INTRODUCTION:
The or ig ina l approach fo r the t reatment
o f car ies was pure ly surg ica l . I t was thought
that the on ly effec t ive method o f e l iminat ing
the d isease was to comple te ly remove a l l o f
the deminera l i zed area o f the tooth
s t ructure . Even the smal les t a rea o f
deminera l i zat ion requ i red the remova l o f
s tandard amount o f sound tooth s t ruc ture to
prevent the progress ion o f d i sease . Th is
techn ique had been deve loped by Dr . G .V .
B lack as “Extens ion fo r prevent ion” wh ich led
to spec ific o f sound tooth s t ruc ture .
Over recent years , the denta l p ro fess ion
has sh i f ted towards prac t i c ing prevent ive
dent i s t ry and adapt ing more conservat ive
and tooth preserv ing procedures .
In today’s seminar , I wou ld l i ke to
d i scuss about newer invas ive techn iques fo r
car ies excavat ion .
1
The techniques available to excavate caries clinically can be
classified according to B.D.J. 2000 as:
Category Techniques
1. Mechan ica l ,
ro tary
2 . Mechan ica l ,
non- ro tary
3 . Chemo-
mechan ica l
4 . Photo -ab la t ion
Hand p ieces + burs
Hand excavat ion ,
a i r ab ras ion
U l t rason ics ,
sonoabras ion
Car idex , car i so lv
and enzymes
Lasers
Each o f the above ment ioned techn iques
have the i r own c la ims o f removing
deminera l i ze dent in se lect ive ly .
An idea l method shou ld fu lfi l l ce r ta in
fac tors to sat i s fy , both the operator as we l l
as the pat ient . They are :
a . Comfor t and ease o f use in the c l in ica l
env i ronment .
2
b. The ab i l i ty to d i ss iminate and remove
d iseased t i ssue on ly .
c . Be ing pa in less , s i lent , requ i r ing on ly
min imal p ressure fo r op t ima l use .
d . Not generat ing v ib rat ion or heat ing
dur ing per iods o f operat ion .
e . Be ing affordable and easy to mainta in .
The handpieces and burs a re in un iversa l
use w i th the i r obv ious d i sadvantages l i ke :
- Sens i t ive to v i ta l pu lp .
- Pressure /heat on tooth .
- Necess i ty o f L .A .
I t was a t th is po in t that chemo-
mechan ica l approach came in . I t was c la imed
to be a non- invas ive a l ternat ive fo r remova l
o f ca r ies .
The techn ique invo lved app ly ing a
so lu t ion onto the decayed dent ina l t i s sue
a l low ing i t to so f ten the t i s sue and fina l ly
sc rap ing i t off wi th b lun t hand ins t rument .3
Many so lut ions were in t roduced and
marketed s ince 1970’s wh ich I wou ld be
d iscuss ing in deta i l .
Before d i scuss ing ind iv idua l products I
wou ld firs t l i ke to en l igh ten the layers
present in car ious dent in . Which have
impor tance in ou r seminar regard ing the
chemica ls .
Carious dentin consists of two layers:
1. Outer layer .
2 . Inner layer .
1. Outer layer:
- Deca lc ified – degenerated co l lagen fibres .
- In fec ted – non remienra l i zab le .
- Necro t i c (Th is layer shou ld be removed) .
2. Inner layer.
- Between outer and norma l den t in .
- Less deca lc ified .
4
- Bacter ia f ree .
- Reminera l i zed co l lagen fibres p resent .
- Vi ta l odontob last i c p rocess present . Th is
layer shou ld be le f t in tac t .
Idea l ly , when prepar ing the decayed
tooth one shou ld remove the outer decayed
dent in layer wh i le re ta in ing the inner
reminera l i zab le layer in tact .
The chemomechan ica l method c la ims to
do so . Let us now see the d ifferent p roducts
ava i lab le to us .
Chemo-mechanical approach:
The chemo-mechanica l approach was
in i t ia l l y in t roduced in 1972 in the fo rm o f
G.K . 101 so lut ion . In 1976, Go ldman and
Kronman repor ted on the poss ib i l i ty o f
remov ing car ies chemica l ly us ing GK-101
(NMG) , which cons is ts o f :
- N-monoch lorog lyc ine (NMG) .
- Sod ium hypoch lor i te .
5
Glyc ine was added to counterac t the
cor ros ive effec t o f NaOCl . A l so ca l led as GK-
101G.
