Instrumentation in endodontics
1-Introduction:
Root canal preparation or shaping is one of the stages of endodontic treatment in which instrumentation is very varied and omnipresent. Indeed, associated with abundant and adapted irrigation, it remains essential to achieve the biological and mechanical objectives of root canal preparation. There is currently a very wide variety of instruments on the market, made of stainless steel or nickel-titanium (Ni-Ti), used with manual and/or mechanized techniques, also called assisted. Sound and ultrasonic instruments can also complete the preparation. Despite the development of mechanized systems, manual instrumentation remains relevant, because assisted techniques generally require an initial manual phase, in particular for the location of root canal entrances and the permeabilization of the canals.
2-Alloys used in the manufacture of endodontic instruments:
Endodontic instruments are made of either stainless steel or a shape memory alloy based on nickel and titanium.
The chemical composition of Ni-Ti alloys is 50% nickel and 50% titanium, but can vary by a few percent.
3- General rules:
An endodontic instrument consists of three parts:
a handle: made of metal or plastic, it allows the manual gripping of the instrument or if it is a mechanized instrument it is adapted to the handpiece on which it will be mounted. This handle includes the indication of the diameter of the instrument.
the rod: it is the rough outline of the metal wire from which the working part of the instrument is made, it is fixed in the handle, it can be of round, triangular or rectangular section depending on the instrument. The variation in length of the rod gives its length to the instrument which can be either 21, 25, 29 mm in total length.
the blade: made of stainless steel, it is the working part of the instrument, located in the extension of the rod, its length is fixed at 16 mm whatever the total length of the instrument and its diameter.
4-Efficiency and work of endodontic instruments:
a – The helix angle:
It is the angle between the axis of the instrument and that of the turns, varies between 20° and 60°. It is proportional to the number of turns and decreases with the diameter of the instrument.
b- The tip angle:
It is the angle formed by the blunt or non-blunt working edges of the end of the blade. It varies from 60 to 90°.
c- The section of the instrument : Gives the instrument its flexibility, its size and its cutting action, therefore the movement that must be applied to it.
5- Standardization of endodontic instruments:
The 1958 International Endodontic Conference in Philadelphia discussed the principle of standardizing root canal instruments.
4 criteria were retained:
The identity of diameters and shapes for all instruments of the same size.
The choice of the conical shape for all instruments.
Uniform progression of diameters for all instruments
Permanence of shapes whatever the diameter of the instrument.
The conclusions of the Philadelphia conference, defining the rules of endodontic standardization were reported by LAURICHESSE and SANTORO:
A numbering system for channel instruments and obturation cones using numbers from 06 to 140.
From n°10 to n°60 the increase in diameter is made by 5/100 mm
From n°60 to n°140 the increase in diameter is made by 10/100 mm
These diameters are measured at their active ends. The diameter of the tip is called D1, expressed in 100ths of a mm it gives the number of the instrument.
All endodontic instruments feature a 16 mm active blade
All instruments according to ISO standard have a taper of 2%
,
A colour identification code is also used internationally:
The numbering system for channel instruments and obturation cones uses numbers from 6→140 with a color code for identification .
- Rose 6
- Gray 8
- Violet 10
- White 15 45 90
- Yellow 20 50 100
- Red 25 55 110
- Blue 30 60 120
- Green 35 70 130
- Black 40 80 140
6-Classification of endodontic instruments:
Endodontic instruments are classified according to ISO and FDI into four groups:
- group 1 : includes exclusively manual canal instruments: pin, type k file (Kerr), type H file (Hedstrom), rat tail file, nerve puller, smooth probe, canal plugger.
- group 2 : includes mechanized canal instruments, they are used on an endodontic or conventional contra angle whose shapes are those of group 1 with the Lentulo paste filler.
- group 3 : is that of mechanized drills: Beutelrock, peeso, gates-Glidden, largo…
- group 4 : relates to absorption and obturation canal tips.
7-Instruments for accessing the pulp chamber and locating canal entrances:
Cameral trepanation is performed using a turbine, with a cylindrical–conical or ball burr.
The cameral opening is made using a long cylindrical-conical cutter (work with the side wall at the blunt end).
Zekrya-endo Strawberry:
Endo Access Bur:
Endo Access:
Probe:
canal excavators : are distinguished from round excavators by their more pronounced angulation and their longer lower segment.
– effective for cleaning pulp chambers and localizing root canals as well as for removing temporary fillings
8-CLASSIC INSTRUMENTS FOR CANAL PREPARATION:
Manual:
- Not standardized:
A- Probe: Are non-standardized instruments
Round, square or conical section, used for canal catheterization.
Very thin and flexible conical.
Allow the localization and opening of root canals to allow access to the appropriate preparation instruments.
- Probe No. “17” to check for any overhang.
