LETTERS TO THE JOURNAL
THE JOURNAL devotes th is section to com m ent by readers on top ics of current interest to dentistry. The m anaging ed itor reserves the righ t to edit all com m unications to fit available space and requires tha t all letters be signed. Printed com m unications do not necessarily reflect the opinion or official p o licy of the A ssociation. Y our pa rticipatio n in th is section is invited.
c a r e f u l a tt e n ti o n t o d e t a il, a n d fa ilu re
Dental econom ics ■ . . .
s tic k to th e t o o t h , n o t to th e r e s t o r a
o f b r id g e w o r k is a c o s t l y a n d d a m a g
ti o n . H o w e v e r , g o ld c a s t i n g s c a n b e
in g e x p e r i e n c e f o r th e p r a c t i t i o n e r .
c h e m ic a lly b o n d e d to p o ly c a r b o x y la te c e m e n t s b y c o a t i n g th e fit s u r f a c e o f
I f t he dent al p ro fe ssio n had
D r . A c h a r y a ’ s r e p ly is e x c e l l e n t b u t
p r o p e r l e a d e r s h i p , th e d e n t i s t w o u ld
t h e r e a r e o n e o r t w o f u r t h e r p o in ts th a t
th e
n o t h a v e a llo w e d h i m s e lf t o b e rip p e d
I w o u ld lik e t o r a i s e . T h e b o n d in g in
m a te ly 2/x t h i c k . 4 T h i s w ill h e lp r e t e n
o ff
tio n o f th e d iff ic u lt b r id g e .
c a s tin g
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a p p ro x i
s u p p lie r s ,
z in c o x i d e e u g e n o l c e m e n t s is v e r y
c o m m e r c i a l la b s , a n d n o w b y th e g o v
w e a k a n d z in c e u g e n o l a te is r e a d ily
e rn m e n t an d d e n tu ris ts , an d so f o r t h ..
h y d r o ly z e d in th e p r e s e n c e o f w a t e r to
t o w a r d u s in g g l a s s - i o n o m e r c e m e n t s
by
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F u tu re
research
is b e in g d i r e c t e d
. . It is p o s s ib le f o r b o th th e d e n tis t a n d
z in c h y d r o x id e a n d e u g e n o l ; th e p r o
w h ic h p o s s e s s th e a d v a n t a g e s o f th e
th e p a t ie n t to c o m e o u t f in a n c ia lly b e t
c e s s c o n t i n u e s , a s e u g e n o l is r e m o v e d
p o l y c a r b o x y l a t e s b u t a ls o h a v e e x c e l
t e r w h e n d e n tis ts p r a c t i c e a s a g r o u p .
b y w a t e r le a c h i n g , u n til th e m a tr i x is
le n t c r e e p r e s i s t a n c e . 2
. . . I m e a n w h e r e s e v e r a l d e n tis ts
e n t ir e ly
g r o u p to g e t h e r in s u f f ic ie n t n u m b e r to
d r o x i d e .1
in c lu d e a t l e a s t o n e m e m b e r o f e a c h s p e c ia lty ,
c o m p le te
la b o ra to rie s ,
tr a n s f o r m e d
to
z in c
hy
W e m a y e v e n t u a l l y s e e th e d i s a p p e a r a n c e o f th e
H o w e v e r , th is is n o t th e o n ly r e a s o n f o r f a ilu r e .
