ENDODONTIC INSTRUMENTS and STERILIZATION by:Ruffalyn P. dela Cruz

OUTLINE: Introduction Instrument for access cavity preparation

• Basic instrument pack • Burs • Rubber Dam

Instruments for root canal preparation • Hand Instruments in endodontics • Power-assisted root canal instruments • Measuring instruments,gauges and stands

Instruments for retrieving broken instruments and posts Instruments for filling root canals

• Lateral condensation • Vertical condensation • Thermoplasticized injectibleible Gutta-percha • Gutta-prcha carrier device

Sterilization of endodontic instrument

Introduction

It is now widely accepted that successin root canal treatment depends upon thorough cleaning and shaping of the root canal system and the placement of the root canal filling of gutta-percha and insert sealer.

Instrument for access cavity preparation

• Basic instrument pack 1.Endodontic explorer →is a double ended, extra-

long, sharp instrument design to help the location of canal orifice and probing for fractures on the pulp chamber floor.

2.Endodontic excavator →is required to scoop out the pulp chamber contents and flick away pulp stones during access cavity preparation.

3.Mouth mirror →is best suited for visibility deep with in the pulp chamber

4.Endodontic locking tweezer →are ideally suitable in handling of paper points, gutta percha points and root canal instruments.

5.Briault and periodontal probes →are necessary for the initial assessment of the tooth for caries and localized periodontal condition.

6.Flat plastic instrument and endodontic pluggers →are needed to place interappoinment restorations .

7. Endodontic ruler →the 0.5 mm ruler is convenient instrument w/c measures files, Gutta-percha cones etc.

8.Irrigating syringe →is important to deposits endodontic irrigants in the pulp chamber.

Luer-lok type is the syringe of choice. • The barrel tip- prevents the needle dislodgement

occuring during irrigation. • Whilst-the tip itself is notched to prevent

accidental forcing of irrigant into the periapical tissues.

• Burs – Several types of burs will be required to

accomplish good access preparation. 1.Friction grip →tapered fissure burs ,are used in

the initial stages of access preparation to established the correct outline form.

2.Round burs→,normal and extra long ,are used to lift the roof off the pulp chamber and eliminate overhanging dentin. The longer and smaller sizes can be used to find calcified canals.

• 3.Safe-ended burs → or tungsten carbide bur, both with a non-cutting tip, is used to taper and smooth the accesss cavity preparation. The non-cutting tip prevents gouging on the floor of the pulp chamber.

4.Gates-Glidden bur →is a one piece rotary cutting instrument with a bud-shaped cutting point mounted on the fine shaft, now widely used in all root canal preparation techniques.

Three main uses: a. The coronal 2/3 of molar canals are generally wider less

curved than the apical 3rd, therefore these parts can be quickly and safely prepared with Gates Glidden burs.

b. The Gates-Glidden bur is useful for removing gutta-percha from a canal during post-space preparation or during retreatment.

c. The bur may be used to widen the canal when an instrument has fractured within it, to aid retrieval of the broken instrument.

• Rubber dam – Is purchased in 150mm squares, and comes in

various thicknesses. The thicker the material has the advantages of a tight fit around the neck of the tooth, thus providing hermetic seal, w/out the use of floss ligatures. The thicker the material does not tear easily.

The rubber dam is used to: 1.Protect the patient from inhalation or ingestion of

instruments, medicaments and debris. 2.Provide a clean, dry field of operation free from salivary

contamination. 3. Prevent the tongue and cheeks from obstructing the operating

field 4. Prevent the patient from rinsing the mouth and interfering

with the efficiency of the treatment.

Instruments for applying rubber dam 1. Rubber dam punch →several types of punch

are available and most are able to punch five or six holes ranging in diameter from 0.5 to 2.5mm. The size of hole that is punched is important:the ease of application with large hole must be balanced by seal at the cervical margin.

The important consideration in a punch is that it cuts a clean hole in the rubber.

