Use of Self Adjusting File to Avoid Failures in Root Canal Therapy

I first heard about SAF when Dr Stephen Cohen visited India in November 2010. He said it is a new concept and that they were still evaluating it. I then heard Ajinkya Pawar’s lecture on SAF when it was introduced in India in WDS 2013. I loved it.

In April 2014 I contacted the SAF Company. I was in luck. The Vatea Pump had been introduced in India.

It’s been over a year since I bought SAF and I want to share this wonderful system with you and my cases; you will realize what a brilliant invention it is; so completely out of the box in thought that it astounds you; at the same time so simple in concept that it makes you wonder – why didn’t anyone think of this before?

Sometimes it just requires some genius; the inventor, Mr. Rafael Hof managed to do something which has revolutionized the way you will do Endodontics; and all because his own root canal treatment failed.

First a bit about my experience in Mechanized Endodontics; I have been practicing since the past 17 years; when I graduated no rotary system was available; the MM 1500 Sonic system was around though.

With the advent of Profiles I started changing the way I looked at Endodontics.

Over the years I have used Profile from Dentsply, Protaper from Dentsply, Protaper Next from Dentsply, Wave One from Dentsply, RACE from FKG Dentaire, V Taper from SS White, Hyflex from Coltene, and NRT files from Mani.

Every system mentioned here, and all systems per se, barring SAF have one thing in common – they all use conical files. The cross sections of the files are different; some rotate, some reciprocate, but in the absolute basic design they are all conical files.

They all prepare round holes in the canal. All do the same thing. Each system has some advantages and some disadvantages, flexibility; debris removal; fracture resistance, but all make round preparations.

The thing is – root canals are not round systems.

Root canals are complex and assume beautiful multifarious shapes.

The Self Adjusting File is the only system in the world that addresses those shapes.

1. It is the only system that has a vertical as well as rotary motion; but the rotation happens outside the canal, the vertical motion happens in the canal.


2. It is the only system that does circumferential filing on its own and the only system that can shape C shaped canals effectively.


3. It is the only system that adapts itself to the shape of the canal and does not impose a shape on the canal.


4. It is the only system in the world that does not convert a negative taper to a positive taper in the canal.


5. It is the only system in the world that allows simultaneous continuous irrigation during the filing process.

What is so special about SAF that it does what no other system does?

Here are some basics about SAF that make it unique:

1. The SAF does not have a solid core; this makes it unlike all other instruments available currently. It is a hollow instrument. This means it compresses on facing resistance. Since the instrument is hollow it can compress and expand according to the will of the canal, hence adapting to the shape of the canal rather than forcing its shape on the canal. This makes it the only system that is formless in its design; that adapts to the vessel that contains it. Thus the instrument compresses and widens; cleaning the canal whilst maintaining the original anatomical shape and ensuring that all parts of the main canal are well instrumented


2. Because it does not rotate, the stress acting on the canal walls is minimal and hence there is no micro-fracture possibility with this - as is seen with rotary instrumentation systems.


3. Another important aspect of this instrument system is that since the instrument does not rotate in the canal but uses a pecking vibratory motion to clean the canal, there is very little chance that instrument separation will occur as it does not bind into the canal during preparation unlike rotary instrumentation systems. Very rarely does this instrument separate in the canal, and if and when it does, it is easily retrievable, thus the risks of instrument separation in the canal have been effectively dealt with.


4. Since it is hollow, it allows simultaneous continuous irrigation during the filing, and thus ensures a constant turnover of irrigant.


5. Also since the instrument does not have a cutting tip and adapts to the shape of the canal, over-instrumentation beyond the apex is a near impossibility. This ensures that not only is the canal perfectly cleaned but it is also easy to fill without the risk of going beyond the apical end of the canal.

Thus you can see that the new SAF system, short for Self Adjusting File, solves major lacunae in current root canal instrumentation systems.

All these features make the SAF system a simple, effective and safe system, the first of its kind in the world, and the game changing technological advance that will make root canal treatments highly predictable and successful.

SAF thus allows you to Simply Avoid Failure.

Now what are the new things that you will have to adapt to when you use SAF? Here they are:

• You will need to learn a filing motion that is not an outward flaring technique as rotary systems require.


• You will need to learn customized obturation techniques to ensure that the beautiful shapes created are obturated as such, unlike making round obturations that we are used to.


• You will need to learn how to use a rubber dam

Let,s look at the beautiful shapes I have achieved with this system:

When should you buy SAF? From my experience, here are a few of the things that you should keep in mind before purchasing the system:

• Buy it when you have had some amount of experience in rotary systems and are looking to upgrade. When you shift from manual endodontics to rotary endodontics, you learn a lot along the way; like better access preparations, coronal flaring technique, the concept of glide-path, apical gauging; and develop a more precise way of working. This experience holds in good stead when you make the transition to SAF. Furthermore over time as the system has being used more and more by clinicians all over the world, the concept of having a minimal glide path of 20 4% before initiating the SAF system has gained ground. Hence, before you start using SAF you must be adept at Rotary Endodontics.


• Ensure that you have a good apex locator and know how to use it.


• Be prepared to damage some files in the R&D phase of learning and to absorb that cost.

The company dealing with this system is extremely professional and the people involved are extremely helpful and genuine. There is a worldwide support system where you are guided on how to manage your cases and help you with all your teething troubles.

