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. .. .. .. .. .. . . . . . . . . . : rr . .. .. . .

Vol. 89 No. 6 June 2000

ENDODONT ICS Editor: Larz Spdmgberg

Prevalence and extent of long oval canals in the apical third

Min-Ka i W u, M D, MSD, PhD, a Athena R 'o r i s , DDS, b Dimi tr i s Ba rk i s , DDS , b and Pau l R .

Wesse l ink , DDS, PhD, c Amste rdam, The Ne the r lands

ACADEMIC CENTRE FOR DENTISTRYAMSTERDAM

Objective. The aim of this study was to investigate the canal diameters in the apical roots of hum an teeth to determin e preva-

lence and extent of long oval canals.

Study design. This investigation was carried out on 180 extracted hum an teeth, 20 for each tooth group. Each root was hori-

zontally sectioned at I, 2, 3, 4, and 5 mm from the apex. Canal diameters were measured with a measuring microscope.

Results. In 293 (25%) of the 1181 cross sections investigated, a long oval ca nal (the long ca nal diame ter was at least 2 times

the short canal diameter) wa s identifie d. In some tooth groups, the percentage of lon g oval canals exceeded 50%. In most cases,

the long diameter decreased apically; that is, the canal tended toward a rounder cross section. A wide range of diameters

existed in all canals.

Conclusion. Long oval canal is common in the apical 5 mm in hum an teeth. Man y long and narrow oval canals wou ld be

impossible to instrument completely w itho ut perforating or significantly weakening the roots. Care should be taken in

cleaning, shaping, and obturating these oval canals.

(Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:739-43)

Dur ing roo t cana l t r ea tment , cana l s a re p repa red by

hand or by eng ine -dr iven ins t rument s . Cu t t i ng i s

achieved by rota t ion or by a c i rcumferent ia l push-pul l

movement . Canal prepara t ion is fac i l i ta ted by i r r iga-

t i on wi th a so lu t ion , such a s sod ium hypoch lor i t e .

Wheth er the ent i re wal l of the main canal can b e safe ly

inst rumented depends on many factors, inc luding the

morp holog y of t he cana l, t he t h i ckness o f t he cana l

wa l l , and the s i ze o f t he i ns t rument used . Ana tomic

studies on tooth roots and root canals have provided

useful treatm ent infor mation . 1-4

Cana l s have d i f fe ren t shapes i n c ross sec t ion ,

including oval shapes, and di ff icult ies have been noted

in cleaning these oval canals. 5,6 Rece sses in oval can als

may not be included in a round prepara t ion created by

rota t ion of inst ruments, and thus they remain unpre-

pared. One percept ion is that these recesses could be

aLecturer, Department of Cariology Endodontology Pedodontology.bGraduate Eudodontics, Department of Cariolog y EndodontologyPedodontology.cprofessor and Chairman, Department of Cariology EndodontologyPedodontology.Receivedfor publication Sept 28, 1999; returned for revisionNov 23,1999; accepted for publication Jan 28, 2000.Copyright © 2000 by Mosby, Inc.

1079-2104/2000/$12.00 + 0 7/15/106344doi: 10.1067/moe.2000.106344

inst rumented by c i rcum ferent ia l f i l ing wi th a smal l f i le .

However , whether that i s rea l ly the case in the apical

root canals remains to be confi rmed becau se the apical

port ion of inst ruments may not be easi ly control led.

As repor t ed by M auger e t a l , 7 a f te r r e sec t ing the

ap ices o f mandibu la r i nc i sor s a t a 20-degree fac i a l

bevel , the average faciol ingual diameter of canals was

0 .75 m m a t 3 mm f ro m the apex . They found tha t oval

cana l s occup ied 42% and long ova l cana l s occup ied

40% of the invest igated tee th. I t seems that most canals

of lower incisors were not round in shape; long oval

canals may be more di ff icul t to c lean, shape, and obtu-

ra te . In another recent study, apical canal diameter in

the f i rst upper molar was invest igated. 8 Cross sect ions

of mos t m es iobucca l cana l s were found to be ova l .

