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`US008876991B2
`
`c12) United States Patent
`Luebke
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,876,991 B2
`*Nov. 4, 2014
`
`(72)
`
`(54) DENTAL AND MEDICAL INSTRUMENTS
`COMPRISING TITANIUM
`(71) Applicant: Gold Standard Instruments, LLC,
`Brookfield, WI (US)
`Inventor: Neill Hamilton Luebke, Brookfield, WI
`(US)
`(73) Assignee: Gold Standard Instruments, LLC,
`Brookfield, WI (US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`( *) Notice:
`
`This patent is subject to a terminal dis(cid:173)
`claimer.
`(21) Appl. No.: 14/167,311
`Jan.29,2014
`(22) Filed:
`Prior Publication Data
`(65)
`
`US 2014/0144022 Al
`
`May 29,2014
`
`Related U.S. Application Data
`
`(60) Continuation of application No. 13/455,841, filed on
`Apr. 25, 2012, which is a continuation of application
`No. 13/336,579, filed on Dec. 23, 2011, now Pat. No.
`8,562,341, which is a continuation of application No.
`12/977,625, filed on Dec. 23, 2010, now Pat. No.
`8,083,873, which is a division of application No.
`11/628,933,
`filed
`as
`application
`No.
`PCT/US2005/019947 on Jun. 7, 2005, now Pat. No.
`8,062,033.
`
`(51)
`
`(60) Provisional application No. 60/578,091, filed on Jun.
`8, 2004.
`Int. Cl.
`C22F 1100
`A61C 5102
`(52) U.S. Cl.
`CPC ...................................... A61C 51023 (2013.01)
`USPC .......................................................... 148/563
`
`(2006.01)
`(2006.01)
`
`(58) Field of Classification Search
`CPC ......... C22C 14/00; C22C 19/03; C22F 1/006;
`C22F 1/10; C22F 1/004; C22F 1/00; C22F
`1/183; A61C 5/023; A61C 2201/007
`USPC .................. 148/402, 421, 426; 433/102, 224;
`29/896.1, 896.11
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,490,112 A * 12/1984 Tanaka eta!. ................... 433/20
`5,080,584 A *
`111992 Karabin .......................... 433/20
`(Continued)
`OTHER PUBLICATIONS
`
`International Search Report corresponding to PCT/US2005/0 19947,
`under date of mailing of Nov. 10, 2005.
`
`(Continued)
`
`Primary Examiner- Cris L Rodriguez
`Assistant Examiner- Matthew Nelson
`(74) Attorney, Agent, or Firm- Quarles & Brady LLP
`
`ABSTRACT
`(57)
`Endodontic instruments for use in performing root canal
`therapy on a tooth are disclosed. In one form, the instruments
`include an elongate shank having a cutting edge extending
`from a distal end of the shank along an axial length of the
`shank. The shank comprises a titanium alloy, and the shank is
`prepared by heat-treating the shank at a temperature above
`25° C. in an atmosphere consisting essentially of a gas unre(cid:173)
`active with the shank. In another form, the endodontic instru(cid:173)
`ments have an elongate shank having a cutting edge extending
`from a distal end of the shank along an axial length of the
`shank. The shank consists essentially of a titanium alloy
`selected from alpha-titanium alloys, beta-titanium alloys, and
`alpha-beta-titanium alloys. The instruments solve the prob(cid:173)
`lems encountered when cleaning and enlarging a curved root
`canal.
`
`16 Claims, 7 Drawing Sheets
`
`

`
`US 8,876,991 B2
`Page 2
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`12/1992 Sagaye et al.
`5,171,383 A
`5,380,200 A *
`111995 Heath eta!. ................... 433/102
`5,653,590 A * 8/1997 Heath eta!. ................... 433/102
`5,775,902 A * 7/1998 Matsutani et a!.
`............ 433/102
`1112000 Farzin-Nia eta!.
`6,149,501 A
`6,206,695 B1 * 3/2001 Wong eta!. ................... 433/102
`6,375,458 B1 * 4/2002 Moorleghem et a!. ............ 433/2
`7/2002 Fischer
`6,422,865 B1
`6,428,634 B1 * 8/2002 Besselink et a!.
`148/421
`6,431,863 B1 * 8/2002 Sachdeva et al . ............. 433/102
`6,485,507 B1
`1112002 Walaket a!.
`8/2004 Aloise et al.
`6,783,438 B2
`7,137,815 B2 * 1112006 Matsutani et a!.
`7,175,655 B1
`2/2007 Molaci
`2002/0137008 A1
`9/2002 McSpadden et al.
`2002/0191878 A1 * 12/2002 Ueda eta!.