HOW TO USE SAF

For canals up to 35 No. foramen size, the SAF 1.5 mm is indicated, and for wider canals having foramen size over 35 No. the SAF 2 mm needs to be used.

Steps:

Achieve straight-line access after adequate coronal flare.

Prepare canal up to 20 No 4% for narrow canals (up to 35 No foramen size) ensuring a reproducible glide path, with any system that you are comfortable with.

Where SAF 2 mm is indicated, directly proceed using the SAF 2 mm file after finishing coronal flare and achieving straight-line access.

Insert SAF manually to check that at least in one position it is reaching working length.

Once you are sure that SAF reaches working length manually, then you attach the file to the SAF RDT3 head and check that it is rotating. Then you attach the tube to the SAF file. You keep your motor off and only start the irrigation system after increasing the irrigation speed to 10 ml per minute. Let the irrigant start dripping out of the file. Stop the irrigation. Reduce the irrigation speed to 4 ml per minute. Now start the motor and adjust the speed of rotation of SAF by tightening or loosening the tubing that is attached to the file. The ideal speed recommended is 80 rpm.
Once you have achieved this initiate the placement of SAF into the canal with irrigation turned on. Your movements have to be a gentle vertical up and down motion. Don’t try to force the instrument in the canal up to WL. Let it work in the middle and coronal third initially. After a minute if it is not moving to the working length, re-verify your glide path and establish it accordingly. Restart SAF. Use it for 4 minutes. You are done

The new instructions from the company are that you use the SAF file with NaOCl as the irrigant for three minutes using the pump. Then you put EDTA in the canal by syringe and use the SAF file without the pump irrigation for 30 seconds. Then you flush out the EDTA with Saline and follow it up with filing with SAF and NaOCl irrigation through pump

OBTURATION

Obturation in the SAF system lends itself to all commonly used methods as per your preference of lateral or vertical condensation. In my practice, I am used to a combination of lateral condensation and warm vertical condensation for my root canal treatments. With SAF I also like to customize my master cones before I proceed with the actual obturation. The reason is that current gutta percha cones available are round in cross-section; however as we have seen SAF does not create round holes, it maintains the original shape of the canal which is anything but round in almost all cases. Cone customization takes just a few seconds and is extremely simple to do. Here is the obturation technique that I recommend:

Start with a master cone of 35 4% for SAF 1.5 mm and about 50 4% for SAF 2.0 mm and then proceed to customize them.

For Oval Canals: Ensure that the cone reaches 2 mm short of Working Length. Then take an artery forcep and compress the cone such that it becomes oval in shape. This will lead to the cone reaching about 5 mm short of working length. Now dip that cone into Chloroform for two seconds, not more, place the cone into the canal with gentle pressure seeing that it reaches Working Length. Leave it in place for 10 to 15 seconds. Make a notch on the cone before you remove it from the canal so as to guide you in placement later. Remove the cone. What you now have is a customized master cone which has taken the shape of the apical portion of the canal. Proceed with sealer application and your regular obturation technique as is your choice. Just be sure to place the master cone in the same position that you removed it, use the notch you made earlier to guide you.

For Other Canals: If the canal is not oval and is some other shape, you need not compress the cone with the artery forcep; only do the customizing as I explained above. Sometimes in wider canals you may need to put more than one cone. You can also do the roll cone technique if required.

Remember there are no round canals in nature, so using round plugs to fill them makes no sense whatsoever.

CASE STUDY

Thirty seven year old male reported to the clinic with a deep Cl 2 amalgam filling in 35. He had pain since a week. On examination, there was distinct pain on percussion and the radiograph revealed evidence of periapical rarefaction, Patient was recommended root canal treatment using the self adjusting file system – SAF. The old amalgam filling was removed. Access cavity revealed a key shaped canal configuration.

Coronal flaring was done with SX of the Protaper system of Dentsply. A glide path was established to 20 no 4% using the Hyflex system from Coltene Whaledent. After that the canal was prepared with SAF 1.5 mm under constant irrigation of sodium hypochlorite at 4 ml per minute. The images show how SAF maintained the original key shape of the canal. The tooth was obturated at the second sitting after customising the GP with chloroform softening.

Obturation was done with lateral condensation and warm vertical condensation by using the Satalec ultrasonic tip ET 40. Post obturation radiograph revealed a short obturation. After giving due consideration, it was decided to keep the tooth under observation, the patient was informed accordingly. The patient returned after one month for the post root canal restoration because he was busy elsewhere.

When he came to the clinic the temporary composite filling had come out and the pulp chamber was exposed to the oral environment. The patient informed that the filling had come out 10 days ago and he had been applying clove oil inside the tooth thinking it to be beneficial since then. As the root canal obturation had been short and the temporary restoration had been out since 10 days it was decided to remove the old obturation and redo it after cleaning the canal.

The old obturation was removed by using a combination of 20 no 4% hyflex file to length and SAF 2mm in the coronal portion. Some portion of gutta percha was also removed by H files. SAF 1.5 was used in the canal again for 4 minutes. Obturation was carried out on the same day. This time full length was achieved. Some amount of change of coronal opening shape was seen because I used the SAF 2 for the coronal portion during the repeat treatment. Had I stuck to SAF 1.5 then even this wouldn’t have happened.

AFTER TREATMENT