The a im of our s tudy was to i nves t iga t e t he cana l

diameters in the apical region of hum an tooth roots o f

d i f fe ren t t oo th g roups . Al so de t e rmined were t he

prevalence and extent of long oval canals.

M A T ER IA L S A N D M E T H O D S

One hundred e igh ty ex t rac t ed adu l t human t ee th ,

which had been stored in 10% formal in solut ion, were

randomly se lected. Twenty tee th were se lected, repre-

sent ing each of the fol lowing tooth posi t ions: maxi l laryinc i sor s and can ine , p remola r s and mola r s , and

73 9

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740 W u e t a l O R A L S U R G E RY O R A L M E D I C I N E O R A L P A T H O L O G Y

June 2000

T a b l e I . M e d i a n ( r a n g e ) o f c a n a l d i a m e t e r s ( in m m ) a t 1 , 2 a n d 5 m m f r o m t h e a p e x

B uc c a l / l ingua l Me s ia l /d i s ta l

T oo th ( c ana l) pos i t ion lmm 2mm 5r am lm m 2r nm 5r am

M a x i l l a r y

Central inc isor 0.34(0.15-0.69) 0.47(0.19-0.94) 0.76(0.30-1.20) 0.30(0.14-0.59 ) 0.36(0.17 -0.72) 0 .54(0.27-0.99)Latera l inciso r 0 .45(0 .27-0 .83) 0 .60(0 .30-1 ,18) 0 .77(0 .46-1 .30) 0 .33(0 .19-0 .54) 0 .33(0 .17-0 .51) 0 .47(0 .24-0 .76)

Ca nin e 0.31(0.16-0.58) 0.58(0.31-0.89) 0.63(0.41-1.26) 0.29(0.11-0.50) 0.44(0.24-0.57) 0.50(0.29-0.67)

P r e m o l a r

S ingle cana l 0 .37(0 .16-1 .35) 0 .63(0 .27-1 .26) 1 .13(0 .47-2 .24) 0 .26(0 .14-0 .37) 0 .41(0 .23-0 .67) 0 .38(0 .29-0 .49)

B 0.30(0.23-0.33) 0.40(0.12-0.67) 0.35(0.29-1.16) 0,23(0,20-0,27) 0,31(0.07-0.52) 0.31(0.20-0.62)

P 0.23(0.17-0.29) 0.37(0.26-0.80) 0.42(0.23-0.67) 0.17(0.17-0.19) 0.26(0.20-0.51) 0.33(0.18-0.50)

M o l a r

Sin gle M B 0.43(0.09-0.99) 0.46(0.34-0.96) 0.96(0.34-2.67) 0.22(0.13-0.39) 0.32(0.13-0.53) 0.29(0.15-0.56)

ls tM B 0.19(0 .12-0 .26) 0 .37(0 .29-0 .91) 0 .46(0 .23-1 .11) 0 .13(0 .08-0 .18) 0 .27(0 .11-0 .41) 0 ,32(0 .16-0 .50)

2nd M B 0,19(0.14-0.23) 0.31(0.22-0.60) 0.38(0,19-1.21) 0.16(0.15-0.16) 0.16(0.09-0.23) 0.16(0.09-0.35)

D 0.22(0.07-0.73) 0.33(0.18-1.33) 0.49(0,24-1.54) 0.17(0.07-0.39) 0.25(0.15-0.31) 0.31(0,20-0.60)

P 0.29(0.09-0.45) 0.40(0.12-0.59) 0.55(0,31-0.91) 0.33(0.11-0.72) 0.40(0.27-0.94) 0.74(0,31-1.45)

M a n d i b u l a r

Inci sors 0.37(0.13-0.80) 0.52(0.28-0.98) 0.81(0.29-1.80) 0.25(0.12-0.33) 0.25(0,12-0.51) 0.29(0.19-0.49)

Ca nin e 0.47(0.18-0.75) 0.45(0.28-0.71) 0.74(0.48-1.68) 0.36(0.18-0.72) 0.36(0,28-0.63) 0.57(0.34-0.85)

P r e m o l a r

Sin gle 0.35(0.20-0.80) 0.40(0.29-1.01) 0.76(0.52-1.67) 0.28(0.16-0.54) 0.32(0,17-0.67) 0.49(0.26-0.80)

