|  | | | | | Online Catalogue > Protocols > Mtwo Mtwo
The ideal requirements of a rotary file system are flexibility, efficiency, safety and ease of use. Mtwo is the latest rotary file system from VDW that gets close to the ideal (1,2,3,4). It has features that are unique and that make this file system a serious competitor in the rotary file market.
The files have been designed to cut very efficiently, giving them maximum strength and flexibility, allowing for excellent debris removal and making the files easier to use in curved canals. Once the glide path has been established preparation can be completed in a matter of minutes.
Unique features of Mtwo This is the only system that uses 10/.04 and 15/.05 instruments. It means that canal preparation with hand files is minimized and that the apical third is easily reached.
Mtwo are the only endodontic instruments that are available with the traditional 16mm working part and also a 21mm working part in 25mm and 31 mm lengths. | |  | Dr Tony Druttman B.Sc., B.Ch.D, M.Sc
Specialist Endodontist who has referral practices in the West End and City of London.
He is also a Clinical Teacher at the Eastman Dental Institute
www.londonendo.co.uk |
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The longer working part allows the instrument to remove coronal interferences more easily than other instruments and in canals of 22mm length and above it allows the instrument to progress to working length with greater ease than conventional instruments, obviating the need for pre-flaring with instruments such as Gates Glidden drills.
Protocol
As with other rotary systems the tooth should be isolated with rubber dam and an access cavity prepared. The canal orifices are identified and the pulp chamber flooded with sodium hypochlorite. The transition between the floor of the pulp chamber and the canal entrance should be smooth and tapered so that the tips of the files do not snag as they prepare the radicular access.
The most critical part of the preparation is the establishment of a glide path. This allows for the smooth passage of the files to the working length and for the use of patency files to prevent blockage at the apical tip. Incorrect use of either hand or rotary instruments may prevent the elimination or creation of obstructions or ledges within the canal. Ledges particularly in the apical third of the canal can be difficult to negotiate.
An ISO size 10 lubricated and precurved hand file is introduced into the canal to approximately 2/3 of the estimated canal length and using a combination of stem winding and pulling motion and is used to file the canal walls in a circumferential motion. If the file does not progress easily or meets apical resistance then the same operation is repeated with an ISO 08 or 06 hand file. Apical obstructions can usually be overcome by using the balance force technique and precurving the tip of the file.
Coronal preparation
The coronal part of the canal can be pre-flared with a10/.04 Mtwo rotary file to remove canal debris, but only in that part of the canal where the file can move freely. The rotating file should be used with a light touch and brushed against the wall of the canal in a coronal direction. It must not be used to attempt to overcome or bypass a ledge. The tip of the file is safe ended and will not therefore not cut through a ledge, but neither will it create a ledge. It therefore must not be used with excessive force. The canal is then re-irrigated with sodium hypochlorite.
The precurved ISO .06, .08, or .10 hand file is then negotiated to bypass any ledges to working length with the aid of an apex locator and canal patency is then established. The Mtwo rotary files are set up to the correct working length and used in sequence, 10/.04, 15/05, 20/06 and 25/06. It is recommended that the canal is re-irrigated between file changes and that patency is checked. The files should be examined on removal from the canal to check the position of the debris on the file. As the file size increases, there should be evidence of debris steadily towards the apical part of the file.
If the file does not progress easily to the working length, it should be removed, the flutes cleaned of debris, the canal irrigated and the file re-inserted. Because of the superb cutting ability of the file it can also be used as a hand file for 'fine tuning'. The canal is shaped by cutting on the outward stroke. This means that canals that are not circular in cross section, (i.e. distal canals of lower molars) can be shaped by the ability of the file to cut laterally (5).
The files should be used at 300rpm with a constant torque motor with pre-set torque setting for each of the files, such as the VDW Silver or Gold motor.
A size 30 hand file is then used to gauge the apex. It is introduced into the canal and the binding length assessed. If the file binds at approximately 0.5 to 1.0mm short of the working length then the 25/.06 is determined to be the master apical file (MAF). If it does not the file sizes can be increased to a size 35 or 40 using 30/.05, 35/.04 or .06 and 40/.04 or .06 and the apex gauged again. Because the tip of the Mtwo rotary files is safe ended, there is less chance of zipping the apex than with systems that use a modified tip.
A note of caution: with any new system there is a learning curve and practice on Endo Vu blocks and a few extracted teeth is a good idea before using the system clinically. While the files cut very effectively, the tips of the smaller instruments can be misshapened easily. The files should always be inserted into the canal entrances with either direct or indirect vision. The files should also be examined every time they are removed from the canal to check for distortion and replaced if necessary. |
Examples of Preparation with Mtwo
 |  | | Tooth 17 with a 90 deg mb root | Tooth 36 |  |  | | Tooth 14 with an S shaped root | Tooth 25 with 3 canals |
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References
1. Comparative study on the shaping ability and cleaning efficiency of rotary Mtwo instruments. Part 1. Shaping ability in simulated curved canals
Schäfer E, Erter M, Dammaschke T, Int Endod J 2006; 39: 196-202
2. Comparative study on the shaping ability and cleaning efficiency of rotary Mtwo instruments. Part 2. Cleaning effectiveness and shaping ability in severely curved root canals of extracted teeth
Schäfer E, Erter M, Dammaschke T, Int Endod J 2006; 39: 203-212
3. Root canal preparation with the NiTi systems K3, Mtwo and Protaper
Sonntag D, Ott M, Kook K, Stachniss V, Australian Endo J 2007; 33: 73-81
4. Cyclic fatigue resistance and three-dimensional analysis of instruments from two nickel-titanium rotary systems
Grande N M, Plotino G, Pecci R, Bedini R, Malagnino V A, Somma F, Int Endod J 2006: 39: 755-763
5. Endodontic preparation of oval root canals: comparison between three techniques Malagnino V A, Passariello P, Sorci E, Giornale di Endodonzia 2004; 18/3: 142-148
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