Indian Journal of Dental ResearchIndian Journal of Dental ResearchIndian Journal of Dental Research
Indian Journal of Dental Research   Login   |  Users online:

Home Bookmark this page Print this page Email this page Small font sizeDefault font size Increase font size         


Table of Contents   
Year : 2014  |  Volume : 25  |  Issue : 4  |  Page : 509-512
Meant to make a difference, the clinical experience of minimally invasive endodontics with the self-adjusting file system in India

1 Department of Conservative Dentistry and Endodontics, YMT Dental College and Hospital, Kharghar, Navi Mumbai, Maharashtra, India
2 Department of Conservative Dentistry and Endodontics, Government Dental College and Hospital, Mumbai, Maharashtra, India

Click here for correspondence address and email

Date of Submission08-Feb-2014
Date of Decision28-Feb-2014
Date of Acceptance15-Jun-2014
Date of Web Publication10-Oct-2014


The vital steps in any endodontic treatment are thorough mechanical shaping and chemical cleaning followed by obtaining a fluid tight impervious seal by an inert obturating material. For the past two decades, introduction and use of rotary nickel-titanium (Ni-Ti) files have changed our concepts of endodontic treatment from conventional to contemporary. They have reported good success rates, but still have many drawbacks. The Self-Adjusting File (SAF) introduces a new era in endodontics by performing the vital steps of shaping and cleaning simultaneously. The SAF is a hollow file in design that adapts itself three-dimensionally to the root canal and is a single file system, made up of Ni-Ti lattice. The case series presented in the paper report the clinical experience, while treating primary endodontic cases with the SAF system in India.

Keywords: Biomechanical preparation and self-adjusting file, endodontic files, instrumentation

How to cite this article:
Pawar AM, Pawar MG, Kokate SR. Meant to make a difference, the clinical experience of minimally invasive endodontics with the self-adjusting file system in India. Indian J Dent Res 2014;25:509-12

How to cite this URL:
Pawar AM, Pawar MG, Kokate SR. Meant to make a difference, the clinical experience of minimally invasive endodontics with the self-adjusting file system in India. Indian J Dent Res [serial online] 2014 [cited 2023 Mar 30];25:509-12. Available from:
The mechanical shaping and chemical cleaning of the root canal system is the decisive step in an endodontic treatment with the aim to remove all tissue debris from the root canal space, removing layers of infected root canal dentin, resulting in cure or preventing apical periodontitis. [1],[2] The evolution and use of rotary nickel-titanium (Ni-Ti) files for the past two decades has revolutionized a major success in the shaping procedures of the root canals and shifted our concept from conventional to contemporary endodontics. The resultant good quality obturation from there shaping procedures has been observed on radiographs. [3]

In literature by studies, it has been reported that Ni-Ti rotary instruments leave around 40-60% of the root canal surface unaltered by their shaping procedure. [4],[5],[6] The prevalence of canals with a long oval cross-section in their apical thirds ranges from 25 to 50% has been reported in literature. [7] Studies have also reported, the rotary Ni-Ti instrumentation being ineffective for cleaning or shaping long oval and flat canals. [8],[9]

Other systems, like the Endo-Eze anatomic endodontic technology (Ultradent, South Jordan, UT) system for shaping and cleaning of root canals were also unable to conquer the challenges of successfully shaping and cleaning the oval canals. [10] Other devices which used along with sodium hypochlorite; helped it to reach mechanically inaccessible areas of the root canal, were also introduced. These included passive ultrasonic irrigation, sonic activation of the irrigant by devices such as the Endoactivator (Advanced Endodontics, Santa Barbara, CA, USA) or F Files (Plastic Endo, Lincolnshire, IL, USA), Canal Brushes (Coltène Whaledent, Langenau, Germany) and negative pressure irrigation systems like the EndoVac (Discus Dental, Culver City, CA, USA). [11]

The self-adjusting file system

The self-adjusting file (SAF) is a hollow file [Figure 1]a designed as a compressible, thin-walled, pointed cylinder of 1.5 mm or 2.0 mm diameter and composed of 120-μm-thick Ni-Ti lattice. The SAF is operated in a trans-line (in- and-out) motion using a vibrating handpiece head (RDT3, ReDent-Nova, Ra'anana, Israel) [Figure 1]b that generates 5000 vibrations/min at amplitude of 0.4 mm. This file adapts itself to the three-dimensional canal morphology both longitudinally and cross-sectionally. It effectively shapes up to 92% of the of root canal walls, while allowing for the continuous flow of fresh NaOCl through the hollow file by using a peristaltic irrigation device ( VATEA, ReDent-Nova, Ra'anana, Israel) [Figure 1]c. The file continuously activates the irrigant by its sonic vibration. These three unique features contributed to the effective cleaning ability, reported by Metzger et al. [12]
Figure 1: (a) The hollow design of the (self-adjusting file [SAF]). (b) Vibrating hand-piece head, RDT3 head. (c) Peristaltic irrigation unit, VATEA Pump. (d) Three-dimensional shaping effect of the SAF file where different shaped root canal were enlarged in the same tooth and extremely challenging C-shaped canals both using micro-computed tomography