B 0.20(0.20-0.62) 0.34(0.27-0.62) 0.36(0.20-1.05) 0,23(0,23-0.28) 0.29(0.28-0.48) 0.41(0.30-1.10)

L 0.13(0.12-0.15) 0.32(0.24-0.38) 0.37(0.16-1.08) 0.18(0.10-0.23) 0.21(0.17-0.34) 0.17(0.12-0.54)

M o l a r

Sin gle M 0.45(0.06-0.60) 0.80(0.37-1.45) 2.11(0.48-2.89) 0.22(0.11-0.54) 0.30(0.14-0.55) 0.29(0.17-0.50)

M B 0.40(0.20-0.52) 0.42(0.28-0.77) 0.64(0.41-1.26) 0.21(0.19-0.39) 0.26(0.18-0.38 ) 0.32(0.24-0.42)

M L 0.38(0.32-0.67) 0.44(0,24-1.08) 0.61(0.12-0.89) 0.28(0.23-0.37) 0.24(0.16-0.42) 0.35(0.12-0.63)

D 0.46(0.28-1.69) 0.50(0.23-l.73) 1.07(0.58-2.78) 0.35(0.18-0.69) 0.34(0.18-0.61) 0.59(0.33-0.82)

M , M e s i a l ; B, b u c c a l ; D, d i s t a l ; P. pa la ta l : L, l i ngua l .

m a n d i b u l a r i n c i s o r s a n d c a n i n e , p r e m o l a r s a n d m o l a r s .N o i n f o r m a t i o n w a s a v a i l a bl e a s t o t he a g e s o f t h e s e

t e e th . T h e p a t e n c y o f e a c h c a n a l w a s c o n f i r m e d b y

i n s e r t i n g a s i z e - 0 8 f il e t h r o u g h t h e a p i c a l f o r a m e n .

T e e t h w i th a p i c a l f o r a m e n t h a t w e r e m o r e t h a n 1 m m

a w a y f r o m t h e a p e x w e r e e x c l u d e d .

E a c h r o o t w a s h o r i z o n t a l l y s e c t i o n e d w i t h a l o w -

sp eed saw a t 1 , 2 , 3 , 4 , an d 5 mm f ro m th e ap ex fo r a

t o t a l o f 1 1 8 1 u sab l e sec t i o n s . Th e sec t i o n s were g lu ed

o n g l as s s l i d es . Can a l d i amete r s were measu red i n t h e

5 c r o s s s e c t i o n s f r o m e a c h t o o t h w i t h a m e a s u r i n g

m i c r o s c o p e ( O l y m p u s S T M , T o k y o , J a p a n ) a t × 3 0

m a g n i f i c a t i o n a n d w e r e d e t e r m i n e d w h e n t h e 2 i n v es t i-g a to r s ag reed . A can a l w as i d en t i f ied as l o n g o v a l wh en

t h e r a ti o o f l o n g t o s h o r t c a n a l d i a m e t e r w a s > 2 ( i e ,

w h e n 1 d i m e n s i o n w a s a t l e a s t 2 ti m e s t h a t o f a

m e a s u r e m e n t m a d e a t r ig h t a n g le s ) .

E v a l u a t i o n a n d c o m p a r i s o n s w e r e m a d e d e s c r i p -

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

s h a p e s w e r e c o m p i l e d a n d r e p o r t e d in a t a b u l a r f o r m a t

fo r t h e t o o th g ro u p s an d d i f f e r en t can a l l ev e l s .

RESULTS

C a n a l d i a m e t e r s a t 1 , 2 , a n d 5 m m f r o m a p e x f o r a l l

t o o th g ro u p s a r e sh o w n in Tab l e I . Th e o ccu r r en c es o f

t h e l o n g o v a l can a l a r e sh o wn in Tab l e I I . Ov era l l , i nt h e 1 1 8 1 c ro ss sec t i o n s ev a lu a t ed , a l o n g o v a l can a l

was i d en t i f i ed i n 2 9 3 (2 5 % ) c ro ss sec t i o n s . Th e o th e r

7 5 % were mo re ro u n d o r s l i g h t l y o v a l i n sh ap e . In a l l

t o o t h g r o u p s , t h e b u c c a l / l i n g u a l d i a m e t e r w a s l o n g e r

th an t h e mes i a l / d i s t a l d i amete r , ex cep t fo r t h e p a l a t a l

r o o t s o f m a x i l l a r y m o l a r s . G e n e r a ll y , th e l o n g d i a m e t e r

d ecreased ap i ca l l y , mean in g t h e can a l t en d ed t o ward a

r o u n d e r s h a p e .

