Ravi Varma Sir Publication

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E N D O D O N T O LO G YE N D O D O N T O LO G YE N D O D O N T O LO G YE N D O D O N T O LO G YE N D O D O N T O LO G Y

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Evaluation of effici ency of th ree N iTi instr um ents in

removi ng gutt a-percha from root canal dur ing retreatm ent

- An in vi t ro study

POO JA LALIT *

N A V N EET GO D A R A * *

K . RA V I V A RM A * * *

* Post-Graduate Student, * * Assistant Professor, * * * Principal, Professor and Head, Department of Conservative Dentistry and Endodontics, Jaipur Dental College, Dhand,

Jaipur, Rajasthan

In t roduct ion

The key to successfu l end odo n t i c t reatm en t i s

to tho rou gh ly d eb r ide the cana l sys tem o f i n fec tedo r necro t i c p u lp t i ssue and m ic roo rgan ism s, and to

comple te ly sea l the cana l space, thus prevent ing

the pers is tence o f in fect ion and/or re- in fect ion o f

the pu lp cav i ty .1 Root cana l therapy, desp i te having

h igh degree o f success, may not lead to desi red

respon se, and fai lu re m ay occu r .2 ,3 W hen roo t cana l

t h e r a p y f a i l s , t r e a t m e n t o p t i o n s i n c l u d e

con vent io na l re t reatm ent , per i rad icu lar surgery, orex t rac t i on .3 , 4

The no n-surg ica l app roach is the treatm ent o f

cho ice w hen access to the roo t cana l is feasib l e

and i t i s the m os t conse rvat i ve m e thod . 5

ABSTRACT

Object ives - Th is study w as und er taken to eva lua te the e f fi c iency o f th ree ro tary n i c ke l t i t an ium ins t rum ents and

hand i ns trum enta tion in rem ovi ng gu t ta-pe rcha and seale r f rom roo t cana ls.

Stu dy d esign - 60 ex t rac ted hum an m axi l l a ry cen t ra l and l a te ral i nc i so rs were ins t rumen ted w i th K- fi l es and f i l l ed

us ing la te ral com pact ion o f gu t ta-pe rcha (GP) and A H P lus sea ler . The tee th w ere rando m ly d i v id ed in to fou rexper im en ta l g roups o f 15 spec im ens each . Remov a l o f gu t ta-pe rcha w as pe r fo rm ed w i th the fo l l o w ing dev ices

and techn iques: ProTaper U n iv e rsa l ro ta ry re t rea tm en t system, R-Endo re t rea tm en t f i l es, M tw o re t reatm en t f i l es

and H edstrom f i l es. T ime to reach w ork in g leng th and to el im ina te f i l l i ng m ater ia l was a l so reco rded . The

spec im ens w ere rendered t ransparen t fo r eva lua t ion o f the a rea o f the rem a in ing gu t ta-pe rcha /sea le r under

ste reom icroscope a t 6X m agn i f i cat i on . Pho tographs w ere taken fo r fu r the r analys i s us ing com pute r im age ana lys i s

p rogram. The resu l t s w ere stat i st i ca l l y ana lyzed us ing AN O VA and Bon fe r ron i tes t.

Results - The ProTaper U niv ersal re t reatm ent system resul ted i n a sm al ler percen tage of canal area covered b y

residua l G P/sea ler than in o the r g roup s, bu t a sign i f i can t d i f fe rence w as found be tw een ProTaper and M tw o g roup

a n d b e tw e e n Pr o T ap e r an d H e d st ro m g r o u p (P < 0 . 0 0 1 ) . T h e M e an o p e r at i n g t i me w a s m i n i m u m w i t h M t wo

g ro u p ( 5 .0 8 ± 0 . 6 4 m i n ) w h i l e i t w a s f o u n d t o b e m a x i m u m w i t h h an d f i l es (7 . 9 3 ± 1 . 0 3 m i n ) .Conclusion - I t w as con c lud ed tha t a l l t est techn iq ues le ft gu t ta-pe rcha /sea ler rem nan ts w i th in the roo t cana l . The

ProTaper Un ive rsa l ro ta ry re t rea tmen t sys tem p roved to be an e f f i c ien t me thod o f removing gu t ta -pe rcha and

sea ler f rom m axi l l a ry cen t ra l and la tera l i nc i so rs.