`384/492
`2004/0121283 A1 * 6/2004 Mason .......................... 433/102
`2004/0129352 A1 * 7/2004 Shiota .
`148/527
`2004/0171333 A1
`9/2004 Aloise et al.
`2004/0193246 A1 * 9/2004 Ferrera
`2005/0090844 A1 * 4/2005 Patel eta!.
`2006/0014480 A1
`112006 Aloise et al.
`
`623/1.15
`606/151
`
`............ 433/102
`
`OTHER PUBLICATIONS
`
`Kuhn eta!., Fatigue and Mechanical Properties of Nickel-Titanium
`Endodontic Instruments, Journal of Endodontics, 2002, 28(10), 716-
`20.
`
`Khier et a!., Bending properties of superelastic and nonsuperelastic
`nickeltitanium orthodontic wires, American Journal of Orthodontics
`and Dentofacial Orthopedics, 1991, 99(4), 310-18.
`Miura et al., The super-elastic property of the Japanese NiTi alloy
`wire for use in orthodontics, American Journal of Orthodontics and
`Dentofacial Orthopedics, 1986, 90(1), 1-10.
`Relevant aspects in the clinical applications ofNiTi shape memory
`alloys, Journal ofMaterials Science: Materials in Medicine, 1996,7,
`403-6.
`F. S. Weine, Endodontic Therapy (6th ed. 2004).
`Brantley et a!., Differential scanning calorimetric studies of nickel
`titanium rotary endodontic instruments, Journal of Endodontics,
`2002, 28, 567-72.
`Schafer et a!., Relationship between design features of endodontic
`instruments and their properties. Part 3. Resistance to bending and
`fracture. Journal of Endodontics, 2001, 27, 299-303.
`Firstov et a!., Surface oxidation of NiTi shape memory alloy,
`Biomaterials, 2002, 23,4863-71.
`Kuhn eta!., Influence of structure on NiTi endodontic instruments
`failure, Journal of Endodontics, 2001, 27(10), 516-20.
`"Declaration of Neill H. Luebke, D.D.S., M.S.", inventor of the
`present application, filed on Aug. 15, 2014 in United States District
`Court for the Eastern District of Tennessee Civil Action No.
`14-00196.
`Tepel eta!., Properties of endodontic hand instruments used in rotary
`motion. Part 3. Resistance to bending and fracture. Journal of
`Endodontics, 1997, 23, 141-5.
`* cited by examiner
`
`

`
`U.S. Patent
`
`Nov. 4, 2014
`
`Sheet 1 of7
`
`US 8,876,991 B2
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`18------
`
`1 2 - - - - ·
`
`10--------
`
`FlG2
`
`c
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`

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`U.S. Patent
`
`Nov. 4, 2014
`
`Sheet 2 of7
`
`US 8,876,991 B2
`
`Fig. 1 a
`
`Fig, 1b
`
`

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`U.S. Patent
`
`Nov. 4, 2014
`
`Sheet 3 of7
`
`US 8,876,991 B2
`
`Figure 3
`250,,-----···--------------------·--····-·--··-····-·------------····-·----·-··----·--------------------·-----·--------~
`= +7%
`
`jMEAN ofTT
`
`[MEAN of Ti-N "' +3%
`
`200
`
`150
`
`100
`
`50
`
`0
`
`sx
`
`S1
`
`S2
`
`F1
`
`F2
`
`F3
`
`!SO size
`
`

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`U.S. Patent
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`Nov. 4, 2014
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`Sheet 4 of7
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`US 8,876,991 B2
`
`Figure 4
`
`1000
`
`900
`
`800
`
`700
`
`600
`
`= 500
`
`""(
`
`400
`
`300
`
`200
`
`100
`
`0
`
`!MEAN ofTT
`
`I MEAN ofTi-N - +0%
`
`"'-1-25%1
`
`+22%
`
`SX
`
`S1
`
`S2
`
`ISO size
`
`F1
`
`F2
`
`F3
`
`

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`U.S. Patent
`
`Nov. 4, 2014
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`Sheet 5 of7
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`US 8,876,991 B2
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`180·r-------------------------------------------------------------~
`
`figure 5
`
`160
`
`140
`
`120
`
`60
`
`40
`
`20
`
`0
`
`!!ill Control
`on
`oTi-N
`
`IMEAN ofTI
`
`= -39%
`!MEAN ofTi-N -- -14%
`
`-33%
`
`1-13% I
`
`-44%
`
`-32%
`
`!-14% 1
`
`-48%
`
`sx
`
`81
`
`S2
`
`ISO size F1
`
`F2
`
`F3
`
`

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`U.S. Patent
`
`Nov. 4, 2014
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`Sheet 6 of7
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`US 8,876,991 B2
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`35~------------------------------------------------------------~
`
`+780%
`
`+"1350%
`
`+12tl0%
`
`+880%
`
`+1010%
`
`+1041%
`
`figure 6
`
`_r_ +560% &
`I
`larger SD
`
`30
`
`25
`
`20-
`
`.
