J Bagh College Dentistry
Vol. 24(special issue 1), 2012
Evidence for feasibility
Evidence for feasibility of aluminum potassium sulfate
(alum) solution as a root canal irrigant
Bestoon M. Faraj B.D.S. H.D.D. M.Sc. PhD. (1)
ABSTRACT
Background: The purpose of this study was to evaluate, in vitro, the antimicrobial activity and cleaning efficiency of
the aluminum potassium sulfate (alum) solution.
Materials and methods: The antibacterial action of alum solution (1 mg /mL, at pH 3.6) against bacterial isolates
found in infected root canals, including facultative anaerobic microorganisms (Escherichia coli , Staphylococcus
aureus and Klebsiella sp.), and aerobic species (Pseudomonus aerogenosa ) ,using agar well diffusion test. The
investigation of the debridement and smear layer removing efficiency, on the cervical, middle and apical thirds of
root canals of freshly extracted human single-rooted teeth were done by a scanning electron microscopy study.
Results: Alum solution were able to demonstrate antibacterial activity against all the bacteria tested, and produced
inhibitions zones of 27, 25, 24 and 22 mm against Staphylococcus aureus, Pseudomonus aerogenosa ,Escherichia
coli, and Klebsiella sp. respectively. Alum solution was effective in removing the debris and smear layer. Removal of
the smear layer and other debris was more effective in the coronal and middle third than in the apical third.
Conclusion: The findings of this study suggested that alum solution has potential for use as an endodontic irrigant,
during chemomechanical root canal preparation.
Key words: antimicrobial, chemomechanical debridement, smear layer removing activity. (J Bagh Coll Dentistry
2012; 24(sp. Issue 1):1-5).
which is used as an astringent and antisepsis in
various food preparation processes such as
pickling and fermentation and as a flocculants for
water purification among other things.
(13)
Moreover the FDAs over the –Counter
Advisory Panel has recommended alum as
category I active ingredient in mouthwashes. (14)
Potassium aluminum sulfate (Alum) in
concentrations of 10% and 100% is used in
mechanico- chemical gingival displacement. (15, 16)
The purpose of this study was to evaluate, in
vitro, the aluminum potassium sulfate (alum)
solution, in respect to their antibacterial action
against common bacterial isolates found in
infected root canals, including facultative
anaerobic
microorganisms
(Staphylococcus
aureus, Escherichia coli and klebsiella sp), and
aerobic bacteria (Pseudomonas aeruginosa), using
agar well diffusion test , and to investigate their
debridement and smear layer removing efficiency
from the prepared root canals on freshly extracted
human teeth, by a scanning electron microscopy
study.
INTRODUCTION
It is known that removal of vital and necrotic
remnants of pulp tissues, microorganisms, and
microbial toxins from the root canal system is
essential for endodontic success. (1, 2) Although
this might be achieved through chemomechanical
debridement. (3) An uninstrumented area with
organic and inorganic debris still present and it is
impossible to shape and clean the root canal
completely. (4, 5) Therefore, irrigation is an
essential part of root canal debridement because it
allows for cleaning beyond what might be
achieved by root canal instrumentation alone. (6, 7)
During mechanical root canal instrumentation,
formation of a smear layer occurs which consists
primarily of fine inorganic particles, along with
some organic material from necrotic and/or viable
pulp tissue, odontoblastic processes, bacteria and
blood cells. (8, 9) Despite controversy over
maintaining the smear layer, it has been shown
that the smear layer itself may contain bacteria
and protect the bacteria within the dentinal
tubules. The smear layer has also been shown to
hinder the penetration of intracanal disinfectants
and sealers into dentinal tubules and can
potentially compromise the seal of the root canal
filling. (10, 11)
Natural products have been used for centuries
in treating human diseases and they contain
components of therapeutic value. Natural products
are environmentally safer, easily available, and
cheap. (12) Alum (Aluminum potassium sulfate),
the crystallized double sulphates with the formula
KAl(SO4)2.12H2O, are generally odourless,
colourless crystalline solids that turn white in air,
MATERIALS AND METHODS
This study received approval from the ethics
committee of the University of Sulaimani,
Sulaimani, Iraq.
