View the SAF System Clinical Guidelines:
You can also download a PDF version of the Clinical Guidelines here.
The Self-Adjusting File (SAF) is a hollow file, designed as an elastically compressible, thin-walled pointed cylinder, composed of a unique nickel-titanium mesh. The SAF's patented lattice-like design makes the instrument extremely flexible, to fit the cross-section of the canal at any location. Unlike standard central-solid-core instruments, the SAF will adapt itself to virtually any root canal anatomy and shape it in a minimally invasive way, removing a uniform layer of dentin from a larger percent of the canal wall than standard instruments, while conserving sound tooth structure.
For the first time, irrigation is performed continuously and simultaneously with the shaping of the canal and without danger of a sodium hypochlorite accident. An irrigation barb, incorporated into the hollow shank of the file, enables the dentist to continuously dispense irrigation fluid, in a pressure-less manner, through the file during the entire shaping process in order to achieve superior cleaning and disinfection of the root canal system.
As the SAF System's operation is different from any other endodontic instrumentation system, it is important to follow these Clinical Guidelines, in order to achieve a uniform circumferential preparation of the root canal system and a high level of cleanliness, while reducing unnecessary mechanical load on the file.
The SAF may be operated with any of the following devices:
- SAFbasic System: includes the VATEA peristaltic irrigation device and the RDT3/RDT3-NX handpiece head. The SAFbasic system may be operated with various endodontic motors (which are not supplied with the system), and provides the ability to work with continuous simultaneous irrigation and to operate the SAF System using the unique RDT3 handpiece head.
- SAFpro System::-includes the multifunctional EndoStation™ endodontic motor, with an integrated peristaltic irrigation pump. It enables the dentist to use various motorized endodontic systems, including the Self-Adjusting File (SAF), as well as all major brands of endodontic rotary and reciprocating instrumentation systems. The autonomic EndoStation™ is operated by a footswitch and provides a high level of workmanship and usability.
- SAFedge System: includes the multifunctional EndoStationmini™ endodontic motor, with an integrated peristaltic irrigation pump. This system is ergonomic and lightweight, rechargeable and activated by a hand-switch located on the micromotor. It enables the dentist to operate the Self-Adjusting File (SAF) System, as well as all major brands of rotary endodontic instruments. The SAFedge System includes the ZipperLine™ cable, that embeds the irrigation tube into the micromotor cord.
- Other electronically-controlled motors with integral irrigation pumps: the SAF System can also be operated by various types of physiodispensers, endodontic motors with an integral irrigation pump and dental units with an integral irrigation pump. The important features of such a compatible device would require it to include either an E-type or an F-type micromotor, torque limitation and speed control that allows operation at 5,000 rpm, as well as a peristaltic irrigation pump that allows continuous simultaneous flow at 4 mL/min with sodium hypochlorite. Such available motors are the EndoPilot by Schlumbohm, EndoCenter and EndoDuo by Acteon (Satelec) and several more.
To get used to the concept of SAF, we suggest that you gradually adopt the use of the system into your clinical routine:
- Start with simple, accessible teeth, preferably incisors, canines or premolars, with initial canal diameters of #20 or more and with straight or mildly curved canals; then move on to more complicated cases.
- An irrigation flow rate of 4 mL/min is recommended. However, if you find this flow difficult to control, it is recommended to adjust the irrigation flow setting to 2-3 mL/minin the beginning and advance to 4 mL/min as you grow accustomed to controlling the continuous irrigation. The irrigation flow rate can be adjusted according to the convenience of the dentist, but it is recommended to always maintain the flow rate at a sufficient level, in order to assure proper cleaning and disinfection. Without continuous irrigation, or with insufficient level of irrigation, the dentin that was removed by the SAF may not be washed away, and might remain in the canal in the form of a thick residue.
- The recommended operation time for the SAF is 4 minutes , during which simultaneous shaping, cleaning, irrigation and irrigant agitation are performed. In cases of extremely contaminated root canals, a usage of 6 minutes may be considered, at your professional discretion.
The patented RDT3 / RDT3-NX handpiece heads by ReDent Nova are the only existing handpiece heads that provide the combined motion of vertical vibration and rotation required for proper operation of the SAF. The head contains a clutch mechanism that inactivates the rotational motion when the file is engaged in the canal. The use of imitation handpiece heads other than the original RDT3 may prevent proper functioning, damage the files, and/or compromise the treatment.
The file’s effective, main mode of operation, is vertical vibration. The motor should be operated at 5,000 rpm, which are converted by the handpiece head to 5,000 in-and-out vibrations per minute. These vibrations, combined with a pecking motion by the operator, serve to circumferentially remove dentin from the canal walls while providing also a gentle scrubbing motion and agitation of the irrigant.
