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.

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).

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).

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.