Ni Ti loai

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NICKEL-TITANIUM ENDODONTICINSTRUMENTS

A new generation of endodontic instruments, made from a remarkable alloy,nickel titanium, has added a striking new dimension to the practice ofendodontics.

The superelasticity of nickel titanium, the property that allows it to return toits original shape following signi cant deformation, di erentiates it fromother metals, such as stainless steel, that sustain deformation and retainpermanent shape change. These properties make nickel-titanium endodontic

les more exible and better able to conform to canal cur ature, resistfracture, and wear less than stainless steel les.History . !n the early "#$%s, the superelastic property of nickel-titaniumalloy, also known as Nitinol , was disco ered by &uehler and 'ang at the() *a al +rdnance aboratory." $ The name *itinol was deri ed from theelements that make up the alloy, nickel and titanium, and nol/ for the *a al+rdnance aboratory.

The trademark *itinol refers speci cally to the rst nickel-titanium wiremarketed for orthodontics.As early as "#01, 2i 3an and associates" 0 reported on potentialapplications of nickel-titanium alloys containing nickel 114 by weight 511-*itinol6 and nickel $%4 by weight 5$%-*itinol6. They found that thecharacteristics of $%-*itinol suggested its use in the fabrication of toughcorrosion-resistant hand or rotary cutting instruments or les for operati e

dentistry, surgery, periodontics, and endodontics. 7urther, it was suggestedthat 11- or $%-*itinol could be used for the manufacture of corrosion-resistant root canal points to replace sil er points.A rst potential use of nickel titanium in endodontics was reported in "#88by 'alia and associates." 8 *umber "1 les fabricated from nickel-titaniumorthodontic alloy were shown to ha e two or three times the elastic exibilityin bending and torsion, as well as superior resistance to torsional fractures,compared with *o. "1 stainless steel les manufactured by the sameprocess. The results suggested that *itinol les might be promising for theinstrumentation of cur ed canals. !n "## , a collaborati e group made adecision to examine and study the possibility of producing *ickel titanium

instruments. The nickel-titanium re olutionin endodontics followed, and in 9ay "## , )erene introduced these new lesto students in the 2ollege of :ental 9edicine at the 9edical (ni ersity of)outh 2arolina. ater these and other similar les became a ailable to theprofession generally.Superelasticity Alloys such as nickel titanium, that showsuperelasticity, undergo a stress-induced artensitic transformation from a

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parent structure, which is austenite. +n release of the stress, the structurere erts back to austenite, reco ering its original shape in the process.:eformations in ol ing as much as a "%4 strain can be completelyreco ered in these materials, as compared with a maximum of "4 incon entional alloys.

!n a study comparing piano wire and a nickel-titanium wire, )toeckel and ;ufound that a stress of 1%% 94strain,as compared with only 1%% 9% ( and drill designs make itpossible to use mechanical 5ie, rotary handpiece6 instrumentation.

9oreo e r, new prototype rotary motors now o er the potential for impro edtor=ue control with automatic re ersal that may ultimately decrease rotaryinstrument breakage.

Finally, nickel-titanium les are biocompatible and appear to ha e excellentanticorrosi e properties.">" !n addition, implantation studies ha e eri ed thatnickel titanium is biocompatible and acceptable as a surgical implant."> !n a "##0AAD =uestionnaire, the endodontic membership answered the following =uestion,

:o you think nickel-titanium instruments are here to stay and will become basicarmamentaria for endodontic treatmentE/ The responses were =uite positi eF yes,/

0 4G maybe,/ "4G and no,/ H4.">>'ith the ability to machine utes, many new designs such as radial lands ha ebecome a ailable. adial lands allow nickel-titanium les to be used as reamers in a>$%- degree motion as opposed to the traditional reamers with more acute rakeangles. Although the most common use


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of this new design has been as a rotary le, the identical instrument is a ailable asa hand instrument. !n addition, a con erter handle is a ailable that allows theoperator to use the rotary le as a hand instrument.

Torsional )trength and )eparation. The clinician switching from stainless to nickel-titanium hand instruments should not confuse nickel titaniumIs superelasticcharacteristics with its torsional strength and so assume that it has super strength.

This misconception has led to unnecessary le breakage when rst using this newmetal. )tudies indicate that instruments, whether stainless steel or nickel titanium,meet or exceed A*)!JA:A )peci cation *o. 8. @owe er, when re iewing theliteratureon this sub3ect the results seem to be mixed.2analda and &eraste=ui foundnickel-titanium les5*iti ex and *a i ex6 5:entsplyG Tulsa, +kla.6 to bemore exiblethan the stainless le stested 57lexo le and7lex- 6. @owe er , the stainless steel

les were foundto be more resistant to fracture. &oth types of metalexceeded allA*)!JA:A speci cations. 2analda et al., inanother study, compared identicalinstrumentsF2anal9aster 5aka !K@T)


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LAlthough instrument breakage should be rare, any instrument, hand or rotary, canbreak. !t is the clinicianIs knowledge and experience, along with the manufacturerIs=uality control, that will ultimately minimiCe breakage.

At both the (ni ersity of Tennessee and (ni ersity of 2alifornia at os Angeles,breakage has not increased with the routine use of nickel-titanium instruments. !fbreakage occurs, the fractured piece can occasionally be remo ed or bypassedusing ultrasonics and hand instruments in con3unction with magni cation.

LThe dentist ha ing problems with le breakage should seek help in e aluating histechni=ue. +ne should practice on extracted teeth until a le el of con dence isreached that will help ensure safe and eMcientpatient care.

The following is a list of situations that place nickeltitanium hand instruments at riskalong with suggestions for a oiding problemsF

i c ke l -T i t a n i u m P r e c a u t i o n s a n dP r e v e n t i o n

1 . +ften too much pressure is applied to the le.*e erforce a leN Theseinstruments re=uire a passi e techni=ue. !f resistance is encountered, stopimmediately, and before continuing, increase the coronal taper and negotiateadditional length, using a smaller,

%.% taper stainless steel hand le. )tainless steel les should be used in siCessmaller than a *o. "1. !f one is using more nger pressure than that re=uired tobreak a *o. pencil lead, too much pressure is being used. &reak a sharp *o. pencil lead and see how little pressure is re=uiredN

2 . 2anals that 3oin abruptly at sharp angles are oftenfound in roots such as themesiobuccal root of maxillary molars, all premolars, and mandibular incisors and themesial roots of mandibular molars. The straighter of the two canals should rst beenlarged to working length and then the other canal, only to where they 3oin. !f not,a nickel-titanium le may re erse its direction at this 3uncture, bending back onitself and damaging the instrument.

