INTRACANAL MEDICAMENTS

CONTENTS
Page No:
INTRODUCTION 1
1
HISTORY 6
RATIONALE FOR INTRACANAL MEDICAMENTS 9
MICROBIOLOGY OF THE PULP 10
ROOT CANAL CULTURES 15
IDEAL REQUIREMENTS 23
INDICATIONS 25
FACTORS INFLENCING ANTISEPTIC ACTION 32
CLASSIFICATION 37
INDIVIDUAL MEDICAMENTS 44
MODE OF APPLICATION 87
FREQUENCY OF MEDICATION 90
RECENT INTRACANAL MEDICAMENTS 92
CONCLUSION 94
BIBLIOGRAPHY
2

INTRODUCTION
The main goal of biological research applied to a clinical discipline is to
provide a scientific basis for the diagnosis and treatment of a determined
disorder, helping to solve clinical problems and enhancing the efficacy of
the therapy. Because microorganisms are essential for the development of
periradicular disease and are the major causative factors associated with
endodontic failure, endodontic research assumes special importance in
finding methods and materials to predictably eradicate the root canal
infection.
It was cited by Turner et al (2004)73
that Kakehashi et al found that the role
of bacteria and their by products in the initiation, propagation and
persistence of periradicular periodontitis has been established. These
microorganisms gain their nutritional supply from vital, degenerating,
necrotic pulpal tissues, saliva from mouth, serum proteins from periradicular
tissues and metabolites from other bacteria. The number of microorganisms
from within an infected root canal system may vary from 108
to 102
(Sjogren
et al 1991) 69
. They are present in all parts of the root canal system including
3

fins, anastomoses and at varying depths of upto 300 micrometers within the
dentinal tubules from the pulpal side.
The aim of root canal treatment is to disinfect thoroughly the root canal
space and completely obturate it so as to entomb any microorganisms that
have escaped elimination and to prevent reinfection; without causing
iatrogenic damage. A chemo mechanical preparation is advocated to
disinfect root canals because it allows greater number of root canals to be
rendered bacteria free; between 20(without the use of an antibacterial) to
around 80% (with the use of an antibacterial agent) of canals can be
disinfected (Bystrom 1985) 9
.
Endodontic success or failure is related to the presence or absence of signs
and symptoms of periapical periodontitis. Root canal treatment can therefore
be considered as the prevention or cure of the disease. It is essential to obtain
a sterile root canal for the successful endodontic root canal treatment. The
removal of debris by using mechanical instrumentation may not always
achieve a complete cleaning because of morphological and physical barriers.
Therefore, the use of chemical methods in the form of various irrigating
solutions and antibacterial temporary dressing material is recommended for
complete benefit.
4

Preventive endodontics entails the treatment of a tooth without previous
signs of apical periodontitis by aseptic pulp extirpation and root canal filling.
Treatment of a tooth with radiographic or clinical signs of disease is the
chemo mechanical elimination of infection in the pulp system. The use of
intracanal medicaments is an adjunct to the prevention or treatment of apical
periodontitis74
.
Intracanal medicament would include any agent with extended
pharmacological action that is introduced in the root canal. Intracanal
dressing more concisely describes medicaments left in the root canal to exert
their effects over a long time, while according to Nicholas54
antiseptic
medication denotes the application of an antiseptic agent to the walls of the
pulp cavity with the objective of eliminating microorganisms still present
after cleaning. Unless an antiseptic is used, the residual microbial population
of the canal will increase in number following root canal preparation
(Bystrom 1985)9
.
Moreover, because of our inability to completely eradicate microorganisms
during cleaning and shaping, and the inability of the present temporary
filling materials to provide a bacteria proof seal between appointments, to
5

stop pathologic process, to achieve local healing and eventually allow for a
restoration of the affected dentin, the bacteria have to be completely
eradicated from the root canal or the bacterial growth has to be suppressed
long enough for the natural defense to eliminate the pathogen(Murray et al
2000)50
. Therefore, the infected root canal is subjected to a
chemomechanical treatment involving instrumentation along copious
irrigation with antibacterial or disinfectants. Still, some bacteria and their by
products could persist in the dentinal tubules, in ramifications of root canals
and in smear layer produced by mechanical instrumentation. So, the use of
intracanal medications has been advocated to further reduce the number of
microorganisms after cleaning and shaping and before obturation of the root
canal.
Bystrom et al9
have shown in experimental studies that intracanal medication
reduces or eliminates the microbial floras in the root canal. When no
intracanal medicament was used between appointments, pathogenic
microorganisms increased in number.
Therefore, to inactivate this bacterial inflammatory burden, long lasting
antibacterial intracanal medication has to be utilized between the endodontic
6

appointments and until the final sealing of the defect. Many chemicals –
phenolics, aldehydes, antibiotics, steroids etc have been used to disinfect the
root canals, thereby to reduce pain and render inert the root canal contents.
7

HISTORY 25
The historical origin of medicaments dates back to very early times. In the
year 200 A.D., the Chinese were using arsenicals to treat pulpitis, preceding
Spooner, who was the first to do so in Europe, by1600 A.D..Scribonius in
1045 A.D. wrote of using oils and wine in the mouth of a patient in pain; a
crude attempt to achieve a topical anesthetics effect on a tooth to be
extracted. In the 1800’s specific medicaments were recommended for
endodontic treatment. Beech wood Creosote was mentioned in the 1840 as
“Creosote and cotton in fang filling “. Dr Grossman divided the era between
1776 and 1976 into four fifty-year periods. During 1776 to 1826, the
treatment was crude – abscessed teeth were treated with leeches or toasted
fig poultices and pulps were cauterized with red-hot wires.
The development of the aseptic – antiseptic era in medicine and dentistry
began in about 1865. Lister in 1867 suggested the use of phenol spray in
operating rooms to keep infection down. By 1826 to 1876, intracanal
antiseptics were being used. However, pulps were still being removed by
driving wooden pegs into the canal, and crowns of the teeth were being
snipped off at the gingival level to cure toothache. Arsenicals were still
being used to devitalize pulps. The third half-century, 1876 to 1926 saw the
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acceptance of antisepsis as a part of endodontic therapy. Phenol creosote and
related drugs of phenol were used in dentistry as well as medicine.
Richmond in 1884, advocated knocking out of the pulp by whittling down
orangewood to small size, soaking it in phenol, and tapping this into the
exposed pulp canal.
Phenol gave way to the salts of the heavy metals along about 1890,
principally bichloride of mercury and silver nitrate. While these protoplasm
poisons killed bacteria rapidly and effectively, they also irritated tissue cells
and were otherwise injurious to the host. The idea of a sterilizing agent,
which would destroy microorganisms but would not injure tissue cells
originated with Ehrlich. He conceived the idea of a “therpia magna
sterilisans” a sort of medical bullet, which would destroy all microorganisms
in the body without injuring the host. In this effort he succeeded to a limited
extent with the development of an organic arsenical. But the organic
arsenicals did not find much application in endodontics.
In 1891, Otto Walkhoff introduced camphorated monochlorophenol
(CMCP) as an intracanal medicament. Beginning about 1912, dentistry in
general and endodontics in particular were set back by the wide acceptance
9

of the theory of focal infection. Extraction of vital and pulpless teeth took
place.
The idea of taming bichloride of mercury, a powerful antiseptic, so that it
was less poisonous to the cells of the host must have offered an attractive
challenge to many pharmacologists. Along about 1925 this led to the
development of a number of organic mercurial such as mercurochrome,
Mercurophen, Metaphen, Merthiolate, Mercresin, etc. but they were found to
be very toxic and irritating and because of the staining potential were not
used in endodontics.
Ehrlich’s dream of one shot killer came to nearest to being fulfilled with the
development of an agent so powerful that it was still effective in a dilution
of 1:80,000,000 against S.aureus. This agent, Penicillin, which was
discovered by Fleming, introduced the highly feverish era of antibiotics.
The final era of 1926 to 1976 saw improvements. Calcium hydroxide made
its appearance. Many root canal medicaments appeared and arsenic finally
disappeared from the dental pharmacopoeia.
Therefore, the introduction of many of these medicaments has simplified
treatment and has saved many teeth.
10

RATIONALE FOR INTRACANAL MEDICATION
The rationale behind intracanal medication is to destroy residual
microorganisms and their toxins and any residual bacteria that have not been
removed during canal preparation. Though the objective of removing the
microbes is mostly fulfilled during canal preparation but the complexity of
the root canal is such that not all microorganisms or the pulp tissue are
removed. Furthermore, anaerobic bacteria may invade the dentinal tubules of
the canals with necrotic pulps. The medicament should inhibit microbial
recolonization of the cleaned parts of the root canal system by preventing
residual microorganisms from growing and new microorganisms invading
through the lateral communication and coronal access.16
11

MICROBIOLOGY OF THE PULP
Bacteria in the root canal system initiate and maintain periapical
inflammatory disease (Kakehashi et al 1965)35
. Anaerobic bacteria dominate
the bacterial flora in root canal infections and several different species are
commonly found. Any microorganism in oral cavity, nasopharynx or the
gastrointestinal tract can infect the pulp or root canal. Many factors
influence the growth and colonization of bacteria in the root canals. These
include availability of the nutrients, low oxygen tension and bacterial
interactions. Vital pulp tissue appears to act as a barrier against the
deployment of a periapical inflammation; periapical destruction rarely
occurs when vital pulp elements are present (Sundqvist G 1992)70
.
Root canal treatment aims to eliminate bacteria from the root canal system
and prevent reinfection. However, it is impossible to completely disinfect
even through cleaning and shaping. It has been found that if the canal is not
filled or dressed with a disinfectant between two visits, they may multiply
rapidly within days to near the original number (Bystorm 1985)9
. It has been
noticed that the number of bacteria in the root canal can be controlled by
enclosing an intrappointment dressing (Chong and Pittford 1992)12
.
12

