Contemporary endodontic tools: kinds using teсhnique.
Actuality of topic: Knowledge of bases of organization of stomatological service, study of variety of tool that is utillized for a therapeutic reception at stomatology, his classification, functions, standardized going near making will enable correctly and rationally to organize work of doctor of stomatology in the future.
Aims: to study the purpose and the task of phantom course, to familiarize with the equipment of cabinet and dental instruments.
3. Base knowledges, abilities, habits which are necessary for study the topic.
Names of previous disciplines
To describe general hygienical norms which are pulled out to the equipment of dental cabinet of therapeutic type. To expect an area, illumination, detailed sizes of cabinet coming from general hygienical norms.
Propedeutics of therapeutic dentistry
To be able to apply basic dental instruments depending on using. To classify and identify every instrument.
Propedeutics of orthopaedic dentistry /
To classify and identify every instrument which is utillized in orthopaedic dentistry. To be able to apply basic dental instrument depending on function.
4. Task for own unaided work during lesson.
4.1. List of basic terms, parameters, descriptions which a student must learn at preparation to lesson:
Universal dental device
mounted in one aggregate, it is a complex of apparatus and adaptations which are necessary for the specialized dental help a patient.
Devices which serve for fixing of all of circulating instruments at therapeutic and orthopaedic works.
Circulating instruments by which conduct preparing of hard tissue of teeth. The dental drills are made for mechanical and turbine dental handpieces.
General dental instruments
Basic instruments which are in the tray of doctor: dental probe, twizer, mirror, excavator, plugger, smoother.
4.2. Theoretical questions for lesson:
To know the organization of dental cabinet.
To transfer and describe the types of dental arm-chairs.
To know the types of dental machine, their structure, principle of work.
To know the types of dental handpieces, their structure and function.
To know the types of dental drills endodontic preparation, their using.
To transfer and describe the groups of dental instruments for endodntic treatment.
4.3. Practical tasks which are executed on the lesson:
1. Be able to identify the dental instrument which is in the dental offered by teacher.
2.To classify dental handpiecesdepending dental drills which are evidently demonstrated teachers.
5. Plan and organizational structure of lesson from discipline.
Distributing of time
Types of control
Facilities of education
practical tasks, situatioonal tasks, verbal questioning, are after the standardized lists of questions.
textbooks, manuals, methodical recommendations.
Oh the Organizational questions.
Forming of motivation.
initial level of knoweledge .
Control of final level of preparation.
General estimation of educational activity of student.
Informing of students is about the topic of next lesson.
Content of topic:
Classification of endodontic instruments:
endodontic instruments for dilatation of tooth canal orifice
endodontic instruments for patency of root canal
endodontic instruments for dilatation and smoothing-out of root canal
endodontic instruments for determination of size of root canal
endodontic instruments for extirpation of contents of root canal
endodontic instruments for root filling
Color codification of thickness of endodontic instruments by ISO:
Rose – 06, gray – 08, violet – 10, white -15, yellow – 20, red – 25, dark blue – 30, green – 35, black – 40.
Endodontic instruments for dilatation of tooth canal orifice
Gates Glidden drills – are bud-shaped with blunt end on the long thin core. The length of the work part with core -15-19mm. There are 6 sizes of these instruments, which are marked by rings on the hand. These are used at slow speed for preparing of orifice and the coronal 2/3 of the canal
Peeso Reamer/ They have prolonged work part on the core and blunt end
Orifice opener . It has tetrahedral work part, which is narrowed to the apex.
For many years the standard cutting instruments have been the reamer, K-type file and Hedstroem file. These root canal preparation instruments have been manufactured to a size and type advised by the International Standards Organisation (ISO). The specifications recommended are complex and differ according to the type of instrument. For most standardized instruments the number refers to its diameter at the tip in one-hundredths of a millimetre; a number 10, for example, means that it has a tip diameter of 0.10 mm. Colour coding originally denoted the size, but now represents a sequence of sizes. All these instruments have a standard 2% taper over their working length.
Endodontic instruments for patancy of root canal
The reamer is constructed from a square or triangular blank of stainless Cr-Ni steel, machine twisted into a spiral but with fewer cutting flutes than a file. The reamer will only cut dentine when it is rotated in the canal; the mode of action described for its use is a quarter to a half turn to cut dentine, and withdrawal to remove the debris. The stiffness of an instrument increases with each larger size, so that larger reamers in curved canals will tend to cut a wider channel near the apical end of the root canal (apical zipping).
