ABSTRACT
http://dx.doi.org/10.1590/1678-775720150090
(I¿FDF\ RI XOWUDVRQLF DFWLYDWLRQ RI 1D2&O DQG
RUDQJHRLOLQUHPRYLQJ¿OOLQJPDWHULDOIURPPHVLDO
canals of m andibular m olar s w it h and w it hout
ist hm us
Mirela Sangoi BARRETO1, Ricardo Abreu da ROSA2, Manuela Favarin SANTINI2%UXQR&DYDOLQL&$9(1$*23, Marco
$QW{QLR+~QJDUR'8$57(3&DUORV$OH[DQGUH6RX]D%,(510DUFRV9LQtFLXV5HLV6Ï2
1- Department of Stomatology, Federal University of Santa Maria, Santa Maria, RS, Brazil.
2- Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
3- Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
&RUUHVSRQGLQJDGGUHVVMirela Sangoi Barreto - Departamento de Estomatologia - Universidade Federal de Santa Maria - Rua Marechal Floriano, 1184 - Santa Maria - RS - Brazil - 97015-372 - Phone: +55-55-3220-9284 - e-mail: [email protected]
6XEPLWWHG0DUFK0RGL¿FDWLRQ$SULO$FFHSWHG$SULO
O
EMHFWLYHV 7KH DLP RI WKLV VWXG\ ZDV WR HYDOXDWH WKH YROXPH RI UHPDLQLQJ ¿OOLQJm at er ial aft er passive ult rasonic ir r igat ion ( PUI ) of sodium hypochlor it e ( NaOCl) and orange oil in m esial canals of m andibular m olar s, w it h and w it hout ist hm us. Mat er ial and Met hods: Thir t y m esial r oot s of m andibular m olar s w er e divided accor ding t o t he pr esence RUDEVHQFHRILVWKPXV&DQDOVZHUHSUHSDUHGDQG¿OOHG0LFUR&7)LOOLQJZDVUHPRYHG using r ot ar y inst r um ent s, and specim ens w er e sub- divided int o t hr ee gr oups accor ding t o t he ir r igat ion pr ocedur es: Convent ional – convent ional ir r igat ion w it h NaOCl, PUI / NaOCl – PUI of NaOCl ( t hr ee act ivat ions, 20 seconds each) , and PUI / orange oil – PUI of orange oil ( Micr o- CT# 2) . Specim ens w er e enlar ged using t he X2 and X3 Pr oTaper Next inst r um ent s and subm it t ed t o t he sam e ir r igat ion pr ot ocols ( Micr o- CT # 3) . Result s: No differ ences w er e found bet w een t he exper im ent al gr oups in each st age of assessm ent ( P> 0.05) . The YROXPHRIUHVLGXDO¿OOLQJPDWHULDOZDVVLPLODUWRWKRVHLQ0LFUR&7DQG0LFUR&7EXW low er t han t hose obser ved in Micr o- CT # 1 ( P< 0.05) . When gr oups w er e pooled accor ding WRWKHSUHVHQFHRUDEVHQFHRIDQLVWKPXVYROXPHRIUHVLGXDO¿OOLQJPDWHULDOZDVKLJKHU in specim ens pr esent ing ist hm us ( P< 0.05) . Conclusions: PUI of NaOCl or orange oil did QRWLPSURYH¿OOLQJUHPRYDO,VWKPXVFRQVLVWVLQDQDQDWRPLFDOREVWDFOHWKDWLPSDLUVWKH UHPRYDORI¿OOLQJPDWHULDOKe y w or ds: Micr o- com put ed t om ography. Endodont ics. Ret r eat m ent . Ult rasonics.
I N TROD UCTI ON
Wh en en dodon t ic failu r e occu r s, n on su r gical endodont ic r et r eat m ent is oft en indicat ed. Mesial r oot can als of m an d ib u lar m olar s ar e u su ally
ÀDWWHQHGPHVLRGLVWDOO\DQGVRPHWLPHVFRQWDLQDQ
ist hm us, w hich com m unicat es t he buccal w it h t he lingual canals22. The inaccessibilit y of inst r um ent s and chem ical irrigant s int o t he ist hm us im pairs root canal disinfect ion31.
'XULQJURRWFDQDOUHWUHDWPHQW¿OOLQJPDWHULDO
m ust be r em ov ed t o enable r e- pr eparat ion and disinfect ion of t he r oot canal syst em23. The m ost
com m on ly u sed t ech n iq u es f or f illin g r em ov al
LQYROYH KDQG ¿OHV RU URWDU\ LQVWUXPHQWV10
. These inst r um ent s can be used w it h chem ical solvent s t o
VROXELOL]HWKHJXWWDSHUFKD¿OOLQJ25,28. How ever, due t he com plexit y of t he r oot canal syst em , com plet e
UHPRYDO RI JXWWDSHUFKD DQG VHDOHU LV GLI¿FXOW
r egar dless of t he em ployed t echnique31.
Organic solvent s can be used during ret reat m ent
WRIDFLOLWDWHURRW¿OOLQJUHPRYDOZLWKRXWGDPDJLQJ
LQGLVVROYLQJURRWFDQDO¿OOLQJ13,14. Addit ionally, it has low er cyt ot oxicit y w hen com par ed t o eucalypt ol, xylene, and chlor ofor m4.
Sev er al r ot ar y sy st em s w er e d ev elop ed f or r oot canal pr eparat ion12. Pr oTaper Next ( Dent sply Maillefer, Ballaigues, Sw it zer land) is a new r ot ar y syst em t hat m ust be used wit h cont inuous rot at ion.