Studies using strict anaerobic techniques have shown a predominance of
strict anaerobes (~90%) in the infected root canal. Polymicrobial infection of
the root canal is characterized by independent relationships of strict
anaerobes and both facultative aerobes and anaerobes, whose presence and
permanency depend on available nutrients and the redox potential provided
by the facultative anaerobes (Sundqvist 1992)70
. Using molecular detection
methods, up to three dozen species have been simultaneously identified
especially during local complications such as apical periodontitis. From a
pathogenic viewpoint, it is unclear whether the infection starts with presence
of a single or multiple specific species. Based on the frequency of detection
and the number of identified virulence factors, Fusobacterium nucleatum,
Peptostretococus micros, Porphyromonas gingivalis and Streptococcus
intermedius are the most important species associated with endodontic
infections (Figdor et al)20
. Bacteria that are found in an infected root canal
with apical periodontitis form a selected group of the total oral micro flora.
It was cited by Haenni et al27
in 2003 that Fabricus et al found that when the
pulp becomes necrotic there is an increase of strict anaerobic Gram negative
and Gram-positive species such as Fusobacterium, Prevotella,
Porphyromonas, Peptostreptococcus, Eubacterium and Actinomyces, which
occurs at the expense of facultative anaerobic species.
13

In the apical part of the root where interaction with periapical tissues takes
place proteolytic bacteria constitute the main proportion of the micro flora.
The close contact with vital periapical tissues may be presumed also to give
a higher oxygen tension inhibiting their growth. However, the small
proportion of facultative anaerobic species present in the apical region may
consume the oxygen resulting in low redox potential favoring colonization
of strict anaerobic species.
The interaction between organisms maybe beneficiated to one or more
microorganisms while it can be antagonist to other. Gomes et al 200324
related pain of endodontic origin with combination of Peptostreptococcus
endodontalis and P. gingivalis to be related to acute symptoms. It was cited
by Haenni et al27
in 2003 that Fabricus et al found that specific combinations
of bacteria had the greatest potential to induce apical periodontitis.
14

Bacteria Associated With Primary Root Canal Infections
The bacterial species commonly associate with primary root canal infections
belong to the genera Bacteriodes, Fusobacterium Provotella,
Porphyromonas, Treponema, Peptostreptococcus, Eubacterium,
Actinomyces and streptococcus.
Actinomyces species is found in 10 – 15 % of primary root canal infections.
They are of low virulence and have fimbral structures, which enable them to
stick to the root canal wall, adhere to the dentinal debris pushed out during
root canal instrumentation and cling to other bacteria and host cells without
necessarily inducing an acute response but maintain a chronic periradicular
inflammation. A.gerencseriae and A.israelli are the most prevalent species in
periradicular abscess cases. Stretptococcus intermedius, S.constellatus,
S.anginosus form a part of the normal micro biota of oral cavity, GIT and
genito urinary tract and are associated with purulent infections. Enzymes,
metabolites, peptidoglycans and lipotechoic acid play an important role in
their pathogenecity .Milleri group of streptococcus act synergistically with
anaerobic bacteria in the development of periapical abscess(Siqueira 1997)
67
.
15

Microbiodata of periapical lesions refractory to endodontic therapy
The periapical infection is usually polymicrobial comprising of anaerobic
and facultative bacteria of the root canal and the periodontal pocket .In 80 –
90% of cases the infection resolves with endodontic therapy but resists in
10-20 %. In these cases extraradicular bacteria may form colonies or
aggregates with diameter of upto 3-4 mm. These granules have a bright
yellow colour and in older literature were referred to as sulphur granules.
Thus the root canal flora of root filled teeth, where treatment has failed, has
been shown to differ markedly from the flora of root canal of untreated teeth
( Molander, 1998)49
.
Thus refractory periapical lesions contain Staphylococcus, Bacillus,
Pseudomonas, Shingomonas, Enterococcus, Enterobacter and candida
species. They have also been found in the sub gingival flora of refractory
adult periodontitis. Actinomyces species has been implicated in treatment
failures, including those associated with periradicular infections (Nair
1984)51
. The oral species include A.gerencseriae, A.meyeri, A.naeslundii,
and A.odontolyticus. Enterococcus faecalis, a facultative anaerobic gram-
positive coccus is most commonly found organism in failed root canal
treatment.
16

ROOT CANAL CULTURES7
CULTURE : cultus – to till or cultivate.
The growth and propagation of microorganisms on or in medium of various
kinds is culture.
Although presence of microorganisms can be recognized histologically if the
tissue has not been destroyed or severely lacerated, culture method was one
of the only way to detect microorganism earlier, though still it is the most
commonly employed method.
Prior to 1940 all the teeth showing periapical changes roentgengraphically
were considered infected. But studies by Sommer and Crawley and later by
Morse and Yate showed negative cultures in periapical lesions shown in the
roentgenograph. Bender stated that areas of periapical rarefaction can be
produced by bacterial, chemical and mechanical irritation. Therefore, a large
number of cases will be sterile when opened first, considerable time can be
saved if cultures are taken immediately.
If the tooth is sterile, a maximum of two treatments and one sitting filling
can complete the treatment instead of waiting for clinical symptoms to
subside. An old notion is that purulent discharge is an indication of infection
but many times negative cultures have been found in pus. Pus is an
indication of foreign body reaction. This body can be a chemo tactile drug,
17

chemical irritant due to breakdown of tissues or a mechanical irritant.
Anything which reacts as foreign body may cause purulent discharge.
Therefore it is possible that at the time of treatment pus is sterile.
SIGNIFICANCE OF CULTURES
In the past years the microbial root canal sampling was done primarily to
obtain a sterile canal before obturation.
As the years passed, the disease process was understood and endodontic
microflora was known, the culturing technique was confined to some special
occasion.
• Any medically compromised patient at risk for development of
serious infection i.e. infective endocarditis.
• For antibiotic sensitivity test.
• In case of patients with progressive infection or persistent signs and
symptoms following surgical or non surgical endodontic therapy.
• In in-vitro studies, for assessing efficacy of intracanal medicaments,
irrigants and sealers.
18

SIGNIFICANCE OF NEGATIVE CULTURES
A negative culture denotes the absence of microorganisms or they are
present in such small numbers that cannot be detected.
False negative cultures:
These may occur due to:
o Operators do not insert the inoculum point to the entire length of
canal.
o Mild disinfectant such as hydrogen peroxide or sodium hypochlorite
used to wash the canal may result in a negative culture.
o Use of very few culture points.
o Drug therapy.
SIGNIFICANCE OF POSITIVE CULTURES
It is a sure indication of bacterial infection but can be an indication of
contamination by saliva when:
• Pulpal exposure is present.
• Fistulous tract is present.
• Same bur is used to cut enamel and enter into pulp chamber
19

• Interappointment dressing leaks.
• Carious dentin is not completely removed.
• Air contamination occurs.
IS IT NECESSARY TO CULTURE ?7
Appleton in an analysis of the work of Rhein , Krasnow ,& Geis found that
these was a 9% greater success in teeth filled after negative root canal
cultures than in those filled following positive cultures7
.
APPLETON :
Time of Follow up no of cases success failure
2 years or more No %
Positive culture 152 130 22 53
Negative Culture 340 319 21 47
Total s492
ZELDOW & INGLE:
Time of Follow up no of cases failure
2 Years or more no %
Positive culture 42 7 16.7
Negative culture 14 1 7.1
20

Total 56
OLIET :
Time of follow up no of cases failure
1Year
Positive culture 67 Greater degree of
Negative culture 31 failure in teeth with
Positive culture
He found that there was greater degree of healing after one year or less when
teeth were filled under negative culture conditions. The results were
subjected to statistically analysis and were found to be significant.
Some supporters (Filgueiras J) of culture concept make definite statements
that presence of positive culture is a contraindication to filling of canal and a
negative culture should be obtained without exception , in all cases prior to
filling.
According to Appleton , Buchbinder , Grossman and Ingle , percentage of
successful results obtained when cultures were used is higher , than when
the culture criteria were not used. Onderdonk in 1901 suggested that
21

microbiological root canal sampling should form an essential part of
endodontic treatment.7
Coolidge in 1919 suggested that MRS be used as a routine procedure, which
was supported by Appleton in 1932 and Grossman in 1938.
BENDER , SELTZER & TURKENKOPF (1964)
Time of follow up no of cases success failure
6 Months no % no %
Positive Culture 500 409 81.1 91 18.2
Negative Culture 1835 1549 84.4 286 15.6
Total 2335 1958 83.8 377 16.2
2 Year Follow up
Positive Culture 213 175 82.0 38 17.8
Negative Culture 493 404 81.9 89 18.1
Total 706 579 82.0 127 18.0
Matsumiya and Kitamura showed that periapical repair occur despite the
presence of microorganisms. They demonstrated in histological sections that
the microorganism which are present in branches and walls of root canals
tend to die out in time following treatment and filling of the root canal .This
22

occurs regardless of whether or not drugs are employed to sterilize the root
canal7
.
Howes pointed out that as soon as an infection localizes or becomes chronic,
fibroplasias, the initial stage of healing , take place , and even an abundant
amount of bacteria in the area dose not seem to deter the process of healing.
These studies supported that culturing was not necessary7
.
Walton7575
in 1999 gave 7 reasons why sampling and culturing may not be
worth making a routine procedure:
1. All of the pathogens have not been definitely identified. Gram negative
rods are usually recovered from these infections. These are likely key
players in synergism with other bacterial species.
2. Contamination during sample is a problem. Oral flora can be easily
introduced into the incision by the scalped or by needle during aspiration.
This normal flora can overgrow the pathogen in culture media.
3. Many of the microorganisms are fastidious. Anaerobes in particular must
be handled carefully. Because, they are first introduced into transport
media and then into appropriate culture media, oxygen may be
introduced.
4. Bacteria grow differently in culture media than in tissues.
23

