ENDODONTIC
`
`THERAPY
`
`FRANKLIN S. WEINE, BS, DDS, MSD, FACD, FlCD
`
`Professor Emeritus, Loyola University (Chicago);
`Formerly Professor and Director, Post—Graduate Endodontics.
`Loyola University School of Dentistry,
`Maywood, Illinuis;
`Visiting Professor of Endudontica, Osaka Dental University,
`Osaka. Japan
`
`SIXTH EDITION
`
`Selected artwork by: Saintly Cello Lang and Don O’Connor
`Photography by: Oscar Izquicrdci and Al Hayashi
`
`
`
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`NA Mosley
`An Affiliate of Elsevier
`
`11330 Westline Industrial Dich
`St. Louis Missouri [53146:
`
`ENDODONTIC THERAPY
`Copyright '39 2004. Mosby. Inc. All rights reserved.
`
`lSBN 0-3 23-01943-9
`
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`NOTICE
`
`The Publisher
`
`Dentistry is an ever-changing i'ieltl. Standard safety precautions must be. followed. 11th as new research and
`clinical experience broaden our knowledge, changes in treatment and drug therapy may become
`necessary or appropriate. Readers are advised to check the most current product Information ptuvicled by
`the manufacturer of each drug to be administered to verify the recommended dose, the method and
`duration of administration. and contraindications. It is the responsibility of the licensed presttriber.
`relying on experience and knowledge of the patient. to determine dosages and the best treatment for each
`individual patient. Neither the publisher nor the author assumes any liability for any injury and/or
`damage to persons or property arising from this publication
`
`Previous editions copyrighted 1996, 1989, 1982, IQTG, 1972
`
`Library of Congress Cataloging-in-I‘tthlicatinn Data
`Weine. Franklin 5.
`Endodontic therapy/Franklin S. Weii-te.—£)tii ed.
`p. ; cm.
`Includes bibliographical references and index.
`ISBN 0—323—01943-9
`1. Entioclonttcs. I. Title.
`I'DNL'M: l. Endotiontics. WU 230 W423e2004l
`RK351.W-i+ 1004-
`617.6'34l—dc22
`
`2003059134
`
`Publishing Director: Linda 1.. Batman
`Exerutive Editor: Penny Rudolph
`Senior Developmental Editor: Kimberly Alvis
`
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`CONTRIBUTORS
`
`
`
`JAMES K. BAHCALL. DMD, M5
`Assistant Professor and Chairman
`
`Department of Surgical Sciences
`Marquette University
`Milwaukee. WI
`
`MANUEL A. BUSTAMANTE, DDS
`Private Practice, Endoclontics
`Los Angeles, CA
`
`JAMES A. DEWBERRY,JI'. DDS, FACD
`Private Practice Limited to Endodontics
`Dallas, TX
`
`SERGIO KUTTLER, DDS, FICD
`Associate Professor and Chairman
`
`Department of Encloclontics;
`Associate Director. Postgraduate Endodontics:
`Director, Advanced Education Programs
`Nova Southeastern University
`College of Dental Medicine
`Fort Lauderdale. FL
`
`CHARLES Q. LEE, DDS, MS
`Associate Professor
`
`Department of Endodontics
`University of Missouri
`School of Dentistryr
`Kansas City, MO
`
`ARTURO VENTURA MORALES. DDS, MS
`Professor
`
`Department of Endodontics
`National University Autonomous of Mexico, Dentistry School
`Mexico City, Mexico
`
`JEROME V. PISAND. DDS, MS. FACD, FICD
`Formerly Clinical Associate Proffisor
`Department of Endodontics
`Loyola University School of Dentistry
`Maywoocl, lL
`
`STEVEN R. POTASHNICK. DDS, FACD
`Private Practice, Prothodontics
`Chicago, IL
`
`jAMES B. SATOVSK'V, DDS
`Private Practice. Endodonties
`
`Hollywood, FL
`
`SHER‘WIN S‘l‘l-‘tALISS. DDS
`Private Practice, Dentistry
`Chicago. IL
`
`CHRISTOPHER 5. WENCKUS, DDS, FICD
`Associate Professor and Head
`
`Department of Endodontics
`University of Illinois at Chicago
`College of Dentistry
`Chicago. Il.