3 . 2ur ed canals that ha e a high degree and small radius of cur ature aredangerous.">8 )uch cur atures 5o er $% degrees and found > to H mm from

working length6 are often seen in the distal canals of mandibular molars and thepalatal roots of maxillary rst molars.

4 . 7iles should not be o erusedN All clinicians ha e experienced more fracture afterles ha e been used a number of times. emember that all uses of a le are not

e=ual. A calci ed canal stresses the le more than an uncalci ed canal. A cur edcanal stresses the le more than a straight canal. +ne must also bear in mindoperator ariability and the use of lubricants, which will a ect stress.

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2onsider discarding a le after abusi e use in calci ed or se erely cur ed canalse en though it has been used only in one tooth. (se new les in hard cases andolder les in easier cases. *o one knows the maximum or ideal number of times a

le can be used. 7ollow manufacturersI instructions and the rule of being bettersafe than sorry./ +nceonly is the safest number.

5 . !nstrument fatigue occurs more often during the initial stages of the learningcur e. The clinician changing from stainless steel to nickel titanium should takecontinuing education courses with experienced clinicians and educators, followed byin itro practice on plastic blocks and extracted teeth. &reak les in extracted teethN:e eloping a le el of skill and con dence

allows one to use the techni=ue clinically.

6. edges that de elop in a canal allow space for de ection of a le. The nickel-titanium instrument can then cur e back on itself. A nickel-titanium instrumentshould not be used to bypass ledges.

+nly a small cur ed stainless steel le should be used, as described, in anothersection of this text.

. Teeth with )/-type cur es should be approached with cautionN Ade=uate aringof the coronal third to half of the canal, howe er, will decrease problems in thesecases. !t may also be necessary to go through a series of instruments an additionaltime or two in more diMcult cases.

! . !f the instrument is progressing easily in a canal and then feels as if it hitsbottom, :+ *+T A


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andJor taper can be used to a oid frictional t. *ickel-titanium instruments withtapers from %.%H, %.%$, and greater, as well as Kates-Klidden drills andsonicJultrasonic instruments, ser e this purpose well.

1#. )udden changes in the direction of an instrument caused by the operator 5ie,

3erky or 3abbing mo ements6 must be a oided. A smooth gentle reaming or rotarymotion is most eMcient.

11 . As with any type of instrument, poor access preparation will lead to proceduralerrors.

12 . Ad ancing or pushing an instrument into a canal in too large an incrementcauses it to act as a drill or piston and greatly increases stress on the metal. Dxceptfor the most diMcult cases and the necessity of using small instruments, the tipshould not be used to cut into or drill into the canalG it should act only as a guide.

egardless of the techni=ue being used, nickel-titanium instruments should bead anced in small increments with a more passi e pressure than that used withstainless steel.

13 . :o not get in a hurryN :o not get in a hurryN :o not get greedy and try to makenickel titanium do more than it is designed to do.

14. !nspection of instruments, particularly used instruments, by sta and doctor iscritical.


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using the more exible nickel-titanium les compared with >%.H4 ledging whenstainless steel les were used. 'hen using nickel-titanium les, the students wereshort of working length in only >4 of the canals compared with H$4 of the canalswhen using stainless steel les. Although the canals were instrumented beyond theintended working length in 14 of the nickel-titanium blocks, the students wereable to de elop an apical stop within " mm between working length and the end ofthe canal. !n the stainless

steel group, $4 of canals fell into this category. The degree of destruction aroundthe foramen was signi cantly di erent 5p O .%16. Apical Cipping occurred >".04 lessoften with the *itinol les.

)tripping of the canal walls was less with the nickel-titanium les. A second study inwhich the blocks were instrumented by a member of the faculty had similar

ndings.

LAn obser ation from these studies was the creation of a smooth belly shape on the

outer aspect of the apical third of the canals instrumented with nickel-titaniuminstruments. This seemed to replace the ledging

that occurred with stainless steel. +ther studies ha e shown that this may beattributable to the techni=ue in which the les were used.Are nickel-titanium handinstruments best used with a push-pull ling motion or with a reaming or rotarymotionE !n one study, nickel-titanium les used in a ling motion caused asigni cantly greater amount of the outer canal wall to be remo ed, between > and $mm short of working length. The stainless steel les, howe er, remo edsigni cantly more of the outer canal wall, at working length and in the danger Cone,than did the rotary or hand nickel-titanium les.

The rotary nickeltitanium les were signi cantly faster and maintained better canalshape than the other groups. The results of this study indicate that nickel-titaniuminstruments

should be used with a rotational or reaming motion and are e ecti e in shaping rootcanal systems.

L(sing computed tomography, Kambill et al. reamed extracted teeth with eitherstainless steel or nickel-titanium les and reported that the nickel-titanium lescaused less canal transportation, remo ed less dentin, were more eMcient, andproduced more centered canals.

L+n the other hand, not all studies are in agreement concerning cutting eMciency. Tepel et al. tested H brands of hand instruments speci cally for cutting eMciency. They found that exible stainless steel les were more eMcient than nickel titanium.@owe er, they did not address the =uality of the completed canal.

LDlliot et al., at KuyIs @ospital in ondon, used resin blocks to compare stainlesssteel 57lexo les6 and nickel- titanium 5*iti ex6 instruments used with either abalanced force or stepback techni=ue.

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LThe authors concluded that it is preferable to use nickel-titanium instruments in abalanced force techni=ue and stainless steel in a ling techni=ue because stainlesssteel les can be precur ed. 2onsidering the results from Tennessee and ondon,nickel-titanium instruments should be used as reamers, not les.

7igure "%- 8 Puantec les/ are more like a reamer, a drill as it

appears, and are used in a rotary motion, not push-pull A, Puantec

safe-cutting tip le. &, Puantec noncutting tip le. The les are

produced in three di erent tapersF %.% , %.%H, and %.%$ mmJmm.

52ourtesy of )ybron-DndoJ?err6

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7igure "%- $ The unusual ight)peed instrument. (/ shaped in

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design with a noncutting tip, the ight)peed cutting head terminates

a "$ mm noncutting shaft.9ade only in nickel titanium in !)+

siCes % to "%% and in half siCes as well, they are used in rotary preparations

at ,%%% rpm. 52ourtesy of ight)peed Technology !nc.6

Cleaning protocol for rotary nickel-titaniumendodontic instruments:

Background: The cleaning of endodontic and all dental instruments prior tosterilization is a prerequisite for their processing for re-use. This study aimed tode elop a clinically practical cleaning protocol for rotary nickel-titanium 5*iTi6endodontic les prior to steriliCation.