The added rotation motion is very slow and almost torque-less. It only serves to repeatedly shift the file’s circular position when entering the root canal during treatment. The rotation motion is not meant to remove any dentin, and only occurs when the file is not engaged with the canal walls. Continuous in-and-out hand pecking motions are required during operation of the SAF and are essential for the circular repositioning of the file to take place. Each out-bound stroke of the pecking motion should reach far enough coronally to disengage the file and allow it to rotate. Such rotation can be observed by the movement of the colored stripe on the rubber stopper. When inserted into the canal, with the in-bound motion, the file should stop rotating but keep vibrating.
Please note: the file should never rotate when engaged with the canal walls. If it does rotate while inside the canal, either (1) the diameter of the file is too small for that given canal (i.e. 1.5 mm diameter file rather than the 2.0 mm diameter file in a wide canal); (2) the pressure applied to the file by the operator was too high and caused file buckling inside the canal; or, more rarely, (3) the RDT3 head clutch mechanism malfunctioned. If the file rotates in the canal for any of these reasons - immediately remove it from the canal.
Please note that the rotation speed should be controlled by stretching / loosening the irrigation tube that is connected to the file, which does not affect the vibration at all. Continuous re-use of the irrigation tubes may reduce their flexibility and thus their ability to control the rotation speed. Periodical replacement of the irrigation tubes is advised.
Markedly fast rotation or excessive pressure applied by the operator may cause unnecessary mechanical damage to the file. The irrigation tube must always be connected to the file during treatment, even when the continuous irrigation has been turned off for any reason (see below), in order to limit and control the rotation speed.
At the beginning of the clinical procedure, make sure that both vibration and rotation function properly. The lack of any of the two functions may lead to improper operation and may indicate a malfunction of the RDT3 handpiece head, which should be reported immediately to an authorized technician. Avoid operating a malfunctioning handpiece head.
The root canal anatomy should be studied and evaluated before and throughout the treatment, and the proper procedure should be adopted accordingly.
- Use a diagnostic pre-operative X-ray for initial evaluation of the case.
- Prepare an endodontic access cavity with clear, unobstructed access to the orifice of each of the root canals.
- Isolate the tooth properly. It is recommended to use a rubber dam and optionally an additional isolator paste around the tooth. Use an effective suction action to collect the overflow of the irrigant, yet refrain from placing the suction tip too close to the SAF itself, to avoid suctioning of the irrigant before it enters the file's lumen and the root canal.
- Enlarge and funnel the canal orifice, if required, using the Pre-SAF OS NiTi rotary instrument, using lateral brushing motion, in order to allow a comfortable insertion path for the SAF. Note that the Pre-SAF OS has a short active part, 10 mm long, that should only be operated in the coronal 2-4 mm part of the root canal. Avoid pushing the Pre-SAF-OS too deep into the canal as it might form a ledge if the canal is curved.
- When used in curved narrow canals (such as mesial roots of mandibular molars), the SAF, similarly to most other motorized endodontic file systems, requires straightening of the coronal access of the canal, to minimize the stress on the instrument. The SAF always requires a direct access to the canal, and should be operated along the vertical axis of the canal. When pushed into the canal in a diagonal manner and not according to the vertical axis, the SAF may buckle, which might lead to ineffective instrumentation of the canal walls and may also result in a mechanical damage to the SAF.
- Establish the working length of the root canal using an X-ray and optionally also using an electronic apex locator.
- Select an SAF with the appropriate length and diameter to match the expected working length and diameter of the canal:
- Length: Note that the length of the active (mesh) part of the SAF varies between the various file lengths. This active part should be at least of the same length as that of the canal when measured from the canal’s orifice to working length. An SAF with an active part that is too short for a given canal may not be able to reach working length, as the SAFs shaft (tubular part) cannot be compressed inside the canal. An SAF with an active part that is too long for a given canal may not properly deliver the irrigant into the root canal, as the irrigant may escape the file before entering the canal.
- Diameter: The diameter of the SAF should allow sufficient compression of the file inside the root canal. The following criteria should be applied:
- SAF 1.5 mm should be used for canals with initial size of up to ISO #30.
- SAF 2.0 mm should be used for larger canals, starting from ISO #35 and larger.
The following illustration describes the available SAF sizes:
When using the Self-Adjusting Files, a preliminary reproducible glidepath should be established and/or verified. After glidepath preparation, it is important to verify its adequacy by manual insertion of an SAF to working length, before attaching it to the handpiece head, and optionally after dipping the file in EDTA lubricant paste.
With most other motorized instrumentation systems, the procedure ends when the final instrument reaches working length. With the SAF, best results are achieved when the SAF reaches working length at the beginning of the use of the file.
Note: The SAF is not a penetrating tool, and works best when compressed inside the root canal at working length, filing and scrubbing the canal walls laterally and circumferentially, all along its path.
The glidepath protocol should be chosen according to the degree of difficulty expected in a given canal. In all the following glidepath protocols, the final aim is first to establish a proper coronal access, then to establish an adequate glidepath:
A. Coronal access: first ensure an unobstructed straight access to the canal. Then, use the Pre-SAF OS (orifice shaper) to funnel the orifice of the canal if required . Operate it only in the coronal 2-4 mm part of the root canal, with slight lateral motions/pressure directed to the outer side of the curvature, in order to create and assure a straight-line access and operation of the SAF along the vertical axis of the root canal.