5. Culturing is time consuming.
6. Local treatment measures like removal of necrotic pulp, canal
debridement, and drainage of abscess via canal or incision along with
antibiotics will resolve the problem before the results of culture can be
obtained.
7. Culturing and susceptibility testing are expensive.
So, according to Walton76
, culturing should be reserved for the patient who
is medically compromised when the dentist has concerns about systemic
involvement. It should not be a routine procedure for all odontogenic
infections.
It was cited by Dr. Walton75
that Dr. Heimdahl stated that we should focus
on the times when culturing methods should be used instead of when they
should not be used. We should choose our empirical therapy from our
knowledge of the microbiology of odontogenic infections, antimicrobial
susceptibility, pharmacological properties and side effects of antimicrobial
agents. A properly obtained microbiological specimen processed by an upto
date method in a good microbiological laboratory is of utmost importance
24

for the clinical outcome of many infected patients even if the specimen need
not be obtained routinely in healthy patients with limited infection.
IDEAL REQUIREMENTS OF ROOT CANAL MEDICAMENTS:
(By Louis I Grossman, Endodontic practice, 10th
edition)25
1. It should be an effective germicide and fungicide.
2. It should be non irritating to the periapical tissues.
3. It should remain stable in solution.
4. It should have prolonged anti – microbial effect.
5. It should be active in the presence of protein derivatives of tissues,
blood and serum.
6. It should have low surface tension.
7. It should not interfere with the repair of periapical tissues.
8. It should not stain tooth structure.
9. It should be capable of inactivation in a culture medium.
10.It should not induce cell mediated immune response.
25

11.It should have no deleterious effect on vital tissues.
12.It should not alter the physiologic activities of the host tissues.
13.It should have good penetrating ability to be effective in the dentinal
tubules.
14.It should reduce pain.
15.It should induce healing and hard tissue formation.
16.It should eliminate apical exudates.
17.It should control inflammatory root resorption.
18.It should have reasonable shelf life.
19.It should be readily available
20.It should be inexpensive.
26

ROLE AND INDICATIONS OF INTRACANAL MEDICATION IN
ROOT CANAL TREATMENT. 12
Intracanal medicaments have traditionally gone hand in glove with
endodontics. Though considered to be an integral part of endodontic
treatment, they also posses’ harmful side effects; each is an effective
chemical or a therapeutic agent. Despite conflicting claims; no medicament
appears superior to other; and their usefulness has been questioned (Walton
1984)74
. Therefore, it is recommended to re evaluate the role and indications
of intracanal medicaments in root canal treatment.
Vital Teeth
It was cited by Chong & Pittford12
that Henrici &Hartzell(1919)found that
the normal vital pulp is sterile. Normal periapical tissues and an absence of
inflammation were observed around teeth where root canal treatment was
carried out under aseptic conditions and no intracanal medicament was used.
27

When a vital pulp has recently become exposed to the oral flora, it is usually
only superficially invaded by bacteria. If pulpectomy is performed under
controlled, aseptic conditions, the superficial bacterial flora and the affected
pulp will be removed, leaving a bacteria free canal. Therefore, in root canal
treatment of teeth where vital tissue existed it is questionable whether an
intracanal medicament is needed. Since intracanal medicaments are irritating
and highly toxic, they have the potential to do more harm than good, they
are not indicated in vital teeth (Murray et al 2000)50
.
Infected Teeth
that, (According to Schroeder A,
Endodontics- Science and practice Quintessence 1981)
Intracanal medicament serves a variety of purposes in an infected canal. It is
used to:
 Eliminate any remaining bacteria after canal instrumentation.
 Reduce inflammation of periapical tissues.
 Render canal contents inert and neutralize tissue debris.
28

 Act as a barrier against leakage from temporary fillings.
 Help to dry persistently wet canals.
As an antibacterial agent to eliminate any remaining bacteria in the root
canal after canal instrumentation:
Antibacterial intracanal medication is used to eliminate any residual bacteria
that have not been removed by canal preparation. Controlled asepsis,
including effective root canal disinfection, was shown to be important for
successful healing of periapical tissues. (Bystrom &Sundqvist 1985)9
.
that Messer & Feigal in 1985 found that
to justify the use of these medicaments, their antibacterial activity must be
significantly greater than their cytotoxic effect. Antibacterial medicament
must be in contact with the residual bacteria in sufficient concentration.
Vapor forming medicaments are considered to work at “long distance”. It
should have a wide spectrum of activity and a reasonable duration of action
to eliminate all the bacteria in the root canal. Since no intracanal
medicament is active against the whole spectrum of root canal microbes,
29

combinations of polyantimicrobials have been devised to overcome this
shortcoming.
that Tronstad et al 1985 found that
contact with tissue fluids can render the medicament inactive within a short
period of time. To overcome this, a controlled release system has been
suggested. But, intracanal medication does not sterilize the root canal , and
is not a substitute for through canal cleaning and adequate canal preparation.
As an anti inflammatory agent to reduce inflammation of the pulp
remnants or periapical tissues particularly when time does not permit
complete removal of the canal contents
that Torabinejad et al, 1988 found that
the reduction of inflammation is primarily aimed ay alleviation of pain and
any acute exacerbation. Unfortunately the use of intracanal medicaments has
been found to have no effect on interappointment and post treatment pain.
Topical corticosteroids have been specifically used as anti inflammatory
agents in root canal therapy. An intracanal solution of corticosteroid has
30

been claimed to be an effective anodyne in inflamed teeth, provided that the
teeth are not infected. Some corticosteroids are combined with antibiotics to
help combat any infection. The pharmacodynamics of such combinations are
dependent on several factors, including the size of apical foramen and the
presence or absence of smear layer (Abbott et al 1990)2
. The periapical
tissue response to such a preparation may be favorable when the root canal
contains vital, uninfected pulp tissue. It was cited by Chong & Pittford12
that
Barker &Lockett in 1971 found that however, in infected root canals, the
periapical reaction is unpredictable and less favorable, and this combination
cannot be relied upon to eradicate bacteria from infected root canals.
To render any remaining canal contents inert and neutralize tissue debris
Intracanal medicaments have been used for chemical fixation of tissue
remnants remaining after canal preparation. The concept of using chemical
fixatives was the treatment modality when endodontic instruments and
techniques were less developed. It was cited by Chong & Pittford12
that
Simon &Van Mullem in 1978 found that by their action fixatives are self
limiting and tissue penetration is limited. A wide surface area of contact and
a sufficient amount of intracanal medicament is necessary for effective
fixation. The tags of pulpal tissues in the apical ramifications of the root
31

canal are not easily accessible, and may not be affected by limited action of
intracanal fixatives.
As a barrier against leakage or breakdown of the temporary filling:
Intracanal medicaments are intended to act as a second front to prevent
invasion of oral microorganisms into the root canal in the event of leakage or
breakdown of temporary filling.
But, in order to prevent canal contamination, attention to provision of a
bacteria tight seal is more appropriate than dependence on the intracanal
medicament, after all, if a canal becomes contaminated, it will still need to
be re cleaned and re disinfected regardless of the presence of an intracanal
medicament. The integrity of the temporary filling is important during all
phases of the root canal treatment (Grossman 1988)25
.
To control persistent abscesses and persistent “weeping /wet canal”
that Heithersay in 1975 found that a
persistently weeping or wet canal results from seepage of apical fluids into
the root canals. Calcium Hydroxide is widely used as an intracanal
medicament to control this continuous exudation. The elimination of
exudation facilitates permanent filling of the root canal. The exact
32

mechanism of action of calcium hydroxide in this type of cases is an object
of much conjecture. Weine78
believes that the action is closely related to the
pH. The acidic pH of periapical tissues is converted to a basic environment.
It could also be due to the calcifying potential of the medicament, which
starts to build up bone in the lesion, other causes can be the caustic action of
calcium hydroxide, which burns residual chronic inflamed tissue.
33

FACTORS INFLUENCING ANTISEPTIC ACTION
(By Calvin D Torneck)72
Root canal antiseptics are used to reduce the bacterial flora in the root canal
and, when possible, to eliminate it entirely. The antiseptic action of these
drugs can be modified by several factors:
DRUG
The drug itself is one of the foremost factor. Some drugs are more effective
toxins than others and therefore have a more extensive and more rapid
antimicrobial effect. Other drugs are less effective toxins and have an
equally extensive but less rapid antimicrobial effect. In therapeutic
concentrations, some drugs may be bacteriostatic rather than bactericidal.
They arrest or impede the growth of bacteria but do not actually destroy
them. Although such drugs produce a zone of growth inhibition when tested
on bacterial infected plates, this action can be misleading; once the drug is
removed, neutralized, or eliminated, the bacteria often resume their growth
and replenish their number. Because of the variety of bacterial and fungal
types and the individual peculiarities of single bacterial strains, the action of
one drug may not be uniform against the entire microbial flora. It can prove
34

to be bactericidal against one type, bacteriostatic against another, and totally
ineffective against the third. For this reason the principle of drug rotation is
advocated in root canal medication. Such rotation implies changing the
antiseptic agent each time the canal is irrigated, dried and remedicated.
CONCENTRATION OF THE DRUG
This refers not only to the initial concentration but also to the therapeutic
concentration at the site of action. Drugs placed in the pulp chamber of the
tooth may not diffuse into the middle and apical third of the root canal in
adequate concentration to be effective. Conversely drugs placed in the apical
third may be diluted by the periapical exudates to an ineffective
concentration. Since diffusability and dilutability of antiseptics vary, the
type of drug chosen should also vary according to the clinical condition of
the tooth under treatment. The same condition dictate whether the drug
should be placed in the pulp chamber or in the apical third of the root canal.
Since many of the drugs used as root canal medicament are injurious to
viable tissues, care must be taken in the placement of the drug to prevent
clinical injury from occurring to the residual pulp and periapical tissues.
Drugs placed in the root canal posses the potential to gain access to the
periapical tissues through the apical foramen. This potential in turn, is
35

influenced by the volume of the drug used and the degree of pressure created
in the root canal following sealing of the access cavity. It is therefore
recommended that when toxic drugs are administered, minimum amount of
the drug be used and there should be no “plugger action” in placing the
access cavity seal to avoid a build up of intracanal pressure.
FORM OF THE DRUG
Paste drugs, which diffuse poorly, are less apt to be effective in
mechanically inaccessible places such as lateral canals and dentinal tubules
than are liquid drugs. Furthermore, antiseptic agents contained in a paste
must be released at a sufficient rate to be therapeutic. Agents that are bound
in the base and not released are totally ineffective. Because pastes are less
readily dissipated, they retain their antiseptic action longer, and the water-
soluble base dissipates more readily. Therefore the length of time interval
between the visits influences the selection of the drug. Many of the liquids
can be changed into paste form by combination with polyglycol base.
TYPE OF MICROORGANISMS
The type, location and the availability of nutrients to the bacteria also
influence the efficacy of intracanal medicaments. Certain type of
36

microorganisms posses an inherent ability to survive the action of certain
antibiotics. The enterococci are more resistant to antimicrobial action than
the viridans group. The development of resistance is also an important
contributory factor.
The location of the microorganisms within the root canal is also a factor in
predisposing them to destruction, in that the more accessible they are, the
more readily they can be placed in contact with the antiseptic. The more
accessible the microorganisms, the more readily their number can be
mechanically reduced by the debridement and enlargement of the root canal.
Areas such as the lateral canals and irregular crevices are more apt to remain
infected, as they are not exposed to the effect of the antiseptic.
The presence of a suitable media is not only essential for the survival of the
microorganisms, but affords them protection by acting as a dilutant or
barrier to the action of the antiseptic. Residual necrotic tissue is such a
media. Root canals that are dry are more easily disinfected than those that
continually remain moist by the seepage of the periapical exudates.
37