,WFRQVLVWVRI¿YHLQVWUXPHQWVZLWKYDULDEOHWDSHU;
( 17/ .04) , X2 ( 25/ .06) , X3 ( 30/ .075) , X4 ( 40/ .06) , and X5 ( 50/ .06) . All of t hese inst r um ent s pr esent a r ect angular cr oss- sect ion and m ust be passively insert ed at t he ent ire working lengt h17. The ProTaper Ret r eat m en t k it ( Den t sply Maillefer, Ballaigu es, Swit zerland) consist s of t hree inst rum ent s designed
VSHFL¿FDOO\WRUHPRYHURRW¿OOLQJPDWHULDOIURPURRW
canals. Pr oTaper Ret r eat m ent inst r um ent s have a convex t r iangular cr oss- sect ion sim ilar t o t hat of t he Pr oTaper Univer sal syst em ( Dent sply Maillefer, Ballaigues, Sw it zer land) .
To im prove root canal disinfect ion, ult rasonic t ips have been used in endodont ics. Passive ult rasonic ir r igat ion ( PUI ) has been used for r em oving r oot canal dr essings, debr is and t he sm ear6,29. How ever,
WKHHIIHFWLYHQHVVRI38,IRU¿OOLQJUHPRYDOKDVEHHQ
poor ly invest igat ed.
Ther efor e, t he aim s of t his st udy w er e: ( 1) t o
FRPSDUHWKHYROXPHRIUHPDLQLQJ¿OOLQJPDWHULDO
aft er convent ional ir r igat ion, PUI of NaOCl, and PUI
RIRUDQJHRLODQGWRHYDOXDWHWKHLQÀXHQFHRIDQ
ist hm us in m esial r oot canals of m andibular m olar s
RQWKHUHPDLQLQJ¿OOLQJYROXPH7KHQXOOK\SRWKHVHV ZHUHWKHUHLVQRGLIIHUHQFHEHWZHHQWKH¿QDO
ir r igat ion pr ot ocols; and ( 2) t he pr esence of an ist hm us does not affect t he volum e of r em aining
¿OOLQJPDWHULDO
M ATERI AL AN D M ETH OD S
This st udy was approved by t he Et hics Com m it t ee of t he Federal Universit y of Rio Grande do Sul. Thirt y m esial root s of m andibular m olars were used in t his st udy. An init ial m icr o- CT scan was used t o select
¿IWHHQ URRWV FRQWDLQLQJ DQ LVWKPXV DQG ¿IWHHQ
w it h independent m esiobuccal and m esiolingual ca n a l s u si n g a d e sk t o p X- r ay m i cr o f o cu s CT sca n n e r ( Sk y Sca n 1 1 7 4 v 2 ; Br u k e r - m i cr o CT, Kont ich, Belgium ) . The scanning pr ocedur es w er e per for m ed using t he follow ing param et er s: 50 kV
;UD\ WXEH YROWDJHV Nj$ DQRGH FXUUHQW DQG YR[HO VL]H RI Nj$ 2QO\ RQH VSHFLPHQ ZDV
scanned at a t im e. Scans w it h 1304x1024 pixels w er e obt ained w it h acquisit ion int er vals of 1° over a t ot al of 360° r ot at ion. Thus, dat a w er e r ecor ded for t oot h select ion, and t he sequences of scans were r econst r uct ed using t he NReconv1.6.4.8 ( NRecon v. 1 . 6 . 3 ; Br u k e r - m i cr o CT, Ko n t i ch , Be l g i u m ) soft war e.
Th e ex clu sion cr it er ia w er e: r oot f r act u r es,
p r esen ce o f cr ack s, i n t er n al o r ex t er n al r o o t resorpt ions, previous endodont ic t reat m ent , and an angle of cur vat ur e higher t han 22°21. Cr ow ns w er e rem oved using a double- sided diam ond disc ( Kom et , Sant o André, SP, Brazil) close t o t he cem ent oenam el j unct ion. Canals w er e ex plor ed using a size 10
.¿OH'HQWVSO\0DLOOHIHU%DOODLJXHV6ZLW]HUODQG :RUNLQJOHQJWK:/ZDVGH¿QHGDVPPVKRUWHU
t h a n t h e d i st a n ce f r o m t h e ce m e n t o e n a m e l
MXQFWLRQWRWKHDSLFDOIRUDPHQZKHUHWKH¿OHZDV
j u st v isible. Can al pat en cy w as obt ain ed u sin g # 1, # 2, and # 3 Pat hFile inst r um ent s ( Dent sply Maillefer, Ballaigues, Sw it zer land) and canals w er e prepared using S1, S2, and F1 ProTaper inst rum ent s ( Dent sply Maillefer, Ballaigues, Sw it zer land) for all WLs. I r r igat ion pr ocedur es w er e per for m ed using 2 m L of 2 . 5 % sod iu m h y p och lor it e af t er each inst rum ent change. Aft er canal preparat ion, 5 m L of 17% et hylenediam inet et raacet ic acid ( Biodinâm ica, I bipor ã, PR, Brazil) was used for t hr ee m inut es. Finally, 2 m L of 2.5% sodium hypochlorit e was used
IRU WKH ¿QDO ULQVH $OO LUULJDWLRQ SURFHGXUHV ZHUH
perform ed using silicon syringes ( Ult radent Product s I nc., Sout h Jor dan, UT, USA) and Endo- Eze t ips ( Ult radent Pr oduct s I nc., Sout h Jor dan, UT, USA) .