Keywords: Gutta-percha, Root Canal Scaler , Rotary Inst ruments

O ri ginal Research



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T h e c l i n i c a l s u c c e s s r a t e o f e n d o d o n t i c

re t reatm ent has been estim ated to vary b etw een

5 0 - 9 0 % .6 , 7 T h e v a r i a b i l i t y o f t h e o u t c o m e i n

endodont ic re t reatment is re la ted to pat ient ’s age

and th e type o f teeth t reated, 8 presence of al terat ion

in n atura l course o f the root cana ls, 7 the possib i l i ty

o f removing the corona l restora t ion to access the

p u l p c h a m b e r 9 a n d p o s s i b i l i t y o f r e p a i r i n g

patho log ic and ia t rogen ic defects . 1 0 Preoperat ive

pe r fo ra t i ons , ap i ca l pe r iodon t i t i s and qua l i t y o f

prev ious f i l l ing mater ia ls are the st rong pred ic tors

fo r the ou tcom e o f endo don t i c ret rea tm en t .1 0 , 1 1

The ma in goa l o f o r thog rade re t rea tmen t i s

regain i ng access to the ap ica l fo ramen b y co m ple te

remo val o f roo t cana l f i l l ing m ater ial thu s fac i l i tat ing

suf f ic ient c lean ing and shap in g o f the com ple te root

cana l system and f i na l o b tu ra t i on . 1 2

O ne o f the greatest techn ic a l d i f f i cu l t ies faced

b y e n d o d o n t i s t s i s t h e c o n v e n t i o n a l r o o t c a n a l

re t rea tmen t , as the f i l l i ng ma te r ia l s rep resen t a

m e c h a n i c a l b a r r i e r t h a t c a n o f t e n r e q u i r e

cons ide rab le t im e and e f fo r t to remo ve .1 3

M a n y t e c h n i q u e s h a v e b e e n d e sc r i b e d f o r

remo val o f gut ta-percha. These inc lud e end od ont ic

hand f i les com bined w i th heat or chem ica l so lvents,

eng ine-dr iven ro tary f i les, u l t rason ic inst ruments,

h e a t c ar r y i n g i n st r u m e n t s, p a p e r p o i n t s w i t h

chemica ls and lasers. 1 4 , 1 5 M o st r ec e n t l y f l e x i b l e

r o t a r y n i c k e l - t i t an i u m (N i T i ) f i l e s h a v e b e e ni n t r o d u c e d .

V a r i o u s n i c k e l - t i t a n i u m ( N i T i ) r o t a r y

endodon t i c i ns t rumen ts have been deve loped to

fac i l i ta te c lean ing and shap ing o f root cana ls . In

o rde r to im prove safe ty p repa ra ti on and to p repa re

m o r e a p p r o p r i a t e s h a p e s , a d v a n c e d i n s t r u m e n t

designs w i th no n-cut t in g tips, rad ia l lands, vary in g

tapers and rake ang les, and ch anging p i tch len gths

have been deve loped . 1 6

T h e a i m o f t h i s st u d y w a s t o e v a l u a te th e

e f fi c i e n c y o f t h r e e r o tar y N i T i i n st r u m e n ts, t h e

P r o T a p e r (D e n t sp l y - M a i l l e f e r , B a l l a i g u e s ,

Sw i tze r land ) , M tw o (Sw eden & M ar ti na , Padov a ,

I ta ly), R-End o (M icro -M ega, Besancon , France) , in

t h e r e m o v a l o f g u t t a - p e r c h a d u r i n g r o o t c a n a l

re t rea tmen t i n compar i son w i th hand ins t rumen ts

u s i n g H e d st r o m f i l e s (D e n t sp l y M a i l l e fe r ,

Ba i l l a igues, Sw i tze r land ). The t im e to reach the

w ork ing l eng th and to e l im ina te f i l l i ng ma te ria l w as

a lso recorded and eva luated.

M aterials and M ethods:Select ion of teeth:

Six ty max i l l a r y cen t ra l and la te ra l i nc i so rs

w i th m a tu re roo t ap i ces and s ing le canal ex t rac ted

fo r pe r iodo n ta l reasons w ere used . Tee th w i th roo t

car ies, cracks on the ro ot sur face, curv ed roo ts and

e x t r e m e l y c a l c i f i e d c a n a l s w e r e ex c l u d e d . So f tt i ssue and ca l cu lus were removed mechan ica l l y

f rom the roo t su r face .