`
`jEFFREY L. WINGS, RPh, DDS
`Private Practice, Periodontics
`Memphis, TN
`
`mascara
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`PREFACE
`
`During the ten years since the publication of my fifth
`edition, endodontic treatment has taken an abrupt
`change. This alteration was alluded to in its incipiency in
`that book with the introduction of nickel
`titanium files
`
`and mechanical handpieces driving rotating instruments.
`In truth, the previous five editions had railed specifically
`against the potential danger attendant to the use of the
`latter technique. As the current edition was being written,
`endodontic treatment clearly became a technologically
`driven procedure.
`Canals are being measured by electronic apex locators,
`preparation is performed by mechanical. means. and many
`canals are filled using heating units to soften the sealing
`materials. All of these methods are not only presented in
`this book, but actually, they are featured. However, it is
`important
`to realize that when technology is not com-
`pletel'},r understood, it can be dangerous- Even the most
`positive studies indicate that apex locators are accurate
`just over 90 percent. of the time. In preparing curved
`canals, mechanically driven instruments may become sus—
`ceptible to breakage. Depending upon the preparation
`method used, softened gutta—pcrcha may be forced into
`the periapical tissues. Discussion of how to avoid these
`pitfalls is also emphasized.
`Although I use many of the new products in my clinical
`practice, my own method of treatment has not changed a
`great deal since the publication ofmy first edition in 1972.
`i do use all of these newer techniques, but not exclusively,
`and usually to supplement my traditional forms of therapy.
`As 1 read the current endodontic literature and listen to
`
`lecrures, 1 notice these new procedures are endorsed in a
`manner that almost negates the efficacy of the treatment
`modalities of the past. Interestingly, many of the com;
`pletion radiographs demonstrating current trends are not
`followed by a realistic period of postoperative evaluations.
`For this reason,
`i have endeavored to get as many long—
`term foIIDW—up films of my previously published cases as
`was possible, accepting the fact that many of the patients
`shoWn in earlier editions were middle-aged or older at the
`time of treatment. Patients who responded to my request
`Were able to return or have their own dentist send me the
`
`desired radiographs and evaluations. providing the
`evidence that
`the tried and true classical methods of
`
`in this edition. we have
`therapy were very effective.
`included almost 70 cases illustrating long—term success of
`l? to 35 years. One example of a long-term follow—up is
`demonstrated on the cover of the book.*
`
`Being cognizant of the interest maintained by general
`dentists in clinical treatment, several other changes were
`made for this edition. Chapters 3 and 4 of the previous
`editions on the biology of pulpal and periapical tissues. so
`well written by Marshall Smulson and aided by Steve
`Sieraski, Sue Ellenz, and others, have been removed. Some
`of this material is still present in the clinically oriented
`chapters. However, the major thrust of this edition is to
`present clear and accurate information on clinical
`treatment procedures.
`A considerable amount of information on new mater-
`
`ials and techniques are presented, some by contributing
`authors. Jerry Pisano, who has contributed material since
`the second edition, again has completely revamped his
`chapter, emphasizing the new nomenclature of the bac-
`teria that we deal with during treatment and the latest
`views concerning the maintenance of asepsis. Chris
`Wencltus discusses the use of neWer techniques for canal
`filling. Arturo Venture Morales has provided HEW views of
`
`*ABOUT THE COVER
`
`26 years after ondodontlo treatment.
`
`The three-part figure shown on the book cover
`is taken from Figure 11-16, found on page 472.