Click here to view

The three-dimensional shaping effect of the SAF file has been reported by a micro-computed tomography (CT) analysis study by Solomonov for long oval canals and C-shaped canals, extremely challenging cases for instrumentation [Figure 1]d. [11]

On this background, considering the unique design of SAF, the principle of its functioning, the promising claims of the users, researchers and availability of SAF in India prompted us to use it 1 st time for biomechanical preparation in six different canal configurations during endodontic treatment.

Clinical experience

Case 1

A 32-year-old healthy male patient with the chief complaint of discomfort and pain in mandibular right posterior region was reported to the Department of Conservative Dentistry and Endodontics. The patient gave a history of intermittent reoccurring pain in the same region for the past 4 months. Clinical examination revealed deep carious lesion located disto-proximally with respect to the right mandibular second premolar (45). No significant findings were recorded in the medical history. Intraoral periapical radiograph showed disto-proximal radiolucency involving the pulp chamber and a curvature in the root apically [Figure 2]a. On electrical and thermal pulp testing, the tooth was nonresponsive to stimuli, suggestive of loss of tooth vitality and confirmed the diagnosis of pulp necrosis. The endodontic treatment was planned and explained to the patient.
Figure 2: (a) Pre-operative X-ray of tooth #45 showing caries involving the pulp. (b) Working length X-ray after access opening. (c) Confirmation of passive placement of the 2.0 mm self-adjusting file till working length before the use. (d) Master-cone X-ray. (e) Final obturation X-ray

Click here to view

After the administration of local anesthesia the tooth was isolated using rubber dam and a standardized oval endodontic access cavity was made under magnification (×2.5 loupes, Carl Zeiss, Germany). The pulpal floor revealed a large single root canal orifice located centrally. The patency of the root canals was achieved by #06, #08, and #10 K-files followed by working length determination by #15 K-file using an electronic foramen locator and confirming it with a radiograph [Figure 2]b.

The #25 and succeeding #30 K-file easily advanced until the working length without any obstruction, hence the glide path was made until #35 to use SAF 2.0 mm diameter file. The placement of the SAF until the working length was confirmed with a radiograph [Figure 2]c. The shaping and cleaning procedure for the canal was carried out for 4 min as recommended by the manufacturers with continuous irrigation. The file was operated in a trans-line motion of 5000 vibrations/min at amplitude of 0.4 mm using RDT3 head with continuous irrigation at a flow rate of 4 ml/min using a VATEA pump.

Following the completion of the shaping procedure, the canal was dried using sterile paper points, mastercone was selected (#35 0.04) and obturation was done with lateral cold condensation by accessory cones, using AH-Plus (De Trey-Dentsply, Konstanz, Germany) as sealer. A post-obturation radiograph was taken to confirm the quality of obturation. The endodontic access cavity was temporarily restored with MD-Temp [Figure 2]d and e.

Similarly, five more different primary cases were treated using the SAF System, which included Case 2 maxillary left lateral incisor (22), Case 3 right mandibular second premolar (45) [Figure 3]a-f. Case 4 maxillary left first molar (26), Case 5 mandibular left third molar (38) and Case 6 mandibular right third molar (48) [Figure 4]a-f.
Figure 3: (a) Pre-operative X-ray of tooth #22. (b) Placement of the self-adjusting file (SAF) till the working length. (c) Final obturation X-ray. (d) Pre-operative X-ray of tooth #45. (e) Placement of the 2.0 mm SAF till the working length. (f) Final obturation X-ray

Click here to view
Figure 4: (a, c and f) Pre-operative X-rays of tooth #26, 38 and 48. (b, d and f) final obturation X-rays

Click here to view

   Discussion Top

The SAF file is made up of a thin-walled cylinder 1.5 mm or 2.0 mm in diameter can be elastically compressed easily to the extent that it assumed dimensions resembling those of an ISO size 20 and 30 K-file respectively [Figure 5]a and b. This is possible because of the special design of the file, that is, the absence of a solid central metal core like in all the other rotary or reciprocating file systems.
Figure 5: (a and b) Adaptation of the 1.5 mm self-adjusting file to the root canal previously instrumented by a #20 K-file in both mesio-distal and bucco-lingual exposures

