The tooth is related to, interacts with and supports the physiology of other body organs. Further, mention should be made to all the psycho-social aspects involved in the preservation thereof. Thus, the endodontic treatment is, in many cases, responsible for the maintenance of the tooth in the buccal cavity.

Only for this aspect, the innumerable concerns about this odontological specialty already would be justified.

Since the Endodonty is the specialty that works inside the pulpal chamber, both in live and dead pulp conditions, with or without apical involvement, it should be understood that such therapy should incorporate principles of mechanical order and biological nature.

As a matter of fact, the emptying of the pulpal tissue that may or not be decomposed or contaminated, as well as the periapical tissues associated with the repairing process could be traced as the biological objective.

As to the aspect related to the emptying of the root canal, there are several techniques and instruments which are recognized in the state of the art that encompass manual and/or ultrasonic and rotation methods (CHENAL & TEPLITSKY, 1985; MEIDINGER & KABES, 1985; SOUYAVE et al., 1985 ; HULSMANN & SCHINKEL, 1999 ; KRELL et al., 1986; NAGAI et al., 1986; ALI & BARKHORDAR, 1988; HÜLSMANN, 1990; HÜLSMANN, 1994; BETTI & BRAMANTE, 2000).

During the endodontic treatment, every practitioner is prone to create an ackward situation such as the breakage of an instrument inside the root canal. This fact has evidently become the great villain of the endodonty, causing the operator discomfort and anguish (SOTOKAWA, 1988; VLAHVEIS & ZERVAS, 1988; FLANDERS, 1996; SVEC & POWERS, 1999).

There are several issues that cause the instruments to break, the most common of which is the wrong choice of the endodontic equipment, error in the instrument kinematics and fatigue of the used material caused by excessive use and abusive force (SOTOKAWA, 1988).

Thus, one cannot be sure on how many times a file or drill can be reused without the risk of breakage. In such circumstances, the common-sense must prevail when situations such as calcified, atrophied or excessively curved canals arise. Files # 06,08, 10 and 15 used in such situations should be used only once, and then discarded (FLANDERS, 1996).

The domain of the art to be used, together with the choice of the suitable endodontic equipment, associated with a good planning, diminishes the risk of accidents and complications, even in adverse situations such as atrophied canals, or even when the root canal is being emptied (VLAHVEIS & ZERVAS, 1988), what can be helped by operational microscopy in the different dental groups, thus preserving a larger amount of dental structure (FLANDERS, 1996).

In order to diminish the dental intercurrences during the instrumentation phase, improve the visualization, extend the insertion into the root canal and even diminish considerably the contamination and compacting of debris inside the root canal, the cervical-apical preparation is a must (AXE, 1993).

This technique uses Gates Glidden drills to carry out such functions besides expanding the cervical and mid portions and facilitating the manual instrumentation procedure. YANG & PAI, 2000, have set up the main accidents

working in narrow and sinuous walls, establishing limits and techniques for a safe use thereof.

When carrying out a cervical-apical operation using Gates Glidden drills, the physical dimensions and torsional properties of Gates Glidden drills as well as the best way they function can be analysed, and the kinematics methodology of said instrument can be outlined, as well as the limits therefor and the predictable types of wear and tensile performance when they are submitted to any pressure, according to the studies conducted by LAUSTEN et al., 1993; LUEBKE & BRANTLEY, 1990; LUEBKE & BRANTLEY, 1991 and BRANTLEY et al., in 1994.

Changes in the resistance to fracture of the Gates Glidden and Peeso drills may be brought about by clinical use (LUEBKE & BRANTLEY, 1992; LAUSTEN et ai., 1993 ; LOPES et al., 1994), improper use, deficiency of the technique used, use of sodium hypochlorite-based irrigating solutions or even sterilization (SVEC & POWERS, 1999).

Currently, the methods for preparation using rotatory instruments have become more and more important because they have highly flexible drills, thus assuring an easy handling and less time spent with the instrumentation of the root canal system. However, in the studies conducted by MANDEL et al., 1999, it was found that the domain of the technique used is material to prevent accidents, such as breakage of the instrument.

Another obstacle that can be found during the endodontic treatment is the presence of silver cones in the root canal filling. This filling technique is classified as that of a sole cone, that is, there are no secondary cones hermetically sealing the canal. Thus, the thickness of the cement becomes too large and shrinks when it hardens and then cures, initiating the marginal infiltration of fluid and corrosion of the silver cones (GESTEIN & WEINE, 1977; ZMENER & DOMINGUES, 1985). The fluids are capable of dissolving silver ions,

depositing same on the apicis, causing an inflammatory reaction, with the macrophage chemiotaxy (ZNMENER & DOMINGUEZ, 1988).