7KHURRWFDQDO¿OOLQJZDVSODFHGXVLQJWKHVLQJOH
cone t echnique w it h an epoxy r esin- based sealer AH Plus ( Dent sply Maillefer, Ballaigues, Swit zerland) an d F1 gu t t a- per ch a con es ( Den t sply Maillefer, Ballaigues, Sw it zer land) . Endodont ic sealer w as m ixed accor ding t o t he m anufact ur er ’s inst r uct ions and inser t ed int o t he canals using a Lent ulo spiral ( Dent sply Maillefer, Ballaigues, Sw it zer land) . The canal opening was sealed w it h Cavit ( 3M ESPE, St Paul, MN, USA) and t he specim ens w er e st or ed at 100% hum idit y and 37°C for one w eek t o allow t he sealer t o set . Then, t he specim ens w er e scanned
WRGHWHUPLQHWKHLQLWLDOYROXPHRI¿OOLQJPDWHULDO
( Micr o- CT # 1) as descr ibed above.
Pr oTaper Ret r eat m ent inst r um ent s ( Dent sply Maillefer, Ballaigues, Sw it zer land) w er e used w it h 500 r pm and 2 N/ cm of t or que for r em oval of t he
¿OOLQJDVIROORZVWKH'¿OHLQWKHFHUYLFDODUHDWKH '¿OHLQWKHFHUYLFDODQGPLGGOHWKLUGVDQGWKH' ¿OHIRUDOO:/V$IWHUHDFKLQVWUXPHQWFKDQJHURRW
canals w er e ir r igat ed w it h 2 m L of 2.5% NaOCl. Aft er using t he Pr oTaper Ret r eat m ent inst r um ent s, specim ens w ere allocat ed int o six groups according
WRWKH¿QDOLUULJDWLRQSURFHGXUHVDQGWKHSUHVHQFH
or absence of an ist hm us ( n= 5) :
- Convent ional – Cont inuous ir r igat ion w it h 10 m L of 2.5% NaOCl in each canal for 1 m inut e.
38,1D2&O ± (DFK FDQDO ZDV ÀXVKHG ZLWK
Baseline 0LFUR&7
1-3 mm 3-5 mm 5-7 mm TOTAL Conventional 0.71A 1.39A 1.81A 3.12A
(±0.22) (±0.36) (±0.43) (±1.21) PUI/NaOCl 0.72A 1.32A 1.80A 3.20A
(±0.25) (±0.49) (±0.56) (±1.74) PUI/orange oil 0.66A 1.07A 1.53A 3.25A
(±0.21) (±0.26) (±0.29) (±0.71)
Filling removal and irrigation procedures 0LFUR&7
1-3 mm 3-5 mm 5-7 mm TOTAL Conventional 0.27B 0.50B 0.46B 1.23B
(±0.18) (±0.31) (±0.34) (±0.75) PUI/NaOCl 0.36B 0.36B 0.37B 1.09B
(±0.30) (±0.38) (±0.43) (±1.05) PUI/orange oil 0.23B 0.21B 0.26B 0.70B
(±0.27) (±0.23) (±0.34) (±0.81)
Re-preparation and irrigation procedures 0LFUR&7
1-3 mm 3-5 mm 5-7 mm TOTAL Conventional 0.22B 0.47B 0.42B 1.12B
(±0.18) (±0.32) (±0.32) (±0.75) PUI/NaOCl 0.27B 0.32B 0.34B 0.93B
(±0.24) (±0.38) (±0.38) (±0.95) PUI/orange oil 0.17B 0.15B 0.23B 0.55B
(±0.21) (±0.17) (±0.34) (±0.68)
Table 1- Mean and standard deviation of the volume (mm3RI¿OOLQJPDWHULDODWEDVHOLQH0LFUR&7DIWHU¿OOLQJUHPRYDO
DQGLUULJDWLRQSURWRFROV0LFUR&7DQGDIWHUUHSUHSDUDWLRQDQGLUULJDWLRQSURWRFROV0LFUR&7
'LIIHUHQWOHWWHUVLQWKHURZFRPSDULQJVLPLODUURRWOHYHOVLQGLFDWHVLJQL¿FDQWGLIIHUHQFHVDIWHUUHSHDWHGPHDVXUHV$129$
and Tukey’s tests (P<0.05)
Paulo, SP, Brazil) . The ult rasonic t ip was passively inser t ed int o r oot canals 2 m m shor t of t he WL. PUI was per for m ed at 40 kHz for 20 seconds in each canal. The PUI pr ot ocol was r epeat ed t w ice w it h 2 m L of 2.5% NaOCl per canal each t im e. Finally, cont inuous ir r igat ion was per for m ed w it h 6 m L of 2.5% NaOCl. The t ot al volum e of NaOCl was 10 m L in each r oot canal.
- PUI / orange oil – 0.5 m L of orange oil was used in each canal ( Biodinâm ica, Paraná, PR, Brazil) . Next , t he PUI pr ot ocol was per for m ed as descr ibed above, using t hr ee act ivat ions of t he solvent for 20 seconds in each r oot canal. Bet w een act ivat ions,
FDQDOVZHUHÀXVKHGZLWKP/RI1D2&ODQG
t he solvent was r efr eshed. Finally, each canal was cont inuously ir r igat ed w it h 6 m L of 2.5% NaOCl. Canals w er e dr ied w it h absor bent paper point s and new m icro- CT scans were perform ed ( Micro- CT # 2) .
I n gr oups t hat r eceived PUI , t he m ovem ent s of ult rasonic t ip w er e per for m ed t owar d t he ist hm us.