Met$o%s& 2leaning experiments were conducted onsix di erent types of lesthat had been used on human teeth. The experiments in ol ed three components of mechanical and chemical remo al of root canal debris from the lesF the use ofsponges soaked with chlorhexidine to remo e gross debris, pre-soaking, andultrasonication. After cleaning, the les were immersed in Ran KiesonIs solution andexamined under magni cation for stained debris. *ew unused les were alsoexamined.

'esults F 9acroscopically, there were no instances of isible debris and all lesappeared clean after all cleaning se=uences. 9icroscopically, new les showed bothstained and unstained debris, and se eral experimental cleaning regimensproduced les that were free of stained debris. 2ombining elements of the moste ecti e cleaning se=uences resulted in a cleaning protocol that predictablyproduced clean les.

(oncnslusio& The results do not support the recommendation for the singleuse of endodontic les based on inability to clean les between uses. (nderexperimental conditions the cleaning protocol de eloped rendered rotary *iTi les"%% per cent free of stained debris. The protocol comprises "% igorous strokes in ascouring sponge soaked in %. per cent chlorhexidine solution, a >% minute pre-soakin an enCymatic cleaning solution, "1 minutes ultrasonication in the same solution,

and a % second rinse in running tap water.

The protocol can be applied to all endodontic les.

Some stu%ies con)rm t$ee*ecti+eness of Ni i instruments&-

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1- +aluation of Sin/le-use 'otary Nic0el-titaniumnstruments

The purpose of this study was to document the number and types of defectsobser ed in a single brand of *i-Ti engine-dri en rotary instruments discarded afterone clinical use in a specialiCed endodontic practice. D ery >> rpm was also used. The instrumentswere then collected, ultrasonically cleaned, steriliCed and inspected with a Klobal:ental 9icroscope at B"$ magni cation. The types and numbers of defects wererecorded and statistical analyCed. A total of 08$ les were e aluated and theinstrument groups di ided into three di erent groups consisting of torsional fatigue,

exural fatigue, and fracture. A total of ""1 5"146 of these instruments showedsome type of defect after one clinical use. The siCe > had the highest defect rate5 >46. The , H, and 1 les had defect rates from "$ "04 and the $ and 0 lesshowed minimal defects of .H and H.84 respecti ely. Torsional fatigue accountedfor the ma3ority of the defects 5" .846, whereas exural fatigue only occurred ".$4of the time. +nly se en of the 08$ les fractured 5.#46. There was no statisticalsigni cance in the o erall rate of failure based on le siCe, in the rate of speci cfailure between le siCes, or within the type of failure seen within each le siCe.*ote that in this study, no control was used for the amount of force applied to theteeth and regardless of the number of canals, they still considered the le as beingused once. 08$ new les were used for a H-week period and 8$4 showed no isiblesigns of defect or distortion after one use. Therefore, it can be assumed that these

les may be used safely for a second procedure but the les should be inspectedwith magni cation prior to a second use and those used in calci ed or sharplycur ed canals should not be reused. 7or maximum safety, the authors recommenda single use.

2- Failure of roFile instruments use% it$ $i/$an% lo tor ue motors.

A M& The purpose of this study was to e aluate the failure incidence of


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experimental groups.' S:7 S F !nstrument separation did not occur in any of the three groups. +ne andtwo instruments were deformed when using the air and high tor=ue motors,respecti ely.( N(7:S NS F The results indicated no di erence between the three motorswith respect to the incidence of instrument failure. The results suggest that the useof < ! in a crown-down manner with air control motors was safe.

3. reparation of se+erely cur+e% simulate% rootcanals usin/ en/ine-%ri+en rotary an% con+entional$an% instruments.

This in +itro study e aluated the eMcacy and safety of six di erent nickel-titaniumengine-dri en instruments used with a tor=ue-controlled engine de ice and nickel-titanium hand and stainless steel hand instruments in preparation of cur ed canals.A total of 8% cur ed 5>$ degrees6 simulated root canals were prepared. !magesbefore and after were superimposed, and instrumentation areas were obser ed.

Time of instrumentation, instrument failure, change in working length and weightloss were also recorded. esults show that stainless steel hand instruments causesigni cantly less transportation towards the inner wall of the canal than do nickel-titanium hand instruments. *o instrument fracture occurred with hand instruments,but >%-$%4 breakage of instruments was recorded during instrumentation with theengine-dri en de ices. The working length was maintained by all types ofinstruments. *ewly de eloped nickel-titanium rotary les were not able to pre entstraightening of the se erely cur ed canals when a tor=ue-controlled engine-dri ende ice was used.

4. (anal s$apes pro%uce% se uentially %urin/

instrumentation it$ ;uantec S( rotary nic0el-titanium instruments& a stu%y in simulate% canals.A MF The aim of this study was to determine the shaping ability of Puantec )2nickel-titanium rotary instruments in simulated root canals.M H 7 89 F 7orty simulated canals consisting of four di erent shapes interms of angle and position of cur ature were prepared with Puantec )2instruments. )e=uential still images were taken of the canals using a ideo cameraattached to a computer with image analysis software. !mages were takenpreoperati ely, and then after instrument 0 5)iCe 1, %.%1 taper6, instrument 8 5siCe

1, %.%$ taper6, and instrument "% 5siCe H1, %.% taper6 were taken to length. Dachse=uential postoperati e image was superimposed indi idually o er the

preoperati e image in order to highlight the amount and position of materialremo ed during preparation.' S:7 S& + erall, the mean preparation time to siCe "% was >.$ min with " mmcanals taking on a erage less time than 8 mm canals. There was a highly signi cantdi erence between the canal types 5< O %.%%%"6. *o instruments fractured withinthe canal or deformed, although one instrument separated from the latch grip. Allcanals remained patent. 7ollowing preparation to siCe "%, "# canals 5H846 retainedtheir length, eight 5 %46 lost length, and "> 5> 46 gained lengthG the magnitude ofthe change in length was always %.1 mm or below. 7ollowing preparation to siCe 0

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instruments all canals showed aberrant shapes. Dxcess remo al of material alongthe outer aspect of the cur e between the beginning of the cur e and the end-point5outer widening6 was found in $ canals 5$146 after instrument 0. At the samestage of preparation six canals 5"146 had Cips, three 5846 had ledges and e5">46 had perforations. 7ollowing preparation to siCe "%, 0 5$846 canals wereperforated.( N(7:S NS F (nder the conditions of the study, Puantec )2 instrumentsconsistently produced aberrations when canals were enlarged to siCe 0 5siCe 1,%.%1 taper6 or abo e. 2are should be exercised when using these instruments in realteeth.