When there is an intra-canal debris that cannot be laterally diverted or even removed after several attempts, the surgical therapy is indicated, thus preserving and conserving the dental element but eliminating its iatrogenic etiology (ZILLICH & PICKENS, 1982; TUNER, 1985).

According to CRUMP & NATKIN, 1970, there is a clinical and radiographical relationship between the broken instrument and the endodontic prognostic, by observing the dental levels, respectively the cervical, mid and apical portion, the presence of apical injury and decrease of the symptoms. There are several factors that may aggravate the prognostic, such as: the tooth localization (HULSMANN, 1999), types of teeth and roots, the position of the fragment in relation to the canal curvature, the length of the fragment and the type of breakage, said debris being either metallic (CRUMP & NATKiN, 1970; HARRIS, 1972) or even foreign matter such as a piece of graphite (LAMSTER, 1977).

By revising the literature, a large number of techniques for removing instruments known in the state of the art is seen, such as Masserann kit idealized by GUNDLACH, in 1972. In this system, the trepans are responsible for the compensatory wear around the fragment or pin, however, in order to introduce the extracting tube it is necessary to carry out a great relief, increasing the lumen of the canal, causing the dental walls to weaken (WiLLIAMS & BJOURDAL, 1983). The procedure for accessing the fragments in the mid and apical portions, together with that used in curve roots, are counter-indicated, thus limiting the use of this technique.

When an instrument breaks inside the root canal, there are several factors that limit its removal, amongst which is the difficulty to visualize same. In 1974, FELDMAN introduced the optic fiber for the purpose of trans-

illuminating the tooth, thus making it possible to determine the position of the metallic fragment caught inside the root canal. He created a method wherein he used trepans and a thinner extracting tube, but it required a large compensatory wear for introducing same, thus counter-indicating its use in apical fragments.

Another limiting factor is the orientation of the wear. If the fragment is located in the cervical portion of the root, it can be removed by using drills, and care should be taken on the adjacent walls and the relationship between the thickness of the pin and the dental wall should be observed. In 1975, DIMASHKIEH idealized a method to direct the wear by minimizing the risk of perforation wherein he used a trepan around the pin and placed a tube that determined its long axis. With such a guide he introduced a drill of lesser diameter consistent with the interior of the tube and a safe wear was carried out.

The described technique also had the same limiting factor, the large compensatory wear and its counter-indication in apical levels and curved canals.

For removing metallic debris, there are several methods and indications (INGLE & BEVERIDGE, 1976; TUNER, 1983; FORS & BERG, 1986), varied techniques and active principles, but the relief between the fragment and the dentine by breaking the cement line is critical to release same. WARREN & GUTMANN, in 1979, invented the Pin Extractor (DR. H. KAHN), wherein, after the compensatory wear, the traction was conditioned and the pin was displaced (FLOCK et al., 1985).

Resources such as Müller and Meisinger long-necked drills associated with Castroviejos hemostactic clamps (FORS & BERG, 1983), injection needles by coupling a orthodontic floss for the purpose of lacing the fragment (ROING-GREENE, 1983), ultrasound associated with K files (MEIDINGER & KABES, 1985; SOUYAVE, 1985; KRELL et al., 1986; NAGAI et al., 1986; ALI & BARKHORDAL, 1988), prepared hypodermic needles (LONGORIA & CEPERO, 1986), Stieglitz clamps and Mutter drills (FORS &

BERG, 1983), EDTA (STEWART, 1986; PAIVA & ANTONIAZZI, 1991), metallic tube with cyanoacrylate (JOHNSON & BETTY 1988), Canal Finder System associated with ultrasound (HULSMANN, 1990), EndoExtrator (GETTLEMAN et al., 1991), hypodermic needles filled with cyanoacrylate (AUN, et al., 1992), Steghitz forceps associated with ultrasound (MCCULLOCK, 1993; COUTINHO FILHO et al., 1998), Gates Glidden, Hedstoem files, metallic tube associated with cyanoacrylate (FLANDERS, 1996), tube associated with Hedstroen file (SUTER, 1998), operational microscope associated with ultrasound (NEHME, 2001) are the main techniques for removing endodontic fragments or metallic pins disclosed in the literature.

The technique that uses hemostactic clamps or forceps have large limitations, making it possible to remove extra-coronary debris, requiring a large wear in the coronary and cervical portion, in the event the fragment is imbedded as far as this level, thus counter-indicating this procedure. The technique that uses the injection needle associated with a lace with orthodontic floss is restricted with respect to the amplitude of the root canal, the depth the metallic fragment is located at, and the skill of the operator in lacing and removing the metallic debris.

