RU2821192C2 - Method of extracting fragment of endodontic instrument from tooth root canal - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to dentistry, and can be used in endodontics in retreatment of root canals. Method for extracting a fragment of an endodontic instrument from a root canal involves obtaining an X-ray image of the tooth, performing a computed tomography of the upper or lower jaw, and extracting a fragment of an endodontic instrument from the root canal. Tooth impression is taken and a plaster model is made, which is scanned with a laser, a digital image of the crown part of the tooth is obtained, the images of the tooth obtained by computed tomography and laser scanning are combined, as well as virtual modelling of a three-dimensional template, using computer program 3 dsMAX, a plastic template is made, the basis of which is fixed on three teeth. Template has a guide limiter, the hole direction of which coincides with the upper part of the broken tool fragment. Endodontic instrument is inserted into the hole of the template until it touches the bottom of the tooth cavity, the template is removed, and reciprocal instruments R25 with taper of 0.8 mm and R40 with taper of 0.6 mm are inserted and pass them through the root canal, performing the root canal preparation until the file enters the prepared space around the fragment. Under X-ray control with a manual flex file of size 25, a lumen of the root canal is found below the border of the fragment, the fragment is extracted with ultrasonic K-files 15, 20, 25, and the root canal is filled with restoration of the tooth with a composite filling material.

EFFECT: invention enables improving the quality of endodontic treatment and preserving the tooth.

1 cl, 3 dwg

Description

The invention relates to medicine, namely dentistry, and can be used in endodontics for repeated treatment of tooth root canals.

There is a known method for removing broken endodontic instruments from the root canal of a tooth, proposed by A.Zh. Petrikas and co-authors (Petrikas A.Zh. Device for removing pins and broken endodontic instruments. / A.Zh. Petrikas, E.V. Sergeeva, G.P. Lobashov // Dentistry. - No. 1. -1991. - P. 72).

The method proposed by A.Zh. Petrikas et al. (1991), has a number of disadvantages:

1) to implement the method, it is necessary to prepare a special device from an injection needle and use a mandrel to insert and wedge a fragment of an endodontic instrument inside the injection needle;

2) when working in narrow root canals, this device cannot be used;

3) it is impossible to use it in curved root canals;

4) when carrying out the method, it is possible to push a fragment of the instrument to the top of the tooth and even beyond the top of the tooth, which will cause an even greater complication and will require surgical removal of this fragment of the instrument and removal of the tooth.

There is a known method for removing a fragment of an endodontic instrument from a root canal using a device for capturing its free tip (US Patent No. 5879160A, dated 03/09/1999). This method uses a mechanical clamp, inserted into the canal through a tube and ensuring the capture of the fragment and its securing by wedging.

Then the clamp, along with the tube and the attached fragment, is removed from the root canal of the tooth.

Implementation of this method using a wedging instrument requires preparation of the tooth cavity, and undesirable expansion of the root canal to access the tip of the endodontic instrument fragment. To capture a fragment, it is necessary to grasp it with a jamming device.

However, due to the difficult access to the narrow root canal (bore diameter 0.2-1.0 mm), effective control of contact and capture of the fragment is necessary. Often the root canal has a curved shape and it is not always possible to transfer sufficient mechanical force to the clamp for reliable capture of the fragment by a jamming device. The necessary force of adhesion of the instrument to the fragment stuck in the root canal is required if it cannot be removed.

There is a known method for removing foreign bodies proposed by I.A. Shlyakhtova (Shlyakhtova I.A. Removal of foreign bodies from root canals. / I.A. Shlyakhtova // Dentsplay News. - 2005. - No. 11. - P. 42-46).

When working in root canals, they need to be expanded only to the extractable fragment of the endodontic instrument in the root canal of the tooth, and the extracting instrument may be smaller or the same diameter as the fragment of the instrument to be extracted.

The method involves the use of ultrasound, one of the properties of which is the release of heat and heating of the environment, which helps to expand the metal fragment of the endodontic instrument from high temperature and further retain it in the root canal of the tooth.

However, removing a fragment of an endodontic instrument from a tooth canal takes an extremely long time and is not always successful.