5. A reconstructe% computeri


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steel 5))6.M H 7 89& Dighty simulated canals with %% and >% degrees 2 cur atureswere prepared using the step-back techni=ue and =uarter turnJpull instrumentmanipulation. 9iddle and apical le el canal sections were taken using computedtomography.' S:7 S F *o signi cant di erence was found between any of the le types ateither le el with respect to canal cur ature 5 % degrees or >% degrees6. At themiddle le el, the stainless steel les caused more enlargement toward the innerpart, compared to nickel-titanium les. At the apical le el, nickel-titanium canal lescaused more enlargement toward the inner part, whereas more outwardenlargement was caused by stainless steel instruments. *o signi cant di erencecould be obser ed at the middle le el 5< U %.%16 related to the enlargement towardthe outer side of the canal cur ature. Transportation at both le els was signi cantlyless 5< O %.%%"6 for the *i-Ti les than the )) ones. 2entring ratios of the le typesat the middle le el were low, but not signi cantly di erent 5< U %.%16, whereas atthe apical le el the centring ratios were signi cantly higher for the *i-Ti les 5< O%.%%"6.

( N(7:S NS F *i-Ti instruments produced preparations with ade=uateenlargement, less transportation, and a better centring ratio.

. (yclic fati/ue of roFile rotary instruments afterprolon/e% clinical use .

A MF The purpose of the present study was to e aluate resistance to cyclic fatigueof new and used


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techni=ues utiliCing nickel-titanium instruments 5


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11. S$apin/ a=ility of Hero 642 rotary nic0el-titanium instruments in simulate% root canals.A MF To determine the shaping ability of @ero $H nickel-titanium rotaryinstruments during the preparation of simulated canals.M H 7 89 F A total of H% simulated root canals made up of four di erentshapes, in terms of angle and position of cur ature, were prepared by @ero $Hinstruments using a crown-down preparation se=uence. #.146 maintained the

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correct working distance, "1 lost distance and eight canals gained length.Dxamination of intracanal impressions demonstrated that the ma3ority of canals50#46 had apical stopsG canal shape had a signi cant in uence 5< O %.%%"6 on the=uality of apical stops. 'ith one exception all canals had smooth canal walls and allof the canals showed good ow characteristics. Taper was poor in >% canals 50#46and good in eight canals 5 "46.( N(7:S NS F @ero $H rotary nickel-titanium instruments prepared simulatedcanals rapidly but with a three-dimensional form that lacked ade=uate taper.

13. 'e%uction of intracanal =acteria usin/ nic0el-titanium rotary instrumentation an% +ariousme%ications.

The purpose of this study was to e aluate the extent of bacterial reduction withnickel-titanium rotary instrumentation and ". 14 *a+2l irrigation. Also, theadditional antibacterial e ect of calcium hydroxide for U" wk was tested. 7orty-twosub3ects with radiographic and clinical signs of chronic apical periodontitis were

recruited. The canals were sampled before treatment, during and afterinstrumentation, and after treatment with calcium hydroxide and the samplesincubated anaerobically for 0 days at >0 degrees 2. The bacteria from each samplewere =uanti ed and the log"% alues were used for calculations and comparisons.

The initial sample con rmed infection of the canals. There was a signi cantlygreater pattern of reduction of bacteria when *a+2l was used as an irrigant,compared with sterile saline 5p O %.%16. After instrumentation with *a+2l irrigation,$".#4 of canals were rendered bacteria-free. The placement of calcium hydroxidefor at least " wk rendered # .14 of the canals bacteria free. This was a signi cantreduction, compared with *a+2l irrigation alone 5p W %.%%%"6. The results of thisstudy indicate that *a+2l irrigation with rotary instrumentation is an important stepin the reduction of canal bacteria during endodontic treatment. @owe er this

method could not consistently render canals bacteria-free. The addition of calciumhydroxide intracanal medication should be used to more predictably attain this goal.

14. or ue %urin/ canal instrumentation usin/rotary nic0el-titanium )les .*ickel-titanium engine-dri en rotary instruments are used increasingly inendodontic practice. +ne fre=uently mentioned problem is fracture of an instrumentin the root canal. Rery few studies ha e been conducted on torsional characteristicsof these instruments, and none has been done under dynamic conditions. Thepurposes of this study were to measure the tor=ue generated and the apical forceapplied during instrumentation with a commercial engine-dri en nickel-titanium le

system, and to relate tor=ue generated during simulated clinical use to torsionalfailure of the instruments. Ten extracted human teeth 5 e with small-siCed and ewith medium-siCed straight root canals6 were instrumented with Puantec )eries

%%% les, and the tor=ue and apical force generated were measured. The appliedapical force was generally low, not exceeding "1% g in either small or mediumcanals. The tor=ue depended on the tip siCe and taper of each instrument, and oncanal siCe. !nstruments with %.%1 and %.%$ taper generated the highest tor=ue,which was greater in small than in medium canals. The tor=ue at failure was

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signi cantly 5p O %.%%"6 higher than tor=ue during instrumentation, but withconsiderable ariation in the extent of the di erence.

15.A comparison of t o nic0el-titaniuminstrumentation tec$ni ues in teet$ usin/microcompute% tomo/rap$y .A MF The aim of the study was to compare the shaping of root canals by two nickel-titanium instrumentation techni=ues using microcomputed tomography 592T6.M H 7 89& Ten mandibular rst molar teeth 5>% canals6 that had intactcrowns and fully formed roots were scanned using 92T. 7ifteen canals wereinstrumented using *iTi7lex hand les 59aillefer6 using balanced force. Theremainder were instrumented using prototype .%, H.1, $.%, 0.1 mm6 from the apex was measured. Transportation and

centring were recorded. !mages constructed at these le els were compared withideo images of e=ui alent physical sections created after the second scan. Theolume of dentine remo ed in the apical 0.1 mm of the root canals of each tooth

was calculated and the di erent techni=ues compared. endered three-dimensionalimages were used to assess the preparations =ualitati ely. The time taken forpreparation was recorded.' S:7 S& There was no signi cant di erence between hand instrumentation with*iti7lex les and machine instrumentation with prototype


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torsional an% =en%in/ tests .@ ( B F 7or a true comparison of clinically rele ant =ualities of instruments

manufactured from di erent alloys, the instrument must be identical in design. Thepurpose of this study was to perform mechanical tests on stainless steel and nickel-titanium instruments of identical design. )T(:; :D)!K*F !dentical experimental

endodontic les of @-type with double helix were fabricated from stainless steel andnickel-titanium alloys. Torsional and bending tests were carried out according toAmerican *ational )tandards !nstituteJAmerican :ental Association speci cation *o.18 and !nternational )tandards +rganiCation *o. >$>%J". 2hanges in instrumentsduring the testing were also analyCed with scanning electron microscope techni=ue.