The following x-rays illustrate how the Pre-SAF OS should be used to ensure straight-line access to the canal according to the vertical axis (adapted from Kfir et al., Int Endod J, 2015):
B. Access to working length : Should allow the SAF to be manually inserted to working length . In cases of straight canals this may be done with a #20.02 hand-file, whereas in narrow and curved canals, an initial preparation of the canal with a Pre-SAF 2 rotary instrument (size #20/.04) is advised. Note that sometimes the curvature of the canal may not be obvious, such as canals with a bucco-lingual curvature, which is not apparent in clinical periapical radiographs. Therefore, such glidepath preparation should also be considered in any canal that has such tendency for curvature in the bucco-lingual plane. Such canals include mesial roots of mandibular molars, palatal roots of maxillary molars, etc., which may appear straight in periapical radiographs, which are taken from the buccal direction.
It is important to keep a minimally-invasive glidepath preparation, for the following reasons:
- To assure penetration of the SAF into buccal and/or lingual canal recesses: Preparation of a larger, more invasive glidepath, by either larger and/or bigger taper rotary instruments or large hand files, will create an excessively large round bore. This might lead the SAF to "recognize" the canal as a round canal and thus stay centralized within the large circular path which has been created. This in turn will diminish the chance for the file to be forced, as requited, into narrow buccal and/or lingual recesses, which are likely to already be packed by debris that was actively pushed there by the large initial rotary or reciprocating instrument that was used to create the wider initial preparation.
- To avoid negative side-effects of a larger initial preparation: Preparation of the canal with larger and/or more tapered rotary/reciprocating instruments (larger than #20/.04) or hand files has been shown to cause a number of side effects, including (a) packing of debris into narrow areas of the canal, (b) apical extrusion of debris, (c) canal transportation of curved canals, (d) excessive removal of sound dentin, and (f) creation of dentinal micro-cracks that may eventually lead to formation of vertical root fractures (VRFs). Most of these negative side-effects cannot be corrected by the subsequent use of the SAF.
Attempts to use the SAF only as a "finishing device" or as an irrigation device after a wider initial circular preparation will not allow the SAF to properly clean the recesses of canal and to shape it in a minimally-invasive way.
For these reasons, it is essential to keep the initial glidepath preparation to the minimum required for the insertion of the SAF and not go beyond #20/.04. This size was tested and proven not to create dentinal microcracks, yet allow the manual insertion of a 1.5 mm diameter SAF to working length (Kfir et al, Int Endod J, 2015)
The glidepath protocol is chosen according to the first hand instrument to bind (FITB) in the apical part of the canal. Each canal should be classified as a Difficult / Moderate / Easy / Wide canal, as described below:
Difficult Canals (FITB ≤ #10):
In difficult canals, with an initial size of #10 or less, the use of small-diameter path-establishment instruments is required.
Ensure coronal access, and then use an instrument that allows the establishment of the glidepath for the SAF:
- In canals with an initial size smaller than #10.02, use stainless steel or NiTi hand files to enlarge the canal to at least size #10.
In canals with an initial size #10 (but not yet #15), use the Pre-SAF 1 rotary instrument (size #15.02) or, alternatively, a #15.02 stainless steel or NiTi hand file.
Moderate Canals (FITB = #15) :
- In moderate difficulty cases, that only allow the insertion of a #15 file to working length, first ensure coronal access, and then use an instrument that allows the establishment of the glidepath for the SAF:
- In straight canals a minimum of #20.02 preparation is required. A #20 stainless steel or NiTi hand file may be sufficient, however the Pre-SAF 2 rotary instrument (see below) may be useful in such cases as well.
- In curved canals, or in canals in which a #20.02 glidepath is insufficient, use the Pre-SAF 2 rotary instrument (size #20.04) to establish the glidepath.
Note: the Pre-SAF 2 may and should be used only in canals in which a #15.02 hand file can freely reach working length, either as the FITB or after initial preparation of narrow canals up to this size (see above). Few small pecking motions will allow the Pre-SAF 2 file to reach working length.
Remove any gross pulp tissue, if present, and verify the glidepath by manually inserting an SAF 1.5 mm to working length (see the "Manual Verification" chapter below).
The SAF 1.5mm is equal in size to a #20 file when fully compressed. However, due to its three-dimensional structure, when it is inserted into curved canals it may be forced to slightly open, which means that a #20.04 glidepath preparation is required. The recommended instrument for such cases is the Pre-SAF 2 rotary instrument (sized #20/.04), that has been tested to enable the manual insertion of the SAF into curved canals, as well as to assure that it creates no dentinal micro-cracks and/or canal transportation.