In i t i a l roo t cana l t rea tm en t :

Each too th w as deco ron a ted a t the cemen to -

e n a m e l j u n c t i o n ( C EJ) w i t h a d i a m o n d d i sc t o

faci l i tate straight l in e access for in strum entation and

ob tura t ion . Proper access w as estab l ished and the

ap ica l patency w as determ ined b y inser t ing an ISO# 1 0 K - f i l e un t i l i t appeared a t the ap ica l fo ram en .

W ork ing l eng th w as de te rm ined by p lac ing a si ze

15 K-f i le in to the cana l u nt i l i t app eared a t the ap ica l

foramen; th is length w as m easured and the w ork in g

leng th w as se t 0 .5m m sho r t o f th i s d i stance . A

ci rcu m ferent ia l ‘stag ing p la t form ’ w as estab l ished

near the cana l o r i f i ce, ensu r ing a un i fo rm w ork in g

P O O JA L A L I T , N A V N E E T G O D A R A , K . RA V I V A R M A



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l e n g th ( W L ) o f 1 5 m m i n e ac h t o o th .

C lean ing and shap ing w ere pe r fo rmed u sing

a m od i f i ed step -back f l a re techn iq ue . The co ro na l

th i rd w as f l ared w i th si zes 1–3 G a tes G l idden d r i l l s

(D entsp ly M ai l le fer). Canal preparat ion w as car r ied

o u t b y t h e s e q u e n t i a l u se o f K - fi l e s (D e n t s p l y

M ai l le fer , Bal la igues, Sw i tzer land ) up to s ize 30 a t

work ing l eng th ; a s tep -back p rocedure i n 1 mm

increm en ts to a f i l e si ze 50 w as then ca r r i ed o u t .

U pon w i thd raw a l o f each inst rum en t , cana ls w ere

i r r i ga te d a l t e r n a t i v e l y w i t h 5 . 2 5 % so d i u m

h y p o c h l o r i t e ( N a O C l ) a n d 1 7 % e t h y l e n e d i a m i -

nete traacet ic ac id (ED TA ) .

Roo t cana l ob tu ra t i on :

The roo t cana l o f each too th was d r ied w i th

paper po i n ts and ob tu ra ted w i th gu t ta -pe rcha (G P)

and A H P lus sea ler (D en tsp l y , D eTrey , Kon stanz ,

G e r m a n y ) u s i n g a c o l d l a t e r a l c o m p a c t i o n

t e c h n i q u e . T h e c o r o n a l a c c e s s c a v i t i e s o f t h e

s p e c i m e n s w e r e s e a l e d w i t h t e m p o r a r y f i l l i n g

m ate r ial (Cav i t , D eTrey D en tsp l y ) . The qua l i t y o f

the roo t f i l l i ngs w as con f i rm ed us ing pos tope rat i ve

r a d i o g r a p h s . A l l t e e t h w e r e st o r e d a t r o o m

temp eratu re fo r 30 days to a l l ow com p le te se t ti ng

of the sealer.

Retreatment Techn iques:

A l l the spec im ens w ere random ly d i v id ed in to

fou r expe r im en tal g roup s (n= 4 ) w i th 15 spec im ens

each fo r rem ova l o f gu t ta -pe rcha by u sing on e o f

the fo l l ow ing techn iques :

Group A: ProTaper U niv ersa l re t reatment f i l es

Group B: R-End o re t reatmen t f i les

Group C: M tw o ret rea tm en t f i l es

G r o up D : H e d st ro m f i l es

A l l i ns trum en tat i on o f the ProTaper U n ive rsa l

retreatm ent f i les, M tw o retreatm ent f i les and R-End o

r e t r ea tm e n t f i l e s w a s p e r f o r m e d u s i n g X - sm a r t

e n d o d o n t i c m o t o r w i t h 1 : 2 0 r e d u c t i o n g e a r

handp iece (N iT i Con t ro l , D en tsp l y ) ope ra ted a t a

cons tan t speed o f 500 rpm .

