Dentistry – Apparatus – Having gauge or guide
Reexamination Certificate
2001-02-08
2002-03-19
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Apparatus
Having gauge or guide
C433S102000, C033S513000, C033S626000
Reexamination Certificate
active
06358049
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to geometric dental tools and more particularly to an instrument serving as a jig to adjust exposed lengths of endodontic tools such as files with respect to encircling stops placed along the length of a file to prevent over-penetration into a root canal of a patient.
2. Description of the Prior Art
When the nerve of a tooth dies or other injury occurs to pulp tissue of a tooth, potentially necrotic and infected tissue must be removed. The canal containing pulp tissue is enlarged and sterilized, and then filled with an inert material. Removal of pulp tissue and enlargement of the canal are performed by drilling a hole through the top of the tooth, then reaming out the canal of each root of the tooth. Reaming of each canal is performed usually in several progressive steps each corresponding to file diameter or file length or both. Each step in file length typically requires a series of endodontic files of progressively greater diameter than the prior file used. For example, a single root canal procedure may require four files of varying diameter for the widest enlargement of a canal nearest the tooth crown, and progressively fewer sets of files as work approaches the apex or tip of the root. The progression culminates in a single file utilized at the apex of the root.
The procedure requires establishment of a fixed point of reference, called the datum point, on the tooth itself. Each canal to be treated requires a datum point that is within the diameter of the stop which encircles each file. The distance from the datum point to the tip end, or apex of the root, is established. This is referred to as the “radiographic tolength”. From this information, the dimensions of progressive file lengths are determined according to the particular surgical technique chosen by the clinical practitioner. Because of the number of files of differing diameter and lengths required, it is not uncommon for a treatment of a single root to include more than sixty file length settings. This number is simply repeated for each canal in a multi-root tooth.
The several sets of endodontic files for each succeeding increment of file length are prepared with great precision to correspond to the length of each section of each root canal. Lengths are determined by radiological images obtained by X-rays. Generally torroidal or disc-like resilient stops are placed over each endodontic file which will be utilized in the procedure. These stops limit maximal penetration of the file into the canal. Precision of placement of a stop on its associated file is of great importance in limiting the exposed portion of the files. The precision required and the large number of settings present a significant risk of error, and multiply time required to perform the procedure. Accordingly, the prior art has proposed gauges for enabling precise placement of a stop on its associated file.
U.S. Pat. No. 4,182,040 issued to Edmund C. Bechtold, Jr. on Jan. 8, 1980, is representative of cylindrical file length gauges. By contrast, the present invention avoids cylindrical configuration.
U.S. Pat. No. 4,028,810, issued to Bobby C. Vice on Jun. 14, 1977, shows a flat or planar file length gauge. The design of Vice lacks a plurality of slidably adjustable positioning members held in a plurality of tracks, as seen in the present invention.
U.S. Pat. No. 3,964,170, issued to Eduard Zdarsky on Jun. 22, 1976, describes a flat file gauge. However, there are no slidably adjustable positioning members in the device of Zdarsky, as there are in the present invention.
U.S. Pat. No. 4,557,690, issued to Jean-Claude Randin on Dec. 10, 1985, and U.S. Pat. No. 5,827,060, issued to Constantin Zdarsky on Oct. 27, 1998, both illustrate devices for handling the torroidal or disc-like stops for endodontic files. Neither of these two patents has slidably adjustable positioning members, as seen in the present invention.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
The present invention provides a convenient instrument for adjusting operational lengths of endodontic files with respect to respective encircling stops preventing overpenetration into a root canal of a patient. The novel instrument or gauge is able to set all necessary operational lengths for all files required for performing root canal procedures on up to four root canals at once. The relatively spread out configuration of the novel gauge provides a number of benefits. One is that when all operational length settings are made to the novel tool prior to performing an endodontic procedure, a dental practitioner can more readily determine and remember the stage to which the procedure has progressed at any point in time.
A second benefit is that a selected endodontic file can be readily inserted into its appropriate place within the novel gauge, set to the proper operational length, and subsequently removed for use. The practitioner is not unduly burdened by having to manipulate the file to adjust it to constantly changing operational length settings, as is required in many prior art devices. Still another benefit is that the present invention is more effectively sterilized in autoclaves, compared to cylindrical devices, due to its spread out planar configuration.
The novel gauge comprises a flat base provided with an anvil or retaining barrier, and four tracks for receiving slidable members, hereinafter called slides, which can be positioned within the base to adjust operational lengths of endodontic files. The retaining barrier serves as a measuring point at which stops are positioned on files being adjusted for operational length. Each slide is configured to present the number and altitude of steps dictated by the particular technique chosen for the procedure, thereby being able to adjust length of all files for one root canal with one manual an adjustment.
The four tracks enable the device to set up all file lengths required for up to four root canals, which corresponds to the maximum number of roots of the overwhelming majority of teeth. Thus one length setting per track can be utilized to prepare all needed endodontic files for any one tooth having up to four roots, and to display the settings in a readily accessible, organized manner. The settings thus displayed visually presents the logical order of each step in file lengths for each root to be treated. The invention anticipates a separate set of slides for each of the known and generally practiced techniques for performing root canal procedures, and additional techniques which may be developed in the future.
Each slide is secured in a selected position relative to the base by a thumbscrew. In one embodiment, the thumbscrew serves as a handle for maneuvering the slide along its track. In a preferred embodiment, the thumbscrew has a combination of compressible O-ring, spacer ring, and washer that selectively establishes two levels of frictional engagement of the slide as the thumbscrew is progressively tightened. The first level of friction prevents unintended, spontaneous dislodging of the slide during a final tightening sequence, but enables the slide to be moved by manual force prior to final tightening. The second level of friction locks the slide in a selected operational position on the base so that not even manual force can dislodge it. The slides are therefore secured within the base in two discrete increments of mobility.
Measurement indicia may be optionally provided for adjusting slides to precise positions on the base relative to the retaining barrier. As an alternative to the measurement indicia, or in addition thereto, an upwardly projecting flange is provided on each slide. The flange facilitates use of an endodontic ruler in measuring the distance from the retaining barrier to a predetermined point on the slide, thereby establishing the radiographic length to which the slide is to be adjusted. Thus two forms of measurement of tools
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