An extractor is known for extracting a fragment of an instrument from the root canal of a tooth (patent No. 2257868, RU, MPK A61C 19/00), containing an electric current source and two metal electrodes insulated from each other connected to it. The current source is configured to pass through a closed circuit an electrical pulse sufficient to weld the fragment to the electrodes due to heating at the contact points. The first electrode is inserted between the fragment and the canal wall. The second electrode, under careful visual control using an optical microscope, is brought directly to the fragment. After contact of the second electrode with the fragment, a discharge occurs, as a result of which the electrode is welded to the fragment. Its removal is carried out using pulling movements.

Removing fragments with a known instrument is a labor-intensive, expensive and complex process that requires direct access to the fragment. In addition, the known tool, when rotated, does not provide reliable welding strength sufficient to remove the fragment.

The closest in technical essence to the claimed solution is a Device for extracting a fragment of a manual endodontic instrument from the root canal of a tooth and a method for its use (patent No. 2681920, RU, IPC A61C 5/46).

The device contains in the handle and working part a sequential chain of neodymium permanent magnets with axial magnetization, with a total adhesive force of 60 kg, the working part in the handle is located at an angle of 45°. The instrument fragment is impacted in the root canal of the tooth with an ultrasonic endodontic file, creating a groove around it. A solution of ferrihydrite nanoparticles with adsorbed ethylenediaminetetraacetic acid is injected into the space between the fragment and the tooth. The end of the working part of the device is used to magnetize a fragment of an endodontic instrument. They are exposed to magnetic laser resonant therapeutic low-intensity radiation with a wavelength of 0.85 microns, a pulse power of 5 W, a pulse repetition rate of 2000 Hz, a pulse duration of 40 ns, a magnetic induction of at least 50 mT, followed by extraction of a fragment from the root canal of the tooth. The exposure is carried out under the control of an operating microscope and radiographs.

However, when working in the root canal, an ultrasonic endodontic file is used to create a groove around the fragment, and complications such as root perforation or pushing the fragment deeper into the root canal are possible. During the passage of the root canal, there is no straight-line access to the fragment and during mechanical processing a ledge may be formed, which further contributes to uneven and poor-quality obturation of the root canal after removal of the fragment. When working with the device, it is not always possible to remove a fragment, since before removing it with a magnet, mechanical processing and creation of a channel taper of 0.6 are not performed.

The task was set to effectively extract a fragment of an endodontic instrument from the root canal, improve the quality of endodontic treatment, and preserve the tooth.

This task is achieved using an individual endodontic template designed for mechanical treatment of the root canal of a tooth and creating a root canal taper of 0.6 mm, providing straight-line access to a fragment of an endodontic instrument in the root canal of a tooth.

Extraction of a fragment of an endodontic instrument from the root canal of a tooth is carried out using a plastic template made individually for each clinical situation. The template consists of heavy-duty plastic, which is made using rapid prototyping and a 3D printer.

Rapid prototyping involves modeling an object on a computer using 3 dsMAX 2009 software (Autodesk, USA). The program creates a model with parameters specified in three-dimensional space. To produce an individual endodontic template, the stereolithography method was used. Printing of templates is carried out using laser stereolithography using a LS-250 installation (IPLIT, Shatura RF), which has a printing accuracy of 0.1 mm and a roughness of 20 microns. An Objet-Eden 500 V 3D printer (Stratasys, Minnesota, USA) was also used for this purpose. Manufacturing material NextDent photopolymer. The material is harmless and biocompatible with oral tissues.

The frame of the template with a guide stop ensures its fixation on the teeth, regulates the direction and depth of immersion of the manual endodontic instrument flex file into the through hole, the direction of which strictly coincides with the upper border of the endodontic instrument fragment.

Making a template for removing a fragment of an endodontic instrument from the root canal of a tooth is carried out as follows.

The patient, depending on the location of the tooth with the instrument fragment, first undergoes a computed tomography scan of the upper or lower jaw to determine the location of the instrument, the length and curvature of the root canal.

An impression is taken from the jaw where the tooth requiring repeated endodontic treatment is located using an impression mass and a plaster model is cast.

A laser scan of a plaster model of the patient’s teeth is performed and a digital image of the crown of the tooth is obtained.

Using the 3 dsMAX 2009 computer program, the obtained data from computed tomography and laser scanning of tooth images are combined. A three-dimensional template is virtually modeled on the resulting digital image of the tooth. The template has a hole, the direction of which coincides with the fragment of the broken instrument along its entire length.