' S:7 S F The results indicated that the torsional moment of the stainless steelles was signi cantly higher than for the nickel-titanium les 5< O.%%"6, whereas the

mean angular de ection for the nickel-titanium les was signi cantly higher. Themean bending moment for the nickel-titanium les was signi cantly lower 5< O.%%"6than the mean alue for the stainless steel les. The scanning electron microscopedemonstrated that the fracture surfaces of the stainless steel les were brittle,

whereas the nickel-titanium les had a ductile fracture.( N(7:S NS F 'hen the design of endodontic instruments of di erent alloys isidentical, the nickel-titanium les are more exible in bending. @owe er, nickel-titanium les re=uire less force to deform to fracture.

1!. An in +itro comparison of canal preparationusin/ t o automate% rotary nic0el-titaniuminstrumentation tec$ni ues .A M& The aim of this study was to compare the eMcacy of root canal preparationusing two automated rotary nickel-titanium instrumentation techni=ues with a

double ared balanced forces hand preparation techni=ue, using stainless steel lesin extracted human teeth.M H 7 89& )ixty root canals in extracted human teeth were matched forcur ature, length and diameter and di ided e enly between three groups 5group "W double are using 7lexo les, group W rotary nickel-titanium using 9cB!9instruments and group > W rotary nickel-titanium using 6 andaccording to a predetermined procedure in group ". A standardiCed radiographictechni=ue using mercury as a contrast medium was used to e aluate the canalshape before and after preparation in the plane of maximum cur ature. The pre-and postoperati e radiographic images were compared against each other and with

a predicted Videal preparationV calculated from a pro3ection of the nal instrumentdimensions. The outcome measures were changes in canal dimensions as =uanti edby measuring the changes in the position of the inner and outer wall at " mminter als. Alteration in canal cur ature could be inferred by comparison with theideal preparation.' S:7 S& The degree of canal cur ature did not in uence the e ecti eness of anyof the techni=ues. The results showed no statistically signi cant di erences in theoutcome measures between the groups 5two-way A*+RA6. There were no signi cantdi erences in canal wall position changes at any le el except the apical three,

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where signi cantly less change occurred in all groups 5< W "46. !nstrumentsfractured in three canals, with acute cur es in groups and >.( N(7:S NS& 2anal cur atures were e=ually and well maintained followingpreparation in all the groups, as long as the instrument did not fracture.

1". entine c$ips pro%uce% =y nic0el-titaniumrotary instruments . This study aime% to compare the cross-sectionalshape of two nickel-titanium rotary instruments, namely


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# canals 50 46 retained their length, 0 5"046 lost length, and H gained lengthG themagnitude of the change in length was always below " mm. Xips were created in >canals 5046 after use of siCe "% instruments, but no perforations or danger Coneswere produced. Dxcess remo al of material along the outer aspect of the cur ebetween the beginning of the cur e and the end-point 5outer widening6 was found in

canals 51146 after instrument 0, in >% 50146 canals after siCe 8 and in >1 canals58846 after siCe "%. There was a signi cant di erence 5< O %.%%%"6 between canalshapes for the incidence of this aberration at all siCes.( N(7:S NS& (nder the conditions of the study, Puantec B instrumentstended to remo e excess material from the outside of the cur e between thebeginning of the cur e and the end-point. These aberrations increased in pre alenceand se erity following the use of larger instruments when they were taken to length.)iCe 8, # and "% Puantec B instruments should be used with care and short oflength, especially in se erely cur ed canals.

21. 'ationale for t$e use of lo -tor ue en%o%onticmotors in root canal instrumentation . 7racture of nickel-titanium rotary les is an iatrogenic error which can seriously 3eopardiCe root canaltherapy. !f a high-tor=ue motor is used, the instrument-speci c limit-tor=ue 5fracturelimit6 is often exceeded, thus increasing the risk of intracanal failure. A possiblesolution to this problem is to use a low-tor=ue endodontic motor which operatesbelow these alues. !f the tor=ue is set 3ust below the limit of elasticity for eachinstrument, the risk of fracture is likely to be markedly reduced. The purpose of thispaper was to discuss mechanical properties of *iTi rotary instruments, the rationalefor selecting low tor=ue alues, and to use clinically a new endodontic motor 5step-motor6 which operates below the limit of elasticity of each rotary le. The step-motor was found to be helpful in reducing the risk of instrument fracture.!rre ersible material damage 5plastic deformation6 and instrument fracture wererarely seen. ow-tor=ue instrumentation also increased tactile sense and,conse=uently, mental awareness of rotary instrumentation.

22. (omparati+e analysis of cur+e% root canalpreparation usin/ nic0el-titanium instruments it$or it$out A .

The purpose of this study was to examine the e ect of the use of D:TA as a rootcanal irrigant in cur ed root canals instrumented with nickel-titanium 5*i-Ti6instruments. Twenty extracted maxillary molars were selected. 9esiobuccal rootswere used. Teeth were mounted in self-curing acrylic resin bases to allowstandardiCed angulation of the initial and nal radiographs. The preinstrumentation

radiographs were made with a S"1 le in the canal. The canals were instrumentedwith *i-Ti instruments by the step-back techni=ue, using or not using D:TA. Thepost-instrumentation radiographs were made with a S>% le in the canal. The lmswere pro3ected 5x"% magni cation6, drawn, and superimposed. *i-Ti instrumentsused with D:TA were less e ecti e in maintaining the original path of cur ed canals.