`
`0..
`0
`<1:
`
`15 --
`
`10 -
`
`5-
`
`0
`
`I
`
`I I Til
`
`+ 1050 % = 11 times higher angle
`
`t---
`
`SX
`
`S1
`
`S2
`
`F1
`
`F2
`
`F3
`
`ISO size
`-----------------------------------------------------------------------------
`
`

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`U.S. Patent
`
`Nov. 4, 2014
`
`Sheet 7 of7
`
`US 8,876,991 B2
`
`Figure 7
`
`MEAN ofTT
`
`::: +300% = 4 times higher resistance
`
`+450% &
`larger SD
`
`+250°/o. &
`larger SD
`
`+230% &
`!arger SD
`
`+480% &
`larger SD
`
`-1·160% &
`larger SD
`
`+260% &
`
`S2
`
`ISO size
`
`F1
`
`F2
`
`F3
`
`

`
`US 8,876,991 B2
`
`1
`DENTAL AND MEDICAL INSTRUMENTS
`COMPRISING TITANIUM
`
`CROSS-REFERENCES TO RELATED
`APPLICATIONS
`
`This application is a continuation of U.S. patent applica(cid:173)
`tion Ser. No. 13/455,841 filed Apr. 25, 2012, which is a
`continuation of U.S. patent application Ser. No. 13/336,579
`filed Dec. 23, 2011, now U.S. Pat. No. 8,562,341, which is a
`continuation of U.S. patent application Ser. No. 12/977,625
`filed Dec. 23, 2010, now U.S. Pat. No. 8,083,873, which is a
`divisional application of U.S. patent application Ser. No.
`11/628,933, now U.S. Pat. No. 8,062,033, filed Dec. 7, 2006
`which is a 371 ofPCTIUS05/19947 filed Jun. 7, 2005 which
`claims priority from U.S. Patent Application No. 60/578,091
`filed Jun. 8, 2004.
`
`STATEMENT REGARDING FEDERALLY
`SPONSORED RESEARCH
`
`Not Applicable.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The invention relates to instruments used in medicine and
`dentistry. More particularly, the invention relates to medical
`and dental instruments such as drills, burs and files, and to
`endodontic instruments such as drills, burs and files used by
`dentists.
`2. Description of the Related Art
`Endodontics or root canal therapy is the branch of dentistry
`that deals with diseases of the dental pulp and associated
`tissues. One aspect of endodontics comprises the treatment of
`infected root canals by removal of diseased pulp tissues and
`subsequent filling.
`FIG. 1 shows a representation of a tooth to provide back(cid:173)
`ground. Root canal therapy is generally indicated for teeth
`having sound external structures but having diseased, dead or
`dying pulp tissues. Such teeth will generally possess intact
`enamellO and dentin 12, and will be satisfactorily engaged
`with the bony tissue 20, by among other things, healthy peri(cid:173)
`odontalligaments 18. In such teeth, the pulp tissue 14, and
`excised portions of the root 16, should be replaced by a
`biocompatible substitute. FIG. 1 also shows the apical fora(cid:173)
`men 22 through which blood and nerves pass to support the
`pulp tissues.
`One method for the preparation of a root canal for filling is 50
`represented by FIGS. 2a-2e. A tooth having a basically sound
`outer structure 24 but diseased pulp 26, is cut with conven(cid:173)
`tional or coated dental drill 28 creating a coronal access
`opening 30. A broach is used for gross removal of pulp mate(cid:173)
`rial26 from the root canal through the coronal access opening
`30. The void 32 formed is enlarged as in FIG. 2d with file 34,
`to result in a fully excavated cavity 36. Debris is removed
`from this cavity by flushing and the cavity cleansed to remove
`all diseased tissue. The excavated canal is then ready for
`filling.
`During this procedure, small endodontic instruments (e.g.,
`file 34) are utilized to clean and enlarge the long narrow
`tapered root canals. While most files perform entirely satis(cid:173)
`factorily when cleaning and enlarging a straight root canal,
`problems have been encountered when using certain files to 65
`clean and enlarge a curved root canal. As will be understood
`by those skilled in the art, a very large portion of the root
`
`2
`canals encountered by a practicing dentist and/or endodontist
`are of the curved variety, and thus this problem is a significant
`one for the profession.
`When performing an operation on a curved root canal with
`5 a smaller diameter file, the file can easily be inserted into the
`curved canal and will easily bend to fit the curved shape of the
`canal due to the flexibility of the small diameter file. In FIG.
