RUETEILE ON

Q ince the beginning of endodontics, there have beenJnumerous concepts, strategies, and techniques forpreparing canals. Over the decades, a staggering arcay of fileshas been produced for negotiating and shaping canals. Inspite of the brand name, number of instruments required, andthe surprising number of techniques advocated, endodontictreatment has been typically approached with optimism forprobable success. Each new generation of files has advancedcanal preparation methods through innovations in design,material, and movement.

From the outset, all instruments used for negotiatingand shaping canals were manufactured from stainless steel,carbon steel, or related alloys. In 1988, Walia proposedNitinol, a NiTi alloy, as it is 2 to 3 times more flexible, in thesarne file sizes, compared to stainless steel. A game-changingoutcome of files manufactured from NiTi was that curvedcanals could be mechanically prepared utilizinga continuousrotary motion. By the mid-1990s, the first commerciallyavailable NiTi rctary files had come to market.

To appreciate the evolution of instruments, it is usefulto know that all first-generation NiTi rotary files have passivecutting radial lands, fixed tapers over the length of theirblades, and require a considerable number of files to achievethe preparation objectives. In 2001, the next generation ofNiTi rotary files came to market. The critical distinctions ofthis generation of instruments are that they have active cuttingedges and reduce the sequence of instruments required tofully prepare a canal. This generation of NiTi files includesthe ProTaper@ (Dentsply Tulsa) roLary files which, unlikeall other passive or active NiTi cutting instruments, havemultipl e increasing or decreasing percent age tapers on a singlefile. This unique and revolution ry design feature has madeProTaper@ the world's number one choice for shaping andfinishing canals. Importantly, the ProTaper@ system affordsthe shortest sequence of files to produce the most optimaideep shape.

During this period, manufacturers began to focus onother ways to improve the manufacturing process in order toincrease the resistance to file separation. Some manufacturerselectropolished their files to remove surface irregularitiescaused from the traditional grinding process. However, ithas been clinically observed and scientifi cally reported thatelectropolishing dulls the sharp cutting edges. This requiresthe clinician to apply a more dangerous inward pressure,undesirably increasing the torque on the rctary file duringwork.

In 2007, manufacturers began to focus on utili zingnew methods [o manufacture NiTi instruments. This thirdgeneration of NiTi instruments reportedly provides greaterflexibility and resistance to cyclic fatigue. Sybron DentalSpecialties introduced R-phase heat treatment, a nongrindingprocess, and a so-called special-surface conditioning.Dentsply Ii:lsa Dental (DTDS) introduced a new proprietarythermal process, which resulted in a new metallurgicaltechnology termed M-wire*'. Research is now available that

64 Endodontic t-rrrrctiic

shows M-wire'" has superior mechanical properties comparedto files manufactured from traditional NiTi alloy.

Recently, there has been an increasing interest andrenewed focus on reciprocation, which m y be defined as anyrepetitive up-and-down or back-and-forth motion. However,all current market version reciprocating motors produce a filemovement where the clockwise (CW) and counterclockwise(CCW) degrees of rotation are equal. Equal bidirectionalmovement requires undesirable inward pressure, limitscutting efficiency, and does not op[imally auger debris out ofthe canal.

The latest advancements in canal preparationtechniques have moved toward the long-hoped-for single-fileconcept. ReDent-Nova (Israel) recently introduced the SelfAdjusting File (SAF) , avatlable in the Unired States rhroughHenry Schein Dental. This file has a compressible open-tubedesign that is purported to exert uniform pressure on thedentinal walls, regardless of the cross-sectional configurationof the canal. The SAF is mechanically driven by u handpiecethat produces both a short 0.4-mm vertical amplitude strokeand vibrating movement with constant irrigation.

A more promising single-file concepr has been recenrlydeveloped by Dentsply International. This single-file conceptwili launch in March 201I and is termed WaveOne'" (nfOSand Maillefer) and Reciproc@ (VDW). This new file represenrsa convergence of a unique design, M-wire'", and a newlydesigned reciprocating motor that produces the mechanicalversion of Roane's manual Balanced Force concept from 1985.The motor has been designed so the engaging or curringangle is less than the elastic limit of the file. Strategically, thebidirectional angles are not equal, which means the file willrotate 360 degrees after a few CCW and CW cutting cycles.This novel reciprocating movement allows the file to morereadily progress, efficiently cut, and effectively augur debrisout of the canal. To address the full range of anatomy, theclinician selects a single WaveOnerM file from among threedifferent apically sized and tapered files to shape and finishsmall, medium, and large diameter canals, regardless of theirlength and curvature.

Over the last 50 years, our profession has envisionedpreparing canals utilizing a single-file technique. The futureis now! The reality is that virtually all canals can now beoptimally prepared using a single-file technique. You willdefinitely want to keep WaveOne'" on your radar so you cancatch this remarkable wave. [iI

Clifford ,f , Ruddle, DDS, FACD, FICD, is founder and Directorof Advanced Endodontics {wWy.endoruddle.corn}, aRinternational :educational source, in Santa Ba,rbara,California, Additionally, he maintains teaching positions atvarious dental,schools. Dr. Ruddle can be reached at info@

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Volume 4 Number 2

The shaping movementWave of the future

Dr. Cli f ford f " Ruddle describes the latestadvancements in endodont ic f i les