In fig. 1 provides a template consisting of a base 1, which ensures its fixation on the teeth; the template guide stop 2 has a through hole 3, with a diameter corresponding to the non-working part of the endodontic instrument.

To regulate the direction and depth of immersion, a manual endodontic instrument, a flex file, is used.

In the appendix, photo 1 shows the occlusal surface of the individual template; Photo 2 shows an individual template installed on 3 teeth.

Removing a fragment of an endodontic instrument from the root canal is carried out as follows.

Under infiltration anesthesia, the patient undergoes preparation of the carious cavity, and the remains of the composite filling are removed. In a clinical setting, according to the generally accepted method, the tooth cavity and the mouth of the root canal intended for retreatment are opened. An X-ray examination and computed tomography of the patient's upper or lower jaw are performed, depending on the location of the tooth with a fragment of the endodontic instrument. After studying the obtained X-ray image of the tooth, in direct and axial projections, using an impression mass, an impression of the crown part of the tooth with a fragment of the endodontic instrument and two adjacent teeth is obtained. A model of the dentition is cast from plaster.

A laser scan is performed on a plaster model of the patient's teeth and a digital image of the coronal part of the tooth with a fragment of the endodontic instrument is obtained. Using the 3 dsMAX 2009 computer program, tooth images obtained by computed tomography and laser scanning are combined. A three-dimensional template is virtually modeled on the resulting image of the tooth. The template has a through hole that determines the direction and depth of immersion of the manual endodontic instrument flex file, strictly coinciding with the upper boundary of the fragment of the broken endodontic instrument.

Using the laser stereolithography method, a plastic model of the template is reproduced on an Objet Eden 500 V 3D printer. The plastic template is placed on the coronal part of the causative tooth and two adjacent teeth using an adhesive light polymerization system. An endodontic reciprocal instrument R 25 taper is inserted into the hole of the template until it touches the bottom of the tooth cavity. 0.8 mm, the instrument is gradually advanced towards the border of the upper part of the endodontic instrument fragment. The template is then removed from the mouth. The root canal of the tooth is unfilled and instrumentally processed next to the fragment of the endodontic instrument along its entire length using a Mercury 222 endomotor with a built-in apex locator in the Reciproc mode (reciprocating movements) at a speed of 400 revolutions, TORK 2.0 - rotational force or torque, reciprocal instrument R25 with a taper of 0, 8 mm and R40 with a taper of 0.6 mm.

After passing the root canal and bypassing the instrument fragment, control is carried out with a manual flex file of size 25 and an x-ray. The instrument is gradually advanced towards the border of the lower part of the endodontic instrument fragment. The depth of advance of the tool is limited by the dimensions of the conical hole created in the template used. After removing the template, through the hole created in the tooth root, an endodontic hand instrument is used to find the lumen of the root canal below the border of the fragment. To gain direct access to the middle third of the root canal, the extraction route requires the removal of too much dentin from the coronal portion of the root canal. In this connection, they choose the strategy of extracting the fragment using a bypass technique. The root canal is prepared in such a way that the file enters the prepared space around the fragment.

After removing the individual template, use K-files No. 15, No. 20 and No. 25, alternately plunging them into the gap around the broken tool, continuing lateral movements with immersing the files. The fragment is removed using ultrasonic K-files No. 15, No. 20, No. 25, and abundant irrigation is carried out according to the protocol. The root canal is filled with an injection system of thermoplasticized α-phase gutta-percha (melting point 200°C) and Diadent-Dia-Proseal sealer. The tooth is restored with a composite filling material.

Using the proposed method for extracting a fragment of an endodontic instrument from a root canal, using an individual template, allows you to remove the fragment without damaging the walls of the root canal of the tooth, avoid complications and save the tooth.

The method is effective and widely applicable in dental clinical practice, as well as in the educational process and in the training of specialists.

Execution example

Patient B., 36 years old, complained of a filling falling out of tooth 2.5. The tooth had previously undergone endodontic treatment.

Clinical examination: there is a carious cavity on the chewing surface of the tooth. Percussion of the tooth is painless. Palpation along the transitional fold does not cause discomfort. There are no pathological periodontal pockets. Probing the bottom and walls of the carious cavity does not cause pain. A dental radiograph of tooth 2.5 clearly shows a partially filled root canal and a fragment of an endodontic instrument located in the middle third of its length. In the periapical area of the tooth, an expansion of the periodontal fissure is noted.