Group A: ProTaper U niv ersal retreatm ent f i les

The roo t cana ls w ere i nst rum en ted in a c row n

dow n sequence as recom m ended . ProTaper D 1 f i l e

(si ze 30 , 0 .09 tape r , l eng th 1 6m m ) was used to

remo ve f i l l i ng ma te ria l fr om the co rona l po r t i on o f

the roo t cana l , w hereas the m idd le and ap ica l th i rd

o f the cana ls w ere i nst rum en ted us ing P ro tape r D 2

(si ze 25 , 0 .08 tape r , l eng th 18m m ) and P roTaper

D 3 f i l e s (si z e 2 0 , 0 . 0 7 t a p e r , l e n g t h 2 2 m m ),

respect iv e ly , us ing a bru sh in g act ion w i th la teral

p ressing m ovem en ts. P roTaper D 3 f i l e w as taken

to t h e w o r k i n g l e n gth .

Group B: R-End o re t reatm ent f i les

R-End o re t reatm ent f i les w ere used in a gent le

in and ou t m o t ion o n the cana l w a l l s acco rd ing to

m anu fac tu re r ’ s i ns truc t i on . A m anua l f i l e Rm w as

used f i rst to re loc ate the cana l o r i f i ces, then the Re

(s ize 25, 0 .12 taper ) inst rument removed the f i rs t

2 -3m m o f the f i l l i ng . R1 (si ze 25 , 0 .08 tape r ) and

R2 (size 25 , 0 .06 taper ) w ere used to on e-th i rd and

t w o - th i r d s o f t h e e st i m a te d w o r k i n g l e n g t h

respect iv e ly . F ina l ly R3 (size 25 , 0 .04 taper ) w as

used a t the w ork ing l eng th to com p le te the remo va l

o f f i l l i ng m a te r ial f r om the canal .

Group C: M tw o ret rea tm en t f i l es

The M tw o re t rea tm en t f i l es w ere al so used

a c c o r d i n g t o t h e m a n u f a c t u r e r ’ s i n s t r u c t i o n s .

Remova l o f the roo t f i l l i ng ma te r ia l s begun w i th

E V A L U A T I O N O F E F FI C I EN C Y O F T H R EE N I T I I N ST R U M E N T S I N R E M O V I N G G U T TA - P ER C H A F R O M R O O T C A N A L D U R I N G R ET R EA T M E N T - A N I N V I T R O S TU D Y



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the use o f s i zes 1–3 Ga tes G l idden d r i l l s i n the

co ron a l po r t i on . The cana ls w ere i ns trum en ted in

a s imu l taneous techn ique to the work ing l eng th

us ing M tw o R2 (si ze 25 , .05 tape r) i n a b rush ing

act ion w i th la teral p ressing m ovem ent. Progression

o f the ro ta ry f i l es w as pe r fo rmed by app ly in g sl i gh t

ap ica l p ressu re and f requen t l y remo v ing the f i l es

to i n spec t the b lade and c lean the deb r i s .

Group D : H e d st ro m f i l es

Remova l o f the roo t f i l l i ng ma te r ia l s begun

w i th the use o f si zes 1–3 G a tes G l idd en d r i l l s i n

t h e c o r o n a l p o r t i o n . W i t h x y l e n e as a so l v e n t ,

H edstrom f i les (D entsp ly M ai l le fer ) sizes 30, 25 and

20 w ere used in a c i r cumfe ren t ial m o t ion to remov e

the roo t f i l l i ngs f rom the m idd le and ap ica l po r t i ons

un t i l the o r ig ina l w o rk ing l eng th had been reached .

U pon w i thd raw a l o f each ins trumen t , adheren t

deb r i s w as remo ved f rom the f i l es and cana ls w ere

i r r i g a t e d w i t h 5 . 2 5 % N a O C l a n d 1 7 % E D T A .

Ret rea tm en t w as com p le ted w hen no deb r i s o f G P/sea ler w as v is ib le o n th e sur face o f in st rum ents and

cana l w a l l s w ere sm oo th .