Easy Canals (FITB = #20 – #30) :
In straight easy canals, usually no additional apical preparation is required. First, ensure coronal access and if necessary funnel the orifice using the Pre-SAF OS rotary instrument. Then use a #20 instrument to check that it can freely reach working length. Even though in easy curved canals, the SAF may be able to reach working length following a hand file size 20/.02 alone, it will be beneficial touse the Pre-SAF 2 instrument to create an easier and reliable glidepath.
Once established, verify the glidepath by manually inserting an SAF 1.5 mm to working length (see the "Manual Verification" chapter below).
Wide Canals (FITB ≥ #35) :
Ensure coronal access and make sure that a #35 hand file can freely reach working length and that the gross pulp tissue has been removed. Follow to verify the glidepath by manually inserting SAF 2.0 mm to working length, as detailed below.
Note that in canals that are ISO size #70 or more, the SAF 2.0 mm might not be sufficiently compressed inside the canals, and might rotate even when it is inside the canal, as it does not bind well enough with the walls of the wider canal. In such cases, make sure to limit the rotation speed of the SAF by pulling the irrigation tube, and perform regular visual inspections of the file during its operation, to rule out mechanical deformation. In those cases, only slight removal of dentin is expected, but this is usually beneficial, since preservation of sound dentin is a desirable goal in such cases.
Operation parameters for the Pre-SAF rotary instruments:
|Pre-SAF OS||Pre-SAF 1||Pre-SAF 2|
|Recommended speed (rpm):||600||500-600||500-600|
|Recommended torque limit (Ncm):||1.5||1||1.5|
Manual verification of the glidepath is extremely important when using the SAF. The verification of the ability of the SAF to reach working length should be done before attaching the SAF to the handpiece head.
EDTA lubricant (i.e. Glyde, RC prep, etc.) may be used when first introducing the SAF into the canal for glidepath verification. The SAF should only be inserted into the canal with a mild manual force, using pecking motion. Note: No “watch winding” or rotation movements should be used.
The manual verification has two roles:
A. To confirm that the SAF can be inserted to working length. Since the SAF has an asymmetrical structure, the flexibility of its tip varies in different directions. In narrow and curved canals, certain circular positions of the SAF will allow it to penetrate all the way to working length, while in other positions it might not, at this initial stage.
If the SAF does not go to working length in the first manual verification attempt – pull it out from the canal until it unbinds from the canal walls, realign it by 90 degrees rotation and try to re-insert it. This realignment shifts the position of the SAF inside the canal and may allow it to go past the curvature and all the way to working length, using a slightly different circular position.
Up to 4 realignment attempts may be required for this examination – each with an unbound SAF and with a ~90 degrees rotation. The goal is to assure that the SAF can reach working length in at least one of these positions. If the SAF cannot reach working length in any of the attempts, make sure that no residual pulp tissue prevents it from entering the canal, and if necessary, re-establish the glidepath.
Note that in narrow and curved canals, just the same as in the manual verification, during its initial motorized operation the SAF might not reach working length in every inbound stroke. However, as long as it does so in some of the inbound strokes, eventually it will smoothen the curvature and be able to reach working length at each of the pecking motions. It is advised to observe the file during operation, to assure the circular repositioning of the SAF, as indicated by the rotation of the colored stripe on the rubber stopper.
B. To examine the root canal's vertical axis. The SAF should be operated according to the vertical axis of the canal, otherwise it might buckle, a phenomenon which might (a) prevent it from reaching working length and (b) inflict unnecessary stress on the file.
Insert the SAF to working length, release it and inspect the direction of the SAF's shank. The shank should show the direction of the vertical axis, with no interference from the margins of the access cavity.
Then, during the motorized operation of the SAF, make sure that the pecking motions follow the vertical axis with no buckling.
- Adjust the rubber stopper on the SAF to indicate the desired working length.
- Please note: To verify the adequacy of the glidepath, it is recommended to manually insert the SAF to working length before proceeding (see the "Manual Verification" chapter above).
- Continuous irrigation should be applied throughout the procedure. The choice of irrigant is at the discretion of the dental professional operator. The recommended irrigant flow rate is 4 mL/min (new users may initially use a lower flow rate). The use of NaOCl irrigant with the SAF system is recommended, as the SAF also inflicts sonic activation of this irrigant.
- A power suction tip, preferably a surgical one, should be placed near the tooth, to collect the expected continuous overflow of the irrigant. Irrigation can be applied by the peristaltic irrigation pump of the given device.
- Attach the irrigation tube to the SAF's irrigation barb, and then pull the tube slightly back. Stretching the irrigation tube that is connected to the file helps to control the speed of the file's rotation. Some rotation is required, to repeatedly shift the circular position of the file when entering the canal, but excessive rotation will inflict unnecessary mechanical stress on the file. The colored stripe on the SAF's rubber stopper allows to visualize the rotation and estimate its speed.