`la, there is shown the file34 ofFIG. 2dina bent position. The
`file 34 has a shank 42 mounted at its proximate end 47 to a
`10 handle 43. The shank 42 may include calibrated depth mark(cid:173)
`ings 45 and further includes a distal end 48. The shank 42
`includes two continuous helical flutes 51 as shown in FIG. lb
`that extend along its lower portion. The flutes 51 define a
`cutting edge. A helical land 53 is positioned between axially
`15 adjacent flutes as shown in FIG. lb.
`While file 34 can easily bend to fit the curved shape of a
`canal due to the flexibility of the small diameter shank 42,
`with increasingly larger sizes of files, the file becomes sig(cid:173)
`nificantly less flexible and becomes more and more difficult
`20 to insert through the curved portion of the canal. In some
`cases, the relatively inflexible file will cut only on the inside
`of the curve and will not cut on the outside of the curvature of
`the root canal. Thus, the problems, which occur during the
`therapy of a root canal, are often the result of the basic
`25 stiffness of the files, particularly with the respect to the instru(cid:173)
`ments oflarger diameter.
`Various solutions have been proposed to limit the problems
`encountered when cleaning and enlarging a curved root canal
`with a file. For example, U.S. Pat. No. 4,443,193 describes a
`30 shaped endodontic instrument that is said to solve this prob(cid:173)
`lem. U.S. Pat. No. 5,380,200 describes an endodontic instru(cid:173)
`ment having an iuner core and an outer shell wherein one of
`the cores or shell is a nickel-titanium alloy and the other core
`or shell is selected from stainless steel, titanium alpha alloy,
`35 titanium beta alloy, and titanium alpha beta alloy. (For back(cid:173)
`groundon beta-titanium, see U.S. Pat. Nos. 4,197,643; 4,892,
`479; 4,952,236; 5,156,807; 5,232,361; 5,264,055; 5,358,586;
`5,947,723; 6,132,209; and 6,258,182.) U.S. Pat. No. 5,464,
`362 describes an endodontic instrument of a titanium alloy
`40 that is machined under certain specific operating parameters
`to produce an instrument having high flexibility, high resis(cid:173)
`tance to torsion breakage, and sharp cutting edges. U.S. Pat.
`No. 6,315,558 proposes the use of superelastic alloys such as
`nickel-titanium that can withstand several times more strain
`45 than conventional materials without becoming plastically
`deformed. This property is termed shape memory, which
`allows the superelastic alloy to revert back to a straight con(cid:173)
`figuration even after clinical use, testing or fracture (separa-
`tion).
`In spite of the aforementioned advances, there remains a
`need for medical and dental instruments, and particularly
`endodontic instruments, such as drills, burs and files, that
`have high flexibility, have high resistance to torsion breakage,
`maintain shape upon fracture, can withstand increased strain,
`55 and can hold sharp cutting edges.
`
`SUMMARY OF THE INVENTION
`
`The present invention overcomes the problems encoun-
`60 tered when cleaning and enlarging a curved root canal. In one
`aspect, the invention provides an endodontic instrument for
`use in performing root canal therapy on a tooth. The instru(cid:173)
`ment includes an elongate shank having a cutting edge
`extending from a distal end of the shank along an axial length
`of the shank. The shank comprises a titanium alloy, and the
`shank is prepared by heat-treating the shank at a temperature
`above 25° C. in an atmosphere consisting essentially of a gas
`
`

`
`US 8,876,991 B2
`
`4
`DETAILED DESCRIPTION OF THE INVENTION
`
`3
`unreactive with the shank. The shank has high flexibility, high
`resistance to torsion breakage, maintains shape upon fracture,
`can withstand increased strain, and can hold sharp cutting
`edges. Thus, it solves the problems encountered when clean(cid:173)
`ing and enlarging a curved root canal.
`In another aspect, the invention provides an endodontic
`instrument for use in performing root canal therapy on a
`tooth. The instrument has an elongate shank having a cutting
`edge extending from a distal end of the shank along an axial
`length of the shank. The shank consists essentially of a tita(cid:173)
`nium alloy selected from alpha-titanium alloys, beta-titanium
`alloys, and alpha-beta-titanium alloys. The shank avoids the
`use of complex two material systems that are expensive to
`produce and are prone to delamination of the materials. This
`version of the invention also solves the problems encountered
`when cleaning and enlarging a curved root canal.