Evaluation

a) Rem aini ng gutt a-perc ha and sealer

A l l sp e c i m e n s w e r e re n d e r e d t r a n sp a r e n t

acco rd ing to the fo l l ow ing techn ique described by

Schi r rm eister e t a l . 1 7

The spec im ens w ere deca lc i f i ed i n 5% n i t r i ca c i d f o r 7 2 h o u r s , w a sh e d f o r 4 h o u r s an d

dehyd ra ted in i nc reasing co ncen t rat i ons o f a l coho l

(8 0 % , f o r 1 2 h o u r s, 9 0 % fo r 1 h o u r s a n d 9 9 % fo r

3 ho urs). The roots w ere cleared sub sequ ently u sing

methysa l icy la te .

The G P/seale r remn an ts on the cana l w a l l s

w ere im aged on a b lack backgroun d in m esio-d is ta l

(M -D ) d i rec t i on us ing a ste reom ic roscope a t 6X

m agni f icat ion. Each cana l was d iv i ded in to co rona l ,

m idd le and ap ical th i rds f rom the ‘ stag ing p la t fo rm ’

to the termi nu s o f the ap ica l preparat ion . The area

of G P/sea ler rem nants as w el l as the cana l w a l l w as

m e a su r e d u s i n g i m a g e a n a l y z e r so f t w a r e

(D ig iPro4 .0 ) .

b) O perat ing t ime

The operating t ime w hich e lapsed f rom in i t ia l

G P remo va l w i th the f i r st i nst rum en t un t i l r each ing

the o r ig ina l w o rk ing l eng th w as reco rded as T1 .T h e t i m e r e q u i r e d t o a c h i e v e s a t i s f a c t o r y G P

r e m o v a l a ft e r r e ac h i n g t h e w o r k i n g l e n g th w a s

reco rded as T2 . To ta l t im e fo r t reatmen t w as the

su m o f T 1 a n d T 2 .

Statist ical An alysis

An a lysi s o f va r iance (AN O VA ) w as used to

ana lyse the d i f fe rences in the percentages o f GP/

sea le r remnan ts cove red a rea amongs t the fou r

g ro u p s. O n e -w a y A N O V A w a s a p p l i ed t o c o m p a r e

t h e o p e r a t i n g t i m e a m o n g s t t h e f o u r g r o u p s .

B o n fe r r o n i t e st w a s p e r f o r m e d a s th e p o s t h o c

m u l t i p l e c o m p a ri so n m e th o d .

Results

a) Rem nant s of m ateri al

Al l i ns trum en ts l e f t f i l l i ng m a te r ial i n side the

r o o t c a n a l . T h e sp e c i m e n s r e t r ea t ed w i t h t h e

ProTaper le f t less f i l l ing mater ia l ins ide the root

cana ls than o ther groups bu t s ign i f icance d i f fe rence

w a s f o u n d b e t w e en P r o T ap e r an d M t w o a n d

P ro T a p er a n d H e d st ro m f i l es (< 0 .0 0 1 ) . (Table I )

The compar i son o f GP/Sea le r remnan ts a t

d i f fe rent leve ls amo ng four group s us ing Bonfer ron i

M e thod test sho w ed tha t d i f fe rence in d i f fe ren t

l e v e ls w a s f o u n d t o b e m a x i m u m b e tw e e n c o r o n a l




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Tab le I I-T im e taken fo r com ple te procedu re in d i f fe ren t group s.

S.No.

1 .

2 .

3 .

4 .

Group

A (Protaper)

B (R-End o)

C (M -T w o )

D (H -Fi le )

N o. of samples

1 5

1 5

1 5

1 5

M ean t ime taken

6 .1 0

6 .4 1

5 .0 8

7 .9 3

SD

1 .0 0

1 .2 1

0 .6 4

1 .0 3

M in

3 .5 8

4 .0 7

3 .4 9

6 .7 0

M ax

7 .4 5

8 .8 1

5 .7 2

1 0 .5 9

“ F”

2 1 .3 5 0

“ p”

< 0 .0 01

Range

Figure 1 - Am oun t o f GP/ s ea le r rem n an t s

A) Group A : P roT aper U n iv e rs a l re t rea t m en t f i l es

B) Group B : R-Endo ret reatment f i les

C) Group C : M t w o r e tr e at m e n t f i l e s

D ) Group D : H eds trom f i l es

Tab le I - Area f rac t ion o f roo t cana l w a l l co vered by G P/sealer rem nants af ter re t rea tm entM -D d i r ec ti o n .