- Insert the SAF gently into the canal while operating the motor, and continue with light pecking motions. Do not force the SAF apically. This file is not a penetrating tool, as opposed to common rotary/reciprocating instruments, and attempting to force the file to working length when difficulty is encountered may result in buckling and damage to the file . Working length will be reached during the SAF operation, usually within 30 seconds of operation. Move your hand in continuous short in-and-out pecking motions to prevent binding of the file in the canal and to allow the file to shift its circular position when entering the canal during every outbound stroke of the pecking motion. View the colored stripe on the rubber stopper to verify that the file indeed rotates when disengaged from the canal and shifts to a different position when it re-enters the canal. If it does not rotate, check (a) if your outbound strokes reach far enough coronally to allow the file to unbind and rotate; (b) if the tube tension is not too tight; or (c) if there is some malfunction of the clutch mechanism in the handpiece head that prevents it from rotating the SAF.
- If resistance to insertion or inability to reach working length within the initial 60 seconds are encountered - stop, remove the file and try the following steps:
- Make sure that the shaft (tubular part) of the SAF does not engage the access cavity walls; this may happen in incisors or premolars that present exceptionally small pulp chambers / access cavities. If so, use a longer SAF, but make sure it does not buckle (fold upon itself) during operation. Further enlargement of the access cavity is usually not required.
- Make sure your coronal canal preparation has been adequately flared by the Pre-SAF OS rotary instrument.
- Re-establish the glidepath by using the Pre-SAF 2 rotary instrument, which at this point may be able to remove gross pulp tissue remnants from the canal, if present. Such remnants may prevent the advancement of the non-penetrating mesh-like SAF.
- Make sure that the length of the active part of the SAF is at least equivalent to the length of the canal from its coronal orifice to working length.
- Optionally, use EDTA lubricant (i.e. Glyde, RC Prep, etc.) when introducing the file into the canal.
Most of the dentin removal by the SAF is accomplished during the first 2 minutes of operation. The remaining 2 minutes of operation allow the agitated irrigant to thoroughly clean the canal.
In extremely contaminated canals, extremely convoluted canals or canals with persistent bleeding, 1-2 additional minutes of operation may be required.
- The advised irrigation protocol for the SAF instrumentation is a sequence of sodium hypochlorite and EDTA. Such combination allows to dissolve organic materials inside the canal (pulp tissue, bacteria, etc.), and to remove inorganic debris and smear layer. Research has shown that this technique of altering between sodium hypochlorite and EDTA may achieve a high level of cleanliness and disinfection.
The following irrigation protocol is advised, although modifications are possible, at your professional discretion:
- Use NaOCl (sodium hypochlorite, Dakin's solution, etc.) for the first 3 minutes of the SAF operation. The sodium hypochlorite, which has otherwise a high surface tension, will be carried mechanically by the SAF to working length, without pressure, to be continuously refreshed in the apical area every 20-30 seconds. The SAF will not only irrigate the canal with fresh, fully active sodium hypochlorite, but will also sonically agitate it, due to its continuous 5,000 vibrations-per-minute. Any clinically-acceptable efficient concentration of sodium hypochlorite may be used (2.5%, 5.75%, etc.). It is advised not to use certain commercial products that contain surfactants, that reduce the surface tension of the irrigant and might not enable sufficient refreshment by the SAF.
- Flush the canal with EDTA solution (17%): Disengage the SAF from the canal. Flush the canal with EDTA solution to remove the remaining NaOCl. Leave the remaining EDTA inside the canal, and turn off the irrigation pump. Operate the SAF for 30 seconds with vibration and pecking motions, without the continuous flow of the NaOCl irrigant, with only the EDTA in the canal. The SAF will push the EDTA into narrow areas and enable the removal of debris and smear layer.
- Use NaOCl again for 30 seconds: turn on the continuous flow from the irrigation pump and operate the SAF inside the canal for additional 30 seconds. This will flush out the remaining EDTA and provide final irrigation of the canal, to affect any organic materials and bacteria under and/or within the smear layer that were exposed by the EDTA action.
- Dry the canal using sterile paper points, according to standard clinical procedure.
9. Gauge the apical region of the canal using a .02 taper gutta-percha cone or with NiTi hand-files to confirm root canal enlargement. Final apical canal dimensions will typically be 2-3 ISO sizes larger than the initial apical size. If apical enlargement is less than desired, another 1 minute of work with the SAF may be applied, including the simultaneous irrigation.
10. Canal shaping is now complete, and your preferred obturation method may be used.
Root canal obturation is an essential part of endodontic treatment. Traditional rotary instrument preparations create large and generally round canal cross-sections, which are imposed by the shape of the instruments rather than by the natural anatomy of the canals. Such round preparations can often leave behind debris, which was actively packed by the instruments into untreated "fins" and natural ramifications. Consequently, such recesses cannot be adequately obturated.
The SAF System generates a more natural and complete three-dimensional cleaning and shaping of the canal systems. When prepared with the SAF, the final canal shapes remain consistent with the original canal shapes and cross-sections. Typically, final apical canal dimensions will be 2-3 ISO sizes larger than the initial apical size and maintain the canal's natural taper .