`These and other features, aspects, and advantages of the
`present invention will become better understood upon con(cid:173)
`sideration of the following detailed description, drawings,
`and appended claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`5
`
`One embodiment of the invention provides an improved
`endodontic instrument for use in performing root canal
`therapy on a tooth. This embodiment of the invention is an
`endodontic instrument as shown in FIG. la that includes an
`elongate shank 42 mounted at its proximate end 4 7 to a handle
`43. The shank 42 may be about 30 millimeters long. The
`proximate end 47 may have a diameter of about 0.5 to about
`10 1.6 millimeters. The shank 42 may include calibrated depth
`markings 45 and further includes a distal end 48. The shank
`42 includes two continuous helical flutes 51 as shown in FIG.
`lb that extend along its lower portion. The flutes 51 define a
`cutting edge. A helical land 53 is positioned between axially
`15 adjacent flutes as shown in FIG. lb.
`The shank 42 comprises a titanium alloy, and is prepared by
`heat-treating the shank at a temperature above 25° C. in an
`atmosphere consisting essentially of a gas unreactive with the
`shank. Preferably, the temperature is from 400° C. up to but
`20 not equal to the melting point of the titanium alloy, and most
`preferably, the temperature is from 475° C. to 525° C. Pref(cid:173)
`erably, the gas is selected from the group consisting of
`helium, neon, argon, krypton, xenon, and radon. Most pref(cid:173)
`erably, the gas is argon. In one example embodiment, the
`25 shank is heat-treated for approximately 1 to 2 hours. In
`another example embodiment, the shank is heat-treated at
`500° C. for 75 minutes. However, other temperatures are
`suitable as they are dependent on the time period selected for
`heat exposure.
`The titanium alloy may be selected from alpha-titanium
`alloys, beta-titanium alloys, alpha-beta-titanium alloys, and
`nickel-titanium alloys. Non-limiting examples of alpha-tita(cid:173)
`nium alloys, beta-titanium alloys, alpha-beta-titanium alloys
`for use in this embodiment of the invention are: Ti-5Al-2.5Sn
`35 alpha alloy; Ti-5Al-2.5Sn-ELI (low 0 2 ) alpha alloy; Ti-3Al-
`2.5V alpha alloy; Ti-5Al-5Zr-5Sn alpha alloy; Ti-6Al-2Cb-
`1 Ta-0.8Mo alpha alloy; Ti-5Al-5 Sn-2Zr-2Mo-0.25Si near
`alpha alloy; Ti-6Al-2Nb-1Ta-1Mo near alpha alloy; Ti-8Al-
`1Mo-1V near alpha alloy; Ti-6Al-2Sn-4Zr-2Mo near alpha
`40 alloy; Ti-6Al-2Sn-1.5Zr-1Mo-0.35Bi-0.1Si near alpha alloy;
`Ti-2.25-AI-11Sn-5Zr-1Mo-0.25i near alpha alloy; Ti-3Al-
`2.5V alpha-beta alloy; Ti-10V-2Fe-3Al alpha-beta alloy;
`Ti-5Al-2Sn-2Zr-4Mo-4Cr alpha-beta alloy; Ti-6Al-2Sn-4Zr-
`6Mo alpha-beta alloy; Ti-4Al-4Mn alpha-beta alloy; Ti-6Al-
`45 2Sn-2Zr-2Mo-2Cr-0.25Si alpha-beta alloy; Ti-4Al-3Mo-1V
`alpha-beta alloy; Ti-6Al-2Sn-4Zr-6Mo alpha-beta alloy;
`Ti-11Sn-5Zr-2Al-1Mo alpha-beta alloy; Ti-6Al-4V alpha(cid:173)
`beta alloy; Ti-6Al-4V-ELI (low 0 2 ) alpha-beta alloy; Ti-6Al-
`6V-2Sn-0.75Cu alpha-beta alloy; Ti-7Al-4Mo alpha-beta
`50 alloy; Ti-6Al-2Sn-4Zr-2Mo alpha-beta alloy; Ti-5Al-1.5Fe-
`1.5Cr-1.5Mo alpha-beta alloy; Ti-8Mn alpha-beta alloy;
`Ti-8Mo-8V-2Fe-3Al beta alloy; Ti-11.5Mo-6Zr-4.5Sn beta
`alloy; Ti-3Al-8V-6Cr-4Mo-4Zr beta alloy; and Ti-3Al-13V-
`11Cr beta alloy (the numbers being percent by weight). An
`55 example, nickel-titanium alloy includes 54-57 weight percent
`nickel and 43-46 weight percent titanium. Preferably, the
`titanium alloy used for the shank includes 54-57 weight per(cid:173)
`cent nickel and 43-46 weight percent titanium and is com(cid:173)
`mercially available as Nitinol 55. Thus, most preferably, the
`60 shank consists essentially of 54-57 weight percent nickel and
`43-46 weight percent titanium thereby avoiding the inclusion
`of elements that affect the superelastic properties of the alloy.