S. N o.

1 .

2 .

3 .

4 .

Group

A (Protaper)

B (R-End o)

C (M -T w o )

D (H -Fi le )

SD

1 .2 9

1 .0 6

1 .1 9

3 .3 5

Mean

5 .1 7

5 .1 5

6 .6 0

7 .6 1

SD

1 .8 1

1 .5 8

1 .3 4

2 .2 6

Mean

7 .5 1

7 .5 4

1 1 .0 1

1 1 .3 1

SD

2 .5 1

2 .0 4

2 .3 3

3 .0 0

Mean

3 .2 4

3 .4 6

4 .4 2

6 .4 0

Coronal M iddle Apical

“ F” 8 .0 5 4 6 .7 3 2 1 0 .6 5 1

“ p ” < 0 .0 0 1 0 .0 0 1 < 0 .0 0 1

SD - St andard D ev ia t i on

F - A n a l y si s o f V a r i an c e ( A N O V A )

p - l ev e l o f si gn i f i c anc e




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G raph I - Bar graph show ing G P/sealer rem-nants af ter retreatm ent at coronal, mi ddle

and apical level among four groups.

G raph I I- Bar graph show ing mean t ime for

retreatment.

and ap ica l l eve l s (4 .062 ) wh i l e i t was m in imum

be tw een co rona l and m idd le l eve ls (1 .751 ).

b) O perat ing t ime

The m ean t im e taken fo r com p le te p rocedure

w a s f o u n d to b e m i n i m u m i n G r o u p C (5 . 0 8 ± 0 . 6 4

m i n ) w h i l e i t w a s f o u n d t o b e m a x i m u m i n G r o u p

D (7 .9 3 ± 1 .0 3 m i n ). (Table II ) The e f ficacy o f group s

i n t e r m s o f m e a n t i m e t a k e n t o c o m p l e t e t h e

p rocedure w as:

M -Two > Pro taper ~ R-Endo > H- f il e

Discussion

The p r imary reason fo r a nega t i ve ou tcome

fo l low ing the ro ot cana l t reatm ent is the persistence

o f bac te r ia w i th in the i n t r i cac ies o f the roo t cana l

system.1 8 Com p le te rem ova l o f p re -ex i s ti ng f i l l i ng

m ater ia l f rom canals is a prerequ i si te for successfu l

n o n s u r g i c a l r o o t c a n a l r e t r e a t m e n t . 1 9 T h i s

pro cedu re can un cov er residu a l necro t ic t issues or

bac te r ia tha t may be respons ib le fo r pe rs i s ten t

per iap ica l in f lam m ation , and al low fur ther c lean ing

and re f i l l i ng o f the roo t cana l system. 2 0

I n t h e p r e se n t s t u d y , t h e t e e th w e r e

deco ronated to ensure standardization o f specim ens

by e l im ina t ing som e va r iab les, such as ana tom y o f

the denta l cro w n and access to roo t cana ls thereby

a l l o w i n g m o r e r el i a b l e c o m p a r i so n b e tw e e n t h e

p rop osed re treatmen t techn iqu es.

D i f fe ren t m e thodo log ies have been repo r ted

to eva luate the am oun t o f fi l l in g mater ia l rem ain ing

ins ide the can a l a f ter re t reatmen t proc edu re. I t can

be assessed radiographical ly 2 1 , roots can be sp l i t

l o n g i t u d i n a l l y a n d r e m a i n i n g g u t t a - p e r c h a a n d

sea le r w ere measured l i nea r l y o r u sing sco r ing

system 2 2 o r m a k i n g t h e t e e t h t r a n s p a r e n t 1 7 . I n

a d d i t i o n c o m p u t e r t o m o g r a p h y 2 3 a n d o p e r a t i n g

mic roscopes2 0 have a lso b een used for th is purpo se.

Ideal l y , th ree -d im ensiona l v i sua l i za t i on o f the roo t

cana l system w oul d prov ide a bet ter un derstand in g

of the d is t r ibu t ion o f the debr is af ter re t reatm ent . 1 6 ,

2 4 Am ongs t them , the t ransparen t tee th m e thod i s

cost-e f fect ive and sensi t ive eno ugh to i dent i fy sm al l

area o f residu a l G P/sea ler on the cana l w a l l . 2 0 , 2 5 In

the present s tud y, the roo ts w ere mad e t ransparent

to a l l ow m easurem en t o f the a rea o f residua l f i l l i n g

mate r ia l .

