For Peer Review
Factors affecting the viscosity sodium hypochlorite and
their effect on irrigant flow
Journal: International Endodontic Journal
Manuscript ID: IEJ-12-00733.R2
Manuscript Type: Original Scientific Article
Keywords: irrigation, sodium hypochlorite, surfactant, critical micellar concentration, dynamic viscosity, Reynolds number, laminar flow, turbulent flow
International Endodontic Journal
International Endodontic Journal
For Peer Review
Factors affecting the viscosity sodium hypochlorite and their effect on irrigant
flow
F. Bukiet1, T. Soler2, M. Guivarch2, J. Camps2, H. Tassery1, F. Cuisinier1, N. Candoni3
1Laboratoire biologie santé et Nanosciences, UFR Odontologie de Montpellier 1,
Montpellier, 2Laboratoire Interface Matrice Extracellulaire Biomatériaux, UFR
Odontologie de Marseille, Aix Marseille Université, Marseille, 3CNRS, Centre
Interdisciplinaire de Nanosciences de Marseille, Aix Marseille Université, Campus de
Luminy, Marseille, France.
Running Title: Endodontic irrigant viscosity and flow properties
Keywords: irrigation, sodium hypochlorite, surfactant, critical micellar concentration,
dynamic viscosity, Reynolds number, laminar flow, turbulent flow.
Correspondence:
Dr Bukiet Frédéric
Laboratoire biologie santé et Nanosciences, UFR Odontologie de Montpellier 1, 545
Av du Prof J.L. Viala 34193, Montpellier Cedex 5, France.
Phone number: +336-43-95-21-83
E-mail : [email protected]
Page 1 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Abstract
Aim To assess the influence of concentration, temperature and surfactant addition to a
sodium hypochlorite solution on its dynamic viscosity and to calculate the
corresponding Reynolds number in order to determine the corresponding flow regimen.
Methodology The dynamic viscosity of the irrigant was assessed using a rotational
viscometer. Sodium hypochlorite with concentrations ranging from 0.6% to 9.6% was
tested at 37°C and 22°C. A wide range of concentrations of 3 different surfactants was
mixed in 2.4% sodium hypochlorite for viscosity measurements. The Reynolds number
was calculated under each condition. Data was analysed using two-way ANOVA.
Results There was a significant influence of sodium hypochlorite concentration
(p<0.001) and temperature (p<0.001) on dynamic viscosity: the latter significantly
increased with sodium hypochlorite concentration and decreased with temperature. A
significant influence of surfactant concentration on dynamic viscosity (p<0.001)
occurred especially for high surfactant concentrations: 6.25% for benzalkonium
chloride, 15% for Tween 80 and 6.25% for Triton X-100. Reynolds number values
calculated for a given flow rate (0.14 mL.s-1) and root canal diameter (sizes 45 and 70)
clearly qualified the irrigant flow regimen as laminar.
Conclusions Dynamic viscosity increased with sodium hypochlorite and surfactant
concentration but decreased with temperature. Under clinical conditions, all viscosities
measured led to laminar flow. The transition between laminar and turbulent flow may be
reached by modifying different parameters at the same time: increasing flow rate and
temperature while decreasing irrigant viscosity by adding surfactants with a high value
of critical micellar concentration.
Page 2 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Introduction
It is generally accepted that periapical pathosis is due to the presence of
microorganisms or bacterial byproducts in the root canal (Kakehashi et al. 1965)
which must be removed to achieve success (Sjögren et al. 1997). However, root
canal anatomy is complex with irregularities areas that contain pulpal tissues and
microorganisms that cannot be approached by instruments (Paqué et al. 2011).
Therefore, an antiseptic and proteolytic fluid is necessary to disinfect and clean these
areas. The way this irrigant spreads onto the canal and reaches the non-
instrumented areas is of primary importance in root canal treatment.
