Comparative Evaluation of Techniques and Devices for the Removal of Fractured Instruments

Author(s)
Study design and sample size
Methods, devices, instruments, techniques, and protocol used
Microscope
Definition of success
Success rate
Shiyakov and Vasileva (2014)
In vivo (n = 26)
Ultrasonics
Yes
Removal
84.6% (22/26)
Shahabinejad et al. (2013)
In vitro (n = 35)
Ultrasonics preceded by 5 min efforts to bypass the fragment using #8 and #10K-files
Yes
Removal
Overall: 80% (28/35)
Middle third 100% (8/8)
Apical third 74% (20/27)
Nevares et al. (2012)
Prospective clinical study (n = 112)
Ultrasonics alone or associated with bypassing the fragment with hand files
Yes
Removal or bypassing
Overall: 70.5% (79/112)
Visible fragment: 85.3% (58/66)
Invisible fragment: 47.7% (21/44)
Fu et al. (2011)
In vivo retrospective study (n = 66)
Ultrasonics
Yes
Removal
88% (58/66)
Cuje et al. (2010)
In vivo
retrospective study (n = 170)
Ultrasonics
Yes
Removal
Overall: 95% (162/170)
Gencoglu and Helvacioglu (2009)
Ex vivo (n = 90)
– K-files in straight and curved canals
Yes
Removal or bypassing
K-files overall 75% (27/36
In curved canals 66.6% (10/15)
In straight canals 80.9% (17/21)
– Ultrasonics in straight and curved canals K-files
Ultrasonics overall 94% (34/36)
In curved canals 93.3%(14/15)
In straight canals 95.2% (20/21)
Alomairy (2009)
Ex vivo (n = 15)
Ultrasonics
Yes
Removal
Ultrasonics: 80% (12/15)
Tzanetakis et al. (2008)
In vivo
retrospective study (n = 134)
Ultrasonics
Yes
Removal or bypassing
Coronal third 100%
Middle third 45.4%
Apical third 37.5%
Skyttner (2007)
In vivo (n = 142)
Ultrasonics
File bypass technique (braiding)
Micro-forceps
Tube technique with glue
Yes
NA
15 cases no treatment
20 cases extraction
64/107 removed
20/107 bypassed
4/107 retro endo
19/107 root filling, fragment retained
Terauchi et al. (2007)
Ex vivo (n = 98)
Ultrasonics (n = 35)
Yes
 