A p p a re n tly
th e
s tr e n g th
z in c p h o s p h a te c e
m e n ts b u t n o t u n til t h e y c a n b e r e p l a c e d w ith m a t e r i a l s o f c o m p a r a b l e
q u a n tity p u r c h a s i n g o f s u p p lie s , a n d
p r o p e r t ie s o f th e E B A
c o m p l e t e u tiliz a tio n o f p e r s o n n e l an d
a d e q u a t e , b u t a v ita l p r o p e r t y th a t is
e r t i e s th a t a r e n e e d e d f o r e x t e n s i v e
e q u ip m e n t.
o v e r l o o k e d b y d e n tis ts a n d s c i e n ti s t s
b r id g e s .
c e m e n ts a re
cre e p
re sista n ce
a n d s tr e n g t h
p ro p
. . . I s n ’ t it a b o u t tim e d e n tis ts d e
is th a t o f c r e e p r e s i s t a n c e . 2 In th is a r e a
JO H N w . M C L E A N , M D S, L D S . R C S
c id e d t h a t d e n tis tr y is a f in e p r o f e s s io n
th e E B A c e m e n t s a r e n o t v e r y g o o d . I
L O N D O N , EN G
a n d s u b s titu te c o u r s e s in d i s s e c tio n f o r
s u g g e s t th a t D r . S h illin g ’ s f a ilu r e s o c
co u rses
c u r r e d b e c a u s e th e c e m e n t “ m o v e d ”
in d e n ta l e c o n o m i c s
to w a r d b e n e f i ts f o r th e
a im e d
p a t ie n t a n d
under
s tre ss .
O n ce
th is
o ccu rre d ,
e a r l y b r e a k d o w n w a s in e v it a b le . W h a t
d e n tis t? G E R A R D S. F R A N K E L , D D S B E V E R L Y H IL L S , C A L IF
w e n e e d in o u r c e m e n t s is high c r e e p r e s i s t a n c e a n d rig id ity , t o g e t h e r w ith a d e q u a t e s tr e n g t h p r o p e r t i e s , r e s i s t a n c e to s o lu b ility , a n d b io lo g ic a l c o m p a tib ility .
C em ent failure in bridges
In
a d d iti o n ,
a d h e s io n
to
to o th s t r u c t u r e is e s s e n t i a l . T h e p o ly c a rb o x y la te
c e m e n ts
fulfill
m ost of
■ T h e l e t t e r f r o m D r . G e o r g e S h illin g
th e s e r e q u i r e m e n t s e x c e p t f o r c r e e p
(The Journal, A u g u s t ) is e x t r e m e l y in
re sista n c e , and h ere
t e r e s tin g . A t th e p r e s e n t t i m e , th e r e
p h a te
a r e fe w a r e a s in r e s t o r a t i v e d e n tis tr y
s e q u e n tl y , in c a s e s w h e r e r e te n t io n o f
w h e r e m o r e c o n t r o v e r s y e x i s t s th a n in
th e c a s t i n g s is m a r g i n a l, th e z in c p h o s
th e field o f c e m e n t a t i o n . D r . S h illin g
p h a te c e m e n t s a r e b e t t e r . 3
has
had
v ery
d is a p p o in tin g
w ith a lu m in a E B A
r e s u lts
c e m e n t s , d e s p ite
c e m e n ts
are
th e z in c p h o s b e tte r.
C on
c e m e n ts
is t h a t t h e y
Toward total health care ■
T h e c r i t i c i s m le v e le d a t th e p o l y c a r b o x y la te
1. Wilson, A .D ., and Bachelor, R .F . Zinc oxide-eugenol cements. 2. Study o f erosion and disintegration. J Dent Res 49:593, 1970. 2. Wilson, A .D ., and others. Experimental luting which is based on the glass-ionomer ce ments. Br Dent J 142:117-122, 1977. 3. M cLean, J.W . Polycarboxylate cements: 5 years’ experience in general practice. Br Dent J 132:9-15, 1972. 4. Hotz, P ., and others. T he bonding o f glassionomer cements to metal and tooth substrates. Br Dent J 142:41-47, 1977.
o n ly
In c o o p e r a t i o n w ith F a i r le i g h D i c k
in s o n
U n iv e rsity
d e n ta l
sch o o l
and
th e B e r g e n C o u n t y D e n ta l S o c i e t y , 11 JADA, Vol. 96, January 1978 ■ 25