O v e r a l l , 5 m m f r o m t h e a p e x , t h e o c c u r r e n c e o f th e

l o n g o v a l c a n a l w a s > 5 0 % i n s o m e t o o t h g r o u p s

( T a b l e I I ) . I n T a b l e I I I t h e s e c a n a l s ( n = 6 7 ) a r e

g r o u p e d i n t o d i f f e r e n t o v a l g r o u p s . I n 2 5 ( 3 7 % )c a n a l s , t h e l o n g : s h o r t d i a m e t e r r a t io w a s < 2 x , t h a t i s ,

m o r e r o u n d o r s l i g h t l y o v a l in s h a p e . I n 2 1 ( 3 1 % )

c a n a l s , > 2 x b u t < 4 x , t h e r e w a s a l o n g o v a l s h a p e . I n

t h e r e m a i n i n g 2 1 ( 3 1 % ) c a n a l s , t h e r e w a s > 4 x , t h a t

i s , a f l a t sh ap e .

Th e ca l cu l a t ed t ap er s o f ap i ca l can a l s a r e sh o wn in

Tab l e IV . In so m e to o th g ro u p s , t h e t ap er i n t h e me s i a l -

d i s ta l d i re c t i o n w a s 0 t o 0 .0 2 m m / m m ; t h e m o s t a p i c a l

p o r t i o n o f ro o t can a l w as p a ra l l e l o r a lmo s t p a ra l l e l . I n

a l l t o o t h g r o u p s , e x c e p t f o r t h e b u c c a l c a n a l i n

m a n d i b u l a r p r e m o l a r s , t h e b u c c a l - l i n g u a l t a p e r w a s

g rea t e r t h an t h a t i n t h e m es i a l -d i s t a l d i r ec t io n .

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ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Wu et al 741

V o l u m e 8 9, N u m b e r 6

T a b l e I I. P e r c e n t a g e o f l o n g o v a l c a n a l s ( r a t io o f l o n g / s h o r t c a n a l d i a m e t e r s _> 2 ) a t 1 - 5 m m f r o m a p e x

T o o t h ( c a n a l ) p o s i t i o n 1 m m 2 m m 3 m m 4 r a m 5 m m

Maxillary

Central incisor 0% 10% 0% 5% 5%

Lateral incisor 16% 35% 10% 10% 15%Canine 0% 6% 0% 0% 5%

Premolar

Single canal 38% 29% 43% 57% 63%

Buccal canal 0% 7% 0% 8% 0%

Palatal canal 0% 15% 7% 0% 0%

Molar

Single mesial-buccal 33% 13% 60% 75% 60%

1st Mesial-buccal canal 0% 27% 33% 17% 33%

2rid Mesial-buccal canal 0% 73% 80% 58% 60%

Distal-buccal canal 11% 30% 20% 20% 25 %

Palatal canal 24% 16% 15% 15% 10%

Mandibular

Incisors 10% 55% 40% 55% 56%

Canine 11% 5% 5% 5% 5%

PremolarSingle canal 13% 13% 13% 20% 27%

Buccal canal 33% 0% 20% 0% 20%

Lingual canal 0% 0% 20% 20% 40%

Molar

Single mesial canal 20% 45% 67% 91% 92%

Mesial-buccal 25% 25% 30% 56% 50%

Mesial-lingual 0% 25% 10% 11% 13 %

Distal canal 24% 25% 25% 25% 30%

D I S C U S S I O N

I n a p r e v i o u s s t u d y , a n o v a l c a n a l w a s i d e n t i f i e d