`At the time of therapy. teeth with
`communicating apical and lateral pockets were
`considered to be “untraatable.” The left film
`
`shows initial files in place. The middle film is the
`final filling with laterally condensed guita-
`porcha, the distal pocket could no longer be
`probed. The right film demonstrates the tooth
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`PREFACE
`
`access preparations for obtaining the most direct path to
`the apex. Jim Satovsky and Jim Bahcall have added mater—
`ial on new aids for surgical. and nonsurgical. treatment.
`Other material was added by Manny Bustamante, Steve
`Potashnick. Charles Lee, Sergio Kutiler, and Jeff Wingo.
`Mark Oliver and Allen Horn {of Dentsply/Tttlsa Dental)
`were very liberal in their advice and products for investi—
`i appreciate all oi their efforts to improve the
`contents of this book.
`
`1 also appreciate the many suggestions offered to me in
`person and by mail from clinicians and educators from all
`over the world for additions and improvements of items in
`past editions. Many of these recommendations formed the
`basis of my clinical
`investigations and, ultimately.
`to
`future editions. Although their names are not
`listed.
`except for in some of the bibliographies, their ideas were
`always considered and evaluated.
`
`New drawings for this book were provided by Sandy
`Cello Lang (who also worked on the previous two
`editions) and Don O‘Connor, and photography was de-
`veloped by Oscar
`lzquierclo and Al Hayashi
`(Loyola
`University, Medical Photography). Editorial assistance
`was provided by Penny Rudolph and her associates,
`Kimberly Alvis and Courtney Sprehev
`I have worked diligently in many areas so that dentists
`all wet the world might make Endodontic Therapy an
`integral part of their practices, even if it meant referral to
`a competent colleague. Literally millions of teeth have.
`been saved, at least partially, by the previous five editions.
`This fact alone has made my professional career very
`satisfying. I wish all of my readers continued success in
`encloclontics.
`
`Frank Weine
`
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`CONTENTS
`
`
`
`1
`
`Basis for Successful. Endodontics, 1
`
`2 Diagnosis and Treatment Planning, 24
`Franklin 5, Weine and jnines A. Dewberry, Jr
`
`3 Endodontic Emergency Treatment. 7'2
`
`4
`
`S
`
`initiating Endodontic Treatment. 104
`Franklin 5. Weine, with new access phottis by Arturo Ventura Mtlrales
`
`Intraeanal Treatment Procedures, Basic and Advanced Topics, 164
`
`6 Calculation of Working Length, 240
`
`7 Canal Filling with Semisolid Materials. 266
`Franklin 5. Weine and Christopher 5. Wenckus
`
`8
`
`9
`
`Solid-Core Canal Filling Materials: Theory, Technique. and Rte-Treatment, 314-
`
`Feriapical Surgery; Intraoral Imaging and Its Use with Surgery and Other
`Procedures, 349
`
`10 Root Amputations, 4-23
`
`11
`
`12
`
`Endodontic—Periodontal Problems, 452
`
`Endodontic—Orthodontic Relationships, 4-82
`Franklin 5. Weinc and Steven R. Pniashnick
`
`13 Microbiology and Sterilization in Endodonties, 498
`jerorfle V. Pisano and Franklin 5. Weine
`
`14- Alternatives to Routine Enclodontlc Treatment, 513
`
`15 Restoration of the Endodontieally Treated Tooth, 546
`Steven R. Potashniek, Franklin 5. Weine. and Sherwin Strauss
`
`16 Endodontic Timetables, 585
`
`1? Drug Therapy Useful in Endodontics, 601
`Franklin 5. Weine and Jeffrey L. Wingo
`
`Index, 611
`
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`CHAPTER 5
`
`
`
` INTRACANAL TREATMENT
`
`PROCEDURES, BASIC AND
`
`ADVANCED TOPICS
`
` CHAPTER OUTLINE .
`
`Basic Intracanal Instruments
`Broaches
`Methods for using reamers and files
`Reamers
`
`Styles of instruments
`Standardization
`Rules for Canal Preparation
`Determination of Correct Width for Canal
`
`Preparation
`Minimal instrumentation at any appointment—do
`reach size 25
`
`Determination of apical Width
`Gaining sufficient enlargement for using guita-
`percha—rlhe flared preparation
`Canal enlargement in moderately wide and/or
`straight canals
`Canal enlargement in smaller. relatively straight.