23. Dcacy of ;uantec rotary instruments for/utta-perc$a remo+al .

%


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A MF The purpose of this study was to e aluate Puantec )2 rotary instruments forremo al of gutta-percha during retreatment of straight root canals.M H 7 89 F The root canals of >% central incisors were instrumented andobturated before the teeth were randomly di ided into three groups of "%specimens each. Puantec )2 rotary instruments and a "$F" reduction handpiecepowered by an electric motor were then used to remo e the gutta-percha andsealer from canals. A di erent speed was used in each group 5group ", >1% r.p.m.Ggroup , 0%% r.p.m.G and group >, "1%% r.p.m.6. The followings factors weree aluatedF time taken to reach working length, time for gutta-percha remo al, totaltime, apically extruded material during lling remo al and number of fracturedinstruments. adiographs were taken after the lling remo al and after the canalwall cleanliness was e aluated. The teeth were groo ed longitudinally, di ided, andthe walls of each half were e aluated isually for cleanliness. They were thendigitiCed using a scanner and the residual debris measured.' S:7 S F The group in which a speed of "1%% r.p.m. was used had signi cantlyfaster treatment than the other groups. The amount of apically extruded materialwas not signi cantly di erent between groups. The only signi cant di erence

between groups for canal cleanliness was the middle third by radiographice aluationF the group of >1% r.p.m. had larger amount of debris than the others. !ngroup ", six instruments fracturedG in group , four instruments fracturedG and ingroup >, one instrument fractured.( N(7:S N )F 2leanliness and residual debris were e=ui alent for each group,but the use of "1%% r.p.m. speed was more rapid and fewer instruments fractured.

24. (yclic fati/ue of ro)le rotary instrumentsafter simulate% clinical use. A MF The purpose of this study was to e aluate cyclic fatigue of was the controlgroup. *a+2l at a concentration of .14 was used as an irrigant. Dach set ofinstruments was steriliCed before each use.' S:7 S F The < ! siCe H% demonstrated the lowest incidence of rotations tobreakage. +ne-way analysis of ariance and TurkeyVs @): test showed statisticallysigni cant di erences among di erent le siCes within each group.( N(7:S NS F The results showed that dry heat steriliCation and simulatedclinical use in the presence of *a+2l did not lead to a decrease in the number ofrotations to breakage of the les.

25. Step-=y-step %escription of a rotary root canalpreparation tec$ni ue. 2 !*!2A TD2@*!P(DF )ince the introduction of nickel-titanium in endodontics,se eral canal preparation techni=ues in ol ing the use of rotary instruments ha ebecome popular. )uch engine-dri en rotary instruments rotate between "1% and

%%% r.p.m. and may be high or low tor=ue orientated. This paper describes one

"


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such engine-dri en system called the % minutesG the " group & samples were exposed to 0 cycles of steriliCation for >%minutesG the " group 2 samples were not steriliCed and ser ed as a control group.2hemical compositions of the near surface layers of samples of each group weredetermined by means of Auger spectroscopy.' S:7 S F The instruments that underwent the greatest number of steriliCations5group A6 showed in-depth distributions of chemical composition that were di erent


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from those seen in the control groupG this was the result of greater amounts oftitanium oxide on the surfaces of the steriliCed instruments. The les of group Ashowed a decrease in cutting eMciency in comparison with those of the controlgroup.( N(7:S NS F +n the basis of this research on nickel-titanium les, wedetermined that repeated steriliCations under autocla e alter the super cialstructure of such instruments.

2!. A comparison of instrumentation usin/ Na+i?e>an% ro)le nic0el-titanium en/ine-%ri+en rotaryinstruments.

This study was designed to compare the changes in canal con guration resultingfrom instrumentation by either


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( N(7:S NS& The results indicate the necessity of mastering this rotary canalpreparation techni=ue, and the importance of impro ing competence throughlearning and experience.

3#. S$apin/ an% cleanin/ t$e root canal system& ascannin/ electron microscopic e+aluation of a neinstrumentation an% irri/ation tec$ni ue.

The purpose of the present scanning electron microscopic study was to in estigatethe eMcacy of a combination of D:TA, *a+2l, and surface-acti e irrigating solutionsduring and after root canal preparation with >>.>> rpm. Theinstruments were e aluated after instrumentation for separation andJor distortion. The results of this study were statistically signi cant and indicate that le distortionandJor separation is four times as likely to occur at >>>.>> rpm s. "$$.$0 rpm.

32. Eear of nic0el-titanium li/$tspee% instrumentse+aluate% =y scannin/ electron microscopy. (sed rotary nickel-titanium instruments re=uire fre=uent replacing. This laboratorystudy e aluated defects of ightspeed cutting tips before and after usage. Theinstruments were xed into custom-made holders, the cutting heads photographedin a scanning electron microscope at x" % to xH%% magni cation at preset points

around the cutting tip 5#%, "8%, 0% and >$% degrees6 and head-on. !nstrumentsiCes % to > .1, >1 to $%, and $1 to "%% were used in #, "8, and >$ canals,respecti ely, and autocla ed after shaping e ery third root canal. The usedinstruments were cleaned and then reexamined in a scanning electron microscopeas before. The presence of "" types of conditions was scored from the pre- andpostusage photographs. *o instruments fractured during the test, but all the cuttingheads had one or more imperfections, e en before usage. The presence of debris,pitting, and metal strips changed signi cantly. !mperfections were found on new andused ightspeed cutting heads, indicating the general diMculty in machining defect-

H


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free nickel-titanium rotary instruments. @owe er, high =uality should remain a goalto impro e instrument eMciency.

33. A comparison of molar root canal preparationusin/ stainless-steel an% nic0el-titaniuminstruments. .7ifty-four extracted human mandibular molars were embedded and sectioned at twole els. The reassembled mesial root canals were prepared with stainless-steel hand?- les 57lexo les6 and either *iti ex or 9ity nickel-titanium hand ?- les using apush-pull anticur ature ling techni=ue. Dach of the three experimental groupscontained >$ mesial canals randomly distributed. )uperimposed pre- and post-instrumentation cross-sectional root images were magni ed using astereomicroscope and transferred to a computer for measurement and statisticalanalysis. The direction and extent of canal center mo ement were e aluated. At theapical le el, the groups produced no signi cant di erence of direction of canalcenter mo ement. !n cer ical sections, all groups tended to mo e in a distolingual

direction. The three groups, howe er, produced no signi cant di erence in thecer ical sections in the extent of canal center mo ement. !n apical sections, *iti exproduced the least canal center mo ement.