Much research has been undertaken to reveal the mechanisms underlying irrigant
penetration so as to draw clinical conclusions. For example, poor penetration depth
of the irrigant beyond the needle tip (Boutsioukis et al. 2009), limiting the disinfection
of the apical part of the root canal, has been reported. However, there is still a lack of
knowledge concerning irrigant penetration because various physical parameters and
complex mathematical calculations oblige researchers to create simulators in order to
approach clinical conditions (Gulabivala et al. 2010). Recently, irrigant flow has been
studied using a Computational Fluid Dynamics model (Boutsioukis et al. 2009,
2010a, 2010b). In these publications, flow was analyzed according to irrigation
technique, needle design, anatomical characteristics of canals and flow rate.
However, the influence of the physico-chemical properties of the irrigant on its
penetration depth has not yet been evaluated.
Two essential parameters must be taken into account to understand fluid dynamics in
root canals. First, fluid surface tension as it influences the spreading properties of the
irrigant on dentine surfaces (De Gennes et al. 2004, Bukiet et al. 2012). When adding a
surfactant to an irrigant, the liquid surface tension decreases with increasing surfactant
Page 3 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
concentration, until reaching the critical micellar concentration (CMC). Above the CMC,
the addition of surfactant contributes to the formation of micelles in the liquid, and the
surface tension remains relatively constant; the best wetting properties are achieved at
this concentration (Bukiet et al. 2012).
Second, fluid viscosity as it describes the internal resistance to root canal irrigant flow
(Viswanath 2007), deformed by either shear or tensile stress. When flowing, the
different layers of the liquid slide against each other at different velocities with a transfer
of energy. In fluid dynamics, two main types of flow exist: laminar flow, characterized by
smooth and constant fluid motion, and turbulent flow which has chaotic eddies, vortices
and other flow instabilities. The type of flow is related to the Reynolds number (Re), a
dimensionless number quantifying the relative importance of inertial and viscous forces
(Guyon et al. 2001). In the case of a root canal, similar to a tube, Re is given by:
Re=(ρ v D)/µ [1]
Where:
ρ is the fluid density (kg.m-3)
v is the fluid velocity (m.s-1)
D is the root canal diameter (m)
µ is the fluid dynamic viscosity (Pa.s or kg.s-1.m-1)
Since Re is inversely related to fluid viscosity, this factor must be taken into account
when assessing the type of flow of the irrigant in a root canal. At a low Reynolds
number (Re<2,300), viscous forces are dominant leading to laminar flow whereas at
high Reynolds number (Re>4,000), inertial forces are dominant leading to turbulent
flow (Holman 2002). Theoretically, laminar flow may be associated with a higher
penetration depth of the irrigant while turbulent flow may allow better removal of debris.
Page 4 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
The factors affecting irrigant viscosity may influence its flow within the root canal in
function of the Re value. For instance, viscosity could be expected to increase with the
concentration of sodium hypochlorite and decrease with its temperature. Similarly,
adding chemical products such as surfactants, often displaying viscous properties, may
increase the viscosity. It would appear that no previous publication has studied the
viscosity of endodontic irrigants. The purpose of the present work was thus to assess
the influence of sodium hypochlorite concentration, temperature and addition of the
surfactants Benzalkonium Chloride (BAK), Tween 80 (TW), Triton X-100 (TR) on the
viscosity of sodium hypochlorite in order to determine the effect of these parameters on
the Re value and therefore on flow properties. The Couette’s method, which is known
to be reliable and accurate in order to determine viscosity measurement (Couette
1890), has been used in the present work. The null hypothesis was that surfactant
addition to NaOCl did not significantly influence the viscosity of irrigant and the Re
value.
Materials and methods
Dynamic viscosity measurement
Dynamic viscosity (µ) was measured using a rotational viscometer (Elcometer 2300,
Manchester, UK). According to the manufacturer’s operating instructions, a constant
temperature (37 or 22°C) was maintained using a thermostat connected to a specific
adaptor wrapped around the sample. The torque required to rotate the spindle in the
fluid depended on fluid viscosity. Thus, the measurements corresponded to the torque
necessary to rotate a cylinder plunged into a constant volume of liquid (18mL) at a
known constant speed (100 rpm). The validity of the protocol was verified recording the
viscosity of pure water warmed at 22°C and 37°C as references.