2. Rubber dam Forceps → the forceps are use to place, adjust and remove the rubber dam clamp.

• 3. Lubricants and floss →if more than 1 tooth is to be isolated, it is sometimes difficult to pass the rubber between the teeth. If the contact point is tight but smooth, the use of the lubricant on the undersurface of the dam is very helpful. Dental floss - apart from preventing the ingestion or aspiration of the clamp, dental floss is particularly useful for accessing the condition of the mesial and distal contact areas, and thus for facilitating the passage of the rubber sheet beneath them.

4. Rubber dam frame → The rubber dam must be stretched over the patients mouth, so as not to obscure the operator’s vision and to provide patient comfort. Rubber dam frames are available in a variety of shapes and size.

• 5.Rubber dam clamps → clamps have two uses: first, they anchor the dam to the tooth, and second, they retract the gingiva. In endodontics, only anchorage is of concern.

– Clamp is consists of a pair of jaws joined by a spring bow. They maybe wingless or winged.

– The latter have a protrusion attached to each jaw. The wings are use to attach the rubber dam to the clamp so that both clamp and rubber may be applied to the tooth together.

– Clamps may be retentive or bland. • Retentive clamps −are

design to make a four-point contact with the tooth and have a narrow, curved and slightly inverted jaws, which may displace gingival tissue to grip the tooth below the level of greatest circumference. They are very useful on partly erupted teeth.

• Bland clamps − have flat jaws w/c grip the tooth around its entire circumference and because of their flatness, they are less likely to impinge on the gingiva. However , they can only be used where a tooth is fully erupted and has a cervical constriction that prevents the clamp from slipping off the tooth.

Method of applying the rubber dam. • In root canal treatment , it is sufficient to

isolate only 1 tooth and this makes rubber dam application more simply. Essentially, there are two method of application: 1. In the first, the rubber dam is attached to

the clamp and frame before it is place on the tooth.

2. In the second, the clamp is attached to the tooth before the dam is placed over the clamp.

Instrument for root canal preparation

-Hand Instruments are group according to their usage by the ISO (International Organization for Standardization). ENDODONTIC INSTRUMENT STANDARDIZATION. In 1959, a new line of standardized instruments and filling material was introduced. 1. A formula for the diameter and taper in each size of instrument and filling material was agreed on. 2. A formula for a graduated increment in size from one instrument to the next was developed. 3. A new instrument numbering system based on instrument metric diameter was established.

-This proposals have been widely accepted, and the endodontic

hand instruments; i.e. files, reamers and barbed broaches, are standardized in relation to size, colour coding and physical properties.

• Barbed broaches → are made from soft steel wire. The cuts are made eccentrically around the shaft so that it is not weakened excessively at any one point. – Barbed broaches are mainly used for the removal

of the pulp tissue from root canals, but also for the removal of the cotton wool dressings.

–Provided the instrument is loose within the canal and the barb is used to engage soft tissue only, the risk of fracture is minimal

The barbed broach must always be fitted loosely in the canal. The barbs of a tightly fitted broach will engage the dentinal walls on the withdrawal stroke, greatly increasing the likelihood of instrument fracture.

• Reamers →are instruments that ream (twisting)—specifically, a sharp-edged tool for enlarging or tapering holes.

Design & Structure – A reamer is manufactured from a triangular or

square steel wire that is twisted to give the typical shape of a reamer. The angle between the long-axis and the cutting blade is small, which is why preparation by reamer is effective only in rotating motion.

– The tip of the instrument is cutting which makes a reamer suitable for the preparation of straight canals only without the risk of ledging.

–Endodontic reamers cut by being tightly inserted into the canal, twisted clockwise one quarter- to one half-turn to engage their blades into the dentin, and then withdrawn—penetration, rotation, and retraction.

Sizes & Codes Reamers come in sizes 06 – 140, all with a

taper of 0.02. Reamer design is identified by the triangle symbol on the handle.

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.

• Files →The tighter spiral of a file establishes a cutting angle (rake) that achieves its primary action on withdrawal, although it will cut in the push motion as well. The cutting action of the file can be effected in either a filing (rasping) or a reaming (drilling) motion. TYPES OF FILES: a. K-files b. Flexofile c. Flex-R/ Flexoreamers d. Hedstrom and Safety Hedstrom e. Nitiflex-file

a. K-file → are manufactured from square or sometimes triangular steel wire that is twisted to give the typical shape of a K-file. The angle between the long-axis and the cutting blade is greater than in a reamer, and therefore preparation by a K-file is effective both in rotary and filing motion.