34. S$apin/ a=ility of .#4 an% .#6 taper roFilerotary nic0el-titanium instruments in simulate%root canals.A MF The aim of this study was to determine the shaping ability of


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ori ce. + erall, transportation was towards the outer aspect of the canal except atthe beginning of the cur e.( N(7:S NS F (nder the conditions of this study the combined use of .%H and .%$ taper 1. ocation of contact areas on rotary


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made with a new force analyser de ice, the Dndographe, that was e=uipped with aholder to record and generate graphs of the ertical forces and tor=ue exertedduring the preparations. These preparations was performed by endodontists orstudents either with a series of instruments of increasing siCe or with the crown-down pressureless techni=ue.' S:7 S& The mean alues for the endodontists of the generated ertical forcesand tor=ue aried, respecti ely, from H to $* and from 0."%1 to " ."%1 *m for thestep-back techni=ue and from .# to H. * and from "8."%1 to %."%1 *m for thecrown-down techni=ue. This suggested that the crown-down techni=ue generatedlower stresses 5lower tor=ue and lower ertical forces6, although these ndings alsodepend on the shape of indi idual canals. The students initially showed wide

ariations in generated forces, with signi cantly lower ertical force the tor=uealues. &y the end of the experimental sessions their alues were similar to those of

the endodontists, which indicated impro ement in the eMciency of manipulation.( N(7:S NS F 7urther work is needed to in estigate the relationship betweenthe force and the tor=ue data from this study and the incidence of instrumentfracture with the two techni=ues, as the clinical implications are considerable. !tmust be noted, howe er, that the Dndographe is unable to take into account thecutting eMciency of the instruments. The use of graphs pro ides a new approach tothe analysis of mechanical preparation.

3 . $e remo+al of t$e smear layer usin/ t$e;uantec system. A study using the scanning electronmicroscope.A M& The aim of this study was to determine the ability of the Puantec )eries %%%rotary nickel-titanium endodontic system to remo e dentinal debris and smear layerproduced during canal preparation.M H 7 89& A rst group 5control6 of " cur ed root canals was preparedusing con entional manual instruments and the step-back techni=ue. A secondgroup of " cur ed root canals was instrumented using the complete Puantecse=uence according to the manufacturerVs instructions. !n both groups, irrigationwas performed using a >4 *a+2l solution. The canal walls were obser ed under ascanning electron microscope and the coronal, middle and apical thirds of eachcanal photographed at a magni cation of 1%%. The iews were di ided into "%subareas by o erlaying a grid, and the absence or presence of a smear layer wasrated and scored on three appearances using the scale described by 2iucchi et al.5"#8#6.' S:7 S& The scores were higher 5i.e. less debris was present6 in the middle third5< O %.%%%"6 and in the apical third 5< O %.%%%"6 of canals prepared with thePuantec system when compared with those prepared with ?- les. *e ertheless, incanals prepared with Puantec instruments, the scores were signi cantly higher inthe coronal third compared with the apical third 5< O %.%%16.( N(7:S NS& The Puantec rotary system produced cleaner canal walls thancon entional manual instrumentation, particularly in the middle and apical thirds.

This nding may imply that stresses applied to the cutting regions of Puantecinstruments by accumulation and compression of the smear layer are minimiCed.

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3!. S$apin/ a=ility of ;uantec Series 2### rotarynic0el-titanium instruments in simulate% rootcanals .

The aim of this laboratory based study was to determine the shaping ability of

Puantec )eries %%% nickel-titanium rotary instruments in simulated root canals. Atotal of H% canals with four di erent shapes in terms of angle and position of cur ewere prepared with Puantec )eries %%% instruments using the techni=uerecommended by the manufacturer.


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a erage 1.0 min and was signi cantly in uenced 5< O %.%"6 by canal shape. +neinstrument fractured and three siCe nine instruments deformedG howe er, canalshape did not in uence signi cantly instrument failure. All of the canals remainedpatent, none became blocked with debris. The ma3ority of the canals maintainedworking distance 5 $ out of H%6, howe er the mean change in length di eredsigni cantly 5< O %.%16 between canal types. + erall, canals with H% degrees cur eslost length whilst those with % degrees cur es gained in length. Dxamination ofintracanal impressions re ealed that preparation with Puantec )eries %%%instruments produced canals with de nite apical stops, smooth canal walls andgood ow and taper. @owe er, the =uality of apical smoothness and ow wasin uenced signi cantly 5< O %.%%%"6 by canal shape with specimens ha ing H%degrees canals displaying less desirable =ualities. (nder the conditions of thisstudy, Puantec )eries %%% rotary nickel-titanium instruments prepared simulatedcanals rapidly, safely and with good three-dimensional form.

4#. ummer, S$apin/ a=ility of Mity 'oto 36#%e/rees an% Na+i?e> rotary nic0el-titaniuminstruments in simulate% root canals . The aim ofthis study was to determine the shaping ability of 9ity oto >$% degrees and*a i ex nickel-titanium rotary instruments in simulated root canals. !n all, 8% canalsconsisting of four di erent shapes in terms of angle and position of cur ature wereprepared by 9ity oto >$% degrees and *a i ex instruments using the techni=uesrecommended by the manufacturers. This study describes the eMcacy of theinstruments in terms of preparation time, instrument failure, canal blockages,change in canal length, and three-dimensional canal form. + erall, the meanpreparation time for canals prepared using 9ity instruments was 1.## min and 1.8"min when using *a i ex instruments. 2anal shape had no signi cant e ect on thespeed of preparation with either instrument. *o instruments separated during the

studyG howe er, "H *a i ex and 9ity instruments were deformed. 2anal type didnot in uence signi cantly the tendency of either instrument to deform. *one of thecanals became blocked with debris during preparation. The ma3ority of canalsprepared by both instruments retained their original working length, and there wasno signi cant di erence between the canal shapes in terms of the mean loss ofdistance or category of distance change for either instrument. Apical stops as

3udged from intracanal impressions were present in # 50 46 of the canals preparedwith 9ity instruments and in >> 58 46 of those prepared with *a i ex instruments.@owe er, the ma3ority were 3udged to be of poor =uality. )igni cant di erences 5p O%.%16 were noted in the =uality of apical stops between the canal types using 9ityinstruments. 2anals prepared with 9ity and *a i ex instruments were found to besmooth in the apical half of the canal in approximately one-half of the specimens

and coronally in nearly all canals. *either instrument produced horiContal orlongitudinal groo es. 7a orable ow characteristics were apparent in o er one-halfof the canals prepared with 9ity oto instrumentsG howe er, nearly all specimenshad poor taper. 7low and taper were generally poor in the specimens prepared with*a i ex instruments. (nder the conditions of this study, 9ity oto >$% degrees and*a i ex instruments prepared canals rapidly, with no separations, canal blockages,and with minimal change in working length. Although, ow was ade=uate using 9ity

oto >$% degrees instruments, the taper characteristics were less than idealcompromising the three-dimensional form of the canals. *a i ex instruments, while

#


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creating better taper, produced poorer ow characteristics. The results suggest thatwhen using 9ity oto >$% degrees or *a i ex instruments, the stepdown se=uenceshould be modi ed to impro e canal ow and taper. Alternati ely, an instrumentwith increased taper should be used to complete preparation before obturation.