w h e n t h e l a r g e d i a m e t e r e x c e e d e d t h e s m a l l d i a m e t e r . 8B e c a u s e t h e r e w e r e v e r y fe w c a n a l s i n w h i c h 1 d im e n -

s i o n w a s e q u a l t o t h at o f a m e a s u r e m e n t m a d e a t r i g h t

a n g l e s , m a n y c a n a l s w e r e o v a l . I n o u r s t u d y , th e p r e v a -

l e n c e o f l o n g o v a l c a n a l s , o f w h i c h t h e l o n g c a n a l

d i a m e t e r w a s a t l e a s t 2 t im e s t h e s h o r t d i a m e t e r , w a s

i n v e s t i g a t e d . T h e g e n e r a l p e r c e n t a g e o f l o n g o v a l

c a n a l w a s 2 5 % .

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

c u t a t 5 m m f r o m t h e a p e x s h o w e d a p e r c e n t a g e o f l o n g

o v a l c a n a l o f 5 0 % t o 9 2 % ( T a b l e II ) ; t h e s e c r o s s

s e c t io n s w e r e f u r t h e r u s e d t o o b s e r v e h o w m a n y c a n a l s

f e l l i n t o d i f f e r e n t o v a l g r o u p s ( T a b l e I I I) . I t w a s f o u n dt h a t i n c r o s s s e c t i o n s , m a n y c a n a l s h a d a f l a t s h a p e ; t h e

l o n g d i a m e t e r w a s a t l e a s t 4 t i m e s t h e s h o r t d i a m e t e r

( > 4 × , T a b l e I I I ). F l a t c a n a l o c c u r r e d i n o n e f o u r t h t o

t w o t h i rd s o f s e v e r a l to o t h g r o u p s . O b v i o u s l y , t h e se

l o n g a n d n a r r o w c a n a l s w o u l d b e v e r y d i f f i c u l t t o c l e an ,

s h a p e , a n d o b t u r a te .

F o r t h e s e t o o th g r o u p s , v e r y l o n g b u c c a l - l i n g u a l

d i a m e t e r s w e r e r e c o r d e d ( T a b l e I) . A c i r c u l a r p r e p a -

r a t io n w o u l d r e q u i r e i n s t ru m e n t s o f a s i ze t h a t m a y

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

m e s i a l - d i s t a l d i r e c ti o n .

T h e t a p e r o f a p r e p a r e d a p i c a l c a n a l i s 0 . 0 5 m l r d m m

w h e n t h e m a s t e r f i l e i s _ <4 5, a s s u g g e s t e d b y W e i n e . 9

H o w e v e r , t h is t a p e r c a n b e 0. 1 m m / m m , a c c o r d i n g t o

W e s t a n d R o a n e . 10 A s s h o w n i n T a b l e I V , th e a v e r a g et a p e r o f t h e o r i g i n a l c a n a l i n t h e b u c c a l - l i n g u a l o r i e n t a -

t io n w a s 0 . 1 0 m m / m m , w h e r e a s t h e t a p e r i n m e s i a l -

d i s t a l d i r e c t io n w a s m u c h s m a l le r . I n s o m e t o o t h o r

c a n a l p o s i t i o n s t h e w a l l s w e r e e s s e n t i a l l y p a r a l l e l

( t a p e r = 0 m m / m m ) . I n s t r u m e n t i n g t h e c a n a l s t o a t a p e r

o f 0. 0 5 m m / m m w o u l d l e a v e u n in s t r u m e n t e d a r e as in

t h e b u c c a l - l i n g u a l o r i en t a t i o n . I n c r e a s i n g t h e t a p e r

f r o m 0 . 0 5 t o 0 .1 0 m m / m m m a y b e b e n e f ic i a l f o r t h e

c l e a n i n g i n t h e b u c c a l - l i n g u a l d i re c t i o n . H o w e v e r , i t

w i l l i n c r e a s e t h e d i a m e t e r o f t h e c a n a l i n t h e m e s i a l -

d i s t a l d i r e c t i o n , t h e r e b y r e d u c i n g w a l l t h i c k n e s s . T o

w h a t e x t e n t t h i s w e a k e n s t h e r o o t i s u n k n o w n .I n s o m e t e e t h , t h e p r e v a l e n c e o f l o n g o v a l c a n a l s is

r e l a t i v e l y l o w , f o r e x a m p l e , _ < 5% in m a x i l l a r y c e n t r a l

i n c i s o r s an d i n b o t h m a x i l l a r y a n d m a n d i b u l a r c a n i n e s

( T a b l e II ) . T h e s e c a n a l s w e r e m o r e r o u n d i n s h a p e .

