Tool for extracting broken endodontic instrument

The tool for extracting broken endodontic instrument has a cylindrical, tubular body. The body has a cap at one end and a conical nose at the opposite end. A gripper tube for gripping a broken endodontic file extends from the conical nose. The body of the tool houses a heating or soldering device equipped with a magazine of balls of solder. The gripper tube has an open tip dimensioned for slidably receiving an end of the broken file and resilient gripper prongs inside the tube allowing insertion of the end of the file but preventing the file from exiting the gripper tube. The heating device may be turned on to melt a ball of solder to solder the gripper prongs to the broken file to further secure the broken file to the gripper tube for extraction of the broken endodontic tube from the root canal.

BACKGROUND

The disclosure of the present patent application relates dental instruments, and particularly to a tool for extracting broken endodontic instrument that may be used, for example, to remove a file broken or separated during a root canal procedure from a patient's dental root.

2. Description of the Related Art

Practitioners in the field of dentistry are sometimes called upon to treat a patient having a cracked or broken tooth. The crack or break may be severe enough that it exposes the pulp inside the tooth to infection and inflammation, and if left untreated, may result in gum disease. In any event, the patient often experiences pain and discomfort, sensitivity when ingesting hot or cold food or beverages, and other symptomatic complaints. Typically, the treatment of choice is a root canal procedure, which is usually performed by an endodontist, followed by installation of a crown or other dental restoration by a dentist to provide some form of permanent protection against future infection or re-inflammation.

In a root canal procedure, an access hole is created in the crown using a drill. The pulp is removed and the canal is cleaned and disinfected down to the roots using tiny files and appropriate cleaning fluids and disinfectants. The canal is filled with gutta percha and a temporary filling may be used to cap the tooth. Afterward, a dentist will install a crown or perform other dental restoration to protect the tooth.

The tiny files used to remove the pulp are made from a nickel-titanium alloy or from stainless steel. Due to the length, width, curvature, and sometimes ledges of dentin form in the canal, some root canals may be very tough to clean. If too much pressure is exerted or if the files or other small instruments are used too many times or for too long a period, the files or other instruments may fracture and separate, leaving a small piece in the canal. In some cases, the separated instrument may be left in the canal or easily removed, but if the broken piece prevents removal of the pulp or obstructs the canal, preventing proper cleaning and disinfection, it may be necessary to resort to some form of tool or instrument to extract or remove the piece of the broken or separated instrument. Thus, a tool for extracting broken endodontic instrument solving the aforementioned problems is desired.

SUMMARY

The tool for extracting broken endodontic instrument has a cylindrical, tubular body. The body has a cap at one end, the cap having a button switch at one end and a conical nose at the opposite end. A gripper tube adapted for gripping a broken endodontic file extends from the conical nose. The body of the tool houses a battery power supply and a heating or soldering device equipped with a magazine of balls of solder. The gripper tube has an open tip dimensioned for slidably receiving an end of the broken file and resilient gripper prongs inside the tube allowing insertion of the end of the file but preventing the file from exiting the gripper tube. The heating device may be turned on to melt a ball of solder, which drains into the gripper tube to solder the gripper prongs to the broken file to further secure the broken file to the gripper tube for extraction of the broken endodontic tube from the root canal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The tool for extracting broken endodontic instrument has a cylindrical, tubular body. The body has a cap at one end, the cap having a button switch at one end and a conical nose at the opposite end. A gripper tube adapted for gripping a broken endodontic file extends from the conical nose. The body of the tool houses a battery power supply and a heating or soldering device equipped with a magazine of balls of solder. The gripper tube has an open tip dimensioned for slidably receiving an end of the broken file and resilient gripper prongs inside the tube allowing insertion of the end of the file but preventing the file from exiting the gripper tube. The heating device may be turned on to melt a ball of solder, which drains into the gripper tube to solder the gripper prongs to the broken file to further secure the broken file to the gripper tube for extraction of the broken endodontic tube from the root canal.

