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 .

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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 .

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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 .

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- 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 .

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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

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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

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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.

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- 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 .

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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 .

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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.

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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.

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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.

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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

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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 .

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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 .

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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 ) .

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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:

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- 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 .

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REFERENCES:

1. Chemo-mechanica l method o f car ies

remova l – Denta l Update , 2000; 27; 398 -

401.

2 .

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