Click here to view

When used for flat oval canals, rotary/reciprocating Ni-Ti files create a shape for the Gutta-percha without respecting the actual cross-sectional shape of the root canal resulting in uneven thickness of the remaining dentin wall. On the other hand, the SAF removes a uniform layer of dentin from the canal walls, resulting in a uniform thickness of the remaining dentinal wall. [13] The flat oval canals are wider buccolingually, while narrow mesiodistally. When SAF is introduced in these canals it gets compressed mesiodistally (as it is narrow) leading to its expansion buccolingually as illustrated in [Figure 5]. This is how it adapts to the original shape of the canal and enlarges the canal maintaining the original shape. Another merit of the SAF is that it does not have any cutting blades or flutes; instead it has an abrasive surface, hence leading to smoother walls when compared with the rotary/reciprocating files.

The SAF instrumentation includes continuous simultaneous irrigation with any desired irrigant. This continuous flow of irrigant does not build up any pressure in the canal as the metal meshwork allows the free escape of irrigant at all times. Furthermore, in the narrowest apical part of a canal prepared up to a #20 K-file, the SAF is effective, leaving more than 38% of the canal cross-section free for backflow of fluid and dentinal debris. [14]

In a high-resolution three-dimensional micro-CT analysis comparing different file systems used for cleaning and shaping procedures, showed high percentage (83.2%) of the root canal wall was affected by the SAF file instrumentation even in oval, flat root canals. [15] Siqueira et al., found that the SAF system was significantly more effective than rotary Ni-Ti instrumentation used with syringe/needle irrigation in disinfecting long oval root canals. [16] In another study on the propagation of microcracks in the dentinal walls during root canal instrumentation, Yoldas et al. concluded that all rotary files used in the study for shaping procedures created microcracks, whereas the samples in the group treated with SAF file and hand instrumentation presented satisfying results with no dentinal microcracks. [17] Alves et al. in their study concluded that the SAF system when used for root canal instrumentation resulted in significant reduction in the bacterial population even after only 2 min of its use regardless of the sodium hypochlorite concentrations, while the most impressive result was seen with SAF after 6 min. [18]

A classification and also the protocol of using SAF effectively has been recently reported. [11] The classification was proposed taking into account the root canal size and patency. The root canals can either accommodate ISO #10, #15 or #20 and larger, passively without any instrumentation, referring them as difficult, medium or simple canals.

The protocol for using the SAF effectively with possibly fewer mishaps was as follows:

Step 1: Glide path preparation

The glide path for accommodating a #20 K-file or larger need not need any preparation of a glide path for using the SAF. Moderate or difficult canals allowing jus the placement of a #15 or #10 K-files, a glide path is needed to be prepared till at least a #20 K-file is reaches the working length freely for the use of 1.5 mm SAF. Larger than #35 K-file the use of 2.0 mm SAF is effective.

Step 2: Canal instrumentation

On confirming the placement of the SAF until the working length, the file is used with short pecking strokes in- and-out continuously for 4 min with a simultaneous irrigation. The irrigation flow should be of 4 ml/min.

Step 3: Obturation

A combination technique may be used; cold lateral compaction, followed by vertical condensation with hot plugger, and followed by condensation with cold plugger.

Taking into consideration the material, design and the flexibility of the SAF along with the facility of continuous simultaneous active irrigation, it meets the vital objectives of most effective mechanical, chemical and physical cleaning of the various root canal configurations, all ensuring predictable success of the endodontic treatment.

   Conclusion Top

The SAF represents a new advent in endodontic file design and use. The SAF does not have a will of its own while preparing the root canals and is advantageous over currently available endodontic files. It also introduces a new era of minimally invasive endodontics. Use of cone beam CT in endodontic practice results in the identification of canals showing cross-sections that are not round, a clear indication for use of the SAF system. Based on the literature supports and our clinical experience, it can be concluded that the SAF system can be a successful means to provide the unmet solution for successfully shaping the oval and oval-flat canals.

   Acknowledgment Top

The authors would like to thank Prof. Metzger and Dr. Solomonov for extending their knowledge for the use of Self-Adjusting File system.