Page 5 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
To obtain accurate and precise data, an optional spindle dedicated to low viscosity
fluids was used. Stable flow conditions were reached quickly and the dynamic viscosity
(µ) readings on the screen were recorded after 30 s (in mPa.s). The process was
repeated 10 times per solution tested (n=10 per group and per concentration). Between
each measurement, the container, spindle and thermal adaptator were thoroughly
cleaned with acetone then ethanol before flushing with ultrapure water (milli-Q,
Millipore, Billerica, MA, USA) and dried.
The mean values and standard deviations were calculated from the 10 values obtained
from each test parameter for further statistical analysis.
Factors affecting dynamic viscosity: concentration, temperature and surfactant
addition
Effect of NaOCl concentration on dynamic viscosity
Different NaOCl solutions at various concentrations (CNaOCl): 0.6%, 1.2%, 2.4%, 4.8%
and 9.6% obtained from the dilution of 9.6% NaOCl with ultrapure water were stored at
37°C prior to measurement (group 1).
Effect of NaOCl solution temperature on dynamic viscosity
The same experimental procedure was followed with NaOCl solutions at the same
concentrations as group 1 but stored at 22°C (group 2).
Effect of surfactant concentration on dynamic viscosity
A 2.4% NaOCl solution stored at 37°C was mixed with one of the following surfactants:
• group 3: Benzalkonium Chloride (BAK) (Sigma-Aldrich B1383 - Semisolid, St
Louis, MI, USA), cationic surfactant at concentrations (CBAK) from 0% to 12.5%.
• group 4: Tween 80 (TW) (Sigma-Aldrich P1754 viscous liquid), non ionic
Page 6 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
surfactant at concentrations (CTW) ranging from 0% to 25%.
• group 5: Triton X-100 (TR) (Sigma-Aldrich X100 laboratory grade), non ionic
surfactant at concentrations (CTR) ranging from 0% to 25%.
All solutions were freshly prepared and energetically homogenized using a magnetic
stirrer immediately before measurements. This was maintained through spindle rotation
throughout the experimentation.
The 2.4% NaOCl solution without surfactant was used as the negative control
(surfactant 0%). Extreme surfactant concentrations (inappropriate for clinical activity)
were tested as positive controls (12.5% for CBAK and 25% for CTW and CTR).
Reynolds number calculation
An irrigant flow rate of 0.14mL.s-1 previously used by Boutsioukis et al. (2009) was
chosen for Reynolds number calculation. The needle tip must be placed about 3mm
short of the working length. Thus, for a given root canal preparation (6% taper with an
apical diameter of 0.25 mm or 0.50 mm), the canal diameter at the needle tip level was
of 0.45 mm or 0.70 mm. Then, the Reynolds number was calculated using these values
according to the equation [1] given in the Introduction.
Statistical analysis
First, after verifying the assumptions for analysis of variance (ANOVA), a two-way
ANOVA, at 5% confidence level, was performed to determine the influence of
concentration (way 1) and temperature (way 2) on the viscosity values. A Duncan
multiple range test was carried out at the same confidence level to create groups which
were not statistically different.
Second, after verifying the assumptions, an ANOVA, at the 5% confidence level, was
Page 7 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
performed for each surfactant, completed by a Duncan multiple range test to evaluate
the influence of each surfactant concentration on NaOCl viscosity. It was not possible
to compare the surfactants between each other because the surfactant concentrations
were adapted to each surfactant and therefore varied from one group to another. The
viscosity was plotted against the surfactant concentration to demonstrate the general
feature of the relationship.
Results
Influence of NaOCl concentration and temperature on dynamic viscosity (Groups
1 & 2) (Table 1)
The two-way ANOVA test revealed a significant influence of CNaOCl (p<0.001) and
temperature (p<0.001) on µ: viscosity statistically increased with NaOCl concentration
and decreased with increasing temperature.