For example, if the initial apical size was #20, the final apical size is likely to be #30-#35. The canals will be thoroughly cleaned, shaped and disinfected, while preserving their natural (round, oval, teardrop, or other) cross-sectional shapes, consistent with their natural morphologies.
Just as round tapered files cannot follow the natural canal anatomy, industrial pre-shaped cone obturation materials cannot match all of the natural and conservatively prepared final canal configurations. Therefore, to generate maximum benefit from the three-dimensional cleaning and shaping offered by the SAF System, it is important to keep in mind the need to create a more thorough three-dimensional sealing of the root canal systems by using one of the conventional canal obturation techniques .
To determine accurate final dimensions, it is recommended to gauge the prepared canal using a gutta-percha master cone or a NiTi hand-file prior to obturation.
Note that after SAF preparation, the apical portion of the canal will typically be 2-3 ISO sizes wider than the original, but not necessarily round in cross-section. Therefore, there is no need for additional apical enlargement. If additional apical enlargement is still desired, further enlargement can be achieved by using the same or larger SAF (2.0 mm if size #35 was reached). Some dentists who prefer a round apical preparation use a final touch with a hand or rotary file for that purpose . Such use should be done with care, to avoid the possible negative consequences, such as packing of debris or creation of dentinal micro-cracks.
The following methods are commonly used for the obturation of canals shaped with the SAF System, and should be applied in their conventional manner. These methods are described below in headlines as typically used and are not detailed, as users should already be acquainted with them:
A. Lateral compaction:The conventional common method of fitting a master gutta-percha cone and adding accessory cones with obturation sealer, whilst using a spreader to laterally compact the cones and to create space for additional cones.
In oval canals, one should consider to use more than a single master cone (two, and sometimes even three) in the oval cross-section. Such an additional master cone would usually be smaller than the main master cone, and its placement can help reduce the chance for extrusion of the obturation material.
B. Warm vertical compaction :A technique that can be excellent for the three-dimensional obturation of irregularly shaped canals created by the SAF system (versus the generally round shape and incompletely cleaned canals that are often created with conventional rotary/reciprocating instruments or hand files):
- Classic: Select a master gutta-percha cone to fit just short of working length, seating and searing it with a heated plugger to fill the apical region, and then adding small segments of gutta-percha to back-fill the coronal portion. Backfilling of the coronal portion can optionally be performed with an injectable warm/softened gutta-percha system.
- Continuous wave technique: Pre-fit the appropriate heat-carrier to the length and shape of the canal, insert gutta-percha with sealer to the apical region, apply a thermoplasticizing temperature (usually 200oC) for 2-3 seconds, sustain apical pressure for 10 seconds, and use a separation burst (300oC) for 1 second to remove the coronal segment. A cold hand-plugger is used to assure proper lodging of the apical mass and to assist in back-filling with increments of thermoplasticized gutta-percha.
- Combination technique - modification for long-oval canals: In oval canals, the combination of the lateral compaction and warm compaction techniques is advised in order to avoid excessive sealer/gutta-percha extrusion. Lateral cold compaction with a NiTi spreader is initially used in the apical area, followed by vertical compaction with a hot plugger, heated to 100oC, followed by further compaction with a cold hand-plugger.
C. Carrier-based obturation : A central solid-core carrier system that provides a simple and consistent method for three-dimensional obturation following an SAF preparation. Application of sealer, pre-heating the obturator and its slow insertion into the canal will result in extremely tacky, adhesive alpha-phase gutta-percha with excellent flow characteristics, which will provide excellent adaptation to the canal walls due to the initial clean and smooth dentin surface of the SAF preparation.
D. Chloroform-dipped customized master cone modification : When applied in oval or large canals (>#35), a chloroform-dipped customized master cone may be initially prepared and used, with either cold lateral compaction or warm vertical compaction. The customized master cone, which will have an imprint of the canal's apical portion on it, should be allowed to dry and re-harden before being used. Make sure that this method is acceptable in your country.
In this technique, it is possible to initially compress and flatten the master cone in order to give it an oval shape. The master cone to be used should reach 2-3 mm short of working length, and be held by lockable tweezers, in order to keep it at a set vertical insertion path. The apical end of the master cone is dipped in chloroform for 2 seconds, enough to soften the outer surface of the cone but leaving the core of the cone intact. It should then immediately be inserted into the root canal and pushed apically with pecking motions all the way to working length. Such pecking motions will also eliminate the interference of potential undercuts. The cone should be immediately removed from the canal and held with the locked tweezers out of the canal to allow it to dry. The chloroform will evaporate within 15 seconds, and the master cone will solidify while presenting the imprint of the apical area of the canal on its surface. The customized master cone should then be applied with some sealer into its seat, followed by either cold lateral compaction or warm vertical compaction.