41. +aluatin/ t$e si%,> .1 and H1 were examined. Dxcept for one cutting head of siCe >%, all the recordeddiameters were o ersiCed compared to the expected diameter and the permittedtolerance 5YJ- %.%%1 mm6. trusion of %e=ris usin/ t o $an% an%t o rotary instrumentation tec$ni ues.

The purpose of this study was to in estigate the =uantity of apical debris producedin itro using two hand and two rotary instrumentation techni=ues. )ixty minimallycur ed, mature human mandibular premolars with single canals were di ided into Hgroups of "1 teeth each and prepared using step-back instrumentation with ?- les,balanced force with 7lex- les, ightspeed nickel-titanium instruments, or .%H taper


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conicity. Dight molars and eight premolars with a total of >$ radicular canals wereexamined. The types of


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instruments are gaining in popularity. This paper in estigated the corrosion ofnickel-titanium ightspeed instruments in "4 and 14 *a+2l solutions. Theinstruments were immersed in ultrasonicated *a+2l solutions for arying times upto " h. 2orrosion was determined by electrothermal absorption spectrometry in "%%micro ali=uots of *a+2l. &ackground contamination of nickel in the "4 and 14*a+2l solutions used was low, but high enough to interfere in detecting anyincreases in nickel after immersing the instruments. The amounts of titaniumrecorded in the "4 *a+2l solutions were insigni cant. @owe er, a statisticallysigni cant amount of titanium was detected from the ightspeed instruments afterimmersion times of >% and $% min in 14 *a+2l. 2linically such instruments do notha e an Vin situV time of >% min, and this corrosion may be considered irrele antclinically.

46. orsional properties of nic0el-titanium +ersusstainless steel en%o%ontic )les.

The purpose of this study was to e aluate and compare the torsional properties ofstainless steel ?-type .% taper and nickel-titanium (-type .% and .%H taperinstruments. Torsion tests were performed on all three designs of instrumentsaccording to A*)!JA:A speci cation number 8. 7or each design, % instruments ofeach of three siCes 5"1, 1, and >16 were tested. The three parameters measuredwere maximum tor=ue, tor=ue at failure, and angular de ection. )tainless steel ?-type .% taper and nickel-titanium (-type .% and .%H taper instruments met orexceeded speci cation standards for maximum tor=ue. They also satis ed and farexceeded the standards for angular de ection at the failure point. The stainlesssteel instruments showed no signi cant di erence between maximum tor=ue andtor=ue at failure, whereas both of the nickel-titanium instruments showed asigni cant di erential between maximum tor=ue and tor=ue at failure.

4 . S$apin/ a=ility of roFile.#4 aper Series 2"rotary nic0el-titanium instruments in simulate%root canals. The aim of this study was todetermine the shaping ability of


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the beginning of the cur e, transportation was more balanced between inner andouter. 9ean absolute transportation, ignoring direction, was generally greater in H%degrees canals and in those with the cur e beginning 8 mm from the ori ce. +fparticular importance was the nding that excessi e resin was remo ed from theouter aspect of the canal at the apex of the cur e which was often associated withirregular widened areas or ledges. This is in contrast to the pattern of tissue remo alfound with stainless steel hand instruments where more resin is remo ed from theinner aspect of the canal at the apex, to create a danger Cone.

4!. S$apin/ a=ility of N n/ine an% McCim rotarynic0el-titanium instruments in simulate% rootcanals.

The aim of this study was to determine the shaping ability of *T Dngine and 9cBimnickel-titanium rotary instruments in simulated root canals. !n all, H% canalsconsisting of four di erent shapes in terms of angle and position of cur ature wereprepared by a combination of *T Dngine and 9cBim instruments using the

techni=ue recommended by the manufacturer.


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>H


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>1


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!* & !D7 There Are )ome Types +f otary *iTi

!nstrumentsF". )ystem & !ntroduced in Zanuary %% by r. o$n Mcspa%%en The system has F1. canal shaping les which are a ailable with aMxed taper of.% ,.%H or.%$.The.%tapered ?> lesare a ailable in "1-H1 tip siCe sand ", 1 and >%mm length.the.%Hand .%$ tapered ?> les are a ailable in "1-$% tip siCes and ", 1 and >%mm length.2. slightly positi e rake angle .

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3. a ariable core diameter. 4. threeradial lands with a relief behind two of the three.

5. asymmetrically placed radial lands as well as une=ual land widths , ute widthand ute depth.

6. An Axxess handle design, which shortens the le handle by approximately 1 mmwithout a ecting the working length of the le.

. A ariable ute pitch . ! . A color coding to distinguish between di erentsiCes and tapers. ". Asafe ended cutting tip.

1#. ?>Dnhanced Taper &ody )haping5DT&)6 les ha e recently been introducedwith an enhanced taper of .%8, ."% and ." .The DT&) can act as canal shaping lesand ori ces opener .

3.FKG S-Apex

Rotary endodonti in!tr"#ent! $it% in&erted taper

The FKG S-Apex line is the ideal complement for endodontic treatments, particularly during the canal preparation near the apical area. The S-Apex is intended to eliminate the risks of tip breakage of standard rotary NiTi instruments.Ex '"!i&e te %ni a' inno&ation! are at t%e root o( FKG S-Apex !" e!!

!. Negati"e conic shape #hich ensures a cylindrical preparation.$. %re-determined eakest& point at !' mm of the tip to a"oid any risks of breaking the tip.(. )ndulating cutting edges #hich pre"ent the scre#ing on*blocking effect and ha"e the ad"antages

of an extremely lo# operating tor+ue.. Sharp cutting edges for an impro"ed efficiency #ith fe#er instruments.. lectro-chemical treatment better resistance to torsion and metal fatigue.

'. xclusi"e rounded Safety tip for a perfect control, staying clear of lateralcanals or for getting round an obstacle.

>0
http://www.fkg.ch/e/instruments/apex.asp


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).GT ROTAR*it need+ !. A high-tor+ue, slo#-speed hand piece is re+uired.$. /perate the hand piece at (00 1%2 3re"olutions per minute4.(. )tili5e minimal apical pressure.

. 6re+uently lubricate the canal throughout the procedure.

. xercise caution in the apical area and around significant cur"atures.

,GT Rotary In!tr"#ent! o#e in (o"r pri#ary !i e! ea % $it%/0 ## dia#eter tip!.

.!$ taper .07 taper

.!0 taper .0' taper

,a'!o in t%ree a e!!ory !i e! ea % %a&in1 a .2/ taper.

( tip 80 tip 0 tip

.4UANTEC

5.6ERO

7.LIG6T S8EED

and t%ere are #any type! !ti'' "nder re!ear %.

Ni Ti loai

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