In group 1 tested at 37°C, µ decreased from 1.31 ± 0.01 mPa.s for CNaOCl 9.6%
(positive control) to 1.15 ± 0.009 mPa.s for CNaOCl 0.6% (negative control). The Duncan
test could distinguish four different subgroups: 0.6% NaOCl and 1.2 % NaOCl were
similar while the following concentrations – 2.4%, 4.8% and 9.6% – were each
statistically different from each other. Re decreased respectively from 379 to 332 and
from 244 to 214 when sodium hypochlorite concentration increased from 0.6% to 9.6%
for both the 0.45 mm canal diameter and the 0.70 mm canal diameter.
In group 2 tested at 22°C, µ decreased from 1.77 ± 0.01 mPa.s for CNaOCl 9.6%
(positive control) to 1.20 ± 0.007 mPa.s for CNaOCl 0.6% (negative control). The Duncan
test distinguished four different subgroups: 0.6% NaOCl displayed the lowest value,
1.2% and 2.4% concentrations were statistically equivalent, 4.8% concentration was
slightly higher and finally 9.6% concentration showed the highest viscosity. Re
Page 8 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
decreased respectively from 363 to 246 and from 233 to 158 when sodium hypochlorite
concentration increased from 0.6% to 9.6% for a 0.45 mm canal diameter and 0.70 mm
canal diameter.
Influence of surfactant concentration at 37°C
Benzalkonium chloride: Group 3 (Table 2)
The ANOVA test revealed a significant influence of CBAK on µ (p<0.001): µ increased
with increasing CBAK. Viscosity increased from 1.186 ± 0.008 mPa.s for CBAK 0%
(negative control) to 2.081 ± 0.008 mPa.s for CBAK 12.5%. The Duncan test
distinguished three different subgroups with non-statistical different values of µ within
each subgroup: the first from 0 to 3.125%, the second at 6.25% and the third at 12.5%.
A clear increase of viscosity appeared from CBAK of 6.25%. Re decreased with
increasing CBAK, respectively from 368 to 209 and from 236 to 135 for a 0.45 mm canal
diameter and a 0.70 mm canal diameter.
Tween 80: Group 4 (Table 3)
The ANOVA test revealed a significant influence of CTW on µ (p<0.001): µ increased
with increasing CTW. Viscosities ranged from 1.186 ± 0.008 mPa.s for CTW 0 %
(negative control) to 4.943 ± 0.009 mPa.s for CTW 25%. The Duncan test distinguished
four different subgroups with non-statistically different values of µ in each subgroup:
from 0 to 6%, 15%, 20% and finally 25%. A significant increase in viscosity occurred
from CTW of 15% and above. Re decreased from 368 to 88 and from 236 to 57 with
increasing CTW for a 0.45 mm canal diameter and a 0.70 mm canal diameter,
respectively.
Page 9 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Triton X-100: Group 5 (Table 4)
The ANOVA test revealed a significant influence of CTR on µ (p<0.001): µ increased
with increasing CTR. Viscosity increased from 1.186 ± 0.008 mPa.s for CTR 0 %
(negative control) to 24.218 ± 0.06 mPa.s for CTR 25%. The Duncan test distinguished
6 different subgroups: 0.000035%, 0.00007%, 0.50%, 0.80%, 1% and 3.12 % none of
which were statistically different from the negative control. The viscosities recorded with
concentrations from 0.0001428% to 0.25% were significantly lower. Finally the viscosity
shown by the following concentrations – 6,25%, 15%, 20% and 25% – were much
higher and significantly different from each other. Re decreased from 368 to 18 with
increasing CTR for a 0.45 mm canal diameter and from 236 to 12 for a 0.70 mm canal
diameter, respectively.
Plotting of µ versus CBAK, CTw and CTR showed that µ generally increased with the
concentration of surfactants. However, when examining low range surfactant
concentration, an initial decrease of µ was observed for all of the surfactants before µ
increased with concentration (Fig. 1). This minimum value of µ was reached for
different concentrations according to the surfactant: 0.004% for CBAK, 0.02% for CTW
and 0.0001428% for CTR. These concentrations are twice the CMC of each surfactant.