I t s mode o f ac t ion has been descr ibed as
ch lor inat ion o f f ree amino g roups i .e .
ch lor inat ion o f amino groups o f pept ide
bonds o f p rote in fo rming NMG compounds
Th is NMG has the ab i l i ty to conver t
hydroxy pro l ine an impor tan t facto r to
pyro le -2 - ( i t s g lyc ine pept ide carboxy
g lyc ine . )
Therefore the part ia l l y degraded co l lagen
in car ious dent in was ch lor inated by NMG
so lu t ion and th i s a l so affected the secondary
and quaternary s t ruc ture o f co l lagen by
d is rupt ing hydrogen bond.
In th i s way car ious mater ia l remova l was
fac i l i ta ted .
GK-101 (NMG) was tes ted in bov ine
Ach i l les tendon co l lagen to observe as what
6
actua l ly happens to the co l lagen fibres . SEM
eva luat ion showed.
1. F ray ing fibr i l s – i .e . essent ia l s t ructu re
was in tact , but there was separat ion o f
few per iphera l fibres .
2 . Sp ina l ing fibr i l s – i .e . a t t ract ion between
ad jacent fibres was los t and there was
shor ten ing o f indiv idua ls fibres .
3 . D issoc ia t ing fibr i l s – i .e . s t ruc ture was
to ta l ly separat ing, fib re or ientat ion was
poor and hard to define .
4. Amorphous mater ia l – i .e . there was l i t t le
defin i t ive s t ructure and mater ia l wh ich
was hard to define as co l lagen .
Advantages:
1. Absence o f pa in .
2 . Absence o f any de leter ious effects on
pu lp .
3 . S tud ies done by Kurosak i e t a l and
Brannstorm et a l showed that i t removed
7
only outer car ious d i seased layer . They
presumed tha t the so f ten ing may be due
to a se lec t ive at tack o f the so lu t ion
spec ifica l ly on degenerated co l lagen
fibres , w i thout affect ing sound fibres o f
the inner layer and norma l dent in
underneath .
Disadvantages:
The process was very s low. Later they
found that the system was more effect ive i f
g lyc ine was rep laced by amino -butyr i c ac id ,
wh ich evo lved in the GK-101E , wh ich was
approved by FDA ( food and drug
admin is t ra t ion) in 1984 and was
commerc ia l i zed as “CARIDEX” GK-101E ,
conta ined instead o f NMG – “N-monochloro -
DL -2 -aminobutyr ic ac id” (NMAB) .
The system consists of:
- reservo i r .
- A heater .
- A pump.
8
- A handp iece wi th appl i cat ion t ip wi th
var ious shapes and s i zes .
In v i t ro s tud ies done by – Go ldman et a l
s ta ted that car idex removed both the layers
o f ca r ies leaving beh ind sound dent in .
Schert z et a l repor ted tha t in h i s to log ica l
eva luat ion a f ter us ing car idex exh ib i ted 90%
of car ies w i th res idua l decay there fore he
conc luded that ca r idex shou ld be used w i th a
spoon excavator .
Cl in ical studies done by:
1. Z inek e t a l showed 90-100% remova l o f
decay w i th car idex (but i t took a very long
t ime. )
Rompen and Chorpent ier found car idex
not bacter i c ida l in 17 samples cu l tured
f rom the decay.
2 . Y ip et a l combined NMAB + 2 urea in
dec iduous teeth and found i t to be bet te r .
9
P ioch and Stach le invest iga ted the shear
s t rength at the DE J a f ter t reatment o f ca r idex
fo r adhes ive and bonding systems.
Car idex was found to reduce the shear
s t rength at the DE J in bov ine teeth . Th is was
at t r ibuted because o f the denaturat ion o f the
co l lagen . Th is d i sadvantage to be re la ted to
f rac ture o f tooth s t i l l needs fu r ther c l in ica l
s tud ies and invest igat ions .
3 . Kurusak i e t a l , Walkman e t a l and
Wedenberg and Burnste in invest igated
ind iv idua l ly the b iocompat ib i l i ty o f ca r idex
to pu lp .
They found i t to be b iocompat ib le
because o f the a lka l in i ty o f car idex , i t was
found to produce a hard t i s sue matr ix
fo rmat ion be low the necrot i c zone .
Zones:
1. Trans ient .
2 . Dark .
3 . Body o f les ion .
4 . Sur face .