The ultrasonic system is used to remove instruments from the root canal (MEIDINGER & KABES, 1985; KRELL et al., 1986; NAGAI et al., 1986; ALI & BARKHORDAR, 1988; NEHME, 2001), detaching and unlocking fragments by breaking the cement line in the case of cemented pins, and in the case of files, drills and lentulos by removing or reducing the attrition of its outer surface in relation to the inner one of the lumen of the root canal, thus becoming neutral and being removed by traction or irrigation and aspiration.

The EDTA, by being a chelant (STEWART, 1986; PAIVA & ANTONIAZZI, 1991), dissolves and softens dental structures by sequestering calcium ions, thus propitiating and facilitating the penetration of files around

endodontic fragments inside the canal, as well as the removal of the dirt and debris that can be compacted, thus making it more difficult to remove the fragment. It is indicated for atresic canals and irrigation where it is needed to remove the sheared compacted dentine inside the dental tubules. The improper or extensive use of this pharmaceutical may cause an unnecessary softening of he dentine, bringing about the risk of root strength and susceptibility to root perforations.

The use of metallic tubes associated with cyanoacrylate is indicated (COUTINHO FILHO et al., 1998; SUTER, 1998; HULSMANN, 1999), however, if one observes the dimensional stability, surface activity and physical properties related to the flow, he may notice the great probability of migration of this glue to the dentine and possibly to the apical region when one tries to introduce the fragment inside the metallic tube. The technique that uses the injection needle associated with a lace with ortodontic floss is restricted with respect to the amplitude of the root canal, the depth the metallic fragment is located at, also depending on the skill of the operator when lacing the metallic obstacle for ulterior removal.

The technique that uses EDTA (a chelant) dissolves and softens dental structures, facilitating the penetration of files around endodontic fragments inside the canal. It is indicated for atresic canals and irrigation where the sheared compacted dentine inside the dental tubes needs to be removed. However its improper use may cause the unnecessary softening of the dentine, compromising the root strength, thus making this region prone to perforations.

The technique that uses metallic tubes associated with cyanoacrylate present the negative aspect related to the difficulty of controlling its application, and this substance may migrate to the dentine or even the apical region.

The solution proposed herein is based on a constructive improvement in a device for removing fragments of endodontic instruments inside the root canal of a tooth wherein the applicant idealized a device that makes it possible to extract fragments from inside the root canal, without the need of traumatic tooth surgical interventions, thus making it possible to have an expressive reduction in the time spent in said intervention, in view of the practical and easy way the operation is handled with the new endodontic instrument.

The applicant idealized a device that departs from the condition of linear rigidity of the endodontics instruments known in the state of the art, presenting a solution that allows for a more flexible guidance of the instrument inside the root canal, irrespective of the degree of complexity found, thus allowing for an optimum coupling between the inventive instrument and the fragment to be extracted.

The constructive improvement proposed herein is a device the main function of which is the extraction of manual and/or rotatory endodontic instruments, said improvement being characterized by assembling three elements integral therewith that are suitably called handle, rod, active spiraled tip and penetration guide for the active spiraled tip.

The object of the handle is to support the rod and the active spiraled tip, and it is designed in such a way that it presents grooves for the purpose of supporting the thumb and forefinger of the practitioner performing the endodontic intervention, thus characterizing an action by bidigital manipulation of the claimed device.

The function of the rod is to connect the handle and the active spiraled tip, and it should be small sized in order to optimize the visualization of the operation field and access to the active spiraled tip.

The main functions of the active spiraled tip are: to provide rotating movement, fitting and support to the action of an extraction force of the several diameters of broken endodontic instruments.

For the purpose of turning the claimed device universally used, the applicant, when defining the composition of the set of spirals, also foresees cases of specific application for rotatory instruments of the Quantec (g) and Profile type, wherein the rotating action of the spiral is contrary to the standards observed for endodontic instruments, since this instrument works as if it were a screw, and the spiral of the active tip must increase its inner diameter in the anti- clockwise direction, and decrease same in the clockwise direction. By foreseeing this case, the applicant assures the adequacy of the active tip element to any type of fragment of endodontic instrument to be removed, since the diameter thereof is a determinative factor for a successful endodontic intervention of such nature.

Also, the applicant has introduced another element, a penetration guide of the active tip, which is located at the front end of the spiral of the active tip. The primary function of this element is to help the active tip to be suitably approached and positioned by the endodontic fragment to be extracted.

To complement the present description in order to obtain a better understanding of the characteristics of the present application for a utility model, a set of accompanying drawings is attached hereto, wherein the following is given in an exemplary but not restrictive way.