`canals
`
`importance of using MA‘F as final instrument after
`using flaring files sltort of the working length
`Overuse and abuse of flaring
`Final test for completion of canal preparation-—
`placement of the finger spreader
`Aids for Preparing Difficult Canals
`Problems encountered in canal preparation
`Precurving of files
`Incremental instrumentation
`New instruments with intermediate sizes
`
`Need for remeasurernent when preparing curved
`canals
`
`Preparation in Extremely Curved Canals
`Determination of canal curvature
`
`Observations that canal shape changes
`Plasuc block studies
`
`Theories [or flaring in complex cases versus crown-
`down preparation
`Rules governing the use of non—ISO tapered
`instruments
`
`Effect of tire nonrlSO tapers on canal curvature and
`resultant changes in canal shape
`Typical cases
`New File Systems for Preparation of Curved Canals
`Effects of increased flexibility on final canal shape
`Flexible file systems
`Nickel-titanium files
`
`Minimizing zipping by [lute removal and modification
`of tips
`Disadvantages of flexible files
`Non-ISO taper file for penetration
`Preparation of Type II Canal Systems
`Complete Endodontic Treatment of Primary Teeth
`Ultrasonics
`
`History of ultrasonics in dentistry
`Method for action
`
`Techniques for use
`Canal preparation
`Related uses for ultrasonics
`
`Irrigants and Chelating Agents
`Functions of irrigants
`Useful irrigants
`Method of irrigation
`Recent studies concerning irrigants and their clinical
`impliCations
`Function of chelating agents
`lntracanal Medicatnents
`Function ofinttacanal medicaments
`
`Phenol and related volatile compounds
`Calcium hydroxide as a medicament for “weeping”
`cases
`
`Standard preparation in the sharply curved canal
`Applications on extracted teeth
`Avoiding the apical zip and the elbow
`
`Sealing Agents for Intertreatment Dressings
`Need for sealing agents
`Types of available sealing agents
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`an additional canal
`
`
`The major objective of the intracanal treatment pro-
`
`cedures is to remove the Contents of the canal and adja—
`cent tissues in such a way that the filling procedures that
`follow will be facilitated This means not only that the
`pulp tissue, necrotic debris, microorganisms, and affected
`dentin must he removed from the treated tooth, but also
`that the canal walls must be prepared to receive a filling
`material that will seal the apical forarnen.
`To deacribe this aspect of treatment lucidly, Schilder
`has dubbed these procedures cleansing and shaping in
`emphasis of the need for debridement and development of
`a specific receptacle for the filling material.
`i prefer the
`term canal preparation but certainly acknowledge that
`cleansing and shaping must be performed to reach the
`desired goal. Canal enlargement should n0t be used;
`merely widening the diameter of the canal may not pro-
`duce the correct shape that must be developed, neither
`does it always remove undesired contents from the canal.
`The importance of canal preparation cannot be over-
`emphasized. It is these intracanal procedures that allow
`for the initiation of healing by removing the irritants to
`periapical tissue that have been harbored within the canal.
`When for some reason a longer than routine period of
`time has elapsed between the start and the completion of
`therapy, it is not unusual to note radiographic evidence of
`healing of a periapical lesion on an x-ray film before canal
`filling (Figure 5—1).
`This chapter will discuss the instruments necessary to
`accomplish the desired objective, the procedures designed
`to produce results effectively and rapidly, and the adjuncts
`needed to retain the tooth in a desirable condition until
`
`the canals are filled. The treatment of teeth With complex
`problems will also be described.
`The calculation of working length is often included in
`the discussion of canal preparation, as it was in the first
`four editions of this book. Because of its importance. this
`subject now has a chapter of its own, Chapter 6. Working
`length calculation may be an object of controversy, and I
`wanted to give sulficient space to each of the several
`techniques. Popularity of several types of apex locators
`also has increased recently.