- DG 16 probe, “Rhein” probe no. 3 after removal of the pulp parenchyma: for locating canal entrances
B- Tire nerf:
Hand instrument machined in stainless steel with a round section, has hook-shaped barbs, used in clockwise rotation of 180° then traction, for eviction of the pulp parenchyma. (Currently almost abandoned). Not standardized
2- Standardized:
Available in 3 main standardized instruments:
Spindle = reamer (rearm)
Lime k (Kerr) = lime (K file)
File H (Hedstrome) (Scraper) (H file)
Symbolized by geometric figures:
These symbols do not correspond to the section of the instruments, they are presented on the packaging and the handles to allow quick visual identification.
-The channel spindle or Reamer (identification symbol: triangle):
-Description :
– Standardized conical instrument. – The broach is the result of the twisting on edge of a triangular stainless steel matrix.
– The file pitch is long; reduced bulk.
– The pyramid ending the file is triangular and pointed.
¼ turn clockwise
The K type file (KERR) (identification symbol: square):
– Description :
Standardized instrument obtained by the edge twisting of a quadrangular stainless steel matrix
This significant twist gives the file tight steps.
The K file differs from the broach by its greater number of turns.
– An average helix angle of 40°
– It is more rigid than the pin and more effective in penetration.
– It is the instrument of choice for catheterization; it performs parietal curettage and even widening.
– The twisted file has some disadvantages: the active part of the instrument unspiralizes in an anti-clockwise direction and the memory is too rigid and risks displacing the apical foramen.
– Dynamic:
– The K file has a scraping action on the dentinal walls.
– The best efficiency is found in longitudinal back and forth movements.
– This file is operated by 45° rotations clockwise and counterclockwise to advance it into fine canals and in the event of interference.
– This movement is dangerous for an instrument obtained by twisting, especially in the anti-clockwise direction.
The type H file (HEDSTROM) (identification symbol: a circle):
Description :
Standardized instrument machined by micro-grinding from a cylindrical metal matrix
Constant pitch wood screw profile, which prevents any rotation in the channel under penalty of blockage and fracture.
The angle of attack of the blades relative to the major axis of the instrument is 90°, therefore very sharp.
– Dynamic:
– The H file works exclusively by pure traction movements; in parietal support.
– Any rotational movement must be avoided under penalty of fracture.
Mechanized:
Giro-Files “mechanized scraper ” :
Is an H file blade equipped with a mandrel, for use exclusively on giromatic contra-angles.
It is a standardized instrument whose conformation where the H file causes known defects relating to rigidity and fragility.
Mechanized Drills:
1- Largo Forests:
It is composed of a cylindrical active part of a small foam,
This type is used for clearances of canal orifices or opening of the pulp chamber. (same profile as GATES)
Glidden).
2- GATES Glidden drills:
Non-working tip drill, having (03) blades on a short active part of 2.5 to 4.5 mm in length varying with the diameter of the instrument
– Used on contra-angle with blue ring at 8000 rpm in pure rotation.
BEUTLEROCK drills:
It is a strong, very flexible cylindrical rod with real wood bits, with a working point, these forests are formidable.
They can drill the canal dentine, their use is very dangerous, should only be reserved for cases of canal calcifications in the coronal third, or the presence of particularly resistant canal paste (resin or permanent sealing cement).
Strawberry LN:
It offers a very long neck with a round active end of very small diameter, it is 28mm long. It allows a visual control in the search for a calcified canal orifice.
– It thus allows the creation of the canal trepanation cavity.
9-New canal preparation instruments:
• These instruments are manufactured either by twisting or by machining
Manual:
1- Obtained by twisting:
Flexofile: Standardized manual instrument with rectangular section, retains the principal of the K file manufacturing with superior flexibility, intended for catheterization, debridement and canal enlargement
K flex: Standardized to a diamond-shaped section for the same caliber or a significant reduction in metal volume, its effectiveness is comparable to that of the K file intended for catheterization and canal enlargement.
2- Obtained by machining:
A- MMC “Micro Mega Catheterizer”:
It has a hexagonal section, the pitch of these blades is very close to the K file, it only exists in numbers 8, 10 and 15 allowing the catheterization of the canals, it is slightly pushed in the apical direction with a rotation of 1/8 turn to the left and right while pushing in the apical direction.
B- MME “Micro Mega Expander”:
Looks like the H file, also only exists in the
Numbers 8, 10 and 15; intended to widen the passage identified by the MMC, it is introduced into the entire canal length without rotation and it widens the space by Single Movement of coronal traction only (used alternately with the MMC).
Uni-file of “BURNS”:
Similar to the H file, but its S section doubles the number of blades, it opposes two active blades rotating clockwise and inactive counterclockwise, it is the only instrument that simultaneously performs catheterization and widening of the canal.
Heli file: Its blade has 3 active blades rotating clockwise and inactive counterclockwise, has the same action as the uni-file .