E. BioCeramic sealer-based obturation : Techniques that are based on BioCeramic (BC) sealers or other similar products, combined with a single obturation cone (gutta percha, C-point, etc.), have become popular in recent years. Such obturation techniques became possible due to the introduction of new materials which are hydrophilic and have the ability to strongly adhere to dentin, while being highly biocompatible. These techniques take advantage of the sealers' flowability to fit effectively into the clean space created by the SAF instrumentation, following the natural canal morphology. Research has shown the high-level of micro push-out bond strength achieved by such obturation techniques following SAF instrumentation (Pawar et al. Int Endod J, 2015). These sealers may be used in various techniques, as advised by their manufacturers, combining the sealer, with designated cones, such as BC-covered gutta percha cones, C-points, etc.
F. Any variation of the aforementioned obturation techniques or others may also be used.
It is important to note that other than the single-cone obturation technique, which is inadequate when addressing irregular canal morphologies, all obturation techniques enable proper sealing following SAF preparation, although some differences may be noticeable during the obturation procedure, including:
- Less noticeable "tug-back" sensation, as such a sensation is more pronounced in round apical preparations, which will only exist after SAF preparation if the canal’s apical region was originally round in cross-section. The SAF preparation does not impose a round cross-section in the apical region and rather follows the natural anatomy of the canal.
- Easier flow of any obturation sealer, as well as easier insertion of spreaders and accessory gutta-percha cones, due to the smoother and cleaner root canal surfaces achieved by the SAF preparation.
- The need to use a variable amount of accessory cones, which could either be less accessory cones (with a customized master cone) or more cones (with lateral compaction) than usual. This is due to the thorough removal of debris from fins and recesses of flat-oval canals.
Note: The probability of causing micro-cracks in the radicular dentin during SAF instrumentation is much lower than when rotary/reciprocating instrumentation systems are used. This eventually implies a lower chance for obturation-related fractures in SAF-treated roots. Nevertheless, it is advised to avoid applying excessive force while obturating.
The first step of any re-treatment procedure is the removal of previous root filling material to allow for proper cleaning, disinfection, and obturation of the root canal.
Studies show that the removal of gutta-percha with commonly used rotary, reciprocating or hand instruments is likely to leave remnants of gutta-percha and sealer attached to the canal walls.
The use of the SAF after any other retreatment instrument will improve the efficacy of gutta-percha/sealer removal and leave significantly less root filling residue on the walls of the root canal. This is especially important in curved canals, whose curvature limits the visual evaluation of canal wall cleanliness, even when a microscope is used.
The following are two examples of re-treatment using popular methods. This is not intended to be an all-inclusive description of re-treatment techniques. Note that all re-treatment techniques require the use of another instrument to remove the bulk of gutta-percha prior to the use of SAF and that the goal of re-treatment is to remove all of the filling material without leaving residue, while minimally widening the already-prepared root canal.
- Method 1 (Shemesh et al., JOE 2012) – NiTi rotary instruments followed by SAF without solvent :
- Use NiTi rotary retreatment instruments (ProTaper/ProFile/other instruments) to remove the bulk of gutta-percha without the use of any solvent.
- Irrigate the canal after each instrument with 2 mL of NaOCl 2%-4%.
- Continue by using SAF 2.0 mm for 1 min without irrigation, followed by 4 min with continuous NaOCl irrigation at a flow rate of 4 mL/min.
- Method 2 (Abramovitz et al., Int Endod J 2012; Solomonov et al, JOE 2012) – NiTi rotary instruments followed by SAF with solvent:
- Use NiTi rotary instruments to remove the bulk of gutta-percha.
- Use the SAF 2.0 mm for 1 min with NaOCl irrigation at a flow rate of 4 mL/min.
- Dry the canal, place 1 drop of solvent (chloroform) in the canal, and operate the SAF again for 1 min with the irrigation pump turned off. Place another drop of solvent in the canal and use the SAF again for 1 min without irrigation and then for an additional 30 seconds with NaOCl irrigation. Flush the canal with 1 mL 17% EDTA and use the SAF for another 30 seconds with the irrigation turned off. Finish with additional 1 min SAF operation with continuous NaOCl irrigation.
Other methods to remove the bulk of the root canal filling may also be used, followed by the SAF.
1. Sterilization : The SAF is provided non-sterile and must be sterilized before use:
a. The SAF should be autoclaved, using a calibrated steam autoclave.
As a new version of the SAF ("SAFneo") with more durable plastic components was introduced in mid-2015, the autoclaving temperature depends on the directions on the package of the SAF. Sterilization can either be carried at a maximum temperature of 1210C (2500F) for 20 minutes , or at a maximum temperature of 1340C (2730C) for 4-10 minutes.
Note: Make sure not to mix files from different batches, that may vary in their temperature resistance, as those designed for 121 >oC (250oF) will be damaged if heated to 134oC (273oF). Using higher temperature settings than the value indicated on the package may result in damage to the plastic shank of the SAF.
b. Avoid using disinfection reagents, as some disinfection reagents might cause deformation of the SAF’s plastic parts. This also applies to certain types of chemiclaves.
c. Avoid placing the SAF in an ultrasonic bath, that may negatively affect its plastic parts.
d. Do not place the SAF in a glass bead sterilizer, as it may damage its plastic parts.