As shown inFIGS.1and2, the tool for extracting broken endodontic instrument, designated generally as20in the drawings, has a cylindrical, tubular body22. The body22has a cap24at one end on the body22that may be threaded onto the open end, or may form a snap fit onto the open end of the body22. As shown inFIG.3, the cap24has an LED indicator26that displays the power status of a battery stored in the body22. For example, the LED indicator26may be a tricolor LED, emitting a green light when the battery is fully charged, a red light when battery voltage is too low to operate the heating or soldering gun, and yellow when the battery is approximately half-charged and needs charging. Alternatively, the LED may be a flashing LED, which may flash green when the soldering gun is not ready to be used and may stay solid green when the heating of soldering gun is ready for use. The cap24may house a pushbutton switch25for turning power to the heating or soldering gun on and off, the LED indicator being embedded in the switch25.

As shown inFIGS.4A and4B, the body22is cylindrical and tubular. The end28of the body22opposite the cap end is internally threaded. As shown inFIGS.2,5A, and5B, the body22houses a battery holder30for holding a battery power supply having at least one rechargeable battery or batteries32of sufficient voltage to power the LED indicator26and the heating or soldering gun. A base end33of the battery holder30has external threads34for engaging the internally threaded end28of the body22. A helical compression spring36is attached to the cap24and selectively engages a terminal end of the battery32through an open end38of the battery holder30when the pushbutton switch25is turned on to close the circuit and apply power to the LED indicator26and the heating or soldering gun. The spring36is retracted away from contact with the battery32when the pushbutton switch25is in the off position, leaving the circuit open.

As shown inFIGS.1and2, the body22includes a cylindrical, tubular grip40. The grip40has an outer surface having a high coefficient of friction, such as axial corrugations, a knurled surface, etc., so that the tool20can be firmly grasped to maneuver the tool20to secure the broken or separated endodontic instrument and extract the instrument from the root canal. The grip40has an open window42defined therein through which a solder magazine for the heating or soldering gun can be manipulated for securing the broken or separated endodontic instrument to tool20for extraction from the root canal. The grip40may be a cylindrical metal tube having a rubber sleeve resiliently disposed over the metal tube.

As shown inFIGS.1,2,6A, and6B, the magazine assembly includes a refill tab44that projects into or through the open window42in the grip40. The refill tab44has a spring retainer lug46extending from one face thereof and a compression spring48attached to the lug46. Normally, the spring48will be extended between the base end33of the battery holder30and the tab44to retain the magazine in the grip40. However, the refill tab44my be pressed towards the battery holder30to compress the spring48and remove the magazine from the grip to refill the solder magazine with solder as needed.

As shown inFIGS.2,7A,7B,8A, and8B, the magazine assembly includes a solder magazine50that is normally carried by a magazine carrier70. The magazine50is a storage container having a removable top plate52, a bottom plate54, and a front face having a finger grip56projecting therefrom. When removed from the grip40, the top plate52is lifted off the body of the magazine50so that the magazine50may be refilled with tiny balls or pellets of solder58. The bottom plate54of the magazine50has a depression60formed therein having an eccentric release aperture62defined therein through which the balls or pellets of solder58may be released under user control one at a time.

As shown inFIGS.8A and8B, the magazine carrier70has a tall, arcuate rear wall72and short, peripheral front and side retainer walls74dimensioned and configured for keeping the magazine50standing upright with the finger grip56projecting through the open window42of the grip40. The carrier70has a bottom wall76having a depression78formed therein, the depression78having a release aperture80defined therein through which the balls or pellets of solder58may be released under user control one at a time. A tube or conduit82aligned with the aperture80extends downward for connection to the heating element of the heating or soldering gun. A pair of vertically or axially aligned compression springs84extend laterally forward from the rear wall72of the magazine carrier70. The laterally extending compression springs84serve to bias the magazine50slightly forward, keeping the release apertures62and80misaligned to prevent the balls or pellets of solder58from dropping down into the heating element. When it is desired to operate the heating or soldering gun, the user can push the finger grip56of the magazine50rearward, moving the magazine rearward against the bias of the laterally extending compression springs84to align the release aperture62of the magazine50with the release aperture80of the magazine carrier70to release a single ball or pellet of solder58at a time to the heating element.

As shown inFIGS.2and9, the tool20has a conical nose90extending from the grip40. The conical nose90includes a conical heating element92coated with or surrounded by a layer of thermal insulation94, which may be, for example, polyvinylidene fluoride. The thermal insulation94may protect the user's fingers and the patient's mouth and tooth from the heat generated in the heating element92when melting the solder. The conical heating element92has a bore96defined therein extending from the base end98through the conical tip end100. A nozzle102extends from the conical tip end100of the bore96for insertion into the open proximal end of a gripper tube. As shown inFIG.8B, a compression spring104is concentrically disposed around the conduit82extending between the magazine carrier70and the heating element92and biases the carrier70away from the heating element92when pressure is released after dropping a ball of solder58into the bore96of the heating element92.