Under infiltration anesthesia, the patient is treated with a carious cavity. Remains of the composite filling are removed. In a clinical setting, according to the generally accepted method, the tooth cavity and the mouth of the root canal intended for retreatment are opened. An X-ray examination and computed tomography scan of the patient's upper jaw are performed. After studying the obtained X-ray image of the tooth, in direct and axial projections, an impression of the coronal part of the tooth 2.5 is obtained using an impression mass. and adjacent teeth. A model of the upper dentition is cast from plaster.

To manufacture the device, a laser scan is performed on a plaster model of the patient’s teeth and a digital image of the coronal part of tooth 2.5 with a fragment of an endodontic instrument is obtained. Using the computer program 3 dsMAX 2009, images of tooth 2.5 obtained by computed tomography and laser scanning are combined. Using the resulting image of the tooth, a three-dimensional template is virtually modeled. The template has a through hole that determines the direction and depth of immersion of the manual endodontic instrument flex file, strictly coinciding with the upper boundary of the fragment of the broken endodontic instrument.

Using the laser stereolithography method, a plastic model of the template is reproduced on an Objet Eden 500 V 3D printer. The plastic template is placed on the coronal part of teeth 2.4, 2.5, 2.6 and secured to it using an adhesive light polymerization system. An endodontic instrument is inserted into the hole of the template until it touches the bottom of the tooth cavity. The root canal of the tooth is unfilled and instrumentally processed next to the fragment of the endodontic instrument along its entire length using a Mercury 222 endomotor with a built-in apex locator, in the Reciproc mode (reciprocating movements) at a speed of 400 revolutions, TORK 2.0 - rotational force or torque, with a reciprocal R25 instrument with a taper of 0 .8 mm and R40 with a taper of 0.6 mm.

After passing the root canal and bypassing the instrument fragment, control is carried out with a manual flex file of size 25 and an x-ray. The instrument is gradually advanced towards the border of the lower part of the endodontic instrument fragment. The depth of advance of the tool is limited by the dimensions of the conical hole created in the template used. After removing the template, through the hole created in the tooth root, an endodontic hand instrument is used to find the lumen of the root canal below the border of the fragment. To gain direct access to the middle third of the root canal, the extraction route requires the removal of too much dentin from the coronal portion of the root canal. In this connection, they choose the strategy of extracting the fragment using a bypass technique. The root canal is prepared in such a way that the file enters the prepared space around the fragment.

After removing the individual template, use K-files No. 15, No. 20 and No. 25, alternately plunging them into the gap around the broken tool, continuing lateral movements with immersing the files. The fragment is removed using ultrasonic K-files No. 15, No. 20, No. 25, and abundant irrigation is carried out according to the protocol. The root canal is filled with an injection system of thermoplasticized α-phase gutta-percha (melting point 200°C) and Diadent-Dia-Proseal sealer. The tooth is restored with a composite filling material.

Using the proposed method for extracting a fragment of an endodontic instrument from a root canal using an individual template allows you to remove the fragment without damaging the walls of the root canal of the tooth, avoid complications and save the tooth.

The method is effective and widely applicable in dental clinical practice, as well as in the educational process and in the training of specialists.

Claims (1)

A method for extracting a fragment of an endodontic instrument from the root canal of a tooth, including obtaining an X-ray image of the tooth, performing a computed tomography scan of the upper or lower jaw, extracting a fragment of an endodontic instrument from the root canal, characterized in that an impression of the tooth is taken and a plaster model is made, which is scanned with a laser, obtaining a digital image of the coronal part of the tooth, a combination of tooth images obtained by computed tomography and laser scanning is carried out, as well as virtual modeling of a three-dimensional template using the 3 dsMAX computer program, a plastic template is made, the basis of which is fixed on three teeth, and the template has a guide limiter, the direction of the hole which coincides with the upper part of the fragment of the broken instrument, an endodontic instrument is inserted into the hole of the template until it touches the bottom of the tooth cavity, the template is removed, reciprocal instruments R25 with a taper of 0.8 mm and R40 with a taper of 0.6 mm are inserted and pass through the root canal, performing root preparation canal until the file enters the prepared space around the fragment, then, under the control of a radiograph, using a manual flex file of size 25, the lumen of the root canal is found below the border of the fragment, the fragment is removed using ultrasonic K-files 15, 20, 25 and the root canal is filled with the tooth restored with a composite filling material.

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