Ca n a l s w e r e r e - p r e p a r e d w i t h X2 a n d X3 Pr oTaper Nex t in st r u m en t s ( Den t sply Maillef er, Ballaigues, Swit zerland) at all WLs wit h 300 rpm and 2 N/ cm of t or que. Aft er using t hese inst r um ent s,
VSHFLPHQVZHUHÀXVKHGZLWKP/RI1D2&O
Fin ally, specim en s w er e su bj ect ed t o t h e sam e irrigat ion procedures previously described. Micro- CT # 3 was per for m ed t o quant ify t he volum e of t he
UHPDLQLQJ¿OOLQJPDWHULDO
Figure 1- A, B and C represent specimens from the Conventional group; D, E and F from the PUI/NaOCl group; and *+DQG,IURPWKH38,RUDQJHRLOJURXS,PDJHVLQUHGEOXHDQGJUHHQLQGLFDWHWKHYROXPHRI¿OOLQJPDWHULDODWWKH EDVHOLQH0LFUR&7DIWHU¿OOLQJUHPRYDODQGLUULJDWLRQSURFHGXUHV0LFUR&7DQGDIWHUUHSUHSDUDWLRQDQGLUULJDWLRQ SURFHGXUHV0LFUR&7UHVSHFWLYHO\
dat a was opened and t he binary value was adj ust ed acco r d i n g t o t h e r aw i m ag es. Th e v al u e w as r ecor ded and used as a param et er for Micr o- CT # 2 and Micr o- CT # 3. Finally, a 3D plug- in analysis was perform ed t o quant it at ively m easure t he am ount of
UHVLGXDO¿OOLQJ7KLVWRRODXWRPDWLFDOO\FDOFXODWHVWKH
overall volum e ( m m3) fr om t he 3D im age of binar y select ed obj ect s ( whit e color) . For each sam ple, t he volum e was calculat ed at t hr ee r oot levels: 1 t o 3 m m , 3 t o 5 m m , and 5 t o 7 m m fr om t he apex. All m easur em ent s and analyses w er e per for m ed by t he sam e operat or w ho was blinded fr om t he ir r igat ing pr ot ocols.
St a t ist ica l a n a ly sis
St at ist ical analy sis w as per for m ed using t he SPSS 16.0 soft war e ( SPSS Co., Chicago, I L, USA) . The Shapir o- Wilk t est show ed nor m al dist r ibut ion of t he dat a ( P> 0.05) . Ther efor e, t he volum e of r em ain in g f illin g m at er ial w as an aly zed u sin g param et r ic t est s. The r epeat ed m easur es ANOVA and Tukey’s post - hoc t est s w er e used t o com par e
WKHYROXPHRI¿OOLQJPDWHULDOLQHDFKH[SHULPHQW
Th e com par ison of t h e ir r igat ion pr ot ocols w as perform ed using a one- fact or ANOVA t est . To assess if t he pr esence or absence of an ist hm us im pair s
WKHUHPRYDORIWKH¿OOLQJ6WXGHQW¶Vt - t est and t he
repeat ed m easures ANOVA t est were used. The level
RIVLJQL¿FDQFHZDVVHWWRIRUDOOVWDWLVWLFDOWHVWV
RESULTS
,QLWLDOO\WKHYROXPHRI¿OOLQJPDWHULDOLQHDFK
exper im ent al gr oup was assessed. No differ ences w er e obser ved bet w een Convent ional, PUI / NaOCl and PUI / or ange oil gr oups at any of t he r oot levels analyzed ( P> 0.05) . Aft er Micr o- CT # 2, all gr oups
VKRZHGDVLJQL¿FDQWUHGXFWLRQRIWKHUHVLGXDO¿OOLQJ
volum e ( P< 0.05) . However, no differences bet ween t hem were observed ( P< 0.05) . When t he specim ens w er e r e- pr epar ed w it h Pr oTaper Next inst r um ent s and t he ir r igat ion pr ot ocols w er e r epeat ed, t he
YROXPHRIUHPDLQLQJ¿OOLQJPDWHULDOZDVVLPLODUWR WKRVHDFKLHYHGDIWHUWKH¿UVWDFWLYDWLRQ3!
Aft er Micr o- CT # 3, no differ ences w er e obser ved bet w een t he ir r igat ing pr ot ocols ( P> 0.05) ( Table 1) . Figur e 1 show s r epr esent at iv e im ages fr om
Convent ional, PUI / NaOCl and PUI / orange oil groups
dur ing t he t hr ee ex per im ent al st ages: Micr o- CT
LQLWLDO0LFUR&7DIWHU¿OOLQJUHPRYDODQG
ir r igat ion pr ocedur es) and Micr o- CT # 3 ( aft er r e-pr eparat ion and ir r igat ion e-pr ocedur es) .
$ODUJHUYROXPHRI¿OOLQJPDWHULDOZDVREVHUYHG
in sp ecim en s t h at con t ain ed an ist h m u s w h en com par ed t o t hose t hat cont ained t w o independent canals ( P< 0.05) ( Table 2) . This pat t er n r em ained unchanged aft er using t he Pr oTaper r et r eat m ent inst rum ent s and aft er re- preparat ion w it h ProTaper
1H[W ¿OHV )LJXUH $ VPDOOHU YROXPH RI ¿OOLQJ
Baseline 0LFUR&7
1-3 mm 3-5 mm 5-7 mm TOTAL Presence of an
isthmus
0.83Aa 1.45Aa 1.91Aa 3.77Aa
(±0.25) (±0.40) (±0.49) (±1.39) Absence of an isthmus 0.57Ab 1.07Ab 1.51Ab 2.62Ab
(±0.12) (±0.28) (±0.28) (±0.76)
Filling removal with rotary instruments 0LFUR&7
1-3 mm 3-5 mm 5-7 mm TOTAL Presence of an
isthmus
0.43Ba 0.57Ba 0.61Ba 1.63Ba
(±0.26) (±0.29) (±0.35) (±0.78) Absence of an isthmus 0.13Bb 0.13Bb 0.13Bb 0.40Bb
(±0.12) (±0.19) (±0.17) (±0.43)
Re-preparation with ProTaper Next 0LFUR&7
1-3 mm 3-5 mm 5-7 mm TOTAL Presence of an
isthmus
0.34Ba 0.52Ba 0.57Ba 1.42Ba
(±0.22) (±0.32) (±0.33) (±0.73) Absence of an isthmus 0.12Bb 0.10Bb 0.10Bb 0.32Bb
(±0.12) (±0.17) (±0.17) (±0.42)
Table 2-0HDQDQGVWDQGDUGGHYLDWLRQRIWKHYROXPHRI¿OOLQJPDWHULDODWEDVHOLQHDIWHU¿OOLQJUHPRYDOZLWKURWDU\LQVWUXPHQWV
and after re-preparation taking into consideration the presence or absence of an isthmus in the mesial root of mandibular molar
Different uppercase letters in rows compare the presence or the absence of an isthmus in the same root level after each stage of retreatment using ANOVA and Tukey’s tests (P<0.05). Different lowercase letters in the columns compare the presence and the absence of an isthmus in each root level and stage of retreatment using Student’s t-test (P<0.05)
( Micr o- CT # 3 ) w h en com p ar ed t o t h e v olu m e at b aselin e ( P< 0 . 0 5 ) , b u t n o d if f er en ces w er e obser ved bet w een Micr o- CT # 2 and Micr o- CT # 3 ( P> 0.05) .