`Because aspects of working length are necessarily
`involved in canal preparation,
`it
`is my hope that this
`subject does not become disorienting to the reader, who
`notes references to working length while reading Chapter
`5, but has not yet read the basis for its calculation. Perhaps
`this should be viewed as are some aspects of intricate spy
`
`
`
`FIGURE 5-1 A, Preoperative radiograph of maxillary second
`bicuspid with large periapical radiolucency. Patient was a college
`student, home only for school vacations. Canal was debu‘ded
`during Thanksgiving holiday with heavy irrigation of NaOCl,
`and second appointment was scheduled for Christmas recess.
`3, The tooth received no further treatment until five weeks later,
`when radiograph was taken for verification of fit. for master cone,
`radiolueency had already healed without canal being filled. Poor
`fixing and scratches on this film have occurred because it is an
`intraueatment film developed ultrafast and generally is dis-
`carded at the conclusion of the fill appointment. The signifi-
`Carter: of this radiograph was not realized until later that day.
`
`novels, where characters and events are referred to but
`
`have not yet been introduced fully in the prose.
`
`BASIC INTRACANAL
`
`INSTRUMENTS
`
`The basic endodontic instruments used within the root
`
`files (K-type and Hedstrom), and
`canal are breaches,
`reamers. Although many engine-driven handpieccs have
`been found to be of dubious value, particularly in the
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`ENDODONTIC THERAPY
`
`more difficult curved canals, recently the introduction of
`some rotary instruments have been found. to be very use—
`ful. Because of their specific use for providing enlarge-
`ment in the more coronal portion of the preparation, these
`systems will be reviewed a bit later in this chapter.
`
`Broaehes
`
`Broaches are available in two types: smooth and barbed.
`The smooth broach had been used by some practitioners
`as an initial instrument to explore the potency and the
`walls of the canal. Most practitioners no longer follow this
`procedure, preferring to remove tissue bulk before the
`placement of any instrument near the apex to avoid
`forcing any inflamed or necrotic tissue through the apex.
`Therefore smooth broaches now are rarely used.
`The barbed broach has been used for many years in
`endodont‘ics and was originally used in canal preparation.
`However, because of its ease of breakage, it is confined to
`removal of soft tissue only.
`it is a tapered instrument of
`soft steel that is notched by a shredder to produce sharp
`barbs extending outward from Lhe shaft (Figure 5-2).
`This design is responsible for the frequency of breakage
`because the notching weakens the shaft by providing a
`place for fracture if stress or torque is applied. In addition,
`misuse within the canal may lead to disastrous results. if
`the operator attempts to force apically a barbed broach
`within a tightly fitting canal, the barbs will be bent toward
`the shaft, allowing for deeper insertion. However, when
`the instrument is Withdrawn, the barbs will extend and
`
`engage the adjacent dentin. As more force is exerted in
`removal, the barbs will dig deeper, and further fatigue may
`result in snapping of the instruments. Therefore, once the
`hard surface of the dentin walls is felt,
`the barbed
`
`broaeh must not be inserted any farther.
`Correct use of the instrument
`involves its careful
`
`insertion through the access cavity until the dentin walls
`are felt or the approximate length of the canal is reached.
`The broach is slightly withdrawn,
`then rotated a few
`revolutions, and removed. Vital or necrotic pulp tissue
`and debris become ensnared on the barbs and removed so
`
`that much of the bulky content of the canal is debrided
`before files are placed toward the apical forarnen. The
`barbed broach is similarly used to remove the paper points
`or cotton pellets of intertreatmeut dressings, which may
`defy removal by excavator or explorer.
`
`
`
`The smallest-sized broach available has approximately
`the width of a size 20 instrument. Because breaches
`
`is wide enough for
`should not be used until the canal
`comfortable accommodation, they are not used initially in
`narrow bucoal canals of maxillary molars and mesial
`canals of mandibular molars. Once these canals have been
`
`enlarged to size 20 or larger, broaches should be used to
`remove the bulky tissue that has been packed into the
`apical portion of the preparation.