K-flexoreamer is more flexible then K-reamer at the expense of more qualitative steel with three-angular cross-section. It is used in thin and curved canals.
Pathfinder has aggressive tip, sharp cutting blade, high flexibility. It is used for narrowed canals. The thickness is corresponded №09 ISO. It has symbol “P” and the hand of instrument is orange.
These instruments were originally made from a square or triangular blank, machine twisted to form a tight spiral. The angle of the blades or flutes is consequently near a right-angle to the shank, so that either a reaming or a filing action may be used.
Files These are more flexible than reamers and are used mainly with a longitudinal rasping action, although some types can also be rotated. The main types of file available are:
K-file—Made by twisting a square metal blank. More twists than a reamer .". more cutting edges.
Hedstroem file— The Hedstroem file is machined from a round tapered blank. A spiral groove is cut into the shank, producing a sharp blade. Only a true filing action should be used with this instrument because of the angle of the blade. There is a strong possibility of fracture if a reaming action is used and the blades are engaged in the dentine. The Hedstroem file is useful for removing gutta-percha root fillings.
Must never be used with a rotary action on the stage of smoothing-out of walls of root canal
Safety Hedstroem file – one of the side of this instrument is smooth. It is used for smoothing-out of walls of curved root canal
K-flexfile is made from a rhomboid or diamond shaped blank. The acute angle of this shape provides the instrument with two sharp blades and the narrower diameter allows greater flexibility in the shaft than a conventional K-file.
Flex-o-file~Looks similar to a K-file but is made from a triangular blank of a more flexible steel. The file also has a blunt tip which means that it is unlikely to create a false channel. This file is more flexible than K-types and is now becoming a popular replacement. It does not fracture easily and is so flexible that it is possible to tie a knot in the shank of the smaller sizes.
File nitiflex - made from nickel-titanium alloy (50% and 50%) by cutting method. It has non-aggressive tip, flexibility and elasticity in 5 time more than standard instruments. It is used for very curved canal which is curved by angle of 90 degree. It must be back-forward motion of instrument.
Conventional hand instruments; top – reamer with red stop; middle - Hedstroem file with black stop; bottom - K-flex file with yellow stop.
The latest developments in file design have seen a move away from the ISO standard 2% taper to files with increasing tapers of up to 12%, made in a nickel-titanium alloy. Although most of these new developments are used with an electric motor, hand files of greater taper are available. These are illustrated in Figure 11.
A pack of hand files of greater taper, 12% taper (blue), 10% (red), 8% (yellow) and 6% (white).
Handpieces providing a mechanical movement to the root canal cutting instrument have been available since 1964. Their function was primarily a reciprocating action through 90° and/or a vertical movement, according to the design and make. Because steel files do not have the flexibility necessary for rotary movements in a curved canal without damaging the canal configuration, these instruments were never really acceptable in endodontic practice.
A totally new concept in canal preparation came with the development of sonic and ultra-sonically activated endodontic handpieces. Much research took place into the mode of action and effectiveness of these machines. It was generally agreed that while the sonic machines were more effective at hard tissue removal, the ultrasonic machines were more effective in irrigation. The piezo-electric machines were found to be more effective than the magnetostrictive. The latter also generated more heat, and irrigation with effective quantities of sodium hypochlorite was found to be difficult.
The ultrasonic action causes acoustic microstreaming of the irrigant, intensive circular fluid movement carried right to the tip of the instrument, found to be very effective at canal debridement. This effect is reduced, however, when the file is constrained by the canal wall. The main use of these instruments today is in irrigation and debridement, using a freely oscillating file in a sodium hypochlorite filled canal, after thorough mechanical canal shaping.2
However, the development of nickel-titanium alloy for endodontic instruments has allowed the concept of an engine driven endodontic instrument to be fully explored. The total flexibility of this alloy, and the use of radial lands on the cutting flutes to keep the instrument centred in the canal, permit controlled cutting of the dentine walls. Most major manufacturers have developed a nickel-titanium rotary system. Lightspeed, Profiles, GT Rotary files, FlexMaster, Quantec system, Hero, K3, Protaper, and no doubt more will appear before this book is even published. It would not be possible to describe each of these fully, but the basic concepts are presented here, with a general description of their use being given in Part 7.