In the present stud y xy lene w as se lected f rom

a v a r i e ty o f d i f f e r en t so l v e n t s w h i c h a r e

r ec o m m e n d e d f o r en d o d o n t i c r et r ea tm e n t w h i c h

inc ludes eucalyp to l , ha lo thane, m e thy l ch lo ro fo rm,

c h l o r o fo r m , t u r p en t i n e .1 4 Xy lene slow ly d i sso l ves

the gu t ta-pe rcha , thus al l ow ing b e t te r con t ro l and

r e m o v a l o f s o f t e n e d g u t t a - p e r c h a r a t h e r t h a n




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l iquef ied gut ta-percha. 2 6 A l t h o u g h c h l o r o fo r m h a s

b e e n s h o w n t o b e m o s t e f f e c ti v e g u t t a -p e r c h a

so lven t w hen com pared w i th o the r so l ven ts bu t i t s

use is controvers ia l . 2 7 I t has been repor ted to be

l o c a l l y t o x i c w h e n i n c o n ta c t w i t h p e r i r a d i c u l a r

t i s s u e s . A d d i t i o n a l l y i t i s h e p a t o t o x i c a n d

nep hro tox ic and is classi f ied as a carcin ogenen .22 , 28

D i f f e r e n t m e t h o d s h a v e b e e n a p p l i e d t o

r e m o v e r o o t c a n a l f i l l i n g m a te r i a l f r o m c a n a l s .

These inc lude use o f hand f i les, u l t rason ic f i les,

e n g i n e d r i v e n i n s t r u m e n t s a n d l a s e r s . 3 , 1 4 , 1 5

Con ven t iona l l y , the rem ova l o f gu t ta -pe rcha using

hand f i l es w i th o r w i thou t so l ven t can be a ted iou s

and t im e consumi ng p rocess, espec ia l l y w hen the

roo t f i l l i ng m a te r ial i s we l l c ond ensed . 1 6 Therefore

the use o f ro ta ry N iT i i n st rum en ts i n ro o t cana l

re t reatment might decrease pat ient and operator

fa t igue.

In the cu r rent study, a l l re treatm ent techn iq ues

le f t GP/seale r remn an ts w i th in the roo t cana l . Th i s

f i n d i n g c o n f i r m s p r e v i o u s r e s u l t s r e p o r t e d b y

nu m erous invest igators us ing d i f fe rent re t reatmen t

i n s t r u m e n t s , t e c h n i q u e s a n d s o l v e n t s . 3 , 1 3 , 1 6

Fur thermo re, the present invest igat ion show ed that

r o t a r y N i T i i n s t r u m e n t s, t h e Pr o T a p e r

ins t rumen ta t i on was s ign i f i can t l y more e f fec t i ve

than M tw o and H edst rom g roup in te rms o f residua l

m ater ia l , w hereas no statistical d i f ference w as foun d

am on gst the ProTaper and R-End o in st rum entat ion

g roup .

D e C a r v al h o M a c i el a n d Z a c c ar o Sc e l z a2 1

found tha t ProTaper w as m ore e f fec t i ve i n remo va l

o f f i l l ing m ater ial f rom ro ot cana l wa l ls than m anual

inst rum entat ion . By con trast , Sch i r rm eister e t a l .1 9

found sim i la r am oun t o f residu a l gu t ta-pe rcha and

sealer a f ter ProTaper and m anual in st rum entat ion .

I n t h e p r e s e n t s t u d y t h e b e t t e r p e r f o r m a n c e o f

ProTaper U niv ersa l re t reatm ent instrum ents m ay

be due to the i r spec i f i c f l u te des ign . The f i l e no t

on ly cu t gut ta-percha but a lso the super f ic ia l layer

o f den t in d u r ing roo t f i l l i ng remo va l . O the r featu res

a re p rog ressi ve tape rs o f D 1 , D 2 , D 3 f i l es w h ich

m ake i t possib l e to shape speci f ic sect ion s o f a root

cana l w i th one f i l e and va r iab le ti p d iam eter w h ich

a l low the f i les speci f ic cu t t ing act ion i n d ef ined area

of the cana l , w i tho ut st ressing the in st rum ent in

o the r sec t i on . The f l u te design and ro ta ry m o t ion

c u t t h e l a r g e a m o u n t o f g u t t a - p e r c h a i n s p i r a l

a round the i ns t rumen t and d i rec t i t towards the

or i f ices.