`
`Methods for Using [learners and Files
`Some confusion exists as to the actions for using enlarging
`instruments and the instruments themselves. Both
`
`reamers and files may be used with either a reaming or a
`filing motion.
`
`Roaming. Rescuing involves placement of the instru-
`ment toward the apex until some binding is felt and then
`turning the handle more than a full revolution. Clockwise
`turning will remove material from the canal by way of the
`llutes‘ revolution, whereas counterclockwise turning will
`force material apically. The major effectiveness of hard
`tissue removal by reaming is
`in the insertion of the
`instrument by shaving the dentin walls.
`
`Filing. Filing involves placement of the instrument
`toward the apex until some binding is felt and then
`removing the instrument by scraping against a side of the
`dentin wall with little or no revolution of the handle. This
`
`dragging against the side of the Wall is also referred to as
`rosping action. The major effectiveness of hard tissue
`removal by filing is in the outstrolte or Withdrawal of the
`instrument by dragging the flutes on the dentin walls.
`Considerable difference exists between using filing
`action and pistonirtg the canal. Pistoning involves going
`up and down forcefully. This push/pull motion tends to
`pack dentinal filings at the apex and alter canal shape in
`small, curved canals to create ledges and short fills. Filing
`involves a passive placement of the instrument
`to its
`working length and a heavier drag motion against
`the
`canal wall.
`
`Circumferential Filing. Circumferential filing is a
`method of filing whereby the instrument is moved first
`toward the buCCal for the labial) side of the canal, then
`reinserted and removed slightly mesially. This continues
`around the preparation to the lingual aspect and then to
`the distal until all the dentin walls have received rasping
`(Figure 5-3). This technique enhances preparation when a
`flaring method is used by widening the orifice of the canal
`considerably, whereas the apical portion is kept relatively
`small.
`Most roots are oval
`
`in cross section and are wider
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`intracanal instruments. used
`Reamers were the original
`since the nineteenth century for removal of the contents
`of the pulp canal and for widening and smoothing the
`canal walls. They are manufactured by twisting triangular
`blanks (Figure 5-4. A) to produce cutting edges (Figure
`5—5, A). Because each angle of the blank is approximately
`60 degrees, a sharp knifelike edge is available to shave and
`reduce canal walls. The cross-sectional area of the blank is
`
`not excessively wide, so the instrument has a high degree
`of flexibility.
`
`A
`
`B
`
`c
`
`v A 9
`
`0"
`
`
`
`Shapes of blanks for basic instrument
`Flaunt; 5+4
`systems, which are twisted to give a different
`instrument. A, Triangular blank, as classically used for the
`rcamer but now used in some files. has three angles of 60" each
`to provide cutting efficiency and a moderate cross~5cctional
`diameter for flexibility. B, Square blank, as classically used for
`the file, has four angles of 90" each, not as sharp as those of the
`triangular blank. with a wide cross-sectional diameter
`decreases flexibility. C, Diamond hlanlt. as used for the K-Flex
`file¢ has opposite angles equal, Angle n is less than 90°. sharper
`than those of the square blank, hut these are the only two cutting
`angles. The crossasectional diameter is narrower than the square
`blanks of the same size, so this instrument has greater flexibility.
`Angle a plus angle I: always equals .130".
`
`
`
`Ftouttr. 5-3 Many roots are oval in cross section. and yet may
`have a single oval canal. if the dentist attempts to prepare such a
`canal with reaming action (top left),
`tlte result will be a canal
`with a keyhole shape (bottom left). This canal. is over-prepared in
`one segment (the upper pole) and hardly prepared through tlte
`remainder of
`the canal—an undesirable situation. However.