Preparation of alum solutions
Seven hundred grams of alum material were
purchased from the local botanical market of
Sulaimani, and were identified in the College of
Science, Department of Chemistry, Sulaimani
University.
Crystals
of
alum
KAl(SO4)2·12(H2O).dissolved completely in hot
(distilled) water at 92Co, to obtain a final
concentration of 1 gm /mL, at pH 3.6
(1) Lecturer,Conservative Department, School of Dentistry,
Faculty of Medical Sciences, University of Sulaimani.
Restorative Dentistrty
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J Bagh College Dentistry
Vol. 24(special issue 1), 2012
the root canals were filled with the tested
endodontic irrigants through the pulp chamber
using 3 ml disposable syringes and 30-gauge
needles, which were placed to approximately 3–4
mm from the working length without binding as
described by Monika and Izabel. (20) Each time the
files were substituted, the canals were thoroughly
rinsed with alum solution, aspirated and refilled
with a new quantity of this solution.
After final irrigation with 5.0 ml of distilled
water to terminate the action and eliminate any
precipitates from the irrigants according to
methodology described by Manuele et al. (21) The
root canals were carefully dried with paper points.
Then, by using a diamond disk mounted on a lowspeed handpiece, with a constant water spray,
longitudinal and transversal grooves, which did
not penetrate into the canal, were prepared along
the buccal and lingual surfaces of each root.
Afterwards, the roots were carefully fractured
with the aid of a chisel and a surgical mallet. The
cervical, middle and apical thirds were divided,
thereby providing three sections from each
portion. The roots were mounted on stubs, put in a
vacuum chamber, sputter coated with goldpalladium ~35 nm thick with a sputter coater for
SEM evaluation. After that an observation with a
scanning electron microscope is given.
Specimen grading
Randomly assessment in each third of each
half-root at a magnification of 1000x was done.
One photomicrograph for each specimen was
taken to visualize the coronal, middle, and apical
portion of the root canal system. The areas
examined for each sample were standardized
using parameters similar to those proposed by
AL-Hadlaq et al. (22), and Soares et al. (23) with
some modifications.
A total of 36 images were analyzed by a
calibrated, blinded evaluator using the following
scoring system : Score 1, clean surface with very
little to no debris, presenting open dentinal
tubules throughout the canal wall (figure 1A);
Score 2, clean surface with some scattered debris
and/or thin homogenous smear layer with some
open or partially open dentinal tubules (figure
1B); Score 3, mostly unclean surface containing
debris and smear layer with few visible open or
partially open dentinal tubules (figure 1C); Score
4, unclean surface with large amount of debris and
smear layer with no visible dentinal tubules
(figure 1D).
Bacterial samples
The bacterial isolates used in this experiment
were obtained from the College of Science
(Department of Biology), University of
Sulaimani. These bacteria were: Staphylococcus
aureus, Klebsiella sp., Psedomonus aerogenosa
and Escherichia coli. All the isolates were
collected from infected root canals and cultivated
in suitable culture medium; Staphylococcus
aureus in Muller-Hinton agar and the other
isolates were cultivated in Mackoncky agar.
Evaluation of antibacterial activity of the alum
solution
Agar well diffusion method was used to
evaluate, in vitro, the antibacterial effect of the
alum against the common bacterial isolates found
in infected root canals, by means of agar-well
diffusion assay. (17, 18) Fifteen milliliters of the
molten agar (45 °C) were poured into sterile petri
dishes (Ø 90 mm).50 μl from each bacterial
isolate (Cell suspensions containing 108 CFU/ml
cells), were taken separately and evenly spread
onto the surface of the agar plates of MuellerHinton agar using a micropipette as described by
Bauer et al. (19) Wells (6mm diameter, and 4mm
height) were bored using a sterile cork borer.