• 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.

• K-file: Recommended use The K-file is suited for the preparation of straight

canals. It prepares dentin effectively both in filing motion (up and down) and when rotated. In slightly curved canals the recommended techniques are continuous rotation (lower picture) when the resistance is small and balanced force (upper picture) against greater resistance. Compared to reamers, the use of continuous rotation is limited because of the screwing effect typical of K-files.

• 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.

• b. Flexo file → has a rhomboid-shaped and twisted instrument has a series of cutting flutes with alternate sharp cutting edges and obtuse non-cutting edges. The cutting efficiency is greater than many brands of k-files, due to its increase flexibility and ability to remove debris as its alternating blades provide a reservoir for debris. Flexofile is well suited for the preparation of evenly curved canals without the risk of ledge formation. A disadvantages of this file is its quicker loss of cutting efficiency.

• Sizes & Codes Flexofiles come in sizes 15 – 40, all with a taper of

0.02. K-file design is identified by the square symbol on the handle.

Flexofiles can be best distinguished from normal K-files by the size code at the top of the instrument: in flexofiles the color of the number is the same as the color of the handle.

• Recommended use . The flexofile prepares dentin effectively both in filing

motion (up and down) and when rotated. In slightly curved canals the recommended techniques are continuous rotation (lower picture) when the resistance is small and balanced force (upper picture) against greater resistance. Use of continuous rotation is limited as compared to reamers because of the screwing effect typical of K-files.

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.

c. Flex-R file/flexoreamer Design & Structure - Flexoreamers are manufactured from a

triangular steel wire that gives sharper cutting blades and more room for debris than the conventional K-file w/c is twisted to give the typical shape of a reamer. The angle between the long-axis and the cutting blade is small, and therefore preparation by flexoreamer is 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.

• Sizes & Codes Flexoreamers come in sizes 15 – 40, all with a taper of

0.02. Reamer design is identified by the triangle symbol on the handle.

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.

• 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 techniques are continuous rotation (upper picture) when the resistance is small and balanced force (lower picture) against greater resistance.

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 it against an even background before introducing it into the canal.

d.Hedstrom • Design & Structure Hedstrom files are manufactured from

round steel wire by grinding. The angle between the long-axis and the cutting blade is close to right angle, which is why preparation by Hedstrom files is effective only when using a filing motion (up and down movement).

• Sizes & Codes Hedstroms come in sizes 08 – 140, all with a

taper of 0.02. H-file design is identified by the circle symbol on the handle.

• Recommended use Hedstrom can be used

both in straight canals and curved canals. The hedstrom prepares dentin effectively only when using a filing, up and down motion. 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

• Safety Hedstrom file- features a non-cutting safety side along the length of the blade w/c reduces the potential for strips perforations. A millimeter scale is etch on to the shaft of the instrument to facilitate length control. The instrument has a good cutting efficiency in either a filling or reaming action. Therefore it could be classified as a hybrid design.

• Safety tips Hedstrom files show a greater risk for

fracture than reamers and K-files if used in a wrong way. However, correctly used H-files rarely fracture. 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.

e.NiTiflex-files • Design & Structure

NiTiflex-files are manufactured from nickel-titan wire that is ground to give the typical profile of a K-file. The angle between the long-axis and the cutting blade is bigger than in reamers, and therefore preparation by NiTiflex-file is effective both in rotating motion and in filing motion (up and down movement).

The tip of the instrument is non-cutting (‘bat-tip’) which makes the NiTiflex-file well suited for the preparation of curved canals without the risk of ledge formation.

• Sizes & Codes NiTiflex-files come in sizes 15 – 60, all with a taper

of 0.02. K-file design is identified by the square symbol on the handle.NiTiflex-files can be best distinguished from normal K-files by the code that in NiTiflex-files is printed with two colors.