`
`circumferential filing (top right) involves placement of the file
`and dragging it out against peripheral walls, emphasizing
`buccolingual directions. The result (bottom right} is a wider oval
`that
`is enlarged in all dimensions and may be filled with
`compressible materials. This method also enhances making the
`orifice portion as wide as possible without gutting the crown.
`Circumferential
`filing is modified itt
`some
`canals
`by
`anticurvature filing (see Figure 5—14.15).
`
`it will be wider buccolingually as well. in these cases the
`circumferential filing is emphasized in the buccolingual
`direction. The oval canal. is made into a wider and larger
`oval. This permits easier placement of precurved
`instruments, gutta-percha cones, and finger spreaders.
`Circumferential
`filing is modified by anticurvature
`filing (see Figure 5-14, E) when flaring the mesial canals
`of maxillary and mandibular molars and some other
`curved canals. This alteration will he addressed later in
`
`this chapter in response to avoiding strip perforations.
`Studies have shown that
`the action of using the
`instrument, rather titan the instrument used. determines
`the general shape of the canal preparation. Therefore
`reaming action produces a canal that is relatively round in.
`shape. The use of filing action develops a preparation that
`
`10 of82
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`|PR2015-00632 - EX. 1025
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`US ENDODONTICS, LLC., Petitioner
`
`10 of 82
`
`IPR2015-00632 - Ex. 1025
`US ENDODONTICS, LLC., Petitioner
`
`

`

`ENDODONTIC THERAPY
`
`Files
`
`Files are useful
`
`instruments in endodontics for
`
`the
`
`removal of hard tissue during canal enlargement.
`Whereas the reamer was the original endodontic in-
`strument, the 'fllE was developed by changing some of the
`principles of design in an effort to make a more efficient
`instrument, one that would remove tooth structure faster.
`A square blank. (see Figure 5-4, B) was substituted for the
`triangular blank and was twisted more to give greater
`numbers of cutting edges (see Figure 5-5, B). Because the
`Kerr Manufacturing Company was the first to adopt this
`method, these files were called K-type for many years. The
`square blank had angles of 90 degrees, which did not cut
`as well as the (SO-degree angle of the reamer. However,
`reamers had a half to one flute per millimeter, whereas
`files were given one and a half to two and a half flutes per
`millimeter (see Figure 5-5, A) and thus had many more
`cutting edges. The cross—sectional area of the file (from
`angle to opposite angle in the blank) was greater than that
`of the reamer, making it
`less susceptible to breakage,
`which was considered a very valuable property in the days
`of the weaker carbon steel instruments. However,
`the
`
`tighter wind of the file and its greater cross-sectional
`diameter decreased its flexibility.
`The action of the file is to scrape the flutes against the
`canal walls to gouge a portion of the dentin and pull it
`from the canal. This action requires periodic cleaning of
`the instrument by the operator so the dentin shavings do
`not clog the flutes.
`Files are efficient removers of tooth structure in any
`one of three techniques because of the. multiplicity of
`cutting edges. They may be used with rasping or pure
`filing action only, in which they are placed in the apical
`portion of the canal carefully and dragged against one wall
`of the canal during removal. They may be used with
`quarter-turn filing, in which the instrument is carefully
`placed, rotated 90 degrees, and dragged out at the same
`time. They also may be used with pure reaming action and
`turned as they enter the canal.
`Files alone may be adequately used in canal prepara-
`tion. Some techniques suggest the use of reamers first and
`then files of the same size before going to the next greater
`width. The rationale for such a method is that the reamer
`
`used clockwise removes debris remaining within the canal
`and that, because rcamers may be slightly smallm than
`files, enlargement
`is facilitated.
`l have not found this
`necessary. Heavy and frequent canal irrigation followed by
`aspiration of excess lavage fluid will satisfactorily remove
`canal debris and dentin filings. Also, some companies
`manufacture reamers larger than files, or this difference
`may occur because of inaccurate quality control of
`instrument width.