Different concentrations of the test solution were
placed into the wells and the plates were
incubated aerobically and under CO2 incubation
at 37°C for 24 h. After 24 hours of incubation, the
plates were removed from the incubator and are
examined for the inhibition zone around each well
(if present), by using the ruler (minimum
calibration: 1mm).
Scanning electron microscopy study
The goal of this part of the study is to assess by
mean of scanning electron microscopy, the
debridement and smear layer removing ability of
alum solution tested as an irrigants, on the
cervical, middle and apical thirds of root canals of
human extracted teeth.Six freshly extracted
human single-rooted teeth with straight roots,
mature apex and less than 5 degree curvature,
were selected for this part of the study. The crown
of each tooth was removed at the cemento-enamel
junction using a diamond disk. The working
length of each canal was determined by placing
and moving a #15 K file apically in the canal until
it exited from the apical foramen.
Root canals were manually instrumented
according to a step-back type of instrumentation
using sequential K-type files up to size #40. First,
Restorative Dentistrty
Evidence for feasibility
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J Bagh College Dentistry
Vol. 24(special issue 1), 2012
Evidence for feasibility
A
B
C
D
Figure 1: (A) This sample received a score of 1. It shows most of the dentinal tubules are open
with a clean surface and very little debris. (B) This sample received a score of 2. It shows a clean
surface with very little debris, a thin homogenous smear layer, and some partially open dentinal
tubules. (C) This sample received a score of 3. It shows a mostly unclean surface containing
debris and smear layer and few open dentinal tubules. (D) This received a score of 4. It shows an
unclean surface with large amounts of debris and smear layer with no open dentinal tubules.
RESULTS
mm against Staphylococcus aureus, Pseudomonus
aerogenosa ,Eschericia coli, and Klebsiella sp.
respectively. The results revealed that the wider
inhibition zone was seen against Staphylococcus
aureus, and the least inhibition zone was against
Klebsiella sp.
Agar well diffusion assay
The mean diameters of the zones of bacterial
inhibition for the tested solution against the
bacterial isolates are shown in Table 1. Alum
solution were able to demonstrate antibacterial
activity against all the bacteria tested, and
produced inhibitions zones of 27, 25, 24 and 22
Table 1: The mean diameters of the zones of bacterial inhibition for the tested solution against
the bacterial isolates
Inhibition zones (in mm)
produced by test solution
Mean
27
25
24
22
Bacterial isolates
Staphylococcus aureus
Pseudomonus aerogenosa
Eschericia coli.
Klebsiella sp
the coronal and middle level than the apical level.
(figure. 2)
Scanning electron microscopy study
The data is summarized in Table 2. The tested
solution removed debris and smear layer better at
Table 2: The effect of alum solution on the debris and smear layer at the three locations in the root
canals
Score 1 Score 2 Score 3 Score 4
Coronal third
9
3
Middle third
7
3
2
Apical third
3
4
3
2
A
B
C
D
Figure 2: Representative SEM photomicrographs of samples attributed to different root thirds:
A) Score 1-coronal third, B) Score 2-Apical third, C) Score 3-Middle third, D) Score-4 Apical
third.
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J Bagh College Dentistry
Vol. 24(special issue 1), 2012
Evidence for feasibility
DISSCUSION
CONCLUSIONS
A biocompatible irrigant with antimicrobial
activity and which removes smear layer along
with necrotic and organic debris is desirable, as
long as predictable and complete bacterial
elimination does not appear to be possible, either
with traditional hand instrumentation or with
newer rotary NiTi – systems. With the latter at
least 35 per cent of root canal surfaces still remain
uninstrumented. (24)
This study is the first to report the feasibility of
alum as an endodontic irrigant, based on the most
important requirements of an ideal root canal
irrigant, which are antimicrobial activity,
debridement and smear layer removing activity.
Two facultative anaerobic bacterial isolates were
tested (S. aureus and E. coli), which are best
representing endodontic infections and were good
models to be tested for antibacterial sensitivity,
because these are present in all phases of the
development of an infection in root canals. (25, 26)
Another two bacterial isolates (Pseudomonas
aeruginosa and Kiebsiella sp.) also tested; they
have been isolated in open necrotic root canal
system and after contamination of the root canal
during the treatment.
