United States Patent [191
`Sema et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,850,867
`Jul. 25, 1989
`
`[54] ENDODONTIC INSTRUMENT
`Inventors: E. Steve Senia; William L Wildey,
`[75]
`both of San Antonio, Tex.
`[73] Assignee: Board of Regents, The University of
`Texas System, Austin, Tex.
`[21] Appl. No.: 152,464
`Feb. 5, 1988
`[22) Filed:
`Int. C1. 4 ................................................ .A61C 5/02 ·
`[51]
`[52] u.s. Cl. .................................................... 433/102
`[58] Field of Search ....................... : ................. 433/102
`[56]
`References Cited
`U.S. PATENT DOCUMENTS
`D. 283,840 5/1986 Matsutani .
`636,359 11/1899 · Schultz ................................ 433/102
`4,299,571 11/1981 McSpadden ........................ 433/102
`4,443,193 4/1984 Roane ................................. 433/102
`. 4,536,159 8/1985 Roane ................................. 433/224
`
`FOREIGN PATENT DOCUMENTS
`631469 5/1936 Fed. Rep. of Germany ...... 433/102
`2524105 4/1976 · Fed. Rep. of Gennany ...... 433/102
`
`OTHER PUBLICATIONS
`ISO Standard 3630/2, First edition-1986-05-01.
`ANSI/ADA Specification No. 28-1981, approved Oct.
`9, 1981.
`Mani Apical Reamer.
`Caulk Gates-Glidden drills.
`Caulk Dynatrak.
`Hygenic Endodontic Cutting Instruments.
`flex-R.
`Photograph of unknown endodontic instrument.
`Brochure for the Mani Apical Reamer.
`Pathways of the Pulp, pp. 340-242 (1980).
`The American Textbook of Operative Dentistry, pp. ·
`452-463 (1900).
`Journal of Endodontics 12:293""300 (1986), Powell et al.
`
`the American Dental Association
`Journal. of
`113:(596-597) 1986, Roane eta!.
`The Dentists Desk Reference, pp. 248-262 (1981).
`Journal of the American Dental Association 58:85-92
`(1959), Luks.
`Clinical Endodontics, pp. 301-318 (1956).
`The Dental Cosmos 54:56 (1912).
`The Dental Cosmos 64:113-1148 (1922).
`Oral Surgery 14:83-91 (1961), Ingle.
`Journal of Endodontics 11:435-441 (1985), Miserendino
`et al.
`·Journal of Endodontics 11:212-217 (1985), Anderson et
`al.
`Journal of Endodontics 11:110-116 (1985), Boger eta!.
`Journal of Endodontics 8:253-259 (1982), Felt eta!.
`Journal of.Endodontics 8:260-264 (1982), Dolan et al.
`Oral Surgery 50:566-568 (1980), Martinet al.
`Oral Surgery 8:1211-1213 (1955), Ingle.
`British Dental Journal 137:239-244 (1974), Harty et at.
`The Dental Cosmos 65:1072-1091 (1923), Kells ..
`ISO Standard 3630, First edition~1984-02-15.
`Jun. 1988, Dental Products Report.
`Johnson paper, p. 185.
`Primary Examiner-Robert Peshock
`Attorney, Age1ft, or Firm-Arnold, White & Durkee
`[51]
`ABSTRAcr
`An endodontic instrument in accordance with the pres(cid:173)
`ent invention includes a substantially non-cutting pilot
`segment, a relatively short cutting segment, and a flexi(cid:173)
`ble shaft segment, which can have a handle at its distal
`end for manual manipulation, or an adapter for attach(cid:173)
`ment to a mechanical handpiece. The non-cutting pilot,
`the short length of the cutting segment, and the flexibil(cid:173)
`ity of the shaft combine to allow the instrument to be
`used in curved root canals without ca'using undue
`change in the natural· root canal contours.