H o w e v e r , t h e r a n g e o f c a n a l d i a m e t e r s w a s w i d e ( T a b l e

I ). T h e r e c o m m e n d e d s i z es u f o r t h e a p i c a l e n l a r g e -

m e n t a t d i f f er e n t to o t h p o s i t i o n s m a y b e u s e d a s r e fe r -

e n c e s . I n s t r u m e n t i n g a l l c a n a l s t o a s i m i l a r s iz e , s u c h

a s N o . 8 0 , w o u l d b e i n a p p r o p r i a t e b e c au s e s o m e c a n a l s

c o u l d b e v a s t l y o v e r p r e p a r e d a n d t h e r o o t s w e a k e n e d ,

w h e r e a s o t h e r s m a y n o t b e s u f f i c i e n t ly c l e a n e d ( T a b l e

I ). I t se e m s n e c e s s a r y t o a c c u r a t e l y m e a s u r e t h e s i z e o f

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742 Wu et al ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY

J u n e 2 0 0 0

T a b l e I I I. C a n a l s t h a t fa l l i n t o d i f fe r e n t o v a l g r o u p s a t 5 m m f r o m a p e x

Num be r o f c ana ls w i t h d i f f e r e n t long: shor t d i am e t e r ra t i os

Tooth (ca na l)P osi tion Total <l.5x <2x _<4x <6x _<8x <<-lOx > Ox

Maxillary

PremolarSingle canal 8 1 2 3 1 1 0 0

Molar

Single MB 10 1 3 2 0 2 1 1

2nd MB 10 3 1 4 1 0 1 0

Mandibular

Incisors 19 7 2 5 3 2 0 0

Molar

Single M 12 0 1 3 3 0 2 3

MB 8 2 2 4 0 0 0 0

67 14 11 21 8 5 4 4

M, M esial; B, buccal.

T a b l e IV . T a p e r o f r o o t c a n a l s

Tooth (canal) posi t ion

T ape r in m m / m m i n 2 or i e n t a ti ons

B uc c a l / l i ngua l M e s i a l / d i s t a l

Maxillary central incisor 0.11 0.06

Maxillary lateral incisor 0.08 0.04

Maxillary canine 0.08 0.05

Maxillary premolar

Single canal 0.19 0.03

Buccal canal 0.03 0.02

Palatal canal 0.05 0.04

Maxillary molar

Single mesial-buccal canal 0.13 0.02

1st Mesial-buccal canal 0.07 0.05

2rid Mesial-buccal canal 0.05 0Distal-buccal canal 0.07 0.04

Palatal canal 0.07 0.10

Man dibular incisors 0.11 0.01

Man dibular canine 0.07 0.05

Man dibular premolar

Single canal 0.10 0.05

Buccal canal 0.04 0.05

Lingual canal 0.06 0

Mandibular molar

Single mesial canal 0.42 0.02

Mesial-buccal canal 0.06 0.03

Mesial-lingual canal 0.06 0.02

Distal canal 0.15 0.06

Av erage 0.1 _+ 0.08 0.04 +_ 0.02

a n y i n d i v i d u a l c a n a l b e f o r e d e c i d i n g o n t h e s i z e o f t h e

a p i c a l e n l a r g e m e n t , r a t h e r t h a n s i m p l y r e l y i n g o n

g e n e r a l r e c o m m e n d a t i o n s .