In this study, no attempt was made to test all
associated organisms, because endodontic
infections are polymicrobial, the antimicrobial
sensitivity testing of all associated organisms is
difficult and produce a great deal of confusing
data, also no absolute correlation has been made
between any specific microbial species or
combination of species with clinical signs and
symptoms. (27, 28)
Analysis of the dentinal walls of all the
specimens demonstrated that cleaning have been
more effective on the coronal and middle thirds
than on the apical third. It is possible that the size
of the canals in these thirds, allowed better
circulation and action of the irrigating solution,
making the complete removal of the smear layer
and debris more possible. These results are in
agreement with those of various authors who have
observed an effective cleaning action on these
thirds even when different volumes of solutions
and times of irrigation were employed. (29, 30)
Based on the results of this investigation, it
seems that alum is an effective solution for the
removal of the smear layer when used as a final
rinse. It does not significantly change the structure
of the dentinal tubules. Studies are in progress to
determine the efficacy of alum as a root canal
irrigant with and without NaOCl for removing the
smear layer and completely disinfecting the root
canal system.
Based on the results of this study, it seems that
alum solutions have acceptable antimicrobial
effect on tested bacterial isolates, however this
finding is promising and warrants further
laboratory experiments on different types of
bacteria, including strict anaerobic and species has
been significantly found to persist after treatment
procedures. The degree of cleanliness obtained
with alum solution (concerning debris and smear
layer), was highly satisfactory, however the
cleaning effect was more pronounced in the
coronal and middle thirds than in the apical parts
of the root canals.
Finally, other properties beyond antimicrobial
and debridement activity must also be
investigated before the final choice of an irrigant
solution for clinical use, such as tissue dissolution
capacity, and acceptable biologic compatibility.
Restorative Dentistrty
REFERENCES
1. 1.Waltimo T, Trope M, Haapasalo M, Orstavik D.
Clinical efficacy of treatment procedures in
endodontic infection control and one year follow-up of
periapical healing. J Endod 2005; 31: 863-6.
2. Siqueira JF Jr, Roˆcas IN. Clinical implications and
microbiology of bacterial persistence after treatment
procedures. J Endod 2008; 34:291–301.
3. European Society of Endodontology. Consensus report
of the European Society of Endodontology on quality
guidelines for endodontic treatment. Int Endod J 1994;
27:115–24.
4. 4.Ferreira RB, Alfredo E, Porto de Arruda M, Silva
Sousa YT, Sousa-Neto MD . Histological analysis of
the cleaning capacity of nickel-titanium rotary
instrumentation with ultrasonic irrigation in root
canals. Aust Endod J 2004; 30:56–8.
5. Gutarts R, Nusstein J, Reader A, Beck M . In vivo
debridement efficacy of ultrasonic irrigation following
hand-rotary instrumentation in human mandibular
molars. J Endod 2005;31:166–70.
6. Svec TA, Harrison JW. Chemomechanical removal of
pulpal and dentinal debris with sodium hypochlorite
and hydrogen peroxide vs normal saline solution. J
Endod 1977; 3:49–53.
7. Gulabivala K, Patel B, Evans G, Ng YL. Effects of
mechanical and chemical procedures on root canal
surfaces. Endodontic Topics 2005; 10:103–22.
8. Heard F, Walton RE. Scanning electron microscope
study comparing four root canal preparation
techniques in small curved canals. Int Endod J 1997;
30:323–31.
9. Peters OA, Barbakow F. Effect of irrigation on debris
and smear layer walls prepared by two rotary
techniques. A scanning electromicroscopic study. J
Endod 2000; 26:6–10.
10. Torabinejad M, Handysides R, Khademi A, Bakland
LK.. Clinical implications of the smear layer in
endodontics: a review. Oral Surg Oral Med Oral Path
Oral Radiol Endo 2002; 94:658–66.