`invention provides an
`Another embodiment of the
`improved endodontic instrument for use in performing root
`65 canal therapy on a tooth. This embodiment of the invention is
`an endodontic instrument as shown in FIG. la that includes an
`elongate shank 42 mounted at its proximate end 4 7 to a handle
`
`FIG. 1 is a cross-sectional view of a tooth.
`FIG. la is a side elevational view of an endodontic instru(cid:173)
`ment.
`FIG. lb is a partial detailed view of the shank of the endo(cid:173)
`dontic instrument shown in FIG. la.
`FIGS. 2a-2e represent a prior art procedure for preparing a 30
`tooth for endodontic restoration.
`FIG. 3 is a graph showing the results of a study of torsion
`(M,) reported in gOcm performed in accordance with "ISO
`Standard 3630-1 Dentistry-Root-canal instruments-Part
`1: General requirements and ANSI/ADA Specification No.
`28, Endodontic files and reamers" for untreated (Control)
`files, heat-treated files (TT), and titanium nitride coated files
`(Ti-N).
`FIG. 4 is a graph showing the results of a study of torsion
`(A,) reported in degrees of deflection performed in accor(cid:173)
`dance with "ISO Standard 3630-1 Dentistry-Root-canal
`instruments-Part 1: General requirements and ANSI/ ADA
`Specification No. 28, Endodontic files and reamers" for
`untreated (Control) files, heat-treated files (TT), and titanium
`nitride coated files (Ti-N).
`FIG. 5 is a graph showing the results of a study of maxi(cid:173)
`mum torque at 45° of flexion (Mf) reported in gOcm per(cid:173)
`formed in accordance with "ISO Standard 3630-1 Den(cid:173)
`tistry-Root-canal
`instruments-Part
`1:
`General
`requirements and ANSI/ADA Specification No. 28, Endo(cid:173)
`dontic files and reamers" for untreated (Control) files, heat(cid:173)
`treated files (TT), and titanium nitride coated files (Ti-N).
`FIG. 6 is a graph showing the results of a study of angle of
`permanent deformation after the flexion test (ADP) reported
`in degrees of deflection performed in accordance with "ISO
`Standard 3630-1 Dentistry-Root-canal instruments-Part
`1: General requirements and ANSI/ADA Specification No.
`28, Endodontic files and reamers" for untreated (Control)
`files, heat-treated files (TT), and titanium nitride coated files
`(Ti-N).
`FIG. 7 is a graph showing the results of a study offatigue
`reported in cycles (revolutions) to failure for untreated (Con(cid:173)
`trol) files, heat-treated files (TT), and titanium nitride coated
`files (Ti-N). This study was performed in accordance with
`the ISO Standard 3630-2 Dental root-canal instruments(cid:173)
`Part 2: Enlargers and ANSI/ADA Specification No. 95, for
`Root canal enlargers".
`
`

`
`US 8,876,991 B2
`
`5
`43. The shank 42 may be about 30 millimeters long. The
`proximate end 47 may have a diameter of about 0.5 to about
`1.6 millimeters. The shank 42 may include calibrated depth
`markings 45 and further includes a distal end 48. The shank
`42 includes two continuous helical flutes 51 as shown in FIG. 5
`lb, which extend along its lower portion. The flutes 51 define
`a cutting edge. A helical land 53 is positioned between axially
`adjacent flutes as shown in FIG. lb. The endodontic instru(cid:173)
`ment is fabricated solely from an alpha-titanium alloy, a beta(cid:173)
`titanium alloy, or an alpha-beta-titanium alloy to avoid the 10
`problems associated with multiple alloy systems.