• Recommended use NiTiflex-file is suited to be used both in straight

canals as well as in curved canals. The NiTiflex-file prepares dentin both in filing motion (up and down) and when rotated. In curved canals the recommended techniques are continuous rotation when the resistance is small and balanced force against greater resistance. Use of balanced force instead of continuous rotation is easier because of the K-file design, which causes a screwing effect in continuous rotation. The use of filing motion in curved canals can cause transportation and ledging, and is not recommended.

• Safety tips NiTiflex-files can be rotated only using

moderate pressure. Use of force may result in fracture also with bigger sized instruments. NiTiflex-files are super-elastic and always return to their original shape (= elastic memory), which makes it difficult or impossible to detect weakened structure by visual observation. Fracture risk is best controlled by correct use and by using the instrument no more than ten times

Power-assisted root canal instruments

• Reciprocating handpieces – Specifically design handpieces providing a

mechanical action to a root canal cutting. They are designed to reduced the time spent in canal preparation.

a. Giromatic- the 1st mechanized handpieces,it accepts barbed-broach-type files and three sided files.

• b. M4 Safety handpiece- it has a simplified chuck mechanism activated by thumb pressure to accommodate a plastic-handled root canal instrument. The handpiece lets the instrument glide along the walls of the canal by mimicking commonly used hand movements.

c. Canal Finder system- is consist of a contra-angle handpiece powered by a micromotor, producing a reciprocal screwing action w/c enables the file to cleave, rather than abrade the canal wall, and advance along the path of least resistance, maintaining the original pathway.

• Ultrasonic Instrumentation

a. Cavi-Endo- the 1st ultrasonic unit specially design for endodontic use. The machine is modified cavitron w/c contains irrigants reservoir that’s supplies a continous flow of sodium hypochlorite through a specially designed handpiece on to the energized file.

b. Piezoelectric- these units is supplied with a multifunctional handpiece, into which different tips are fitted. This unit is additionally used for the location of calcified canals, removal of broken instrument s, removal of cemented posts, and for root end cavity preparation during periradicular surgery.

• Sonic Instrumentation-The Endo MM1500 was developed as a sonic vibratotory handpiece to be attached to the turbine line of a dental unit. The sonic instrumentation avoids transportation of curved canals in the smaller sizes.

Nitimatic system – has a hand piecerun by an electric motor which provides load-torque compensation and constant speed even at a very low speed.

- in using Ni-Ti instruments is to prevent heavy hand pressure and binding. If you use light hand pressure, the binding is minimal. You will remove less tooth structure at any one time, but will be compensated for it by increasing the number of instrumentation cycles.

Measuring instrument, gauges and stands

• The importance of instrumentation to a known canal length cannot be overstressed.

• A rubber stops-provides the simplest and most positive stop instrumentation and some files have already a stopper.

• A ruler-is necessary to set the stop, or alternative measuring devices have been developed to make the procedure easier.

• Stand- is useful as the instruments can be placed in order, and are easily accessible at the chairside.

Instrument for retrieving broken instrument and posts

• As prevention is much easier than the removal of a fractured instrument from the root canal, all root canal instrument should be used carefully. When an instrument fractures, it may be possible to remove it w/ one of number of different instrument.

1. Forceps-can be used to removed a broken instrument only if the end of the fractured instrument is visible and not jammed firmly within the canal.

2.Cancellier kit- if the obstruction is loose but not free, cancellier extractors are simply hollow pluggers, can be used to fit over the obstruction. A single drop of cyanoacrylate glue depositsed into the cancellier sticks the instrument into the extractor, it is retrieve.

• 3.Post remover- these devices exerts a strong pull on the post and there is a risk of tooth fracture. Atraumatic post removal can be achieved with a n ultrasonic scaler tip.

4.Masserann kit-can be used to free obstruction w/c is jammed in the canal. The principle of this method consists of freeing around the periphery of broken post using hollow trepan burs, the trench created around the broken instrument reduces the resistance of the fragment to removal and create space for the insertion of 2nd instrument in the kit w/c grips and extracts the broken instrument.

Instrument for filling root canals • LATERAL CONDENSATION Hand spreader- are design to facilitate the

placement of accessory gutta-percha points around a well fitting master gutta-percha point during the lateral condensation method.

• Finger spreader- these instrument is colour-coded to match the standardized or gutta-percha points. Their short length affords a high degree of tactile sense and allows them to rotate freely around their axis, thus freeing the instrument for easy removal.