`
`13 Claims, 3 Drawing Sheets
`
`16
`/
`
`.24
`
`12
`
`I
`
`10
`
`18
`
`GOLD STANDARD EXHffiiT 2005
`US ENDODONTICS v. GOLD STANDARD
`CASE IPR2015-01476
`
`

`
`U.S. Patent
`
`Jul. 2s, 1989
`
`Sheet 1 of3
`
`4,850,867
`
`FI•1-IA
`(PRIOR ART)
`
`Fl•1•ll3
`(PRIOR ART)
`
`1
`
`Fl•l-21\
`(PRIOR ART)
`
`FI.,.#C
`(PRIOR ARTl
`
`

`
`U.S. Patent
`
`Jul. 25, 1989
`
`Sheet 2 of3
`
`4,850,867
`
`FI•1-2EJ
`(PRIOR ART)
`
`A
`
`F;.,.2C
`(PRIOR ART)
`
`FI•,.2E
`(PRIOR ART)
`
`F.I•1-21J
`(PRIOR ART)
`
`16
`
`12 24
`
`I
`
`18
`
`22
`
`18
`
`10
`
`

`
`4,850,867
`
`3
`and therefore cause much less unintended cutting of
`dentin and change of the natural curvature.
`A variation of the present invention comprises a cut(cid:173)
`ting segment whose length is no greater than about 14
`mm; and a shaft whose proximal end is attached to the
`distal end of the cutting segment. This particular varia(cid:173)
`tion is suited for cleaning the apical 0.75 mm of the root
`canal of a human tooth, i.e., the most apical part of the
`root canal not cleaned by the non-cutting pilot of the
`previous embodiments.
`
`10
`
`25
`
`4
`An endodontic instrument in accordance with the
`present invention can include three principle parts: a
`substantially non-cutting pilot tip segment, a cutting
`segment, and a flexible shaft segment. The pilot segment
`5 can be either totally non-cutting, with a smooth surface,
`or it can have some minimal cutting or abrasive surface
`to give it a very minor cutting effect. The term "sub(cid:173)
`stantially non-cutting" is intended to cover both of
`these possibilities.
`In FIG. 3, the non-cutting pilot segment 10 is a
`smooth tapered cylinder located at the proximal end of
`the instrument 12. The distal end of the pilot segment 10
`is attached to the proximal end of the cutting segment
`14. The distal end of the cutting segment 14 is attached
`to the shaft segment 16. The shaft segment 16 will nor(cid:173)
`mally have a circular cross section.
`The substantially non-cutting pilot segment 10 is pref-
`erably a smooth tapered cylinder with a blunt or
`rounded (bullet shaped) proximal end. However, it
`would also be possible to use a pilot segment which has
`some raised edges or other projections on its surface, as
`long as they do not cause the pilot segment to have a
`substantial cutting effect. A goal of the pilot segment 10
`is to serve as a guide for the cutting segment 14, not to
`perform a significant amount of cutting itself.
`The cutting segment 14 depicted in FIG. 3 includes a
`plurality of spiral cutting edges 18, similar to the cutting
`portion of a K-type file. This embodiment of the cutting
`30 segment can have any number of configuration of cut(cid:173)
`ting edges, preferably from 1-12 such edges. The cut(cid:173)
`ting segment 14 could also be flattened, rather than
`cylindrical. In a flattened cutting segment, the two
`outer edges and the front edges would normally do the
`cutting. The cross section of such a cutting segment
`would be a relatively thin rectangle. The tightness of
`the spiral can also be increased, or decreased, even to
`the point of having no spiral. The cutting segment 14
`could also be flattened, rather than cylindrical. In a
`flattened cutting segment, the two outer edges and the
`front edges would normally do the cutting. The cross
`section of such a flattened cutting segment would be a
`relatively thin rectangle. The cutting segment 14 could
`alternatively employ any cutting apparatus known to
`those skilled in this field, such as a K-flex cutting config(cid:173)
`uration, an H-type cutting configuration, a diamond
`cutting surface, or other cutting or abrasive materials.