Discussion
The purpose of the present study was to assess the impact of NaOCl concentration,
temperature and surfactant addition on the dynamic viscosity of the irrigant to calculate
the corresponding Reynolds number. It can be concluded that dynamic viscosity
statistically increased with NaOCl concentration and with surfactant concentration
beyond the critical micellar concentration but decreased with temperature. The
Page 10 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Reynolds number values calculated from the data corresponded to laminar flow and
were a long way from the threshold for a turbulent flow (Guyon et al. 2001).
Calculation of the Reynolds number (Re) was carried out by applying the equation [1]
under “typical” endodontic conditions: an irrigant flow rate of 0.14mL.s-1 and mean root
canal diameter of 0.45 mm (Boutsioukis et al. 2009). The 2.4% NaOCl viscosity at 37°C
was 1.186 mPa.s, leading to a Reynolds number of 277 which means a laminar flow.
According to equation [1], this flow could be switched to turbulent by increasing the flow
rate or decreasing the root canal diameter. When working with µ=1.186 mPa.s, the
calculations showed that Re could be increased beyond 4000, either by using a flow
rate larger than 1.6mL.s-1 or when working on root canals with a diameter smaller than
0.04 mm. Unfortunately, a flow rate of 1.6mL.s-1 is inappropriate for clinical activity due
to the risk of NaOCl extrusion, which has been observed for flow rates higher than 0.3
mL s-1 (Chow 1983). Concerning the canal diameter, only lateral canals and
ramifications have diameters smaller than 0.04 mm. Therefore, neither the irrigant flow
nor the canal diameters are sufficient to switch from a laminar to a turbulent flow. A
substantial decrease in viscosity combined with these parameters may be required to
change the flow regimen. With this aim in mind, the present work focused on the effects
of temperature, NaOCl concentration and surfactant concentration on irrigant viscosity.
Root canal irrigant temperature can be heated before using (Sirtes et al. 2005). In the
present study, when temperature increased from 22°C to 37°C, NaOCl viscosity
decreased. This well-known phenomenon may be explained by thermal agitation of the
molecules which move more easily at 37°C than at 22°C (Guyon et al. 2001). This
result must be related to those of other studies, which have evaluated the influence of
NaOCl temperature on its protein dissolving ability (Sirtes et al. 2005, Stojicic et al.
2010) and its antibacterial efficiency (Sirtes et al. 2005). Irrigant flow remains laminar
Page 11 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
because temperature only has a limited effect on NaOCl viscosity. The low viscosities
(near 0.2mPa.s for µ) required to switch from laminar to turbulent flow correspond to
higher temperatures not compatible with clinical applications.
Previous studies had reported that the irrigant viscosity statistically increased with
CNaOCl (Guerisoli et al. 1998). The result of the present study confirmed those given by
another methodology (Guerisoli et al. 1998). Despite significant differences between
the concentrations, viscosity only varied from 1.20 ± 0.007 mPa.s for 0.6% NaOCl to
1.77 ± 0.01 mPa.s for 9.6% NaOCl. Thus, the choice of CNaOCl influences the proteolytic
and antibacterial activities more than the flow properties. Consequently, a 2.4%
concentration within the recommended range between 1% and 5.25%, can be used as
irrigant without modifying irrigant flow properties.
The addition of a surfactant to NaOCl or EDTA in order to enhance wetting properties
has already been evaluated with encouraging results (Abou-Rass & Patonai, 1982,
Berutti et al. 1997, Pecora et al. 1998, Gambarini, 1999, Giardino et al. 2006, Stojicic et
al. 2010, Merivale et al. 2009, Palazzi et al. 2012, Bukiet et al. 2012). However, no data
is available concerning the modification of irrigant viscosity through surfactant addition,
despite the potential impact that viscosity may have on irrigant flow. In this study, 3
surfactants with a wide range of concentrations were studied. BAK is a cationic
detergent which has already been used in dentine bonding agents (Pashley et al.