T e x ts h a v e r e c o m m e n d e d t h e e n l a rg e m e n t o f t h e

a p i c a l r o o t c a n a l t o 3 s i z e s la r g e r t h a n t h e f i r s t b i n d i n g

f i le . 9 -1 2 T h e f i l e is t a p e r e d a n d h a s i t s s m a l l e s t d i a m e t e r

a t t h e t i p . T h i s f i l e m a y n o t b i n d a t th e w o r k i n g l e n g t h

b u t m a y b i n d a t an y l e v e l c o r o n a l ; t h u s t h e s i z e o f th e

f i rs t b i n d i n g f i le m a y n o t p r o v i d e i n f o r m a t i o n f o r t h e

d i a m e t e r o f t h e a p i c a l c an a l . A N o . 1 0 f il e m a y b i n d i n

a v a r i e t y o f c a n a l s . 9 B i n d i n g b y i t s e lf d o e s n o t n e c e s -

s a r i l y in d i c a t e t h e c a n a l d i a m e t e r ( T a b l e I ) .

I t i s a ls o r e c o m m e n d e d t h a t th e c a n a l b e e n l a r g e d t o

a s u i t a b l e s iz e , t h at i s, " e n o u g h t o p e r m i t a d e q u a t e

d e b r i d e m e n t , a s w e l l as to p e r m i t m a n i p u l a t i o n a n d

c o n t r o l o f o b t u r a t i n g m a t e r i a l s a n d i n s t r u m e n t s , b u t n o t

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

a n d n e e d l e s s l y w e a k e n i n g t h e r o o t a r e i n c r e a s e d . '1 2

T h e s e s t a t em e n t s a r e r e a s o n a b l e ; d i a m e t e r s a t 1 a n d 2

m m f r o m a p e x ( T a b l e I ) ar e u s e f u l i n s e l e c ti n g f i le s o f

s u i t a b l e s i ze s f o r a p i c a l e n l a r g e m e n t . T o p r e v e n t o c c u r -

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

a d v i s e d p r e p a r a t i o n o f c u r v e d c a n a l s w i t h s m a l l i n s t ru -m e n t s , p r e f e r a b l y n o l a r g e r t h a n N o . 2 5 .1 2, 13 I n s o m e

c a s e s , a c u r v e d c a n a l m a y h a v e a l a r g e r d i a m e t e r t h a n

a s t ra i g h t c an a l . T h e c u r v e d c a n a l s m a y n o t b e c l e a n

a f t e r p r e p a r a t i o n t o N o . 2 5 ( T a b l e I ) . 14

B e c a u s e o f l o n g o v a l c a n a ls , l a r g e r c a n a l t a p e r s i n t h e

b u c c a l - l i n g u a l d i r e c t i o n , a n d a w i d e r a n g e i n a p i c a l d i a m -

e t er s o f c a n a l s a n d t h e l a c k o f t e c h n o l o g y t o m e a s u r e

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

a d e q u a t e l y d e b r i d e a l l ca n a l s b y i n s t r u m e n t a t i o n o n l y .

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

o f i r r ig a t i o n . A c o u s t i c m i c r o s t r e a m i n g b y u l t r a s o n i c i r ri -

g a t i o n m a y c l e a n t h e o v a l c a n a l b e t t e r . 5 F i v e p e r c e n ts o d i u m h y p o c h l o r i t e m a y b e h e l p f u l in d i s s o l v i n g

o r g a n i c m a t e r i a l s i n t h o s e u n i n s t r u m e n t e d r ec e ss e s. 1 5, 1 6

T h e m e a n v a l u e o f a p e x t o a p ic a l c o n s t r i c t i o n

d i s t a n c e w a s f o u n d t o b e 0 . 9 m m . 4 T h u s , t h e d i a m e -

t e r s at 1 m m f r o m a p e x s h o w n i n T a b l e I a r e l i k e l y

t h e s m a l l e s t d i a m e t e r s o f r o o t c a n a l s . I t h a s b e e n

s u g g e s t e d t h a t a p a t e n c y f i le b e u s e d i n t h e a p i c a l

f o r a m e n t o r e m o v e t h e d e b r i s in t h e a p i c a l 1 t o 2 m m

o f t h e r o o t c a n a l . 1 7.1 8 " T h e g o a l i s t o c l e a n b u t n o t

e n l a r g e t h e f o r a m e n . q ° T h u s , t h e d a t a in T a b l e I a r e

u s e f u l i n s e l e c t i n g p a t e n c y f i l e s o f s u i t a b l e s i z e s f o r

d i f f e r e n t c a n a l s .