10
Y ip e t a l invest igated the minera l i zat ion
o f dent ina l sur face remain ing a f te r car idex
usage in a sma l l sample . They used “back
scat te red e lec t ron imag ing” (BS I ) and
“e lec t ron p robe mic ro -ana lys i s” (EPMA) wh ich
measured the sur face leve l o f Ca + + and P - .
The authors conc luded tha t the amount o f Ca
and P was 2 :1 wh ich matched wi th the sound
dent in because i t i s bet ter .
5 . Other s tud ies have repor ted tha t o f ten
usage o f car idex , the dent ina l su r face
produced .
- High degree o f roughness .
- Undercuts .
- Dent in sca les .
- Dent in tubu les were part ia l l y patent .
- Smear f ree sur face .
They postu la ted that i t was bet ter fo r
adhes ive res torat ive mater ia l w i thout the
necess i t y o f ac id e tch ing.
11
6. Z inck e t a l a l so eva luated pat ient
acceptance and found out 93%
acceptance leve l .
A l though car idex had many advantages i t
was
- Very expens ive .
- T ime consuming.
- Had bu lky de l ivery system.
- Needed add i t ional mechan ica l means to
remove decay .
- Large vo lumes o f so lu t ions were requ i red
f rom (200-500ml . )
- Fo l low ing th i s , a ge l based system was
in t roduced in co l laborat ion w i th med i
team (Denta l a t t ract ing : Got iberg AB) in
1998 ca l led car i so lv (Denta l update
2000) .
Car i so lv was in i t ia l l y approved for
c l in ica l use in denta l p rac t i ce by the Swed ish
counter par t to US . FDA.
12
Composi t ion:
The formulat ion i s i so ton ic in na ture and
cons is ts o f 2 sy r inges .
I . Syr inges – 0 .5% NaOCl
I I . Syr inge 3 amino ac ids g lutan ic
Luc ine .
Lys ine .
Ge l substance – ca rboxy methy l
ce l lu lose
Sod ium ch lor ide .
Sod ium hydrox ide
Erythros ine – to make the ge l v i s ib le .
Sa l ine so lut ion ( i .e . co lon iz ing
ind icator ) .
Mode of act ion:
Car i so lv i s a lka l ine in na ture w i th a pH o f
a round 11.
13
Upon mix ing , the pos i t ive ly and negat ive ly
charged groups o f aminoac ids become
ch lor inated due to presence o f NaOCl and
NaOCl cons t i tuents . Th is leads to
in teract ion w i th dent in which invo lves
proteo lyt i c degradat ion o f co l lagen rather
than deminera l i za t ion o f co l lagen, th i s
so f ten ing and remova l o f the car ious
a l tered dent in and preserv ing the sound
dent in .
The ge l cons is tency a l lows the act ive
molecu les access to the dent in fo r a longer
per iod than the equ iva lent i r r igat ing
so lu t ion in car idex sys tem. Th is ge l a l so
he lps by lub r icat ing the hand ins t rument
spec ifica l ly des igned for ca r i so lv .
The ins t rument cons is ts o f 4 d ifferen t
hand le w i th 8 in te rchangab le t ips ranging
f rom 0.3mm-2mm.
These ins t ruments resemble excavators ,
but they are des igned to be used in rap id
14
whisk ing or cure t t ing fash ion , thereby
l im i t ing on ly to d i seased t i s sue .
The configurat ion o f ins t rument a l lows
access to a l l a reas o f les ion .
Helps to g ive a tact i le sensat ion .
Helps in d ifferent ia t ing between car ious
and non-car ious .
Helps to app ly the ge l .
Cavity preparat ion:
The two sy r inges shou ld be mixed jus t p r io r
to use , as i t s efficiency decreases a f ter 20-
30mts .
The two ge ls are mixed t i l l a un i fo rm co lour
i s obta ined in a dapen d ish .
The mixed ge l i s then appl ied to ca r ious
les ion and le f t in p lace fo r 30 seconds to
a l low i t to degrade the d iseased dent in
be fo re ins t rumentat ion .
Rap id , l ight p ressure i s app l ied w i th
ins t rument to fac i l i ta te ca r ies remova l .15
As the ca r ies remova l , the ge l becomes
c loudy wi th debr i s ind icat ing c lean ing w i th
water .
Gel i s app l ied aga in fo r fur ther remova l .