D I SCUSSI ON
The goal of r oot canal r et r eat m ent is t o r em ove
DVPXFK¿OOLQJDVSRVVLEOHWRPD[LPL]HURRWFDQDO
d isin f ect ion1 1. How ev er, t h er e is n o t ech n iq u e capable of com plet ely r em oving gut t a- per cha and endodont ic sealer fr om r oot canal walls, especially
ZKHQWKHFDQDOLVÀDWWHQHG31.
Som e st udies used invasive, dest r uct ive and t w o- d im en sion al m et h od olog ies t o assess t h e
DPRXQWRIUHPDLQLQJ¿OOLQJPDWHULDO24. Só, et al.24 ( 2008) sect ioned t he specim ens longit udinally t o
DVVHVV WKH DUHD RI UHPDLQLQJ ¿OOLQJ PDWHULDO E\
using a dent al operat ing m icr oscope, w hich m akes it im possible t o evaluat e one sam ple by differ ent st ages of ret reat m ent . On t he ot her hand, m icro- CT is a quick, accurat e and non- dest r uct ive m et hod
WR DVVHVV ¿OOLQJ UHPRYDO9. Micr o- CT enables t he visualizat ion of t hr ee- dim ensional im ages w it h a high level of det ail. However, t he m ain advant age of m icr o- CT over ot her m et hodologies is t hat it allow s for t he acquisit ion of im ages of t he sam e sam ple dur ing differ ent exper im ent al st ages18.
The aim of t his st udy was t o com pare t he volum e
RI UHPDLQLQJ ¿OOLQJ PDWHULDO DIWHU FRQYHQWLRQDO
ir r igat ion, PUI w it h NaOCl, and PUI w it h orange oil. Micr o- CT # 1 was per for m ed t o ensur e t hat t he
YROXPHRI¿OOLQJPDWHULDODWEDVHOLQHZDVVLPLODUIRU DOOH[SHULPHQWDOJURXSV7KHUHVXOWVFRQ¿UPHGWKDW WKH¿OOLQJYROXPHVLQWKHConvent ional, PUI / NaOCl and PUI / or ange oil JURXSV ZHUH QRW VLJQL¿FDQWO\ GLIIHUHQW3!7KXVWKH¿UVWQXOOK\SRWKHVLV ZDVFRQ¿UPHG1HLWKHURIWKH38,SURWRFROVZDV FDSDEOHRILQFUHDVLQJWKHUHPRYDORI¿OOLQJPDWHULDO
Cavenago, et al.7 ( 2014) evaluat ed t he volum e
RIUHPDLQLQJ¿OOLQJPDWHULDODIWHUUHWUHDWPHQWZLWK
differ ent pr ocedur es per for m ed sequent ially ( i.e., m echanical r em oval, post - x y lene and post - PUI ) . I n cont rast t o t he r esult s of t he pr esent st udy, t he
DXWKRUVIRXQGDVPDOOHUYROXPHRI¿OOLQJPDWHULDO
aft er PUI w hen com par ed t o m echanical r em oval. I t should be not ed t hat t hose aut hor s per for m ed all r et r eat m en t p r oced u r es u sin g an op er at in g m i cr o sco p e w i t h 5 × m ag n i f i cat i o n . Li t er at u r e r e p o r t s t h a t u si n g a n o p e r a t i n g m i cr o sco p e
HQKDQFHVWKHGHWHFWLRQRIUHWDLQHG¿OOLQJPDWHULDO
especially at t h e cer v ical an d m iddle t h ir ds of m esial r oot s of m andibular m olar s20. At t he apical por t ion, such visualizat ion m ay be im pair ed due t o t he degr ee of cur vat ur e. This st udy also found
UHVLGXDO¿OOLQJPDWHULDOLQDOOVSHFLPHQVVLPLODUWR
m any endodont ic r et r eat m ent st udies7,12.