`The dimensions of the instrument are very important
`in achieving the desired results. The diameter of the
`pilot segment at its widest point is preferably about 0.17
`mm but can range between about 0.009 and 1.0 mm. The
`diameter of the cutting segment at its widest point is
`preferably between about 0.01 and 2.0 mm, most prefer(cid:173)
`ably between about 0.20 and 1.4 mm. The diameter of
`the shaft segment should preferably be less than the
`diameter of the cutting segment at the latter's widest
`point, in order to increase flexibility and provide space
`for pulp and dentin debris to be removed from the ca(cid:173)
`nal. However, the diameter of the shaft segment could
`be equal to or greater than the diameter of the cutting
`segment. The shaft diameter will usually be between
`about 0.2 and 0.8 mm.
`The pilot segment is preferably between about 0.01
`and 14 mm long, most preferably between about 0.75
`and 3 mm. The cutting segment is preferably between
`about 0.5 and 14 mm long, most preferably between
`about 0.5 and 4.0 mm long. The shaft is preferably be(cid:173)
`tween about 10 and 28 mm long.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 shows the use of a prior art endodontic instru(cid:173)
`ment and an inherent problem in its use.
`FIG. 2 shows four different problems caused by prior 15
`art instruments.
`FIG. 3 shows an endodontic instrument in accor(cid:173)
`dance with the present invention.
`FIG. 4 shows an endodontic instrument in accor(cid:173)
`dance with the present invention with a handle 20
`mounted on its distal end.
`FIG. 5 shows an end view of an instrument such as
`that shown in FIG. 4, with the instrument's proximal
`end being frontmost.
`FIG. 6 shows an endodontic instrument in accor(cid:173)
`dance with the present invention which does not have
`at its proximal end a non-cutting pilot segment.
`
`DETAILED DESCRIPTION OF A SPECIFIC
`EMBODIMENT
`FIG. 1 shows how a prior art endodontic instrument
`is inserted into the root canal of a tooth. In FIG. 1A, the
`instrument has a small enough diameter so that it is
`sufficiently flexible to bend around the curvature of the 35
`root canal. FIG. 1B illustrates the forces at work when
`the instrument is at rest in a curved root canal. Under
`basic lever and fulcrum principles, the inherent rigidity
`of the instrument causes a force 1 to be exterted on the
`root canal wall in its middle. A corresponding forcre 2 40
`is exerted on the opposite root canal wall near the apex
`of the canal. When the instrument is withdrawn, as
`shown in FIG. 1C, these forces are effectively increased
`and applied in a way that causes undesired cutting of the
`root canal walls. The force 3 acting near the middle of 45
`the root canal causes greatly enhanced cutting at that
`point during withdrawal. Even worse, the lever arm
`length below this fulcrum point is being decreased as
`the instrument is withdrawn, thereby increasing the
`force acting at the lower end. This increased force 4 so
`digs away dentin at the apical end of the root canal, as
`can be seen in FIG. 1C.
`FIG. 2 shows several problems that result from prior
`art instruments. FIG. 2A shows a typical curved root
`canal. FIG. 2B shows that instruments which have 55
`insufficient flexibility in relation to the diameter of their
`cutting segment, as mahy prior art instruments do, tend
`to form a ledge. Once such a ledge is formed, it is very
`difficult to advance an instrument beyond it. In FIG.
`2C, the phenomenon shown in FIG. 1 has caused trans- 60
`portation of the apical foramen. This tends to make the
`filling that will be inserted into the tooth spill out into
`the surrounding tissue, which is very undesirable. In
`FIG. 4D, a similar effect known as zipping has oc(cid:173)
`curred. In FIG. 4E the zipping is so pronounced that 65
`the side of the root has actually been perforated, which
`again will cause filling to spill out into the surrounding
`tissue.