Figure 1 is an anatomical view of the dental element, emphasizing the root canal, Figure 2 is a perspective view of the claimed constructive improvement, Detail 1 is a detailed view of the active tip and penetration guide of the active tip,

Figure 3 is a side cut view of the active tip and penetration guide of the active tip, Figure 4 is a view of the initial stage wherein the active tip approaches the endodontic fragment to be extracted, Figure 5 is a view of the stage during which the active tip is coupled to the endodontic fragment to be extracted, Figure 6 is a view of the initial stage wherein the fragment is extracted, Figure 7 is a view of the stage wherein the fragment is extracted from the root canal, Figure 8 is a view of the root canal free from the fragment previously lodged therein.

With reference to the illustrated drawings, the present utility model is directed to a constructive improvement in a device for removing fragments of endodontic instruments inside the root canal of a tooth wherein, for a better understanding of its field of application, the applicant illustrates in Figure 1 a dental element wherein the anatomy can be recognized, mainly with respect to the root canal (g) which the inventive improvement is applied to. The anatomy of the dental body is divided into two parts, viz : crown (a), and root (b); which is lodged in the bone (f). The enamel (c) is located at the outmost region of the crown (a). The dentine (d) can be seen right below same, inside which is the pulp (e) and the root canal (g).

Figure 2 is a view of the claimed instrument for removing fragments (1), which is comprised of the handle (2) for providing the device with support and rotational movement through bidigital contact. For the purpose of maximizing the contact and"catch"between the thumb and forefinger of the endodontist and the handle (2), it is made in such a way that a rough surface (2a) full of protuberances is provided.

The rod (3) is closely connected to the handle (2), the function of which is to connect the handle (2) and the active spiraled tip (4).

The active spiraled tip (4) is defined as a body preferably made of a material such that provides same with characteristics of resistance against torsional and traction forces, which is conformed in the shape of a spiral. The solution of the spiral shape incorporates a characteristic of flexible movements which is better seen in Figure 3. Said characteristic assures the dentist the possibility of accessing any type of root canal complexity.

In detail 1, the diameter of the spiral body (d3) as well as the outer diameter (d2) and inner diameter (d1) that are defined consonant to the different diameters of the existing endodontic instruments of the state of the art can be seen. This situation results in the formation of a number of different specifications of active spiraled tip (4) the surgeon must always have in hand when initiating the intervention using the claimed device.

The inventor also establishes that he function of the penetration guide (5) of the tip, which is an extension of the active spiraled tip (4), is to make it easier to approach and position same on the fragment (6).

Before initiating the endodontic intervention for extracting the fragment (6) from the root canal (g), the dentist proceeds to a radiographic planning of the breakage of the instrument, and the ulterior clinical analysis of the broken instrument (6). Then, the practitioner carries out the compensatory wear of the entrance of the root canal (g), thus freeing the edges of the broken endodontic instrument (6), displacing same to the root canal (g). He proceeds then to choose the type of active spiraled tip (4) that is better suited to the fragment (6) of the endodontic instrument, based on a previous clinical analysis of the broken instrument.

Figure 4 shows the approaching movement of the active spiraled tip (4), wherein the penetration guide (5) of the tip helps to position and approach

same correctly. The active spiraled tip (4), when in use, exhibits a dimensional expansion on its first spiral as soon as it contacts the fragment (6) and the consequent attrition on its inner surface (d1), as illustrated in Figure 5. As it expands, both the inner diameter (d1) and outer diameter (d2) increase. Since the inner diameter of the active tip (d1) was nominally the same as the diameter of the broken endodontic instrument (6), said expansion propitiates a natural coupling of the fragment (6) inside the spiral of the active tip (4).

When the rotational movement in the rolling direction of the spiral ceases, the diameter of the spiral (d1) returns to its original nominal dimension, thus assuring the optimum coupling of the spiraled active tip (4) to the endodontic fragment (6) to be removed.

Figure 6 illustrates the beginning of the procedure for extracting the fragment (6), by rotating the device (1) in the opposite direction in order to assure the coupling of the fragment (6), resulting in a rotational movement, then beginning to compress the fragment (6) due the reduction of the nominal inner diameter (d1) of the spiral of the spiraled active tip (4). Once the fragment (6) and the spiraled active tip (4) are duly coupled, the removal is initiated by keeping the fragment (6) of the endodontic instrument to be extracted rotating in the clockwise or anti-clockwise direction, depending on the type thereof, thus releasing same as shown in Figure 7.

Also, the applicant points out that, when the traction force is applied, the spirals of the active tip (4) that were juxtaposed are displaced thereby, thus remaining spaced apart in view of the opposite resistance caused by the fragment (6). This kinematics provides a reduction of the inner diameter (d1) of the spirals, grasping more tightly the fragment (6) inside same, assuring the full extraction thereof, thus leaving the root canal (g) free from the strange matter, as shown in Figure 8.