7KHJUHDWHVWUHGXFWLRQLQ¿OOLQJPDWHULDOYROXPH
w as obser v ed aft er using Pr oTaper r et r eat m ent inst r um ent s and applying t he ir r igat ion pr ot ocols ( Mi cr o - CT # 2 ) ( P< 0 . 0 5 ) . N e v e r t h e l e ss, t h e m ech an ical act ion of t h e in st r u m en t s w as t h e
PDLQUHDVRQIRUWKHVLJQL¿FDQWUHGXFWLRQLQ¿OOLQJ
volum e. On t he ot her hand, neit her PUI / NaOCl nor PUI / orange oil pr ot ocols w er e capable of r educing
WKHYROXPHRI¿OOLQJPDWHULDOZLWKLQWKHURRWFDQDO
sy st em af t er r e- p r ep ar at ion u sin g X2 an d X3 Pr oTaper Next inst r um ent s ( P> 0.05) . Even new ly developed inst r um ent s ar e not able t o cont act all dent inal walls dur ing a r oot canal pr eparat ion30. Addit ionally, Rödig, et al.19 ( 2014) observed residual
¿OOLQJ PDWHULDO LQ DOO VSHFLPHQV DIWHU XVLQJ WKH
ProTaper Ret reat m ent syst em , Reciproc inst rum ent s an d Hed st r oem h an d f iles. Th e Pr oTap er Nex t syst em has a var iable t aper and r ect angular cr oss-sect ion, and uses an asym m et r ic r ot ar y m ot ion17. The com binat ion of t he r ect angular cr oss- sect ion w it h asym m et r ic r ot ar y m ot ion r esult s in cont act of only t w o cut t ing edges of t he inst r um ent w it h dent inal walls. The ot her t w o edges m ove fr eely, w hich r educes t he t or sion on t he spirals and, t hus, t he r isk of t or sional fract ur es.
Several solvent s have been evaluat ed for t heir
HI¿FDF\LQ¿OOLQJUHPRYDODQGWR[LFLW\OHYHOV4,13,14. Chlor ofor m , xylene, eucalypt ol and orange oil ar e t he m ost com m only used solvent s in endodont ic r et r eat m ent . The m ain goal of com bining solvent s
ZLWK38,LVWRUHDFKDUHDVWKDWRIGLI¿FXOWDFFHVV
w i t h en d o d o n t i c i n st r u m en t s. Or an g e o i l w as chosen because of it s low t oxicit y and for being able t o dissolv e gut t a- per cha, r egar dless of it s con cen t r at ion . Accor din g t o Magalh ães, et al.1 3
( 2007) orange oil, eucalypt ol and chlor ofor m can sim ilar ly dissolve gut t a- per cha, but less so t han xylene. On t he ot her hand, Mar t os, et al.14 ( 2006) found t hat xylene and orange oil sim ilarly dissolved gut t a- per cha and t hr ee endodont ic sealer s ( i.e., Roek oseal, En d of ill an d Sealer 2 6 ) . Th e m ain draw back report ed concerning solvent s is t hat t hey for m a t hin lay er of soft ened gut t a- per cha and sealer t hat adher es t o t he canal walls and hinder it s r em oval8.
I n t his st udy, PUI / NaOCl and PUI / orange oil were
QRW DEOH WR UHGXFH WKH DPRXQW RI UHVLGXDO ¿OOLQJ
m at er ial ( P> 0.05) . This r esult can be explained by t he solvent cont act ing gut t a- per cha and for m ing a past e t hat adher es t o t he r oot canal walls by penet rat ing int o canal ir r egular it ies. This im pair s
WKH UHPRYDO RI UHVLGXDO ¿OOLQJ HVSHFLDOO\ ZLWKLQ DQ LVWKPXV 7DEOH VKRZV WKH YROXPH RI ¿OOLQJ PDWHULDO DW EDVHOLQH DIWHU ¿OOLQJ UHPRYDO ZLWK
r ot ar y inst r um ent s, and aft er r e- pr eparat ion in t he pr esence and absence of an ist hm us. Specim ens w it h an ist h m u s con t ain ed a lar ger am ou n t of
UHVLGXDO¿OOLQJPDWHULDODWDOOOHYHOVHYDOXDWHGZKHQ
canals ( P< 0.05) . The penet rat ion of gut t a- per cha and sealer int o t he ist hm us and ir r egular ar eas
PDNHVUHPRYDORIWKH¿OOLQJPRUHFULWLFDOLQURRWV
w it h such anat om ical feat ur es.
PUI appear s t o be effect ive for debr is r em oval b ecau se of a p h en om en on k n ow n as acou st ic m icr ost r eam ing and cavit at ion, w hich act s on r oot canals1. Cast agna, et al.6 ( 2013) found t hat PUI u sed w it h 1 7 % EDTA pr om ot ed gr eat er debr is rem oval, especially at t he cervical t hird. I n addit ion, t he apical t hir d w as t he m ost cr it ical ar ea t hat r equir ed cleaning. Som e st udies have evaluat ed t he effect iv eness of PUI on r oot canal dr essing r em ov al2 , 5. Accor d i n g t o Cap ar, et al .5 ( 2 0 1 4 ) PUI was t he m ost effect ive pr ot ocol for calcium
K\GUR[LGHUHPRYDOIURPDUWL¿FLDOVWDQGDUGJURRYHV
in t he apical t hir d. Cor r oborat ing t hese r esult s,
$KPHWR÷OXet al.2 ( 2013) obser ved t hat PUI was
VLJQL¿FDQWO\PRUHHIIHFWLYHWKDQ6HOI$GMXVWLQJ)LOHV
and convent ional ir r igat ion for r em oving calcium hydr ox ide r esidue fr om t he cor onal, m iddle and apical t hir ds. Calcium hy dr ox ide past e does not pr esent adhesive pr oper t ies, w hich facilit at es it s rem oval from t he canal6. Epoxy resin- based sealers, in cont rast , pr esent good m echanical pr oper t ies
DQGFRKHVLYHUHVLVWDQFHZKLFKPDNHPRUHGLI¿FXOW
t o det ach t he endodont ic sealer fr om t he dent in wall w hen using PUI27. These fact or s m ay explain t h e p r esen ce of sealer in t h e can al w alls an d anfract uosit ies aft er endodont ic r et r eat m ent .
