . Barb height- half of core diameter (Broach ) Rasp height- one third of core diameter (rasp) BARBED BROACH, RASP AND APPLICATORS

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Barbed broach – Thin, flexible, tapered and pointed removal of intact pulp tissue, paper points and cotton dressings. Identification symbol – 8 pointed star Rasps – rough walled canal preparation

ISO GOUP I INSTRUMENTS:

MANUFACTURE: First made from carbon steel Now made universally of NiTi and stainless steels Produced by two techniques: 1 st technique- Grinding graduated sizes of round “ piano ” wire into various shapes and second grinding for taper. Then, twisted in counter clockwise direction for programmed number of times 2 nd technique- Grind spirals into tapered wire rather than twisting. NiTi instruments are produced by this technique. ISO GOUP I INSTRUMENTS

INSTRUMENT STANDARDIZATION:

1955- first attempt to standardize instruments by Ingle & Levine Last revised in 2002 Numbers from 6 to 140 – based on the diameter of the instruments in hundredths of a millimeter at the beginning of the tip of blades (D1) Extends up the blade to the most coronal part of the cutting edge at D2 – 16 mm in length INSTRUMENT STANDARDIZATION

COMPONENTS OF A FILE::

Taper – it is expressed as the amount the file diameter increases each mm along it ’ s working surface from the tip towards the file handle Flute – the flute of the file is the groove in the working surface used to collect soft tissue and dentin chips removed from the wall of the canal. Land – It is the surface that projects axially from the central axis as far as the cutting edge between the flutes. Land reduces the tendency of a file to screw into the canal. COMPONENTS OF A FILE:

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Direction and action of the leading (cutting) edge. A negative angle (left) results in a scrapingaction , whereas a positive angle (right) results in a cutting action

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Helix Angle – the angle formed by the cutting edge with the long axis of the file Rake Angle – It is the angle formed by the leading edge and radius of the file. It can be positive or negative

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The full extent of the shaft, up to the handle, come in three lengths: Short – 21 mm Standard – 25 mm Long – 31 mm

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The instruments enlarge by 0.02 mm/mm from D0 to D16 The tip angle of an instrument should be 75 +/- 15 o Color coding of instruments – easier identification of instruments

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Instruments have a taper of 0.02 mm per mm Presently, instruments with a taper greater than the ISO 0.02 mm/mm have become popular: 0.04 0.06 0.08

Parts of a File:

Parts of a File

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 Files & Reamers

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K File and Reamer are the oldest instruments used to machine dentin These instruments work by the Compression – and – Release destruction of dentin surrounding canal Reaming motion causes less transportation of the apical dentin than a Filing motion

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Produced by grinding graduated sizes of round Piano wire into either a square or triangular configuration Second grinding operation properly tapers these instruments To give the instruments the spirals that provide the cutting edges, the square or triangular stock are then grasped by a machine that twists it counter clockwisse a programmed number of times – tight spirals for files, loose spirals for reamers

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The cutting blades that are produced are the sharp edges of either the square or the triangle In any instrument, these edges are known as the “ Rake ” of the blade The more acute the angle of the rake , the sharper the blade There are approximately twice the number of spirals on a file than on a reamer of a corresponding size

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The clinician should understand the importance of differentiating endodontic files and reamers from drills Drill are used for boring holes in solid materials such as gold and enamel Files, by definition, are used by a Rasping Motion

Reamers:

Reamers, are instruments that ream – specifically, a sharp-edged tool for enlarging or tapering holes They cut by being tightly inserted into the canal, twisted clockwise ¼ to ½ turns to engage their blades into dentin & then withdrawn Penetration  Rotation  Retraction Cut is made during Retraction Reamers

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Reaming is the only method that produces a round tapered preparation (In straight canals) In a curved canal, the reamer should be rotated only ¼ turn, as more stress can cause breakage Heavier reamers (Size 50 and above), can be turned without breakage Newer NiTi reamers are flexible and resist breakage in smaller sizes

K Flex Files:

The Kerr Manufacturing Company in 1982 introduced a new instrument design that they termed the K-Flex File (Sybron Endo/Kerr; Orange, California) The cross-section of the K-Flex is Rhomboidal or Diamond shaped The spirals or flutes are produced by the same twisting procedure used to produce the cutting edge of the standard K-type files K Flex Files

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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 are for increased debris removal

CLEANING AND SHAPING INSTRUMENTS: K FILES:

Instruments with tighter spirals 1.97 to 0.88 cutting flutes per mm of operating head Produced mainly from square blank. Cutting action – either filing (rasping) or reaming (drilling) motion Filing – rake of flutes rasp the walls as the instrument is withdrawn without turning Reaming – penetration, rotation and retraction CLEANING AND SHAPING INSTRUMENTS: K FILES

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More work hardened – stiffer than reamers Identification symbol – square

K REAMERS:

Instruments with lesser number of flutes 0.80 to 0.28 cutting flutes per mm of operating head Produced mainly from triangular blanks Cutting action – Penetration, rotation and retraction Identification symbol – equilateral triangle K REAMERS

K-STYLE MODIFICATION:

K-FLEX : Forerunner of hybrid instruments Hybrid – strength and versatility of K-type + aggressive cutting of H-type Cross-section – Rhombus or diamond Cutting edge – Two acute angles Space reservoir – reduced compacting dentinal filing Increased flexibility K-STYLE MODIFICATION

HEDSTROEM FILES:

Cutting spiraling flutes into shaft of round, tapered stainless steel wire Very positive rake of flute design Impossible to ream or drill Cut in one direction – retraction Cross-section – Single helix teardrop HEDSTROEM FILES

H-type FILE MODIFICATION::

The Hyflex file in cross-section presents a ‘ S ’ shape rather than single helix teardrop cross-sectional shape of true hedstroem file. The S file has double helix configuration H-type FILE MODIFICATION:

U-File:

An instrument for which there is no ISO or ADA specification It is marketed as ProFiles, GT Files and LIGHTSPEED. The U-files cross-sectional configuration has two 90 0 cutting edges at each of the three points of the blade. The flat cutting surfaces act as planing instrument and are referred to as ‘ radial lands ’ A non-cutting pilot tip ensures that the file remains in the lumen of the canal, thus avoiding transportation and zipping at the apex U-File

QUANTEC “FILES”:

The Quantec instrument (Sybro-Endo/Kerr), although called a “ file ” , was more like a reamer. It was not designed to be used in the file ’ s push-pull action but rather in the reamer ’ s rotatory motion. The radial lands of the Quantec were slightly relieved to reduce frictional contact with the canal wall, and the helix is configured to remove debris. It is no longer manufactured QUANTEC “ FILES ”

FLEXOFILES::

Flexible file – triangular cross-section, stainless steel blank Non-cutting tip (1.81 flutes per mm) Golden medium – similar in design FLEXOFILES:

INTERMEDIATE FILES:

Produced by trimming 1 mm from tip of file and rounding off sharp edges on a diamond file Files changed from 10 to 12 15 to 17 20 to 22 25 to 27 Advantage- smooth progress through files Disadvantage – disposable, edges difficult to smooth may cause ledging INTERMEDIATE FILES

OBTURATING INSTRUMENTS ENDODONTIC CONDENSERS AND SPREADERS::

Smooth tapered metal instruments – compress and compact gutta-percha Pluggers or condensers – blunt or flat-ended tips Spreaders – more tapered pointed tips Long handled – chrome plated or stainless steel OBTURATING INSTRUMENTS ENDODONTIC CONDENSERS AND SPREADERS :

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M series plugger – spreaders Double-ended Long-handled instruments Handles color 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

ENDODONTIC PLIERS AND FORCEPS::

Handling and placement of silver point and gutta-percha cones. Pliers – tapered groove in beak for grasping silver cone. Forceps – grooved or serrated beaks for holding gp cones. Have latch mechanism for locking in closed position ENDODONTIC PLIERS AND FORCEPS:

NiTi SPREADERS:

NiTi finger spreaders Used in curved canals for good obturation NiTi SPREADERS

ISO GROUPS II AND III:

Engine driven instruments use 3 types of contra angle handpiece A full rotary handpiece – latch or friction grip Reciprocating/Quarterturn handpiece Special handpiece – vertical stroke with reciprocating quarterturn ISO GROUP II – Instruments with shaft and operating head as separate pieces ISO GROUP III – Instruments with shaft and operating head as one piece ISO GROUPS II AND III

ULTRASONIC INSTRUMENTS::

System in which sound as an energy source activates an endodontic file resulting in a 3 dimensional activation of the file File – Vibrates in a sinus wave like fashion Antinodes – maximal displacement (tip) Nodes – no displacement Fracture – at the nodes Debriding action – Cavitation and acoustic streaming Cavitation – positive pressure followed by a negative pressure in the fluid Cavity formed in the negative phase implodes with great force during next positive pressure phase Acoustic streaming – small, intense, circular fluid movement Occurs closer to the tip ULTRASONIC INSTRUMENTS:

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