PHYSICAL DISPOSITION OF THE BACTERIA
Bacteria grouped in clumps or colonies are more resistant to destruction than
those that are finely dispersed. Since this is usually the way they are
clinically located, the use of seeded bacterial plates to test drug effectiveness
can sometimes prove to be misleading.
METABOLIC ACTIVITY OF THE BACTERIA
Metabolic activity of the bacteria also influences whether the antiseptic
readily destroys them, particularly when the antiseptic action of the
medicament is related to its ability to interfere with bacterial metabolism.
This is in contrast to those drugs that act as protoplasmic poisons. Therefore,
with the antibiotic group of drugs, an active metabolite rate is a significant
asset to its antibacterial action and dormancy is a disadvantage.
38

CLASSIFICATION
Because of a variety of usages of intracanal medicaments, there is a varied
array of agents.
According to PV Abbott (1990)1
, intracanal medicaments can be classified
as
1. Antiseptic medications
• Paraformaldehyde
• Parachlorophenol
• Camphorated paramonochlorophenol
• Formocresol
• Cresol
• Creosote
• Thymol
• Eugenol
• Metacresylacetate
• Sodium Hypochlorite
• Iodide compounds
• Quaternary ammonium compounds
39

• Quartenary chlorine compounds
• Cresophene.
2. Antibiotic medications
• Ledermix paste
• Septomixine forte paste
• Pulpomixine paste
3. Combining medicaments
• Ledermix and Calcium hydroxide.
Depending on their usage, intracanal medicaments can also be classified into
two groups:
(By Calvin D Torneck (1961)72
I. Non- specific intracanal medicaments.
II. Special purpose medicaments.
40

I. Non- specific intracanal medicaments
Essential oils
• Alcohols
• Phenolic compounds
• Cresol
• Formacresol
• Metacresylacetate (Cresatin)
• Camphorated parachlorophenol
• Parachlorophenol-camphor-metacresyl acetate
• Iodine potassium iodide
• 2-4% formalin
• N2
• Salts of heavy metals
• Halogens
• Chlorhexidine
• Thymol
41

II. Special purpose medicaments
• Corticosteroids
• Antibiotic steroid combination
• Calcium hydroxide
• Quaternary ammonium compounds
According to Grossman (1990),25
intracanal medicaments can be
classified as
1.Essential oils
• Eugenol
2.Phenolic compounds
• Phenol
• Camphorated para chlorophenol
• Cresol
• Formocresol
• Creosote
42

• Cresatin
• Cresanol
3. N2
4. Salts of heavy metals
• Metaphen
• Merthiolate
• Mercurophen
5. Halogens
• Sodium hypochlorite
• Iodides
• Chlorhexidine
6.Quaternary ammonium compounds
• 9-aminoacridine
7.Fatty acids
• Propionic acid
• Caproic acid
• Caprylic acid
8. Sulphonamides.
43

According to Franklin S Weine(1995)78
intracanal medicaments can be
1.Phenol and related compounds
• Eugenol
• Camphorated paramonochlorophenol
• Metacresyacetate
• Cresol
• Thymol
2.PBSC
• Penicillin
• Bacitracin
• Streptomycin
• Caprylate
3.Sulphonamides
4.Corticosteroid – antibiotic combinations
5.Calcium hydroxide.
According to D.Orstavik(1990)16
(Harty’s Endodontics in Clinical Practice)
Root canal disinfectants can be classified as:
44

1. Aldehydes
Formocresol (dressing: 19 % formaldehyde, 35%cresol, 46% water and
glycerine)
2. Halogens
Chlorine
Irrigating solution: sodium hypochlorite 0.5%in 1% sodium
bicarbonate as Dakin’s solution, 0.5- 5.25% in aqueous solution.
Iodine
Irrigating solution and short term dressing: 2% I2 in 5%KI aqueous solution
3. Phenols
Camphorated phenol
Dressing: 30%phenol, 60%camphor, 10%ethanol
Paramonochlorophenol (PMCP)
Irrigating solution; 2%aqeouis solution
Dressing: camphorated PMCP; 655camphor, 35%PMCP
Eugenol
Dressing: full strength.
4. Chlorhexidine
45

Chlorhexidine: 0.12-2%
5.Calcium hydroxide
Dressing: aqueous solution / paste.
PHENOL25
Phenol is one of the oldest antiseptic; was introduced by Lord Lister into
medicine in 1867.
It is a white crystalline substance with a characteristic odor, which is
derived from coal tar or from processing of petroleum. Liquefied phenol
(carbolic acid) consists of 9 parts of phenol and 1 part water. Phenol
crystals become liquefied on the addition of camphor, menthol, or
thymol. Liquefied phenol, commonly referred to as phenol, has been used
46

for sterilization of dentin after cavity preparation, for disinfection of
infected root canals, and as a caustic for destroying pulp remnants.
Phenol has been used as a basis for determining the relative effectiveness
of other antiseptics. The term applied is phenol coefficient, which
represents an ability to kill a well-dispersed suspension of Salmonella or
Staphylococci relative to that of phenol. Unfortunately, the test if little
practical application to the clinical use of these antiseptics, since some
pathogenic microorganisms cannot exist under the conditions required by
the test and because most bacteria and yeasts are often clumped together
rather dispersed.
The use of phenol as a root canal antiseptic has declined appreciably over
the past several years because of its caustic nature, pungent aroma and its
relative inferiority as a germicide when compared to other commonly
used root canal antiseptics. Important root canal antiseptics such as
parachlorophenol, metacresylacetate and cresol are derived from it.
47

MECHANISM OF ACTION
The antibacterial action of phenol is derived from its ability to disrupt and
penetrate the cell wall of bacteria and subsequently precipitate protoplasmic
protein. Its action, rather than being bactericidal, is best described as
cytocidal, since it is as toxic to viable tissues as it is to bacteria. In lower
concentrations, or in some of its altered forms, its action is less direct, in that
it inactivates essential enzyme systems than precipitate protoplasm to cause
cell death.
Bacteria in root canals are found usually clumped together rather than
dispersed. This limits the antibacterial action of phenol as root canal
antiseptic. Owing to its capacity to precipitate protein, its penetration is
limited, so bacteria in the central potion of these clumps often remain
protected and viable.
Phenol is only slightly soluble in water, but is fully miscible in alcohol.
Where phenol inadvertently contacts viable tissues, the tissues should be
washed with alcohol followed by glycerin to lessen its toxic effect.
48

FORMOCRESOL25
Introduced by Buckley in 1905 and later by Sweet, it is a combination of
Formalin and Cresol. It is a clear slightly reddish liquid with a distinctive
odour. The proportion of formalin and cresol varies from 1:2 to 1:1.
Formocresol is a mixture of three isomers. The formula is
Formaldehyde 19%
Cresol 35%
Water and glycerin 46%
49

FORMOCRESOL: CH3CH(OH)CH2OH.
MECHANISM OF ACTION
Upon combining with albumin, an insoluble, indecomposable substance is
formed. Solutions of formaldehyde are strong disinfectants, which have a
great affinity for many organic substances.
It is a drug of choice in vital pulp therapy of primary teeth and a widely
used root canal antiseptic. Solutions of formaldehyde are highly irritating to
the tissues, producing marked inflammatory response followed by necrosis.
The irritating potential has made it less popular as a root canal antiseptic
than as a pedodontic “mummifying” agent. Grossman, Schilder, Amsterdam
have demonstrated the highly irritating effects of Formocresol. Persistent
inflammation occurred
in all the cases tested.
It was cited by Grossman (1976)25
that Streffon and Han found that even in a
1:50 concentration of formocresol, cells degeneration occurred and that a
20% concentration of formocresol was highly effective and less damaging to
connective tissues.
50