86% (30/35)
Souter and Messer (2005)
Ex vivo (n = 45)
Ultrasonics with staging platform
Yes
Removal
Ex vivo 91% (41/45)
Coronal third 100% (14/14)
Middle third 100% (16/16)
Apical third 73% (11/15)
In vivo (n = 60)
In vivo overall: 70% (42/60)
Coronal third 100% (11/11)
Middle third 100% (22/22)
Apical third 33% (9/27)
Souter and Messer (2005)
In vivo
prospective study (n = 97)
Ultrasonics
Yes
Removal
80% (66/78)
Shen et al. (2004)
In vivo
retrospective study (n = 72)
Ultrasonics
Yes
Removal or bypassing
Overall: 75% (34/47)
Wei et al. (2004)
In vivo retrospective study (n = 47)
Ultrasonics
Yes
Removal
Extracted mandibular first molars 86.6% (26/30)
Ward et al. (2003b)
In vivo clinical cases (n = 24)
Ultrasonics
Yes
Removal
Overall: 67% (16/24)
Ward et al. (2003a)
(A) In vitro simulated canals (n = 60)
Bypassing the fragment with hand files and then removing it using ultrasonic vibration of a modified spreader
Yes
Removal
Overall: 67% (16/24)
(B) Ex vivo (extracted mandibular teeth) (n = 30)
Overall: 91% (20/22)
Nehme (1999)
In vivo (n = 22)
Bypassing the fragment by hand files and then removing it by ultrasonic vibration of a modified spreader
Not available at the time
Removal
Overall: 91% (20/22)
Nagai et al. (1986)
Ex vivo-1 (n = 39)
Ultrasonic vibration of K-files
Not available at the time
Removal
In vivo: 67% (26/39)
Ex vivo-1 (n = 42)
Ultrasonic vibration of K-files (visible fragment)
Ex vivo-1: 79% (33/42)
Ex vivo (n = 57)
Ultrasonic vibration of K-files (not visible fragment)
Ex vivo: 68% (39/57)
One of the first studies on the use of ultrasonics for fragment removal by Nagai et al. (1986) reported a success rate of 68% (39 out of 57 fragments) in extracted teeth. In vivo 33 out of 42 fragments (79%) were removed. In another in vitro study by Alomairy (2009) on 30 extracted teeth, fairly balanced allocated to two groups of 15 teeth each, the application of ultrasonics was successful in 80% of the cases, whereas the Instrument Removal System (IRS) was able to remove only 60% of the fragments. Ward et al. (2003a) in an in vitro study investigated the so-called Ruddle technique, including preparation of a staging platform and use of ultrasonic tips, and reported success rates of 75% (resin blocks) and 86.8% (extracted teeth). In 24 clinical cases, this technique performed successfully in 66.7% (16 out of 24) of the cases (Ward et al. 2003b). Nevares et al. (2012) in 112 clinical cases achieved a success rate of 70.5%. For fragments visible under the microscope, the success rate was 85.3%, while that for fragments not visible was only 47.7%. In each of both subgroups, one perforation occurred. Gencoglu and Helvacioglu (2009) in an experimental study using the Ruddle technique were able to remove 95.2% (20 out of 21) of intentionally fractured instruments from straight root canals and 93.3% (14 out of 15) from curved root canals. The comparative values for a so-called conventional technique, also using a dental operating microscope, were 80.9% and 66.6%, respectively. The Masserann technique was successful only in 47.6% in straight canals. Souter and Messer (2005) in an experimental study on 45 extracted mandibular molars with intentionally fractured instruments, using a modified Ruddle technique, successfully removed 41 fragments (91%). Four cases failed with three perforations, all of these in the apical third of the roots. In 60 clinical cases 42 fragments were removed (70%), while 18 attempts failed. Suter et al. (2005) in 97 consecutive clinical cases removed 87% (84 out of 97) of the fragments. In 78 cases ultrasonics was successful, while in 12 cases this technique failed. Cuje et al. (2010) reported on a 95% (162 out of 170) success rate for the removal of fractured instruments in a dental office limited to endodontics. The authors used a strictly standardized procedure based on the Ruddle technique . The highest success rates were achieved for fragments in the coronal third (100%, 16 out of 16), in the coronal and middle third (100%, 19 out of 19), and straight root canal (100%, 14 out of 14). Six fragments could not be removed, one was only bypassed, and one perforation occurred.
There are no studies demonstrating the superiority of any available ultrasonic device or tip.