11. Shahravan A, Haghdoost AA, Adl A, Rahimi H, and
Shadifar F . Effect of smear layer on sealing ability of
4
J Bagh College Dentistry
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Vol. 24(special issue 1), 2012
canal obturation: a systematic review and metaanalysis. J Endodon 2007; 33: 96–105.
Osuala FI, Ibidapo obe MT, Okoh HI, Aina OO, Igbasi
UT, Nshiogu ME .Evaluation of the efficacy and
safety of Potassium Aluminium Tetraoxosuiphate in
the treatment of tuberculosis. European J of Biol Sci
2009; 1:10-14.
Clark, J.D .North Carolina popular beliefs and
superstitions. North Carolina Folklore 1970; 18:1-66.
Olmez A,Can H,Ayhan H ,Olur H . Effect of an alumcontaining mouthrinse in children for plaque and
salivary levels of selected oral microflora. J Clin
Pediatr Dent 1998; 22:335-41.
Woody R D, Millar A, Staffanou R S. Review of the
pH of hemostatic agents used in tissue displacement. J
Prosthet Dent 1993; 70: 191-92.
Dimashkieh M R, Morgano S M. A procedure for
making fixed prosthodontic impressions with the use
of preformed crown shells. J Prosthet Dent 1995; 73:
95-6.
NCCLS. Performance Standards for Antimicrobial
Disc Suspectibility Tests. Approved Standard NCCLS
Publication 1993; M2- A5, Villanova, PA, USA.
Yogish K V , Maheep B , Kanika S .In vitro
evaluation of antibacterial activity of an herbal
dentifrice against Streptococcus mutans and
Lactobacillus acidophilus. Indian J Dent Res 2008;
19(1).
Bauer AW, Kirby WM, Sherris JC, Turck M.
Antibiotic susceptibility testing by a standardized
single disk method. Am J Clin Pathol 1966; 45: 493–
96.
Monika C, Izabel C .A scanning electron microscopic
evaluation of different root canal irrigation regimens.
Braz Oral Res 2006; 20:235-40.
Manuele M, Emiliano A, Adriano C, Loredana C,
Luigi C . A Comparative study of smear layer
Restorative Dentistrty
22.
23.
24.
25.
26.
27.
28.
29.
30.
5
Evidence for feasibility
removal and erosion in apical intraradicular dentine
with three irrigating solutions: A scanning electron
microscopy evaluation. J Endod 2009; 35:900–3.
Al-Hadlaq SM, Al-Turaiki SA, Al-Sulami U, Saad AY
.Efficacy of a new brush-covered irrigation needle in
removing root canal debris: a scanning electron
microscopic study. J Endod 2006;32: 1181-4.
Soares F, Varella CH, Pileggi R .Impact of
Er,Cr:YSGG laser therapy on the cleanliness of the
root canal walls of primary teeth. J Endod 2008; 34:
474-7.
Peters OA, Sch¨onenberger K, Laib A. Effects of four
Ni-Ti preparation techniques on root canal geometry
assessed by micro computed tomography. Int Endod J
2001; 34:221-30.
Sundqvist G. Associations between microbial species
in dental root canal infections. Oral Microbiol
Immunol 1992; 7:257-62.
Luciana MS, Rivail AS, Sandra RF, Marina RH.
Antimicrobial activity of different concentrations of
NaOCl and Chlorhexidine using a contact test. Braz
Dent J 2003; 14: 99-102.
Sundqvist G, Johansson E, Sjogren U . Prevalence of
black-pigmented Bacteroides species in root canal
infections. J Endod 1989; 1: 13–19.
28.Wasfy M, McMahon K, Minah G, Falkler W.
Microbiological evaluation of periapical infections in
Egypt. Oral Microbiol Immunol 1992; 7:100–5.
Torabinejad M, Khademi A, Babagoli J, Cho Y,
Johson WB, Bozhilov K, Kim J, Shabahang S . A new
solution for the removal of the smear layer. J Endod
2003; 29:170-5.
Teixeira CS, Felippe MCS, Felipp WT. The effect of
application time of EDTA and Naocl on intra canal
smear layer removal: an SEM analysis. Int Endod J
2005; 38: 285-90.