It was cited by Grossman (1976)25
that Wesley et al found that 0.0025 to
0.005 ml was sufficient to destroy S. faecalis or S. aureus in dentin in 48
hours. They quantified the minimum effective dose of formocresol as being
the amount remaining when #4 cotton pellet soaked in formocresol was
squeezed dried 3 times in a 2X2 sponge. Furthermore, he showed that the
vapors alone were effective. 0.005 of 25% formalin solution in 80% alcohol
is the minimal amount which one needs for an adequate bactericidal and
fungicidal effect.
It was cited by Grossman(1976)25
that S. Gravenmade(1975) found that
glutaraldehyde instead of formocresol because of its better fixative and
sterilizing properties. He emphasized that pulp protein constitutes an
important nitrogen source for microorganism so that obtaining its fixation is
important. The principal chemical compound in both vital and necrotic pulps
are the biologically important macromolecules: collagen,
glycosaminoglycans, glycogen, enzymes, nucleic acids and other molecules
such as cholesterol and phospholipids, carbon dioxide, hydrogen sulphide.
So, he proposed glutataldehyde than formaldehyde.
Dankert14
compared formocresol with glutaraldehyde and found that the
latter did not diffuse out of the root canal via the apical foramen.
51

formacresol not only fixed but also produced an immunologic reaction
through the T cells, while glutaraldehyde did not.
Lewis and Chestner43
reviewed extensively the mutagenic and carcinogenic
potential of formaldehyde in dentistry. The main critical statements they
emphasized about formocresol were:
The activity of formocresol is unrelated to cresol, and its presence in
solution is questionable.
Formocresol has known toxic and mutagenic and carcinogenic potential.
Interaction is possible with other mutagenic substances always present in the
environment in air, clothing, and cosmetics.
It has been shown that formocresol has the ability to diffuse through dentin
in direct proportion to the quantity of it used.
Cwilka13
concluded that germicidal vapors pass through the root apex and
affect the periapical tissues. This long distance effect should be considered
as Powell noted abscess formation and necrosis of tissues when even the
minimal effective dose described was used in experimental animals. But, in
contrast, according to Gutierrez et al26
, systemic absorption of formocresol
52

appears to be of no importance because it vaporizes and is rapidly eliminated
by urine.
PARA-CHLOROPHENOL25
It is a derivative of phenol that has three isomers of which parachlorophenol
is the most effective. These colorless needle like crystals, like phenol turn
dark on exposure to light. It is a substitution product of phenol. Chlorine
replacing one of the hydrogen atom (C6H4OCl). The crystals are soluble in
alcohol, ether, alkalies and slightly soluble in water. By trituration with gum
camphor it combines to form an oily liquid.
MECHANISM OF ACTION:
53

It causes coagulation of proteins and thus fixes the pulp.
Monochlorophenol is more toxic, but it is also more active antiseptic
compared to phenol. In dentistry it is frequently used as camphorated
paramonochlorophenol (CMCP), (monochlorophenol 35%, camphor 65%),
which is highly toxic, having a cytotoxic effect at less than 5/100th
of 1 %
monochlorophenol. The antimicrobial effect is good, and approximately 1 %
monochlorophenol is needed for elimination of typical root canal flora.
Mixing crystals of paramonochlorophenol with camphor, when liquifaction
occurs spontaneously makes camphorated paramonochlorophenol. Although
it is more powerful bactericidal agent than phenol it is much less irritant and
when compared does not coagulate albumin. CMCP has been used as a root
canal medicament since the 19th
century and still enjoys considerable
popularity in spite of its known toxic properties.
Harrison and Madonia30
(1970) studied the toxic effect of various materials
by means of conjunctival inflammatory tests and intradermal injections into
the abdomen of rabbits. Amongst the materials investigated were 35%
camphorated paramonochlorophenol and 1 or 2 % aqueous
parachlorophenol. They found that CMCP was severely toxic and also
54

coagulates proteins. The aqueous MCP produced only mild inflammatory
reaction and there was no evidence of tissue necrosis. Comparison of the
effectiveness of these two materials showed that there was no basis for
considering a 35% concentration of CMCP as the optimum concentration for
the anti microbial effectiveness of the drug. They also showed that 1%
concentration of parachlorophenol provides a nine fold increase beyond the
effect in vivo concentration against most resistant microorganisms tested.
The dentinal tubules of teeth undergoing endodontic treatment have been
shown to harbor microorganisms and thus any medicament used to disinfect
the root canal must be able to penetrate the tubules. It was cited by
Grossman25
that Anvy and co workers investigated the penetratability of
aqueous and camphorated parachlorophenol by means of autoradiographic
studies. They found that aqueous parachlorophenol penetrated into the
dentin from the pulp chamber and the root canal and traveled at least to the
cemento dentinal junction where as camphorated parachlorophenol did not.
In vitro tests conducted by Harrison and Madonia30
, the aqueous solution
destroyed a variety of microorganisms ordinarily found in infected root
canal. In addition they have shown that the aqueous solution is stable and
not effected by dentin, EDTA, saliva or light but is affected by blood and
55

necrotic tissue. By means of radioactive tracer they showed that 2% aqueous
solution of parachlorophenol diffuses 5 times further into the dentinal
tubules than the camphorated chlorophenol preparation.
CAMPHORATED P- CHLOROPHENOL25
Composed of two parts P-chlorophenol and 3 parts gum camphor, it was
introduced into dentistry as root canal antiseptic by Walkoff in 1891 and has
enjoyed a high degree of popularity ever since. It is transparent, oily, light,
amber colored liquid, having a characteristic aromatic odor. The camphor
serves the purpose of a dilutent and vehicle and reduces the irritating effect
of pure P-chlorophenol. Grossman has assessed its antimicrobial effect
compared with some other root canal medicaments. Ostrander and Crowley
have reported a clinical evaluation of camphorated Parachlorophenol as root
56

canal disinfectant. Wantulok and Brown have demonstrated that the vapors
of camphorated chlorophenol and of cresatin will pass through the apical
foramen.
COMBINATION OF PARACHLOROPHENOL, METACRESOL
ACETATE, AND CAMPHOR
Dietz17
introduced the combination of parachlorophenol, metacresol acetate
and camphor as a root canal disinfectant in 1957. The proportions by weight
are parachlorophenol, 25%; metacresol acetate, 25%; and camphor, 50%. In
vitro testing indicated that the combination was equal antiseptically to
parachlorophenol but was less irritating. It appeared to possess a greater
permeability than parachlorophenol and was therefore thought to be more
effective clinically.
57

The combination of parachlorophenol, metacresol acetate and camphor to
which 1% prednisolone has been added is also available through commercial
outlets for the use as a root canal antiseptic. It was introduced for the
purpose of reducing pulpitis following cavity preparation. It was theorized
that the addition of corticosteroid would reduce the inflammation initiated
by caries or the restorative procedures while the antiseptic will remove all
the microorganisms.
EUGENOL:72
Although classified as an essential oil, eugenol is chemically related to
phenolic compounds. In general, the essential oils are a mixture of
substances and derive their name from the fact that they are oily distillates of
naturally occurring substances such as plants. Clove and eugenol are used
almost interchangeably in dentistry despite the fact that clove oil is a
compound of substances whereas eugenol is a pure chemical.
58

In low concentrations it has some anodyne effect. As an antiseptic, it is more
effective and less irritating than phenol, though it is one of the irritating
substances. Because it has hemolytic action, contact with blood results in
disruption of the blood cells and release of blood pigments. It has been
found to increase the microhardness of dentin owing to its coagulating effect
of dentin collagen. The explanation for the anodyne effect of it may be
because of its ability to impair or eliminate the conduction of an impulse in
nerve tissue. Because of this property it is used in temporary dressings and
antiseptic dressing following pulpectomy. Only small amounts have to be
used as these will not cause chemical injury to the apical tissues.
Freshly prepared eugenol is colorless to pale yellow liquid. With exposure to
air or sunlight it hydrolyses to become dark. In case it occurs in the pulp
chamber, discoloration of the dentin and crown can occur as it causes
haemolysis of blood. Therefore, care has to be taken when using eugenol to
ensure that all blood has been removed from the canal and hemorrhage has
been arrested.
As an antibacterial agent it is effective against a wide variety of
microorganisms found in the infected root canal. In therapeutic
concentrations, its action is bacteriostatic than bactericidal. Since it is
59

insoluble in water, serum, it requires contact with the microorganisms to be
effective.
CREOSOTE25
This clear yellowish oily liquid has a pungent aromatic odor, which once
filled the air of most dental offices. It is a better a disinfectant than phenol
and is less toxic and irritating. In dentistry Beech wood variety of creosote
should be used.
It is a mixture of phenol and phenol derivative; Guaiacol (C64OHO, CH3 –
monomethyl) ether constitutes 60% and 90% creosote. Limited research data
is available on creosote, but there are several reports on severe tissue
60

irritation and necrosis. There is no reason to believe that creosote is less
damaging than other phenolic compounds.
CRESATIN25
Metacresylacetate or cresatin is the acetic acid ester of metacresol. This
antiseptic has a phenolic acetic odor. It is a clear, stable, oily, and liquid of
low volatibility. Its antibacterial effect is enhanced because of its low
surface tension and its low vapor pressure prolongs its effect. The
antimicrobial effect of cresatin is not as marked as that other members of
this group as demonstrated by Grossman but the drug is less irritating. It is
not a caustic and does not precipitate albumin.
61

Biocompatibility studies show that the effect on tissue ranged from mild to
severe. Based on the adverse possibilities, the use of cresatin as an intracanal
medicament should be discouraged.
FORMALDEHYDE25
FORMALDEHYDE:HCHO
It is 37% solution of formaldehyde gas. The gas is readily soluble in water
and dissolves in it to its extent at room temperature. Commercially it
contains stabilizers such as menthol 8% - 15%, to reduce the release of
formaldehyde from the solution in the form of solid polymers. This release
is accelerated when the solution is chilled or kept for too long. For this
reason it is purchased in small amounts and not refrigerated.
Formaldehyde can be merely placed in the pulp chamber or in the cervical
third of the root canal space and still be effective in the apical portion
62

provided the canal is reasonably clean and dry. It is always advisable to
restrict its use in the cervical third of the root or the pulp chamber. Since the
toxic effect of formaldehyde containing solution is often rapid and
characterized by coagulation necrosis. It is often described as producing
fixation than destruction. Since tissue affected this way displays a user
tendency to break down and since it may at times even be phagocytosed and
replaced by fibrous tissue. Formaldehyde containing compounds have been
used with considerable success rate. However, its use can only be
recommended as a means of remedial therapy for the deciduous teeth, where
tenure is limited and not in the permanent teeth where tenure is longer.
N2:54
Claimed to be both an intracanal medicament and a sealer, N2 contains
paraformaldehyde and phenylmercuric borate. According to Sargenti and
Richter(1961) who introduced N2 , the term is used to denote the ‘second
nerve’ of the tooth.
MATERIALS:
Two N2 preparations exist, each in the form of a powder and liquid, which
are mixed to form a cement. One is known as ‘N2 normal’ and is used for
root filling. The other is known as ‘N2 apical’ and is used for antiseptic
63

medication of the canal. A third product ‘N2 universal’ has the combination
of both. The formula for N2 as given by Sargenti is:
Zinc oxide 69%
Lead tetraoxide 12%
Paraformaldehyde 6.5%
Bismuth subcarbonate 5%
Bismuth subnitrate 2%
Titanium dioxide 2%
Barium sulphate 2%
Hydrocortisone 1.2%
Prednislone 0.2%
Phenylmercuric borate 0.09%
LIQUID: eugenol
He recommends the use of N2 apical in conjunction with an ophthalmic
preparation containing oxytetracycline, polymixine and hydrocortisone.
Technique:
In a tooth with necrotic pulp, the canal is prepared the entire length and
dressed with N2 apical and is subsequently filled with N2 normal.
Tissue response to N2:
64