6.1.2 Tube Technique

After nearly more than half a century since its introduction, the Masserann system, the first tube technique described in the literature, is still in use (Okiji 2003; Suter et al. 2005; Pai et al. 2006; Terauchi et al. 2007; Gencoglu and Helvacioglu 2009) and is considered effective in selected cases, especially in those where the instrument fragment is located in a readily accessible position. The Masserann system and a variety of other tube techniques in different modifications have been investigated in in vivo and ex vivo studies (Table 6.2). The Masserann system has limited application in posterior teeth, particularly in patients with limited mouth opening and in teeth with thin and curved roots. More or less the same restrictions apply for the Mounce extractor , which can be used eventually only when fragments are located in the most accessible coronal portion of the root canal due to its relatively large ball tip. Yoldas et al. (2004) found Masserann drills to increase the risk of perforations in curved canals. There are great variations in the sizes of the instruments used in the various holding techniques; for example, the trephine burs in the Endo Rescue Kit are considerably smaller than those in the Masserann kit. Nevertheless, all holding techniques such as the Masserann technique, the Feldman et al. (1974) technique, the Meitrac Endo Safety System (Hager and Meisinger, Neuss, Germany), the Instrument Removal System (IRS) (Dentsply, Ballaigues, Switzerland), and the Endo Rescue Kit (Komet/Brasseler, Savannah, GA) are able to gain a strong mechanical grip on a fragment. However, the bulk and rigidity of their armamentarium does not allow their use in narrow and curved root canals, and actually the external diameter of some of them limits their application only to the coronal segment of larger root canals. For example, the approximately 1.50 mm external diameter of the smallest Meitrac I (Hager and Meisinger, Neuss, Germany) trephine and extractor obviously permits its use only in the coronal part of root canals with a very large diameter.

Table 6.2

Success rates as reported from in vivo and ex vivo studies using the Masserann kit or any other tube technique in different modifications for the removal of fractured instruments
Author(s)
Study design and sample size
Methods, devices, instruments, techniques, and protocol used
Microscope
Definition of success
Success rate
Gencoglu and Helvacioglu (2009)
Ex vivo (n = 90)
Masserann only in straight canal
Yes
Removal or bypassing
Masserann: 47.6% (10/21)
Alomairy (2009)
Ex vivo (n = 15)
Instrument Removal System
Yes
Removal
Instrument Removal System: 60% (9/15)
Suter et al. (2005)
In vivo (n = 12)
Tube and Hedstrom file method
 
Removal
91% (11/12)
Hassan (2012)
In vitro (n = 112)
Ultrasonics (N = 57)
Yes
Removal
Ultrasonics: 81.8% (45/55)
EndoRescue (N = 55)
EndoRescue: 54.4% (31/57)
Terauchi et al. (2007)
Ex vivo (n = 98)
Masserann kit (N = 33)
Yes
Removal
Masserann kit (N = 33)
91% (30/33)
File Removal System (N = 30)
File Removal System (N = 30)
100% (30/30)
Sano et al. (1974)
In vivo (n = 100)
Masserann kit
Not Available
 