`Non-limiting examples of alpha-titanium alloys, beta-tita(cid:173)
`nium alloys, alpha-beta-titanium alloys for use in this
`embodiment of the invention are: Ti-5Al-2.5Sn alpha alloy;
`Ti-5Al-2.5Sn-ELI (low 0 2 ) alpha alloy; Ti-3Al-2.5V alpha 15
`alloy; Ti-5Al-5Zr-5Sn alloy; Ti-6Al-2Cb-1Ta-0.8Mo alpha
`alloy; Ti-5Al-5Sn-2Zr-2Mo-0.25Si near alpha alloy; Ti-6Al-
`2Nb-1Ta-1Mo near alpha alloy; Ti-8Al-1Mo-1V near alpha
`alloy; Ti-6Al-2Sn-4Zr-2Mo near alpha alloy; Ti-6Al-2Sn-
`1.5Zr-1Mo-0.35Bi-0.1Si near alpha alloy; Ti-2.25-Al-11Sn- 20
`5Zr-Mo-0.2Si near alpha alloy; Ti-3Al-2.5V alpha-beta
`alloy; Ti-10V-2Fe-3Al alpha-beta alloy; Ti-5Al-2Sn-2Zr-
`4Mo-4Cr alpha-beta alloy; Ti-6Al-2Sn-4Zr-6Mo alpha-beta
`alloy; Ti-4Al-4Mn alpha-beta alloy; Ti-6Al-2Sn-2Zr-2Mo-
`2Cr-0.25Si alpha-beta alloy; Ti-4Al-3Mo-1V alpha-beta 25
`alloy; Ti-6Al-2Sn-4Zr-6Mo alpha-beta alloy; Ti-11Sn-5Zr-
`2Al-1Mo alpha-beta alloy; Ti-6Al-4V alpha-beta alloy;
`Ti-6Al-4V-ELI (low 0 2 ) alpha-beta alloy; Ti-6Al-6V-2Sn-
`0.75Cu alpha-beta alloy; Ti-7Al-4Mo alpha-beta alloy;
`Ti-6Al-2Sn-4Zr-2Mo alpha-beta alloy; Ti-5Al-1.5Fe-1.5Cr- 30
`1.5Mo alpha-beta alloy; Ti-8Mn alpha-beta alloy; Ti-8Mo-
`8V-2Fe-3Al beta alloy; Ti-11.5Mo-6Zr-4.5Sn beta alloy;
`Ti-3Al-8V-6Cr-4Mo-4Zr beta alloy; and Ti-3Al-13V-11Cr
`beta alloy (the numbers being percent by weight). These
`alloys of titanium include phase stabilizing amounts of a 35
`metal selected from molybdenum, tin, bismuth, tantalum,
`vanadium, zirconium, niobium, chromium, cobalt, nickel,
`manganese, iron, aluminum and lanthanum. An endodontic
`instrument according to this embodiment of the invention has
`improved sharpness, cutting ability, and instrument longevity 40
`compared to instruments fabricated from untreated nickel(cid:173)
`titanium. Alpha-titanium, beta-titanium and alpha-beta-tita(cid:173)
`nium are superior because they are harder and hence will hold
`an edge better and still maintain near the flexibility of nickel(cid:173)
`titanium to negotiate curved canals. These alpha-titanium, 45
`beta-titanium and alpha-beta-titanium instruments may
`include medical, dental and endodontic instruments (both
`hand and engine driven), cutting burs (drills), and enlarging
`instruments including hand, mechanical and rotary.
`Present medical and dental practice entails cutting of hard 50
`tissues such as bone or teeth with instruments manufactured
`of carbide steel, stainless steel and nickel-titanium. Present
`endodontic practice entails the preparation, cleaning, and
`shaping of root canals in teeth utilizing carbide steel, stainless
`steel and nickel-titanium instruments for hand, mechanical 55
`and rotary applications. This version of the invention would
`use an alpha-titanium alloy, a beta-titanium alloy, or an alpha(cid:173)
`beta-titanium alloy to fabricate these instruments. It may be
`coated (as described below) or uncoated. Today a growing
`number of physicians and dentists ( endodontists) are utilizing 60
`engine driven drills and files with various names and appli(cid:173)
`cations. This aspect of the present invention pertains to the
`fabrication of these cutting instruments such as drills and files
`solely from an alpha-titanium alloy, a beta-titanium alloy, or
`an alpha-beta-titanium alloy to produce a sharper cutting 65
`edge that should provide for better cutting or a smooth fin(cid:173)
`ished surface. This includes instrumentation that will facili-
`
`6
`tate the cleaning and sealing of the root canal system. In
`addition, a coating or heat-treatment may relieve stress in the
`instrument to allow it to withstand more torque, rotate
`through a larger angle of deflection, change the handling
`properties, or visually exhibit a near failure of the instrument.
`This aspect of the invention relates to all drills, burs, files, and
`instruments used in medicine and dentistry.
`In another aspect, the present invention provides for coat(cid:173)
`ing and optionally thereafter heat-treating dental and medical
`instruments including the coatings to maintain and/or
`improve their sharpness, cutting ability, and/or instrument
`longevity. Such an instrument may be manufactured from
`nickel-titanium, an alpha-titanium alloy, a beta-titanium
`alloy, or an alpha-beta-titanium alloy, stainless steel, carbide
`steel, as well as other materials. These instruments may be
`electropolished before or after coating or heat-treating. These
`instruments will include medical, dental and endodontic
`instruments (both hand and engine driven), cutting burs
`(drills), and enlarging instruments including hand, mechani(cid:173)
`cal and rotary.