2. Lubrication : Lubricate and wipe the handpiece head after each treatment.
Lubrication should be done through the suitable handpiece adapter. Make sure the lubrication nozzle is well fitted into the handpiece and spray for several seconds, until clear oil comes out of the other side of the handpiece head. Oil the RDT3 handpiece after every use.
3. Irrigation system maintenance : Irrigation fluids such as NaOCl may harm the electrical parts™, etc.).
- Always use a funnel (supplied) to fill the irrigation reservoir of the VATEA. The bottle of the EndoStation™ is detachable and should be filled away from the main device, thus does not require a funnel.
- Avoid spillage of irrigation fluids while filling or emptying. If spillage occurs, wipe immediately with a wet wipe, followed by a dry wipe.
- Irrigation solutions, such as NaOCl, may clog the tubes if they are of low quality or not properly handled. Make sure to replace the solution at the end of each day
- At the end of the work day, carefully empty the irrigant container through its filling orifice and then fill it with water. Flush with water to remove residual irrigant from the container and tubing system:
- VATEA: By running the pump on 10 mL/min for 2 minutes.
- EndoStation™: By pressing the "Rinse" key for 30 seconds.
Proper cleaning after the use of NaOCl is extremely important to avoid crystallization and clogging of the tubes and connectors.
e. When storing the VATEA or EndoStation™, disconnect the irrigation tubes. In such a case, it is recommended to draw air into the tubes before storage, to dry them.
4. General instructions:
- Regularly inspect the device and its parts for insulation defects and replace if necessary. Assure clear air vents to avoid overheating.
- Do not sharply bend the electrical cords.
- Do not drop or impact the device.
- Do not disassemble the device in any case – if a problem occurs, approach a manufacturer-authorized technician.
- Follow the "Instructions for Use"> manuals for each device and accessories.
- Do not lubricate the EndoStation's micromotor or sterilize it by autoclave or subject it to an ultrasonic cleaner.
Difficulty in reaching working length
Under normal conditions, working length should be reached during the first 30 seconds of operation. If you are unable to reach working length within 60 seconds in any of the in-bound pecking strokes, stop and follow these steps:
- Make sure that the shaft of the SAF does not engage the access cavity walls; this might happen in incisors or premolars that present exceptionally small pulp chambers and/or access cavities. If so, use an SAF with a longer active portion and make sure it does not buckle. Further enlargement of the access cavity is usually not necessary.
- Make sure that your coronal orifice preparation is adequately flared and that you have an unobstructed straight access to the canal. Use the Pre-SAF OS rotary instrument if needed.
- Verify the adequacy of the glidepath by manually inserting the SAF to working length. If the SAF cannot be inserted freely, realign the SAF, by rotating it by 90 degrees when it is not engaged with the canal walls, and re-insert it into the canal. You may need to repeat this realignment up to 4 times, and if this still does not allow to insert the SAF to working length - re-establish the glidepath using the Pre-SAF 2 rotary instrument.
- Make sure that the canal is clear of gross pulp tissue remnants .
- Make sure that the length of the active part of the SAF is at least equivalent to the length of the canal from the canal orifice to working length.
- Do not attempt to force the SAF to working length. Such attempts will result in buckling and damage to the file.
- Use EDTA lubricant
File breakage & file seperation
Unlike rotary instruments, the SAF’s lattice-like design allows it to partially tear without separating completely (see top figure). This safety feature greatly reduces the risk of file separation. If you encounter frequent file breakages despite using the file in accordance with its specifications, please check the following:
1. Make sure that the access cavity offers an unobstructed straight line access to the canals.
2. Make sure your glidepath allows the SAF to reach working length freely.
3. Make sure to operate the SAF according to the vertical axis of the canal, and operate it in pecking motions in the vertical axis only, without any brushing or circumferential motions.
Insufficient glidepath, improper vertical axis operation or indirect access to the canal may lead to buckling of the file (bottom figure) and subsequent file damage.
4. Stretch or loosen the irrigation tube connected to the file to control the amount of rotation required – higher rotation speed may increase the risk of mechanical damage, whereas lack of rotation may not allow the required circular repositioning of the file during the pecking motions.
5. Make sure to lubricate the RDT3 handpiece head after each use; lack of proper lubrication may increase the head torque values.
Excessive pressure and increased rotation speed will create a torsional stress on the file and should be avoided.
6. In the rare case of complete file separation (chance of 0.6% or less according to a Solomonov et al., J Conserv Dent, 2015), use a Hedström file to remove the separated segment. It is usually an easy procedure that does not require any additional removal of dentin, as opposed to separated rotary or reciprocating file that is usually screwed into the dentin wall of the canal.