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ORAL SURGERY ORAL MEDICINE O RAL PATHO LOGY ~ W u e t a l 7 4 3

Volume 89, Number 6

W i t h t h e f i n d i n g s o f t h is a n a t o m i c s t u d y , i t c a n b e

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

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

l a r g e r t h a n 2 t im e s t h e s h o r t c a n a l d i a m e t e r ; t h i s

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

R E F E R E N C E S

1 . Ke re k e s K, T ro n s t a d L . M o rp h o me t r i c o b se rv a t i o n s o n ro o tcanals o f hum an an terio r tee th . J Endo d 1977;3 :24-9 .

2 . Ke re k e s K, T ro n s t a d L . M o rp h o me t r i c o b se rv a t i o n s o n ro o tcanals o f huma n premolars . J Endod 1977;3 :74-9 .

3 . Ke re k e s K, T ro n s t a d L . M o rp h o me t r i c o b se rv a t i o n s o n ro o tcanals o f huma n molars . J End od 1977;3 :114-8 .

4 . Du m me r PM H, M c Gi n n JH, R e e s DG. Th e p o s it i o n a n d t o p o g -raphy of the ap ica l canal const r ic t ion and ap ica l fo ramen. In tEnd od J 1984; 17 :192-8 .

5 . Lum ley PJ, Walmsley AD , Wal ton RE, Rippin JW. Clean ing ofoval canals using u l t rasonic o r son ic ins t rumenta t ion . J Endod1993; 19:453-7.

6 . Wu M -K, Wessel ink PR. A prima ry observat ion on the prepara-t ion and ob tura t ion in oval canals . In t End od J . In p ress .

7 . M a u g e r M J , Sc h i n d l e r WG , Wa l k e r WA. An e v a l u a t io n o f c a n a lmorphology a t d i fferen t levels o f roo t resec t ion in mandibularincisors. J Endod 1998;24:607-9.

8 . Gani O, Visv is ian C. Apica l canal d iameter in the f i rs t uppermo lar a t various ages . J Endo d 1999;25:689-91 .

9 . Weine FS. Endodo nt ic Therapy . 5 th ed . St Louis : Mosb y; 1996 .

p. 93.

10 . West JD, Roan e JB. Clean ing and shap ing the roo t canal system.In : Cohe n S, Burns RC. ed i tors . P a thways of the pu lp . 7 th ed . StLouis : Mosb y; 1998 . p . 203-57 .

11 . T ronstad L. Cl in ica l Endod ont ics . New York : Thieme; 1991 . p .202 .

12 . W al ton RE, Torab inejad M. Princ ip les and prac t ice o f endodo n-

tics. 2nd ed. Philadelphia: W B Saunders Com pany; 1996. p. 204.13 . Ing le JI . Endodont ics . 4 th ed . Bal t imore: Wil l iams & Wilk ins;

1994 .14 . Wu M -K, Wessel ink PR. Efficacy of th ree techniques in c lean ing

t h e a p i c a l p o r ti o n o f c u rv e d ro o t c a n a l s . Ora l Su rg Ora l M e dOral Patho l Oral Radio l End od 1995;79:492-6 .

1 5 . Ha n d R E, Smi t h M L, H a r r i so n JW. An a l y s i s o f t h e e f fe c t o f d i l u -t i o n o n t h e n e c ro t i c t i s su e d i s so l u t i o n p ro p e r t y o f so d i u mhypoch lori te . J Endo d 1978;4 :60-3 .

1 6 . M o o re r WR , We sse l i n k PR . Fa c t o r s p ro mo t i n g t h e t i s su ed i s so l v i n g c a p a b i l i t y o f so d i u m h y p o c h l o r i t e . In t En d o d J1982;15:187-96.

1 7 . B u c h a n a n LS . M a n a g e me n t o f t h e c u rv e d ro o t ca n al . C a l De n tAssoc J 1989;17 :40~7.

18 . Wu M -K, Wesselink PR , Wal ton RE. Apica l te rminus locat ion ofroo t canal t rea tment p rocedures. Ora l Surg Oral M ed O ral Patho l

2000;89:99-103.

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