• VERTICAL CONDENSATION Schilder pluggers-consist of long-handled

instruments w/c are larger diameter than spreaders and have a blunt end; they are used to pack thermally softened gutta-perchainto the root canal.

Thermoplasticized injectable Gutta-percha

Obtura II heated Gutta-percha System –

the heated delivery gun extrude gutta-percha through the fine needle, the temperature is controlled by the main unt.

Hygenic Ultrafill system – Canullae filled with Gutta-percha are heated in the main unit, when the gutta percha is softened , the canulla is loaded into the delivery syringe.

Gutta-percha carrier devices

Thermafil obturator – the mould heated

gutta-percha is placed to root canal file, the plastic carrier is coated with gutta-percha which carry gutta percha to the canal.

Inject-R-Fill. A stainless steel tube contains

gutta-percha which is design for backfilling the canal after the apical parthas been plugged by gutta-percha during vertical condensation, w/c is after heating the is forced out of the tube by pressure from the handle.

J S Quick-fill- a thermocompactor instrument precoated with gutta-percha.

Instrument use in taking radiograph

• X-ray film – Dental radiographs, commonly referred to as X-

ray films, or informally, X-rays, are pictures of the teeth, bones, and surrounding soft tissues to screen for and help identify problems with the teeth, mouth, and jaw.

• Film holder

– is a device which holds one or more pieces of photographic film, for insertion into a camera or optical scanning device such as a dedicated film scanner or a flatbed scanner with film scanning capabilities.

• X-ray Machine -a device used to

generate X-rays. These devices are commonly used by radiographers to acquire an x-ray image of the inside of an object (as in medicine or non-destructive testing)

STERILIZATION

Sterilization of endodontic instrument

While it is generally recognized that the aim of root canal preparation is to eliminate infection from a canal, it is very important that all instrument used in the root canal should be sterile, or at least have been sterilized between patients. Various method have been advocated.

Sterilization – Sterilization is the destruction or complete removal of all forms of micro organisms.

Disinfection – Disinfection is the destruction of many microorganisms but not usually the bacterial spores.

General Principles

• Universal precautions – use of mouth mask, head cap, protective eye were gloves are recommended.

• Hand washing and care of hands

• PRE-STERILIZATION CLEANING - Bio-films of vegatitive form of bacterias

spores and the organic matter formed on the surface of the instrument have to be washed with the suitable disinfectant before proceeding with the sterilization process.

Pressure steam(autoclaving) sterilization. →Long cycle of 15 min – 121 degree Celsius and 15 lbs pressure.

Short cycle of 7 min – 134 degree Celsius and 30 lbs pressure.

• Advantage of autoclaves - Most rapid and effective methods for sterilization of commonly used dental equipments and root canal files.

• Disadvantages of Autoclaves – Can cause rusting of carbon steel instruments.

Dental burs can be autoclaved after dipping it into 2 % sodium nitrite sol.

• Dry Heat Sterilization

– Hot air oven

Dry heat at 160 degree Celsius is commonly used for this purpose. Microbial inactivation by dry heat is primarily an oxidation process.

Employed for sterilization of glassware, glass syringes, oily injection as well as metal instruments.

Cotton wool and paper points can be placed in a metal boxes and sterilized and sealed afterwards until used.

• Gas sterilization

– Using ethylene oxide gas131 degree celsius 20 pounds pressure is use for this purpose. Heat sensitive plastic instrument are sterilized by this method. Because water is absent from this method, cotton wool and paper points do not get wet and so do not need to de dried; also metal instrument do not corrode.

• Sterile packs - increasingly, disposable items are produced in sterile blister packs; these were initially confined to syringes, needles, scalpel blade and sutures but now include some filles and paper points.

• Glass bead/salt sterilizer –used for sterilization of endodontic files.This method is effective, provided the instrument to be sterilized is held in the heat conducting material for a minimum of 10 sec.

• Chemical disinfectant - useful for those items w/c would be damage by methods of sterilization. Disinfectant such as sodium hypochlorite and glutaraldehyde may be used to wipe over working surface of instrument.

Thank you