   References Top

1.Baugh D, Wallace J. The role of apical instrumentation in root canal treatment: A review of the literature. J Endod 2005;31:333-40.  Back to cited text no. 1
2.Peters LB, Wesselink PR, Buijs JF, van Winkelhoff AJ. Viable bacteria in root dentinal tubules of teeth with apical periodontitis. J Endod 2001;27:76-81.  Back to cited text no. 2
3.Cheung GS, Liu CS. A retrospective study of endodontic treatment outcome between nickel-titanium rotary and stainless steel hand filing techniques. J Endod 2009;35:938-43.  Back to cited text no. 3
4.Peters OA, Schönenberger K, Laib A. Effects of four Ni-Ti preparation techniques on root canal geometry assessed by micro computed tomography. Int Endod J 2001;34:221-30.  Back to cited text no. 4
5.Paqué F, Ganahl D, Peters OA. Effects of root canal preparation on apical geometry assessed by micro-computed tomography. J Endod 2009;35:1056-9.  Back to cited text no. 5
6.Paqué F, Balmer M, Attin T, Peters OA. Preparation of oval-shaped root canals in mandibular molars using nickel-titanium rotary instruments: A micro-computed tomography study. J Endod 2010;36:703-7.  Back to cited text no. 6
7.Wu MK, R'oris A, Barkis D, Wesselink PR. Prevalence and extent of long oval canals in the apical third. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:739-43.  Back to cited text no. 7
8.Elayouti A, Chu AL, Kimionis I, Klein C, Weiger R, Löst C. Efficacy of rotary instruments with greater taper in preparing oval root canals. Int Endod J 2008;41:1088-92.  Back to cited text no. 8
9.De-Deus G, Reis C, Beznos D, de Abranches AM, Coutinho-Filho T, Paciornik S. Limited ability of three commonly used thermoplasticized gutta-percha techniques in filling oval-shaped canals. J Endod 2008;34:1401-5.  Back to cited text no. 9
10.Taha NA, Ozawa T, Messer HH. Comparison of three techniques for preparing oval-shaped root canals. J Endod 2010;36:532-5.  Back to cited text no. 10
11.Solomonov M. Eight months of clinical experience with the Self-Adjusting File system. J Endod 2011;37:881-7.  Back to cited text no. 11
12.Metzger Z, Teperovich E, Zary R, Cohen R, Hof R. The self-adjusting file (SAF). Part 1: Respecting the root canal anatomy-A new concept of endodontic files and its implementation. J Endod 2010;36:679-90.  Back to cited text no. 12
13.Peters OA, Boessler C, Paqué F. Root canal preparation with a novel nickel-titanium instrument evaluated with micro-computed tomography: Canal surface preparation over time. J Endod 2010;36:1068-72.  Back to cited text no. 13
14.Hof R, Perevalov V, Eltanani M, Zary R, Metzger Z. The self-adjusting file (SAF). Part 2: Mechanical analysis. J Endod 2010;36:691-6.  Back to cited text no. 14
15.Peters OA, Peters CI, Schönenberger K, Barbakow F. ProTaper rotary root canal preparation: Effects of canal anatomy on final shape analysed by micro CT. Int Endod J 2003;36:86-92.  Back to cited text no. 15
16.Siqueira JF Jr, Alves FR, Almeida BM, de Oliveira JC, Rôças IN. Ability of chemomechanical preparation with either rotary instruments or self-adjusting file to disinfect oval-shaped root canals. J Endod 2010;36:1860-5.  Back to cited text no. 16
17.Yoldas O, Yilmaz S, Atakan G, Kuden C, Kasan Z. Dentinal microcrack formation during root canal preparations by different Ni-Ti rotary instruments and the self-adjusting file. J Endod 2012;38:232-5.  Back to cited text no. 17
18.Alves FR, Almeida BM, Neves MA, Rôças IN, Siqueira JF Jr. Time-dependent antibacterial effects of the self-adjusting file used with two sodium hypochlorite concentrations. J Endod 2011;37:1451-5.  Back to cited text no. 18

Correspondence Address:
Ajinkya M Pawar
Department of Conservative Dentistry and Endodontics, YMT Dental College and Hospital, Kharghar, Navi Mumbai, Maharashtra
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.142552

Rights and Permissions


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

This article has been cited by
1 Reciprocal and continuous rotation is two sides of the same coin
Sarah Salloum,Chadi Torbey,Sanaa Bassam,Claudia DIB
Journal of Dental Health, Oral Disorders & Therapy. 2018; 9(3)
[Pubmed] | [DOI]
2 Reciprocal and continuous rotation is two sides of the same coin
Sarah Salloum,Chadi Torbey,Sanaa Bassam,Claudia DIB
Journal of Dental Health, Oral Disorders & Therapy. 2018; 9(3)
[Pubmed] | [DOI]
3 An in vitro comparative Evaluation of Fracture Strength of Roots Instrumentated with Self-adjusting File and Reciproc Reciprocating File, with and without Obturation
Pooja Kabra
International Journal of Clinical Dentistry and Research. 2017; 1(1): 20
[Pubmed] | [DOI]


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Email Alert *
    Add to My List *
* Registration required (free)  

    Article Figures

 Article Access Statistics
    PDF Downloaded194    
    Comments [Add]    
    Cited by others 3    

Recommend this journal