`The coating processes may include but not limited to the
`following processes: composite electro less plating (see, e.g.,
`U.S. Pat. Nos. 4,820,547; 4,997,686; 5,145,517; 5,300,330;
`5,863,616; and 6,306,466); chemical vapor deposition (see,
`e.g., U.S. Pat. No. 4,814,294); microwave deposition (see,
`e.g., U.S. Pat. No. 4,859,493); laser ablation process (see,
`e.g., U.S. Pat. No. 5,299,937); ion beam assisted deposition
`(see, e.g., U.S. Pat. No. 5,725,573); physical vapor deposition
`(see, e.g., U.S. Pat. Nos. 4,670,024, 4,776,863, 4,984,940,
`and 5,545,490); electropolishing; coatings including titanium
`nitride and titanium aluminum nitride commercially avail(cid:173)
`able under the trademark Firex™; coatings such as titanium
`nitride (TiN), titanium carbonitride (TiCN), titanium alumi(cid:173)
`num nitride (TiAlN), aluminum titanium nitride (AITiN); or
`multiple coatings or combinations of coatings.
`As detailed above, present medical and dental practice
`entails cutting of hard tissues such as bone or teeth with
`instruments manufactured of carbide steel, stainless steel and
`nickel-titanium. Present endodontic practice entails the
`preparation, cleaning, and shaping of root canals in teeth
`utilizing carbide steel, stainless steel and nickel-titanium.
`These can be manufactured as hand, mechanical and rotary
`instruments. Today a growing number of physicians and den(cid:173)
`tists ( endodontists) are utilizing engine driven drills and files
`with various names and applications. This aspect of the
`present invention pertains to the application of coatings and
`optionally heat-treatment to cutting instruments such as drills
`and files to produce a sharper cutting edge and a higher
`resistance to heat degradation that should provide for better
`cutting, a smooth surface and/or different metallurgical prop(cid:173)
`erties than the material from which it was manufactured. This
`includes instrumentation that will facilitate the cleaning and
`sealing of the root canal system. In addition, a heat-treatment
`separately applied or as utilized in the coating process may
`relieve stress in the instrument which should allow for more
`instrument longevity by the ability to withstand more torque,
`rotate through a larger angle of deflection, change the han(cid:173)
`dling properties, remove shape memory or visually exhibit a
`near failure of the instrument. This aspect of the invention
`relates to all drills, burs, files, and instruments used in medi(cid:173)
`cine and dentistry.
`One example process of this aspect of the present invention
`for such instruments is a titanium nitride coating. This coating
`process is done with physical vapor deposition with an inher(cid:173)
`ent heat-treatment. Another process is a multilayer process
`utilizing a titanium nitride coating and then a titanium alumi-
`
`

`
`US 8,876,991 B2
`
`8
`ment. These are labeled "Ti-N" in FIG. 4. A, was determined
`for each of the thirty files, and the mean and standard devia(cid:173)
`tion for each group (Control, TT, Ti-N) of ten files were
`calculated. The ten files that were heat-treated in a furnace in
`an argon atmosphere at 500° C. for 75 minutes showed the
`best results with the highest A,.
`
`Example 3
`
`7
`num nitride coating. This last coating process is commer(cid:173)
`cially available under the trademark FIREX™.
`Another example process of this aspect of the present
`invention for such instruments is a metal or metal alloy coat(cid:173)
`ing incorporating particulate matter. One process to produce 5
`such a coating to an instrument includes contacting the sur(cid:173)
`face of the instrument with a stable electro less metallizing
`bath comprising a metal salt, an electro less reducing agent, a
`complexing agent, an electroless plating stabilizer, a quantity
`of particulate matter which is essentially insoluble or spar- 10
`ingly soluble in the metallizing bath, and a particulate matter
`stabilizer, and maintaining the particulate matter in suspen(cid:173)
`sion in the metallizing bath during the metallizing of the
`instrument for a time sufficient to produce a metallic coating
`with the particulate matter dispersed.
`
`The following Examples have been presented in order to
`further illustrate the invention and are not intended to limit the 20
`invention in any way.
`
`EXAMPLES
`
`Example 1
`
`Thirty ISO size SX files, thirty ISO size S1 files, thirty ISO
`size S2 files, thirty ISO size F 1 files, thirty ISO size F2 files
`and thirty ISO size F3 files were used in a study of maximum
`torque at 45° of flexion (Mf) reported in g·cm performed in
`accordance with "ISO Standard 3630-1 Dentistry-Root-ca(cid:173)
`nal instruments-Part 1 : General requirements and ANSI!
`15 ADA Specification No. 28, Endodontic files and reamers".
`The shank is held in a torque meter, flexed at an angle of 45°,
`and then torque is measured. The results are shown in FIG. 5.
`The files were made from a titanium alloy comprising 54-57
`weight percent nickel and 43-46 w