Removal: 55% (55/100)
Bypassing: 45% (45/100)
In an early study by Sano et al. (1974), a success rate of 55% was reported, but no data are available on the location of the fragments inside the root canal. Removal in anterior teeth was more successful (73%, 8 out of 11) than in posterior teeth (44%, 4 out of 9). Gencoglu and Helvacioglu (2009) removed 47.6% of intentionally fractured instruments from straight root canal in an in vitro study with the Masserann technique, which was significantly less than with the ultrasonic technique (95.2%). Further tube retrieving techniques such as the Instrument Removal System (Dentsply, Ballaigues, Switzerland), Meitrac (Hager and Meisinger, Neuss, Germany), Endo Extractor (Brasseler, Savannah, USA), Cancellier Extractor Kit (Sybron Endo, Orange, CA), Endo Rescue Kit (Komet, Lemgo, Germany), and the hypodermic surgical needle techniques, along with the holding techniques and the technique described by Fors and Berg (1983) that utilize a modified needle holder used in microsurgery by ophthalmologists, frequently require over-enlargement of the root canal down to the fragment. Thus, excessive removal of hard dental tissue eventually structurally weakens the root and predisposes creation of ledges, perforations, or root fractures. When cyanoacrylate is used as an adhesive for bonding the fragment to the tube, it should be remembered that it is not “designed” to bridge a gap of >0.1 mm (Wefelmeier et al. 2015) and also care should be exercised to use only a few drops as excessive adhesive when set could inadvertently block the root canal. The same care should be exercised when using auto-polymerizing resins or Core Paste XP (DenMat Company, CA, USA), instead of cyanoacrylate adhesive. The Core Paste XP is radiopaque, and thus any excess left in the canal can be seen in the radiograph. In an in vitro study on the tube technique in which cyanoacrylate, dual-curing (Rebilda DC; Voco, Cuxhaven, Germany), or light-curing (Surefil SDR, Dentsply, York, PA) composite resin were utilized as adhesives, the amount of force required to break the connection between the microtube and the instrument was investigated (Wefelmeier et al. 2015). The results revealed that significantly higher values in pullout tests were achieved with both tested composites than with cyanoacrylate, and the best results were achieved with light-cured composite used for fixation (Wefelmeier et al. 2015). Polymerization of the light-cured composite through an optical fiber inserted into the microtube and pushed forward until the fiber came into contact with the endodontic instrument resulted in leaving the excess material outside the tube not polymerized and thus easily removable (Wefelmeier et al. 2015).
For the Endo Extractor , comparable to the Masserann kit but using a trephine bur, a hollow tube, and an adhesive to fix the fragment inside the hollow tube (Brasseler, Savannah, USA), only a case series comprising four successful clinical cases (two posts, one fractured instrument, and one silver point) has been published (Gettleman et al. 1991). The fractured instrument extended from near the orifice to the apical part of the root canal in a maxillary incisor, thus being easy to grasp even with a large tube. Suter et al. (2005) applied the tube-and-Hedstrom file technique in 12 clinical cases and were successful in 11 cases (91%), with one failure. It should be noted that this technique was applied only in 11% of 97 cases with fractured instruments.
In a study on 30 extracted teeth (Alomairy 2009), the Instrument Removal System (IRS) performed successfully in 60% of 15 teeth while ultrasonics in 80%.
The Endo Rescue Kit (Komet, Lemgo, Germany) represents a modified tube technique: following preparation of an access cavity and cutting around the top of the fragment, a center drill, named Pointer, excavates the last few millimeters of the canal coronal to the fragment, providing access to the broken instrument. A drill exposes the fragment’s surface, and an extremely fine trephine bur is placed onto it, holding it in place using residual dentin shavings. The broken file is removed from the canal in a counterclockwise rotational motion of the trephine bur. In a comparative experimental study on 112 extracted teeth with intentionally fractured instruments, the total success rate was 67.9%, with a success rate of 81.8% for ultrasonics and only 54.4% for the Endo Rescue Kit. The difference was statistically significant. In curved canals the ratio was 78% (Ultrasonics) to 21% (Endo Rescue). In cases of successful removal, the working time was not significantly different for both systems (Hassan 2012).

6.1.3 Loop Techniques

Although the wire loop technique has been essentially replaced by more practical or successful techniques (Ruddle 2004), it remains a technique which utilizes equipment available in almost all dental offices and it is still in use (Terauchi 2012). Four successful cases have been demonstrated with the use of the Terauchi technique by the inventor of the device himself (Terauchi et al. 2006). The technique starts with the preparation of a staging platform, followed by ultrasonically troughing the fragment and finally grasping and removal using a wire loop. A similar device has just recently been developed and has not been investigated so far: the Frag Remover (HanCha-Dental, Zwenkau, Germany).

6.1.4 Canal Finder System

The Canal Finder is a rotary preparation system with a relatively flexible working mode variably combining rotary and vertical movement of the inserted instrument. The removal of fractured instruments is based on forced attempts to bypass fragments and then trying to remove the fragments in a pulling motion. The system has been used for instrument removal, but has been investigated for that purpose only in three studies (Table 6.3) reporting acceptable success rates (Hülsmann 1990a, b; Hülsmann and Schinkel 1999). Operating microscopes were not available at that time.

Table 6.3

Success rates as reported from in vivo and ex vivo studies using the Canal Finder System for the removal of fractured instruments
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Oct 21, 2018 | Posted by in Endodontics | Comments Off on Comparative Evaluation of Techniques and Devices for the Removal of Fractured Instruments
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