`
`Virtually no innovations in instrument design occurred
`
`r: e;
`
`13:32:! mem-
`
`
`
`FIGURE 5-5 A, Instruments are manufactured in different
`lengths as well as widths. From top. File, 21 mm; rcamcr, 21 mm;
`two film, 25 and 31 mm; and reamer, 31 mm. B, Different types
`of handles are available. From top, Short plastic handle,
`measurement control (or test) handle, long metal handle (very
`rarely used now). C, Measurement control handle (top)
`is
`adjustable to allow for varying canal working lengths. Assembly
`consists of a file shaft
`(middle) placed in a handle and bolt
`(bottom). D, Once correct working length is set, bulky handle
`prevents overinstrumentation of apex by being physically
`stopped by incisal edge oftooth.
`
`Reamcrs are used during canal preparation to shave
`dentin. When used with a rasping action,
`they are less
`efficient than a file. They remove intracanal debris with
`clockwise reaming action and are used in this manner to
`remove old gutta-percha canal fillings that have been
`softened with chloroform or xylene. By turning reamers
`
`11 of 82
`
`IPR2015-00632 - Ex. 1025
`US ENDODONTICS, LLC., Petitioner
`
`

`

`the dental community.
`
`Need for Flexible Files. From the start of this cen-
`tury until the 19705, molar teeth and teeth with sharply
`curved canals were rarely treated. When they were, a high
`percentage of failures resulted. in fact. Grossman wrote in
`his textbooks as late as 1967 that teeth with canal curva—
`
`tures of 4-5 degrees and greater could not be treated
`successfully without surgery. Although this was not
`known at that time, the reaSDn was that most endodontic
`files used then were rather inflexible.
`
`increasing
`As mentioned in the discussion of files,
`cross-sectional diameter decreases instrument flexibility
`Because the triangular blank, used for the reamer (see
`Figure 5-4, A], has a narrower cross-sectional. diameter
`than the square blank, used for the file {see Figure 5-4, B),
`the reamer has greater flexibility than the file in similar
`sizes. However,
`files became the dominant
`instrument
`for canal preparation, and as such, a total decrease in
`flexibility of
`intracanal
`instruments resulted. Smaller
`files, such as sizes 10, 15, and 20, have narrow diameters
`(Table. 5-1) and thus have sufficient flexibility to retain
`canal shape. However, in larger sizes, such as 30, 35, and
`40,
`the files lose their
`flexibility very quickly. and
`alterations of canal shape may be devastating (see
`Figure 5'23).
`
`I TABLE 591 Diameters of Standardized
`
`_ {till-input) and .04 Taper Instruments
`Dimeter (mm) at
`
`Instrument no.
`08
`10
`15
`20
`25
`30
`35
`40
`45
`50
`55
`60
`70
`80
`90
`
`Du (original DI)
`0.08
`0.10
`0-15
`0-20
`0'25
`0'30
`0.35
`0‘40
`0‘45
`0'50
`055
`0.60
`0.70
`0.00
`UQG
`
`D", (original D2)
`0.40
`0.42
`0-47
`0'52
`0‘5:
`0‘6"
`0.67
`0'72
`037
`032
`037-
`0.92
`1.02
`1.12
`1.3.2
`
`.iJ-i D";
`NA
`0,74
`0-79
`0‘84
`0'89
`0'94
`0.99
`1.04
`1.09
`1.14
`1.19
`1.24-
`1.34
`13H
`154'
`
`difficult to use a good condensation system to fill
`minimally enlarged canals, so failures front inadequate
`filling were cotnmon. The result was that as an increased
`demand for treatment of these more complicated teeth
`occurred, it was necessary to develop new file systems.
`in its first design change in. more than 60 years, the
`Kerr Manufacturing Company modified its basic blank to
`develop the K-Flex file (see Figure 5-4, G). Rather than
`using a square or triangular blank, 3 diamond—shape blank
`was employed (see Figure 5-4. C) to decrease the cross-
`sectional diameter (the distance between the two bs in
`
`Figure 5—43 C) and impart greater flexibilit