Mechanized:
The Rispi: This is a non-standardized instrument, used on a giromatic contra-angle, it has a mandrel, a very short inactive rod, a long conical active part with barbs and a 1.5 mm blunt end, it is intended for the preparation of the coronal 2/3 of the canals.
The Dynatrak:
Also used on giromatic contra-angle, its blade resembles that of the uni-file, its end is fitted with a small foam, it also performs catheterization and canal preparation.
10- Current instruments for root canal preparation:
- The required properties of a Nickel-Titanium instrument:
Advantage :
Shape memory. Super elasticity
Disadvantages:
-high cost -risk of fracture due to fatigue
B-Classification criteria:
Nickel titanium instruments are classified according to 2 criteria:
1–the major conicity : constant or variable
2–the design of the blade : there are two groups:
- passive or non-cutting
B- active or cutting
Instrumentation in endodontics
11- Root canal obturation instruments:
Manual :
Spreaders: Lateral spreaders: non-standard channel spreaders with pointed ends used for the lateral condensation of cold conical and fine GUTTA.
Instrumentation in endodontics
Pluggers: Vertical pluggers, non-standardized channel pluggers with flat ends, used for the vertical condensation of hot gutta, they are conical and thin with a long or short, single or double handle.
Meanized:
1- The dough stuffing:
-Lentulo:
(Maillefer) (worm screw).
The oldest system, not standardized, is used in a clockwise direction only on a low-speed contra-angle (300/1000 rpm)
, available in 4 diameters: (1 = extra fine, 2 = fine, 3 = medium, 4 = large) and 3 lengths (17mm short) (21mm long), (25 extra long).
– Pastinject (micro-mega):
Same profile as Lentulo but whose blank is a blade and not a wire, corresponds to ISO standards, available in 5 diameters from n° 20 to n° 40, and 3 lengths 21 and 25 and 29 mm, the instrument is very efficient, requires an excellent apical stop, otherwise it frequently overshoots .
The compactors:
Instrument developed by Mac Spadden, allowing the thermomechanical compaction of gutta percha, the profile instrument resembling an inverted H file (truncated cone with apical base with helical screw thread)
Mounted on a blue ring contra-angle (fast speed 8000 rpm) allows the gutta to be softened by heating, then pushed back in the apical direction thanks to the profile of the instrument. The instrument is very effective requiring an excellent apical stop, dangerous in curved canals.
Other root canal obturation system:
The elements of System B
System B (Buchanan, 1994), derived from Schilder’s technique, is based on the use of a single instrument acting as a rammer and heater. This rammer is used to compact vertically, and in a single downward wave, a gutta-percha cone that has been previously adjusted
Gutta percha cones:
Non-resorbable, biocompatible, malleable material adapts to canal walls, plastic and radiopaque
Instrumentation in endodontics
12- Other instruments:
Paper tips : These are highly absorbent and designed to absorb moisture from prepared channels (ISO colored).
Endodontic ruler :
The Maillefer metal endometrium, or endodontic ruler, was created with the aim of facilitating canal preparation by adjusting the silicone stops directly on the instrument by placing it in the tunnel corresponding to the working length calculated beforehand.
Transfer sponge:
It contains a hypochlorite solution in the tank which ensures temporary decontamination of the instruments.
– Very useful for quick cleaning and presentation of instruments during endodontic treatment.
Silicone Stops:
Small silicone washers 1.5 to 2.5mm wide, perforated in the middle to be able to adjust the working length directly on the instrument placed at the level of the endometrium.
– Integrated Stop systems can be found on the instrument
Endodontic boxes:
Aluminum storage boxes,
– Different colors (silver, red, blue)
– Different sizes (Small, medium, large)
– Different shapes (round, square, rectangular) Used for storing endo instruments (files, burs, drills, paste fillers, etc.) – Sterilizable in an autoclave.
– Resists chemical disinfection
– Irrigation syringe:
The endodontic syringe is used to deliver the irrigation solutions into the root canal.
Ultrasonic inserts:
Mounted on piezoelectric ultrasonic handpieces, these inserts are mainly used to remove calcifications in the pulp chamber. Depending on the manufacturer, their surface is smooth or diamond-coated, and they are used with or without spray. Dentsply-Maillefer offers a range of 8 inserts (ProUltra® Endo), the first 4 of which have their active part covered with a layer of zirconium nitrate.
Instrumentation in endodontics
14-Conclusion:
The success of an endodontic treatment depends on several parameters from the diagnosis to the definitive restoration, each step is very important. But the instrumentation remains the essential condition to succeed in all the steps of an endodontic treatment.
Instrumentation in endodontics
Wisdom teeth can cause infections if not removed.
Dental crowns restore the function and appearance of damaged teeth.
Swollen gums are often a sign of periodontal disease.
Orthodontic treatments can be performed at any age.
Composite fillings are discreet and durable.
Composite fillings are discreet and durable.
Interdental brushes effectively clean tight spaces.
Visiting the dentist every six months prevents dental problems.