Assessment ( i .e . when to stop):
1. When the ge l no longer becomes c loudy.
2 . Tac t i le sensat ion on the car ious dent in
w i l l present wi th “a catch” whereas in a
sound dent in the ins t rument w i l l pass
eas i ly .
3 . A f te r comple t ion , the cav i ty appears
f ros ted and i r regu lar appearance as
compared to smooth preparat ion o f
convent iona l bur and hand p iece .
The reason fo r the i r v i sua l d ifference i s
that in a convent iona l p repara t ion the
presence o f smear layer , wh ich i s over the
under ly ing dent in , g ives a smooth , g lossy
appearance. In cont rast , in chemo-
mechan ica l ly t reated dent in lacks smear
layer and a lso fo rms i r regu lar dent in layer
g iv ing a mat t fin ish .
16
Patients acceptance:
1. Shor te r t ime.
2. No pa in and d iscomfor t .
A number o f theor ies have been
postu la ted as to why there i s reduce pa in .
They are :
a . Lack o f cut t ing into car ies - f ree dent in .
b . Re la t ive ly few dent ina l tubes are exposed .
c . There are no v ib rat ions f rom dr i l l i ng .
d . No temperature var ia t ions .
e . Dent in i s a lways covered w i th a i so ton ic
ge l a t body tempera ture .
f . Psycho log ica l ly qu iet and less t raumat ic
exper ience.
Indicat ions:
1. Where preservat ion o f tooth s t ruc ture i s
impor tan t .
2 . Remova l o f root / cerv ica l car ies .
17
3. Management o f corona l car ies w i thout
cav i ta t ion .
4 . Remova l o f car ies a t the marg ins o f c rown
and b r idge abutments .
5 . Comple t ion o f tunne l p repara t ion .
6 . Where L .A . i s cont ra ind icated.
7 . In anx ious pat ients .
8 . In dec iduous dent i t ion .
9 . A t raumat ic res torat ive techn ique (ART) .
Advantages over Caridex:
1. Three amino groups are incorporated
ins tead o f one because in te rac t ion and
degradat ion efficiency i s inc reased .
2 . Car i so lv has h igher v i scos i ty , wh ich a l lows
fo r app l i cat ion of h igher concentrat ion o f
aminoac ids and NaOCl w i thout inc reas ing
the to ta l vo lume or amount (on ly 0 .2 -
1 .0ml car i so lv requ i red as compared to
car idex i .e . 250 -500ml ) .
18
3. Inc reased v i scos i ty a l so he lps in p rec is ion
p lacement .
4 . The ge l does not need to be heated or
supp l ied through a pump.
5 . Improved she l f l i f e .
In v it ro studies:
J epsen e t a l ana lyzed co l lagen s t ructure o f
res idua l dent in a f te r usage o f car i so lv .
They found that i t d iffered f rom sound
dent in and had charac ter i s t i c denatured
co l lagen .
In c l in ical studies:
From the abst rac ts pub l i shed in
S tockho lm d ifferent au thors conc luded
ind iv idua l ly that a l though car i so lv removed
99% of decay, i t was s lower as compared to
convent iona l techn iques .
Enzymes:
Stud ies have examined tha t car ies cou ld
be removed by enzymes:
19
- 1989, Go ldberg and Ke i l success fu l ly removed so f t car ious dent in us ing bac ter ia l achromobacter co l lagenase which d id not effect sound dent in .
- Enzyme pronase, a non spec ific proteo ly t i c enzyme or ig ina t ing f rom st reptomyces gr i seus a l so he lps in removing car ies .
- St i l l exper iments are go ing on fo r the va l id i ty o f such enzyme.
CONCLUSION:
As wi th a l l new procedures , there are the uncerta inty o f learn ing new techn iques , us ing new techniques , c l in i ca l t ime, cost e tc , which need to be cons idered on an ind iv idua l leve l . Over the decades , dent i s t ry has changed dramat ica l ly and pract i t ioners fo l low the new t rends and master new techn iques . Chemo-mechan ica l means removes less sound tooth s t ructure and reduced pu lpa l i r r i ta t ion . Th is techn ique can he lp to supplement and complement other methods o f ca r ies remova l , fu r ther research and c l in ica l ly based exper iments are requ i red fo r acceptance o f such new techniques .
20
REFERENCES:
1. Chemo-mechanica l method o f car ies
remova l – Denta l Update , 2000; 27; 398 -
401.
2 .
21