2011), orthodontic resin (Othman et al. 2002) and in a commercial EDTA solution
(Salvizol, Pierre Rolland, Merignac, France). Moreover, a recent study showed that
BAK is an antiseptic which decreases bacterial adherence and biofilm growth (Jaramillo
et al. 2012). TW and TR are both non ionic surfactants with a syrupy appearance. They
have also been included in root canal irrigant products like Biopure™ MTAD (for TW)
and Chlor-Xtra™ (for TR) but with undisclosed concentrations. Although Gulabivala et
Page 12 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
al. (2010) asserted that the effect of additives would be to increase its viscosity and
reduce its Reynolds number, it has never been proven or invalidated before the present
work.
The study demonstrated that for low surfactant concentrations, viscosity first
decreased until a minimum value (Fig. 1). This decrease is likely related to the
neutralization of surfactant charges by the sodium cations present in NaOCl
solutions. As a result, the conformation of surfactants is more compact and viscosity
decreases (Onesippe & Lagerge 2009). The minimum µ value occurred for each
surfactant at different concentrations. It is interesting to note that these
concentrations are twice the CMC in 2.4% NaOCl solutions: 0.0076% for CMCBAK
(Bukiet et al. 2012), 0.01% for CMCTW and 0.00035% for CMCTR.
This relation between viscosity and CMC has already been used to determine CMC
through viscosity measurements (Tyuzyo 1960). So, while viscosity decreases due to
neutralization of surfactant charges, it then increases after formation of micelles. Thus,
it has been logically shown that the initial decrease in viscosity was more efficient for
TW which has the highest CMC. Consequently, adding a surfactant at concentration
near the CMC reduces irrigant viscosity and increases Re. On the contrary, adding a
surfactant at high concentration larger than CMC increases irrigant viscosity and
decreases Re.
In the present work, the increase in viscosity beyond CMC is more noticeable at very
high concentrations of surfactants not used in endodontics: 6.25% for BAK, 15% for TW
and 6.25% for TR. However, regardless of the surfactant and the concentration,
viscosity was high enough to give Reynolds numbers lower than 250 corresponding to
a laminar flow (Re<2500).
The clinical significance of irrigant flow regimen is still undetermined. Laminar flow is
Page 13 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
due to friction forces and likely more appropriate for allowing the irrigant to flow into the
unshaped areas and ramifications due to its regularity. However, a previous work
clearly highlighted a stagnation of the irrigant beyond the needle tip (1.5mm), whatever
the flow rate (Boutsioukis et al. 2009). This contradiction is due to gas bubble formation
in the apical area, acting as a vapor lock when the irrigation needle is placed deeply
(Tay et al. 2010). Theoretically, turbulent flow may improve root canal cleaning
efficiency by breaking the biofilm, like the cavitation phenomenon reported with
ultrasounds, but likely to a lesser extent. In practice, factors such as dentine
irregularities, canal ramifications and agitation technique may also contribute to
turbulent flow.
Conclusion
Calculations from the results of this laboratory study, using clinically relevant
parameters, such as canal diameter and irrigant flow rate, showed that all of the
viscosities would likely lead to laminar flow. The transition between laminar and
turbulent flow may be reached by modifying different parameters simultaneously: 1)
increase in irrigant flow rate, 2) increase in temperature and 3) decrease in irrigant
viscosity by adding surfactants with a concentration close to their CMC.
Acknowledgement.
We thank Caroline Montet for the English revision.
.
Page 14 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
References
Abou-Rass M, Patonai FJ (1982) The effects of decreasing surface tension on the
flow of irrigating solutions in narrow root canals. Oral surgery, Oral Medicine, Oral
Pathology, Oral Radiology, and Endodontics 53, 524–6.
Berutti E, Marini R, Angeretti A (1997) Penetration ability of different irrigants into
dentinal tubules. Journal of Endodontics 23, 725-7.
Boutsioukis C, Lambrianidis T, Kastrinakis E (2009) Irrigant flow within a prepared
root canal using various flow rates: a Computational Fluid Dynamics study.
International Endodontic Journal 42, 144-55.
Boutsioukis C, Gogos C, Verhaagen B, Versluis M, Kastrinakis E, Van der Sluis LW
(2010a) The effect of root canal taper on the irrigant flow: evaluation using an
unsteady Computational Fluid Dynamics model. International Endodontic Journal 43,
909-16.