It was cited by Nicholas(1992)54
that several investigations have shown that
N2 enters the systemic circulation. In experimental animals, Harndt et al
(1973) demonstrated the presence of lead in various organs after the
placement of N2. The histological reports on pulp and periapical tissues are
also unfavorable. Overdicck et al showed that the application of N2 in
primary as well as permanent teeth in pulpotomy resulted in pulp necrosis.
Although Rowe et al reported the presence of uninflammed pulp and hard
tissue formation under N2, majority of studies report necrosis or fixation of
the pulp, sometimes with periapical inflammation. Claims that N2 has a
permanent disinfectant action and unusual antiseptic properties have been
denied by the council on dental therapeutics of the ADA.
HEAVY METAL SALTS25
:
Mercury salts are normally good antiseptics for disinfecting non-living
materials. However, they are impractical alternatives for intracanal
medicaments because they are easily rendered less effective by the tissue
fluid proteins. In addition, environmental concerns should restrict the use of
mercury compounds.
65

As a group they are protoplasmic poisons. They precipitate albumin and
produce new compounds, which stain tooth structure. At one time
ammoniated silver nitrate was used for disinfection of root canals but it
stained tooth structure.
Salts of silver, copper and mercury coagulate proteins act as enzyme
inhibitors and are generally toxic. With the exception of mercury salts , they
have no practical value. In the mercury salts group are Mercurophen,
Metaphen, Mercurochrome and Methiolate. Phenylmercuric borate is
another organic mercury antiseptic well known in endodontics because of its
inclusion in N2 formula.
HALOGENS16
:
Chlorine and iodine are the bases of a number of oxidizing antiseptics
commonly used in endodontic practice. Chlorine is antimicrobially more
effective than iodine.
66

Hypochlorite was first used by Semmelweis in 1847 as a hand disinfectant.
This initial use of potassium hypochlorite was later followed by sodium
hypochlorite as carrel and Dakin introduced its use for wound disinfection.
When hypochlorite contacts tissue proteins, nitrogen, formaldehyde and
acetaldehyde are formed within a short time. The peptide links are broken
down to dissolve the proteins. During the process hydrogen in the amino
group (-NH-) is replaced by chlorine forming chloramines (-N,Cl-) which
plays an important role for the antimicrobial effectiveness. Thus necrotic
tissue and pus are dissolved and the antimicrobial agent can better reach and
clean the infected area. Temperature increase will significantly improve the
antimicrobial effect of the sodium hypochlorite.
Dakin suggested a 0.5% solution (Dakin’s solution) with a low toxicity
affecting only necrotic tissue. A 1% sodium hypochlorite solution however
is more aggressive and provides a more antimicrobial effect. Higher
concentration of sodium hypochlorite (2.5% and 5%) actively attack living
tissues without contributing significantly to the treatment. Its effect is
severely limited to the confined areas. Because the effect of weak solution
decreases rapidly, irrigation should be frequent and copious. The use of
67

protein coagulating antiseptics (such as formocresol) alters pulp tissue to
such a degree that significantly higher concentration of irritant is needed (or
must remain in place for a longer period of time) before dissolution of the
tissue occurs. Thus when formocresol or parachlorophenol are used as
antiseptics, concentrations of hypochlorite 2 to 3 times higher than usual are
needed to dissolve the necrotic tissue remnants.
To prepare fresh hypochlorite solution mix one part of a 5% solution of
NaOCl such as “household bleach” with four (1%) or 9 (o.5%) parts of
sterile 1% sodium bicarbonate solution. This preparation will have a pH of
commercial solution, which is about 13 to 14. Sodium hypochlorite is
unstable when diluted and the pH adjusted. It should therefore be stored in a
cold place and protected from light. This provides a stable solution for
several weeks paired with minimal caustic irritation.
Chloramine is a chlorine compound with excellent antimicrobial properties.
Chloramine (5%) which has a low toxicity is a good alternative intracanal
dressing when allergic history prevents the use of iodine compounds. It is
also used for disinfecting gutta percha points. It also remains stable for a
long period if stored in cold and protected light.
68

Iodine72
Iodine has been used for many years and is known for its mild effect on
living tissues. The two most common preparations used in dentistry are
iodine tincture (5% in alcohol) and iodine potassium iodide (iodine 2%, w/w
potassium iodide 4%, distilled water 94%). The former solution is used for
the disinfection of endodontic surgical fields and the latter for intracanal
medication.
Iodine potassium iodide has excellent antimicrobial properties with
minimum tissue toxicity and irritation. It continues to have an antimicrobial
effect at a concentration not cytotoxic. The vapor forming effect is good and
antimicrobial. Before any iodine medicament is used patient should be asked
regarding any iodine sensitivity.
Iodophores25
Iodophores are organic solutions of iodine and excellent aids because of
their low surface tension for cleaning root canal. Iodine in iodophores does
not cause allergic reactions. The most commonly used preparations are
wescodyne providing 1.5% iodine (9.1% polyewthoxy polyproxy
polyethoxy ethenoliodine complex) and iodopax providing 5% iodine. Both
are stock solutions having the same cyotoxicity based on their iodine content
69

to be antimicrobially active against some of the microorganisms found in the
oral cavity. The iodine concentration must be at least 0.05%, which
corresponds to a 3% solution of wescodyne, and 1% of iodopax.
QUATERNARY AMMONIUM COMPOUNDS25
(CATIONIC DETERGENTS)
The quaternary ammonium compounds, which are cationic detergents and
wetting agents, are mildly effective disinfectants. They are practically non-
irritating in the weak solution (1:20,000 – 1:5000) and because of their
foaming detergent action; they could be used for irrigating root canals
without fear of causing an inflammation of the periapical tissues. The
“quats” are stable compounds which lower surface tension of solutions, are
70