5HPRYDORIWKH¿OOLQJPDWHULDODQGUHSUHSDUDWLRQ
of nar r ow and cur ved canals pr esent s a challenge for clinicians19. When cent er ing r ot ar y inst r um ent s dur ing r e- pr eparat ion of t he canal it is com m on t o leave unpr epar ed ar eas w it hin t he ist hm us and
ÀDWWHQHGFDQDOV12. Because of t his, m esial r oot s of m andibular m olar s w er e included in t his st udy. I n addit ion, t hese r oot s have an ist hm us in 55% of cases15. Ther efor e, 50% of t he sam ples st udied w er e m esi al r o o t s w i t h an i st h m u s an d 5 0 % cont ained independent m buccal and m esio-lingual canals. Because no difference was observed am ong t he irrigat ion prot ocols, dat a w ere pooled t o
DVVHVVWKHLQÀXHQFHRIWKHSUHVHQFHRIDQLVWKPXV RQWKHUHVLGXDOYROXPHRI¿OOLQJPDWHULDO
This st udy m odel cont ains som e lim it at ions. All pr ocedu r es w er e per f or m ed in a con t r olled envir onm ent w it h ext ract ed and cr ow nless t eet h t hat m ay not be equivalent t o an average clinic si t u a t i o n . Ad d i t i o n a l l y, a n o p e r a t i n g cl i n i ca l m icr oscope was not used. Accor ding t o Pécora and Andr eana16 ( 1993) , t he use of an operat ing clinical m icroscope enhances t he visualizat ion of root canal anat om y and im pr oves sanit izat ion and r oot canal pr eparat ion pr ocedur es.
CON CLUSI ON S
Gi v e n t h e f i n d i n g s o f t h i s st u d y a n d t h e lim it at ion s descr ibed, it can be con clu ded t h at passive ult rasonic act ivat ion of NaOCl and orange oil
GLGQRWLPSURYHWKHUHPRYDORI¿OOLQJPDWHULDOIURP
m esial r oot s of m andibular m olar s w hen com par ed t o convent ional ir r igat ion w it h NaOCl. Addit ionally, t he ist hm us is an anat om ical obst acle t hat im pair s
WKH UHPRYDO RI ¿OOLQJ PDWHULDO IURP PHVLDO URRW
canals of m andibular m olar s.
ACKN OW LED GEM EN TS
7KH DXWKRUV GHFODUH QR FRQÀLFWV RI LQWHUHVW
r elat ed t o t his st udy.
REFEREN CES
1- Ahm ad M, Pit t For d TR, Cr um LA. Ult rasonic debr idem ent of r oot canals: acoust ic st r eam ing and it s possible r ole. J Endod. 1987; 14: 490- 9.
$KPHWR÷OX)ùÕPúHN1.HOHú$2FDN06(U.(I¿FDF\RI VHOIDGMXVWLQJ¿OHDQGSDVVLYHXOWUDVRQLFLUULJDWLRQRQUHPRYLQJ calcium hydroxide from root canals. Dent Mat J. 2013; 32: 1005- 10. 3- Bodr um lu E, Er O, Kayaoglu G. Solubilit y of r oot canal sealer s w it h differ ent or ganic solvent s. Oral Sur g Oral Med Oral Pat hol Oral Radiol Endod. 2008; 106: 67- 69.
4- Bram ant e CM, Fidelis NS, Assum pção TS, Bernardineli N, Garcia RB, Bram ant e AS, et al. Heat r elease, t im e r equir ed, and cleaning abilit y of MTw o R and Pr oTaper univer sal r et r eat m ent syst em s in WKHUHPRYDORI¿OOLQJPDWHULDO-(QGRG 5- Capar I D, Ozcan E, Ar slan H, Er t as H, Aydinbelge HA. Effect RI GLIIHUHQW ¿QDO LUULJDWLRQ PHWKRGV RQ WKH UHPRYDO RI FDOFLXP K\GUR[LGHIURPDQDUWL¿FLDOVWDQGDUGL]HGJURRYHLQWKHDSLFDOWKLUG of r oot canals. J Endod. 2014; 40: 451- 4.
6- Cast agna F, Rizzon P, Rosa RA, Sant ini MF, Bar r et o MS, Duar t e 0$HWDO(IIHFWRISDVVLYHXOWUDVRQLFLQVWUXPHQWDWLRQDVD¿QDO ir r igat ion pr ot ocol on debr is and sm ear lay er r em oval- a SEM analysis. Micr osc Res Tech. 2013; 76: 496- 502.
7 - Cav enago BC, Or dinola- Zapat a R, Duar t e MA, del Car pio-3HURFKHQD $( 9LOODV%{DV 0+ 0DUFLDQR 0$ HW DO (I¿FDF\ RI [\OHQHDQGSDVVLYHXOWUDVRQLFLUULJDWLRQRQUHPDLQLQJURRW¿OOLQJ m at er ial dur ing r et r eat m ent of anat om ically com plex t eet h. I nt Endod J. 2014; 47: 1078- 83.
*X/6/LQJ-4:HL;+XDQJ;<(I¿FDF\RI3UR7DSHU8QLYHUVDO r ot ar y r et r eat m ent syst em for gut t a- per cha r em oval fr om r oot canals. I nt Endod J. 2008; 41: 288- 95.
9 - Ham m ad M, Qu alt r ou g h A, Silik as N. Th r ee- d im en sion al evaluat ion of effect iveness of hand and r ot ar y inst r um ent at ion IRUUHWUHDWPHQWRIFDQDOV¿OOHGZLWKGLIIHUHQWPDWHULDOV-(QGRG 2008; 34: 1370- 3.