As shown inFIGS.2and11A-11D, the tool20has a disposable gripper tube106removably attached to the conical nose90. A clamp107, shown inFIGS.1,2,10, and13, is slidably disposed at the conical tip end of the conical nose90. The gripper tube106is slidably disposed over the nozzle102. The clamp107is pushed forward to lock the gripper tube106to the nozzle102, and retracted to release the gripper tube106from the conical nose90. The gripper tube106is bent at an acute angle adjacent the end attached to the conical nose90so that the broken endodontic instrument does not extend too far into the gripper tube106and for ease in manipulating the tool20to capture the broken instrument. The gripper tube106may be furnished in several different diameters (at least three) to accommodate endodontic files, reamers, etc. of different diameter. The gripper tube106has two annular rings108just below the acute angle bend, which may be color-coded to provide a quick visual indicator of the size of the gripper tube106. As shown inFIGS.11B,11C, and11D, the open end105of the gripper tube106has at least two vertically spaced rows of gripper prongs110inside the tube106for mechanically gripping the broken or separated endodontic instrument. As with the conical nose90, the gripper tube106may be coated with a layer of thermal insulation109(e.g., polyvinylidene fluoride) to protect the patient's mouth from excessive heat during soldering operations.

As shown most clearly inFIG.12C, an endodontic file or reamer112is a thin, tapered wire having a spiral or helical cutting edge114winding down the working end of the instrument, defining flutes116between adjacent cutting edges114. The gripping prongs110are each thin strips of metal resiliently attached to the interior wall of the gripper tube106and extending inward at an angle of about 45° relative to the interior wall of the gripper tube106. Each row of prongs110includes three prongs equally spaced radially (about 120°) and the prongs110in the two rows are staggered, resulting in at least one prong110every 60° apart around the inner circumference of the open end of the gripper tube106. In use, the open end of the gripper tube106is placed over the top end of the broken or separated endodontic instrument112, as shown inFIG.12A, and pushed down the instrument112. The cutting edge114compresses the prongs110against the interior wall of the gripper tube106as they pass by, the prongs110resiliently expanding into the flute116below he cutting edge114to hook the cutting edge114from below, as seen inFIGS.12B,12C, and12D. When the gripper tube106is pulled in the opposite direction, the prongs110remain hooked beneath the cutting edge114, mechanically gripping the broken instrument112so that the broken file or reamer112may be extracted from the root canal.

In order to further secure the gripper tube's106grip on the separated endodontic instrument112, each prong110and the interior wall of the gripper tube106is pretreated with a thin layer or coating of tin-lead (Sn−Pb) solder. The tin-lead solder has the lowest melting point (183° C. or 361° F.) of the various solder alloys. The solder balls58in the slodering gun magazine50are composed of tin (96.5%), silver (3.0%), and copper (0.5%), have a diameter of about 0.89 mm, and a melting temperature of 217° C. Once the gripper tube106has been inserted over the separated endodontic instrument112far enough to hook the two rows of gripper prongs110below the cutting edge114, the user may push the magazine50against the magazine carrier70far enough to align the release apertures62and80to drop a ball of solder58into the heating element92(seeFIG.13) and turn the heating or soldering gun on using the pushbutton switch25to melt the ball of solder58. The melted solder passes through the nozzle102and drains down to the prongs110, the heat from the melted solder joining the pretreated prongs110to the broken instrument112to solder the two together, reinforcing the mechanical connection between the prongs110and the separated instruments112. The soldering operation may be repeated as needed.

In use, other endodontic instruments may be used, e.g., to apply an ultrasonic tip to the area around the broken endodontic instrument to clean enough pulp or tissue away to expose the broken or separated instrument or to excavate the area enough to expose the broken or separated instrument. The tool20is then manipulated to place the gripper tube106over the separated instrument112, hooking the prongs110under the cutting edge114and securing the attachment by soldering. The broken or separated instrument may then be extracted from the root canal, and the gripper tube106with the endodontic instrument attached thereto may be removed from the tool20and disposed of.