A low-speed, controlled-torque motor is necessary when using these instruments, as illustrated in
A low-speed, high-torque motor required for use with nickel-titanium rotary instruments.
The use of rotary cutting instruments in a standard handpiece is condemned because of the danger of fracture of the instrument or perforation of the root canal. The exception to this rule is the Gates-Glidden bur, which has a safe-ended tip. In addition, the site of fracture, if it does occur, is almost always near the hub so the fractured piece is easily removed. In the past this bur has been recommended for initial flaring of the coronal portion of the canal. This may now be carried out in a more controlled manner with a nickel-titanium orifice shaper. The Gates-Glidden bur may also be used to make post space and to remove gutta-percha from the canal. Gates-Glidden burs are manufactured in six sizes; their use is described in Part 7.
Endodontic instruments for determination of size of root canal
Root needle- on cross-section has round form
Round depth measuring instrument – is manufactured from soft steel, has small diameter, high flexibility. It is used for determination of patency and direction of root canal.
There are two established methods of assessing the working length of a root canal: one by radiography and the other with the use of an electronic device apex locator (Fig. 16). Both methods will be described in Part 7.
Once the working length has been confirmed, the individual preparation instruments must be accurately marked to length accordingly. There are many different gadgets available for transfer of the working length; the author prefers the device shown in Figure 17.
There are also different stops for the instrument, the most popular being rubber or silicone stops. These should always be placed at right angles to the shank of the instrument. Ideally the stops should be either notched, or pear shaped, so that in curved canals the notch or point of the pear may be directed towards the curve placed in the instrument.
Endodontic instruments for extirpation of contents of root canal Barbed broach
This instrument has near 40 sharp rasps or cogs pointing towards the handle. They may be used to remove the contents of the root canal before commencing shaping procedures. A vital pulp may be extirpated when carrying out elective endodontic procedures, or when treating a tooth with an irreversible pulpitis, by introducing the barbed broach deep in the canal, twisting it a quarter to a half turn, and withdrawing, as shown in Figure 20.
During root canal treatment of a tooth diagnosed as having an irreversible pulpitis, the vital pulp has been extirpated on a barbed broach.
Root rasp –has 50 sharp cogs which is located by straight angle pointing towards the handle. Cogs are very firm or solid. These are not bended or twisted. The tip of the instrument is round and has no cogs. It is used for dilatation and extirpation of soft tissue from root canal.
Endodontic instrumentsfor root filling
Spiral root canal fillers
It is conical wire spiral with handle. The spires if spiral are twisted antni-clock-wise. Their main use is for the insertion of filling material into the root canal. There are machine and handy root canal fillers.
Cold lateral compaction using gutta-percha requires either long-handled or finger spreaders (Fig. 26). These have a long, tapered shank with a sharp point. The instrument is used to compact gutta-percha laterally against the walls of the root canal and provide a space for the insertion of further gutta-percha points. There are several sizes available, and these are selected according to the canal size and the size of the gutta-percha point. The choice of long-handled spreaders or finger spreaders depends on personal preference. The advantage of finger spreaders is that less force can be used, and this reduces the risk of root fracture.
Cold lateral compaction may be carried out with either finger spreaders or long-handled spreaders.
It is used for warming up gutta-percha during lateral and vertical compaction in the root canal. One side is working part of the instrument. It has various sizes, and has both a pointed tip for lateral spreading, and a flat tip for vertical compaction. Another side is plugger, which condensate gutta-percha in r/c.
Machtou heat carrier/pluggers for warm lateral and vertical compaction
Plugger (vertical condenser) – has cylindrical or conical work part and stopfer-shaped tip. There are Finger Plugger and Handy Plugger. It is used for vertical condensation gutta-percha in root canal.
Materials are for self-control:
A. Tasks for self-control (example)
What does instrument use for dilatation of root canal?
c) root needle
d) orifice opener
2. What does instrument use for extirpation of pulp from canal?
a) nitiflex file
*b) barbed broach
3. What is basic function of hedstroem file?