colorless and practically odourless and are more effective in alkaline than
acidic media.
MECHANISM OF ACTION37
:
They are slightly affected by the presence of organic media such as serum,
etc. They are inactivated by anionic compounds such as soap, sodium decyl
sulphate, etc. Because they are positively charged and the microorganisms
are negatively charged a surface active effect results in that the quaternary
ammonium compound clings to the microorganism and reverses the charge.
Of the quats, benzalkonium chloride (Zephiran) is probably the best known.
9- aminoacridine also belongs to the group of mild cationic antiseptics. It
has been used as an intracanal medicament since 1950. Compounds of
acridine series such as acriflavin and proflavin are used extensively as mild
antiseptics which retain their activity in the presence of serum and pus and
do not injure tissue or retard wound healing. Albert et al selected it as an
intracanal medicament in 1945. It stimulates osteogenesis. It has the ability
to stain carious dentin in the pulp chamber, which is an added advantage. 9 –
aminoacridine with benzakolium chloride in 1:1000 is found to be less
irritating than CMCP, eugenol and has greater antibacterial effect than
eugenol or cresatin against streptococcus, staphylococcus and candida
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microorganisms. As it tends to stain the tooth structure, it should not be left
in the pulp chamber.
CHLORHEXIDINE53
It is a cationic bisguanide. Chlorhexidine in gel formulation has important
properties like low toxicity to periapical tissues, viscosity that keeps the
active agent in contact with the canal wall and dentinal tubules.
Mechanism of action19
:
It seems to act by adsorbing onto the cell wall of microorganisms and causes
leakage of intracellular components. At low concentrations small molecular
weight compounds leak out, resulting in a bacteriostatic effect. At higher
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concentrations, it has a bactericidal effect due to precipitation or coagulation
of cytoplasm, probably caused by protein cross linking.
The combination of chlorhexidine and calcium hydroxide inhibits the
complete growth of E. faecalis after 1 to 2 days of contact, but the
antimicrobial activity decreases after 7 days. The antibacterial action in the
first two days is due to high pH (12.8) (chlorhexidine, pH 7.0; calcium
hydroxide pH 11), suggesting an increase in the ionized capacity of
chlorexidine molecule. The gel base of chlorhexidine is, natrosol, which is
methyl cellulose which is an aqueous vehicle, which helps in the increase in
the pH and dissociation of calcium hydroxide.
But by day 7, calcium hydroxide losses its capacity to adhere to bacterial
cell wall because of competition between positive charge of chlorhexidine
and calcium hydroxide for common binding sites such as negatively charged
phosphate groups on the bacterial cell wall. Other hypothesis may be the
buffer effect of dentine exerted over calcium hydroxide, reducing its
antibacterial activity. Consequently the combination may have a decreased
antibacterial effect. Moreover there occurs deprotonation of chlorhexidine
molecule at pH higher than 10, thus causing marked decrease in solubility
and altered interaction with the bacterial surface wall due to change in the
charge of the molecule. In case it is mixed with NaOH instead of calcium
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hydroxide, its antibacterial activity is maintained due to the lower buffering
capacity of NaOH.
CALCIUM HYDROXIDE47
Hermann introduced calcium hydroxide to dentistry in 1920 as Calxyl
though the earliest reference of use of calcium hydroxide goes to Nygren
1838.
It is recommended in the treatment of various defects such as root fractures,
perforations, resorptions, traumatic injuries, etc.
It is a white odorless powder with the formula Ca(OH)2 and a molecular
weight of 74.08. It has a high pH of 12 – 12.8 and is insoluble in alcohol.
Mechanism of action:
It induces mineralization in tissues. The high pH activates the alkaline
phosphatase activity, which helps in hard tissue deposition. The hydroxyl
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ions present provide an alkaline environment, which helps in early healing
and has an antimicrobial action.
Antimicrobial action of calcium hydroxide is related to release of hydroxyl
ions in an aqueous environment. Hydroxyl ions are highly oxidant free
radicals that show extreme reactivity. The lethal effect as on bacterial cell
wall are due to:
1.Damage to bacterial cytoplasmic membrane:
Hydroxyl ions induce lipid peroxidation, resulting in destruction of
phospholipid structure of the cell membrane. Hydroxyl ions remove
hydrogen atoms from unsaturated fatty acids, generating free lipidic radical.
This free lipidic radical reacts with oxygen, resulting in the formation of
lipidic peroxide radical, which removes another hydrogen atom from second
fatty acid, generating another lipidic peroxide. Thus peroxides themselves
act as free radicals, initiating an autocatalytic chain reaction and resulting in
further loss of unsaturated fatty acids and extensive membrane damage.
2.Protein denaturation:
The alkalinization provided by calcium hydroxide induces the breakdown of
ionic bonds that maintain the tertiary structure but the polypeptide chain is
randomly unraveled. These changes result in loss of biological activity of the
enzyme and disruption of cellular metabolism.
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3.Carbon dioxide adsorption
Calcium hydroxide adsorbs carbon dioxide such that the bacterial ecosystem
in the root canal is disturbed which also is one of the antimicrobial action of
calcium hydroxide.
VARIOUS PREPARATIONS AVALAIBLE54
Calyxl:
It is one of the oldest manufactured pastes, introduced by Hermann in 1920,
for the purpose of dressing vital pulp and inducing calcific bridge formation
at the site of amputation. Varella suggested the addition of corticosteroid to
this (2% methylprednisolone stearate) for direct pulp capping in human teeth
for reducing pain and inflammation.
Pulpdent
It is calcium hydroxide in aqueous suspension of methylcellulose, initially
employed in direct pulp capping.
Calvital
Originally proposed by Skiene, it is composed of a powder and a liquid.
Calcium hydroxide (78.5%), iodoform (20%), guanoflacin (0.1%) and
sulphatiazol (1.4%), while the liquid is composed of T- cain (0.5%),
propyleneglycol(50%) and distilled water(49.5%).
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Calasept
Introduced in the 1980’s it consists of calcium hydroxide (56%), calcium
chloride (8mg), sodium chloride (0.35mg), sodium bicarbonate (4mg),
potassium chloride(8mg) and water sufficient for 100mg of paste.
Hypocal
It is composed of calcium hydroxide 45%, barium sulphate 5%,
hydroxymethylcellulose 2%, and water 48%.
Calcipulp
It is composed of calcium hydroxide and carboxymethylcellulose.
BIOCALEX54
Biocalex, originally developed by Bernard in 1952 under the name of
‘ocalex’, consists of powder and liquid containing heavy calcium oxide and
zinc oxide, and ethylene glycol and water respectively. The powder and
liquid are mixed to form a paste, which is intended to work as a medicament
and root filling.
After setting it expands to six times its original volume and is said to fill the
entire root canal.
Calcium oxide and water combine in the root canal and form calcium
hydroxide which ionizes to form Ca++
and OH-
ions which have an antiseptic
action and decompose necrotic pulp to form carbon dioxide and water. The
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residual calcium oxide reacts with water to form calcium hydroxide further
and the calcium hydroxide reacts to form calcium carbonate, which is
deposited on the root canal wall. It is claimed that the end result is “chemical
incineration”, with sterilization occurring by the action of the OH- ions and
sealing of the canal by the calcium carbonate.
But studies by Harty in 1979 showed that it expands only to fill the empty
spaces and does not breakdown necrotic pulpal tissue, making doubtful that
carbon dioxide necessary for calcium carbonate is formed. But by virtue of
the formation of calcium hydroxide it has some antibacterial effect.
Various vehicles used for calcium hydroxide”:
There are three types of vehicles used:
Aqueous vehicles
Viscous vehicles
Oily vehicles.
Aqueous vehicles
The various aqueous vehicles used are sterile water, distille3d water,
bidistilled water, sterile saline, anesthetic solutions, ringer’s solution,
methylcellulose, carboxy methylcellulose.
Viscous vehicles
These are glycerine, polyethylene glycol, propyleneglycol.
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(calen, calen+CMCP, )
Oily vehicles:
Olive oil, fatty acids, camphorated parachlorophenol, metacresylaceytate,
eugenol.
(endoapex, vitapex)
Influence of mixing vehicle on dissociation of calcium hydroxide in
solution5
Calcium hydroxide is poorly soluble in water (0.16g in 100g of water at
30°
C) but its aqueous solutions are highly alkaline (pH 12.0 at 37 C). Its low
solubility and high pH of aqueous solutions is responsible for its
antimicrobial effect as an intracanal medicament and its concomitant
biocompatibility to periapical tissues. The antimicrobial activity is
dependant on the presence of hydroxyl ions in the solute. In slightly soluble
substances, as long as undissolved solute is present in the saturated solution
the concentration of the ions remain constant. As the hydroxyl ions are
consumed by the bacteria, the dissolution will continue to maintain its
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equilibrium. Thus an aqueous solution of calcium hydroxide can potentially
maintain its pH for a long time.
Commonly used aqueous solutions such as saline, anesthetic solutions do
not affect the pH of calcium hydroxide. But it has been found that glycerin
and propylene glycol reduce the conductivity of calcium hydroxide thus, it
does not dissociate in these solutions. Therefore, its action is better in
aqueous solutions.
ANTIBIOTICS 2
Certain selected antibiotics satisfy many of the requirements of a root canal
antiseptic, in that they are active in the presence of tissue fluid, do not stain
the tooth and are virtually non-irritant to tissue cells. Since they are non
irritant very high concentrations may be used to achieve a bactericidal effect.
However there is no single antibiotic effective against all the root canal flora
and therefore combinations are used in the form of pastes.
They are generally effective during the cell reproductive phase and therefore
are not suitable for short term use such as irrigants. However, they are an
attractive therapeutic component in interappointment dressing.
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POSSIBLE OBJECTIONS TO ANTIBIOTICS
Two main criticisms have been proposed:
DEVELOPMENT OF RESISTANT STRAINS OF MICRORGANISMS
The development of resistance would result from using an inadequate
concentration of the antibiotic in the root canal. However if the root canal is
filled completely, the concentration of the antibiotic in the canal would
virtually correspond to the original preparation. Thus, so long as the vehicle
permits a high concentration of the antibiotic and provided the pulp cavity
has been thoroughly prepared, the possibility of organisms becoming
resistant appears remote.
ALLERGIC REACTION
This may be elicited in a patient already allergic to a particular antibiotic,
particularly penicillin. Grossman25
found this allergy in several thousand
people treated with polyantibiotic pastes containing penicillin.
Antibiotic preparations available:
The following antibiotic preparations are available: polyantibiotic root canal
paste, Septomixine Forte, Pulpomixine, Ledermix paste.
Polyantibiotic paste consists of
Crystalline penicillin 150000 units,
Streptomycin sulphate 0.15g,
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Chloramphenicol 0.15g, and
Sodium caprylate 0.15g.
The incorporation of anti- inflammatory agents such as prednisolone and
dexamethasone are said to be advantageous.
Septomixine forte consists of:
Dexamethasone 0.05%
Polymixine B sulphate 20 million IU
Tyrothricin 1.50gm
Neomycin sulphate 10 million IU
Haletazole 0.40gm
Barium sulphate 30.32 gm
Pulpomixine consists of:
Framycetin 1.675 million IU
Polymixine B sulphate 2 million IU
Dexamethasone 1.0%
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PBSC
As mentioned by Grossman25
, PBSC has enjoyed wide use among dentists.
It consists of
Penicillin: - effective against gram positive microorganisms
Bacitracin: - effective against penicillin resistant microorganisms
Streptomycin- effective against gram negative microorganisms
Caprylate- as the sodium salt, effective against fungi
Nystatin replaces sodium caprylate as the antifungal agent in a similar
medicament, PBSN. Both are available in a paste form that may be injected
into the root canal or impregnated on paper points. Because there is no
volatility, the drug must be placed in the canal to have an effect in that area.
PBSC may interfere with subsequent culturing procedures, and penicillinase
may be added to culture media to inactivate penicillin should it be
transferred on the paper point taken to incubate.
But with the decline in popularity of intracanal medicament in general, and
because of the potential for sensitivity due to topical use of antibiotics,
PBSC, largely has fallen into disuse.
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LEDERMIX PASTE:54
It is a glucocorticoid antibiotic compound, this preparation contains, as the
active components, Triamcinolone acetonide (a glucocorticosteroid) and
dimethylchlortetracycline (demeclocycline, a tetracycline antibiotic) at
concentrations of 1% and 3.21% respectively. Triamcinolone is
approximately four times more potent than cortisone and hence can be used
in low concentrations. Demeclocycline is generally effective against most of
the common Endodontic bacteria at concentration s ranging from 0.05 to
128mg/L. Since Demeclocycline is present within ledermix paste at a
concentration of 3.21% (50,000mg/L) then this material should be very
effective within the root canal itself. However, within the peripheral parts of
the dentinal tubules and the periradicular tissues, it has been shown to be in
insufficient quantities to be predictable against all the bacteria. Despite this
ledermix paste remains the root canal medicament of choice as an initial
dressing agent in all the cases.
But ledermix paste placed in the root canal has the capability to diffuse into
the dentinal tubules and cementum to reach the periodontal ligament and
periapical tissues. The ability of the components of this paste to diffuse
through dentin adds to its efficacy and supports the many clinical
observations regarding it. The material can be used in all cases involving
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inflammation or infection associated with root canal system and periapical
tissues even if the apical foramen is blocked or closed. The placement of
ledermix paste in the root canal space has been reported to add to the
efficacy of the treatment of periapical infections.
It has also been shown to histologically eliminate experimentally induced
external inflammatory root resorption in vivo. It has no damaging effect on
the periodontal membrane and is effective in progressive root resorption in
traumatically injured teeth. It can be used to prevent inflammatory resorption
or arrest this resorption already present in an avulsed tooth.
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SULFONAMIDES:2
They are chiefly bacteriostatic, rather than bactericidal agents which
interfere with bacterial metabolism and thereby render the microorganism
more vulnerable to destruction by the defensive mechanism of the body.
They are ineffective in the presence of pus, protein breakdown products,
tissue debris, and p- aminobenzoic acid. In a blind study, Grossman25
found
that neither sulfanilamide nor sulfadizine was any more effective than older
intracanal medicaments.
Sulphathiazole was used as a part of dressing in the 1950’s and 1960s. While
irrefutably antibacterial, clinical studies showed variable results in
comparative studies. Although effective against gram positive and gram-
negative microorganism, these are ineffective against Enterococci and
Pseudomonas aeruginosa.
INDICATIONS FOR ANTIBIOTIC PASTES:
Although there is little or no clinical advantage in employing an antibiotic
paste in preference to a chemical antiseptic, instances do arise when there
use is justified. In teeth where infection persists despite the use of antiseptic
medication their use is justified. Since they are less irritating to the
periapical tissues compared to the chemical antiseptics, there is an argument
86