T h e m a n u f a c t u r e r o f R - E n d o i n s t r u m e n t s

c la ims that inst rument is designed especia l ly fo r

re t rea tmen t as a re mach ined in to a round b lank

and they have a t r iangu lar cross-sect ion w i th three

equal ly spaced cut t ing edges; the inst rument has

ne i ther rad ia l land nor an act ive t ip . Th is system

has su f f i c i en t r i g id i t y to rem ove m a te r ial f r om theroo t cana l . The p resent s tud y in d ic ate that R-End o

system , le f t alm ost sim i la r amo unt o f f i l l ing m ater ia l

i n the cana l w a l l s com pared w i th P roTaper ro tary

system . Tasdem ir e t a l . 1 6 repor ted that ProTaper , R-

E n d o a n d m a n u a l i n s t r u m e n ta t i o n g r o u p s h a v e

sim i la r e ffec ti veness i n rem ov in g f i l l i ng m a te r ial i n

st ra ight roo t cana ls .

In the present stud y sign i f icant d i f fe rence w as

fo u n d b e tw e en P r o T ap e r g ro u p a n d M tw o , t h i s i s

i n acco rdance to the s tudy done by Tasdemi r e t

al .1 6 The M tw o in st rum ents have an S-shaped cro ss-

sec t i oned , an i nc reasing p i t ch l en g th i n the ap ica l -

corona l d i rect ion and ch aracter ized by posi t ive rake

ang le w i th tw o cu t t i ng edges, w h ich a re c laim ed

t o c u t d e n t i n e f f e c t i v e l y . 2 9 U n l i k e o t h e r N i T i




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87

i ns trum en ts, the M tw o ro ta ry i ns t rum en ts do n o t

requ i re a c row n-dow n ins trum en tat i on sequence .

U sing the M tw o ins trum en ts w i th the sing le l eng th

p repa rat i on l eave m ore f i l l i ng m a te r ial i n the cana l

du r in g re t rea tm en t .

In prev io us stud i es, ro tary in st rum ents w ere

repo r ted m ore rap id i n rem ov in g gu t ta-pe rcha than

m anua l i ns trum en ts.3 , 16 , 25 In co ntrast , Im ura e t a l .3 0

found tha t H edst rom f i l es requ i red l ess t im e fo r

re t reatment than Q uantec group as i t remo ve gut ta-

pe rcha in l a rger p ieces. I t w as conc l uded in th i s

study tha t ro tary i n st rum en ts w ere sign i f i can t l y

fas te r than hand f i l es i n remov ing gu t ta -pe rcha ,

w h i l e M tw o requ i re l ess t im e than P roTaper and R

End o in st rum ents. Th is is du e to the speci f ic d esign

of M tw o, resu l t i ng in aggressive cu t t ing edges and

po si t iv e rake ang le w hic h requ i re less energy to

cu t den t in . The n um ber o f i ns trum en ts i n P roTaper

a n d R - E n d o a l s o a f f e c t t h e w o r k i n g t i m e e v e n

though they a re more e f fec t i ve i n rem ova l o f gu t ta -

pe rcha .

Conclusion

W i t h i n t h e p a r am e t er s o f t h i s st u d y , t h e

fo l l o w i n g c o n c l u si o n s m a y b e d r aw n :

N o n e o f t h e t e c h n i q u e s r em o v e d a l l f i l l i n g

m ate r ial s from roo t cana l w a l l s.

ProTaper U niv ersa l re-t reatm ent f i les and

R-End o retreatm ent f i l es left sign i f ic antly less gutta-

percha and sea ler than M tw o system and H edstrom

fi les.

Re-t rea tm en t w i th M tw o sys tem N iT i ro tary

sy s t e m s w a s si g n i f i c a n t l y f a st e r t h a n m a n u a l

i ns t rumen ta t i on i n the remova l o f gu t ta -pe rcha /

sealer.

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