10- I m ura N, Zuolo ML, Fer r eira MO, Novo NF. Effect iveness of t he Canal Finder and hand inst r um ent at ion in r em oval of gut t a- SHUFKDURRW¿OOLQJVGXULQJURRWFDQDOUHWUHDWPHQW,QW(QGRG-1996; 29: 382- 6.
.RVWL(/DPEULDQLGLV7(FRQRPLGHV11HR¿WRX&Ex vivo
VWXG\ RI WKH HI¿FDF\ RI +¿OHV DQG URWDU\ 1L7L LQVWUXPHQWV t o r em ove gut t a- per cha and four t ypes of sealer. I nt Endod J. 2006; 39: 48–54.
Oral Res. 2007; 21: 303- 7.
14- Mart os J, Gast al MT, Som m er L, Lund RG, Del Pino FA, Osinaga 3:'LVVROYLQJHI¿FDF\RIRUJDQLFVROYHQWVRQURRWFDQDOVHDOHUV Clin Oral I nvest ig. 2006; 10: 50- 4.
15- Pablo OV, Est evez R, Péix Sánchez MP, Heilbor n C, Cohenca N. 5RRWDQDWRP\DQGFDQDOFRQ¿JXUDWLRQRIWKHSHUPDQHQWPDQGLEXODU ¿UVWPRODUDV\VWHPDWLFUHYLHZ-(QGRG 16- Pécora G, Andr eana S. Use of dent al operat ing m icr oscope in endodont ic surgery. Oral Surg Oral Med Oral Pat hol. 1993; 75: 751-8.
17- Per eira ES, Singh R, Ar ias A, Pet er s OA. I n vit r o assessm ent of t orque and force generat ed by novel ProTaper Next I nst rum ent s dur ing sim ulat ed canal pr eparat ion. J Endod. 2013; 39: 1615- 9. 18- Pirani C, Pelliccioni GA, Marchionni S, Mont ebugnoli L, Piana G, Prat i C. Effect iveness of t hr ee differ ent r et r eat m ent t echniques in FDQDOV¿OOHGZLWKFRPSDFWHGJXWWDSHUFKDRU7KHUPD¿ODVFDQQLQJ elect r on m icr oscope st udy. J Endod. 2009; 35: 1433- 40.
1 9 - Röd ig T, Reich er t s P, Kon iet sch k e F, Du llin C, Hah n W, +OVPDQQ0(I¿FDF\RIUHFLSURFDWLQJDQGURWDU\1L7LLQVWUXPHQWV for r et r eat m ent of cur ved r oot canals assessed by m icr o- CT. I nt Endod J. 2014; 47: 942- 8.
20- Schir m eist er JF, Her m anns P, Meyer KM, Goet z F, Hellw ig E. Det ect abilit y of residual Epiphany and gut t a- percha aft er root canal r et r eat m ent using a dent al operat ing m icr oscope and radiographs - an ex vivo st udy. I nt Endod J. 2006; 39: 558- 65.
2 1 - Sch n ei d er SW. A co m p ar i so n o f can al p r ep ar at i o n s i n st raight and cur ved r oot canals. Oral Sur g Oral Med Oral Pat hol. 1971; 32: 271- 5.
22- Skidm or e AE, Bj or ndal AM. Root canal m or phology of t he KXPDQPDQGLEXODU¿UVWPRODU2UDO6XUJ2UDO0HG2UDO3DWKRO 1971; 32: 778- 84.
UHWUHDWPHQWV\VWHPHI¿FDF\FRQVLGHULQJURRWFDQDOWKLUGVXVLQJ t hr ee endodont ic sealer s. Micr osc Res Tech. 2012; 75: 1233- 6. 6y096DUDQ&0DJUR0/9LHU3HOLVVHU)90XQKR]0(I¿FDF\ RI3UR7DSHUUHWUHDWPHQWV\VWHPLQURRWFDQDOV¿OOHGZLWKJXWWD per cha and t w o endodont ic sealer s. J Endod. 2008; 34: 1223- 5. 25- Takahashi CM, Cunha RS, Mar t in AS, Font ana CE, Silveira CF, Silveira Bueno CE. I n vit r o evaluat ion of t he effect iveness of Pr oTaper univer sal r ot ar y r et r eat m ent syst em for gut t a- per cha r em oval w it h or w it hout a solvent . J Endod. 2009; 35: 1580- 3. 7DúGHPLU7<LOGLULP7&HOLN'&RPSDUDWLYHVWXG\RIUHPRYDO RIFXUUHQWHQGRGRQWLF¿OOLQJV-(QGRG
27- Vilanova WV, Car valho-Junior JR, Alfr edo E, Sousa- Net o MD, Silva- Sousa YT. Effect of int racanal ir r igant s on t he bond st r engt h of epoxy resin- based and m et hacrylat e resin- based sealers t o root canal walls. I nt Endod J. 2012; 45: 42- 8.
:ROFRWW-)+LPHO97+LFNV0/7KHUPD¿OUHWUHDWPHQWXVLQJD new ‘‘Syst em B’’ t echnique or a solvent . J Endod. 1999; 25: 761- 4 29- Xu LL, Zhang L, Zhou XD, Wang R, Deng YH, Huang DM. 5HVLGXDO ¿OOLQJ PDWHULDO LQ GHQWLQDO WXEXOHV DIWHU JXWWDSHUFKD r em oval obser ved w it h scanning elect r on m icr oscopy. J Endod. 2012; 38: 293- 6.
3 0 - Zh ao D, Sh en Y, Pen g B, Haapasalo M. Micr o- com pu t ed t om ography evaluat ion of t he pr eparat ion of m esiobuccal r oot FDQDOVLQPD[LOODU\¿UVWPRODUVZLWK+\ÀH[&07ZLVWHG)LOHVDQG K3 inst r um ent s. J Endod. 2013; 39: 385- 8.