for the use of paste where the apical foramen has been inadvertently
widened by over instrumentation and in an immature teeth with wide apical
foramen., also there is an evidence that the chemical antiseptics lose their
potency faster in a canal as compared to antibiotics. Thus if the
interappointment time is more than 14 days, the use of antibiotics is
advantageous.
In view of the potential dangers of an allergic reaction, a preparation
containing an antibiotic to which the patient is allergic should not be used.
TECHNIQUE OF USING ANTIBIOTIC PASTES:
For the maximum antibiotic effect to be obtained, more care is needed in
handling antibiotics than chemical antiseptics.
To avoid dilution of the paste, or inactivation of one or more of its
constituents, an absorbent point is first inserted into the canal to check that
the irrigant has been completely removed. The instrument used to handle the
paste should be sterile and dry, and it should not be hot as heat destroys the
antibiotic. To avoid unnecessary risk of sensitization, the paste should not be
allowed to touch the soft tissues of the patient or operator.
Since pastes are less diffusible than chemical antiseptics, it is necessary to
ensure that they touch the entire canal wall. This is done by transferring the
87

paste to the pulp chamber with a plastic instrument and then propelling it
apically along the root canal with a paste carrier. This pattern of instrument,
also known as ‘spiral root filler’ or “ rotary paste filler” is made in various
widths and may be used in conjunction with a right angle or straight
handpiece. These instruments are fragile and should be handled carefully.
Some operators use an absorbent paper into the canal to bring the
preparation into close contact with the root dentin. This inevitably reduces
the amount of dentin which may be used. Care must be taken not to drive the
paste periapically due to chemical irritation and the risk of sensitivity.
88

MODE OF APPLICATION:25
Another important factor in the selection of an intracanal medicament is the
mode of application. There are basically two methods:
1. The medicament can be placed on a cotton pellet and placed in the
pulp chamber, or,
2. The root canal can be flooded with the preparation.
The latter method allows a more precise application of the medicament as it
is brought in contact with the target organisms. Furthermore, it simplifies
determining optimal concentration. But a medicament like formocresol or
CMCP must be avoided. The cotton pellet mode is more empiric and does
not lend itself to the same exactness.
After the final recapitulation, the pulp chamber and the root canals are
thoroughly dried up with sterile cotton pellets and paper points. If the
medicament is to be used, a bottle containing the medicament should be
inverted to allow the liquid to cling to the side near the mouth of the bottle.
The cover is removed and the sterile cotton pellet is lightly wiped on the
inside, picking up some of the liquid. The cotton pellet is then squeezed in a
sterile gauze sponge. The amount of medicament remaining in the pellet is
more than sufficient to render its temporary antibacterial action.
89

The medicated pellet is placed only in the pulp chamber. Paper points
medicinally impregnated or not, should never be left in the root canal; nor
should the canal be flushed or filled with the medicament between visits.
Considerable care should be taken in sealing the pulp chamber to prevent
recontamination from marginal leakage or actual loss of seal before the next
appointment. A fast setting cement based on zinc oxide eugenol is used,
since it has been shown by Grossman25
to give a seal superior to other
materials. Proprietary zinc oxide pastes, such as cavit, give as effective seal
as cement mixed at the chairside. But a thickness of 3-5mm is necessary to
ensure an effective seal with cavit. If the interappointment time is long, then
the seal should be given with IRM or amalgam. There is evidence that IRM
provides a less effective seal and it is softened by CMCP to a depth of
1.0mm; it should therefore be carefully adopted and a generous thickness
used.
According to radioisotope studies, silver amalgam plus cavity varnish
provide the most effective seal, but it is difficult to use these materials at the
end of each sitting and then drill out at the next sitting.
Fortunately, zinc oxide eugenol provides excellent seal and is much easier to
place and remove than amalgam. The addition of zinc acetate crystals speeds
up the reaction without decreasing the sealing properties.
90

The use of double seal of zinc oxyphosphate cement over gutta percha was
advocated for many years. However, neither of these materials alone or in
combination has been shown to be resistant to isotope or dye penetration
studies.
The use of gutta percha as an intermediate layer beneath ZOE is acceptable;
not as sealing agent but to prevent the falling of hardened ZOE into the pulp
chamber and forced into the thin canal by the explorer, or an intracanal
instrument. To avoid this problem, at the time of closure, a cotton pellet is
placed into the pulp chamber and this is covered by heated and softened
gutta percha, over which ZOE is placed as a seal. At the next appointment,
the seal is removed and the gutta percha is removed with a hot instrument.
When the antiseptic dressing is in the form of a paste, particular care has to
be taken to ensure that the pressure used in placing the seal does not force
the paste into the periapical area. The patient is asked to warn the operator
immediately if any discomfort is felt. The pressure used to consolidate the
cement is directed against the wall of the cavity rather than in an apical
direction. Exacerbation following the treatment can occur if these
precautions are not followed.
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FREQUENCY OF MEDICATION:25
In accordance with general principles of root canal management, antiseptic
or disinfectant dressings should preferably be changed after a week and not
longer than two weeks. The antiseptic should be renewed often because it
will be diluted by the periapical exudates and decomposes by the interaction
with the bacteria in the root canal.
In dressing a root canal, an absorbent paper moistened with the medicament
is carried into the root canal, a cotton pellet also moistened with the
medicament is placed in the pulp chamber, the excess medicament is
absorbed, and a double seal is inserted. In narrow canals, a moist paper point
does not have the stiffness to be inserted into the canal, in such cases, a dry
absorbent point is inserted and a cotton pellet moistened with the
medicament is placed in contact with it to moisten it. A dry cotton pellet is
used to absorb the excess medicament and a double seal is placed.
Some dentists depend on the vapors issuing from the medicament on a
cotton pellet in the pulp chamber for antibacterial action, omitting the paper
point. Their contention is that the root canal should not be filled with an
absorbent paper point so as to allow room for the exudates into the root
canal.
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This is considered good when treating teeth with an acute abscess or where a
flare up might occur. On the other hand, from a bacteriologic stand point,
depending upon vapors alone is less effective in destroying microorganisms
than having the medicament on an absorbent point in close contact with the
microorganisms.
93

RECENT INTRA CANAL MEDICAMENTS
There has been a constant search for an intracanal medicament which can
effectively kill the therapy resistant bacteria within the root canals and
radicular dentin with minimal or no host toxicity. Nisin is one of the
antimicrobial, which is being tried as an intracanal medicament recently.
NISIN73
It is a naturally occurring antimicrobial peptide. It was discovered in 1928
and is produced by strains of Lactobacillus lactis. It was cited by Turner et al
that Klaenhammer in 1993 found that it is an antibiotic peptide, and is a
class I bacteriocin. It is safe to humans and is used extensively in food
preservation, mainly in meat and dairy product and is approved for use in
unlimited concentration.
MODE OF ACTION
It was cited by Turner et al that Driessen et al in 1995 found that the mode
of action is not completely understood but is likely that it interacts with
phospholipid membrane of the target bacterial cell. It disrupts the cellular
membrane inducing leakage of small intracellular contents from the cell.
The use of nisin in dentistry has been limited. The few experiments which
have been done using nisin (Turner et al 2004)73
have shown that it can kill
94

all the bacteria effectively in the canal and the results were comparable to
calcium hydroxide.
The delivery mechanism of nisin is by dissolving it in sterile water. The
minimal bactericidal concentration (MBC) required to kill E. faecalis is
much lower than the minimal safe dose permitted for humans. The
incorporation of nisin as gel or paste at a higher concentration may result in
increased quantity of it available in the canal for dentinal tubule disinfection
and may increase its antimicrobial efficacy.
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CONCLUSION:
After reviewing through all the intracanal medicaments, it can be concluded
that most of them are not in use today because of their toxic, mutagenic
potentials. It is also doubtful whether they are needed routinely in teeth with
vital pulps. When the root canal is extensively infected and when
interappointment time periods are long, there is a merit in using an
antibacterial intracanal medicament as part of controlled sepsis. Intracanal
medicaments play a secondary role, and should not be used as an alternative
to thorough cleaning and adequate shaping of the root canal.
When a tooth does not respond to root canal treatment, bacteriological
sampling should be done to determine the bacteria present. This can aid in
the choice of intracanal medicament to be used and monitoring of the
treatment progress. Every case should be judged on the advantages and
disadvantages of using an intracanal medicament. After all, what is removed
from the root canal is of greater significance with regard to the success of
root canal treatment than what is placed in the root canal system.
GLYCEROL:CH2OHCHOHCH2OH
96

IODOFORM:CHI3
PARACHLOROPHENOL:C6HnClmO (m=1-5, n=1-4)
CRESOL: 4- MEHTYL PHENOL.
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