Boutsioukis C, Gogos C, Verhaagen B, Versluis M, Kastrinakis E, Van der Sluis LW
(2010b) The effect of apical preparation size on irrigant flow in root canals evaluated
using an unsteady Computational Fluid Dynamics model. International Endodontic
Journal 43, 874-81.
Bukiet F, Couderc G, Camps J, Tassery H, Cuisinier F, About I, Charrier A, Candoni
N (2012) Wetting properties and critical micellar concentration of benzalkonium
chloride mixed in sodium hypochlorite. Journal of Endodontics 38, 1525-9.
Chow TW (1983) Mechanical effectiveness of root canal irrigation. Journal of
Endodontics 9, 475–9.
Couette M (1890) Etudes sur le frottement des liquides. Annales de Chimie et de
Physique 6, 433–510.
De Gennes PG, Brochard-Wyart F, Quéré D (2004) Capillarity and wetting
Page 15 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
phenomena. Drops, Bubbles, Pearls, Waves. pp. 1-31. Ed Springer.
Gambarini G (1999) Shaping and cleaning the root canal system: a scanning electron
microscopic evaluation of a new instrumentation and irrigation technique. Journal of
Endodontics 25, 800-3.
Giardino L, Ambu E, Becce C, Rimondini L, Morra M (2006) Surface tension
comparison of four common root canal irrigants and two new irrigants containing
antibiotic. Journal of Endodontics 32, 1091–3.
Guerisoli DMZ, Silva RS, Pecora JD (1998) Evaluation of some physico-chemical
properties of different concentrations of sodium hypochlorite solutions. Brazilian
Endodontic Journal 3, 21-3.
Gulabivala K, Ng YL, Gilbertson M, Eames I (2010) The fluid mechanics of root canal
irrigation. Physiological Measurement 31, R49-84.
Guyon E, Hulin JP, Petit L, Mitescu CD (2001) Physical hydrodynamics. Oxford
University Press.
Holman J. P (2002) Heat Transfer. McGraw-Hill.
Jaramillo DE, Arriola A, Safavi K, Chávez de Paz LE (2012) Decreased bacterial
adherence and biofilm growth on surfaces coated with a solution of benzalkonium
chloride. Journal of Endodontics 38, 821-5.
Kakehashi S, Stanley H, Fitzgerald R (1965) The effect of surgical exposures of
dental pulps in germ-free and conventional laboratory rats. Oral surgery, Oral
Medicine, Oral Pathology, Oral Radiology, and Endodontics 20, 340-9.
Merivale C, Gulabivala K, Ng Y-L (2009) Influence of surfactant/thickener on NaOCl-
induced removal of applied collagen from canal walls during ultrasonic irrigation.
International Endodontic Journal 42, 1140.
Onesippe C, Lagerge S (2009) Study of the complex formation between sodium
Page 16 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
dodecyl sulphate and gelatin. Colloids and Surfaces A: Physicochemical and
Engineering Aspects 337, 61-6.
Othman HF, Wu CD, Evans CA, Drummond JL, Matasa CG (2002) Evaluation of
antimicrobial properties of orthodontic composite resins combined with benzalkonium
chloride. American Journal of Orthodontics and Dentofacial Orthopedics 122, 288-94.
Palazzi F, Morra M, Mohammadi Z, Grandini S, Giarino L (2012) Comparison of the
surface tension of 5.25% sodium hypochlorite solution with three new sodium
hypochlorite-based endodontic irrigants. International Endodontic Journal 45, 129-35.
Paqué F, Boessler C, Zehnder M (2011) Accumulated hard tissue debris levels in
mesial roots of mandibular molar after sequential irrigation steps. International
Endodontic Journal 44, 148-53.
Pashley DH, Tay FR, Imazato S (2011) How to increase the durability of resin-dentin
bonds. Compendium of Continuing Education in Dentistry 32, 60-4.
Pecora JD, Sousa-Neto MD, Guerisoli DMZ, Marchesan MA (1998) Effect of
reduction of the surface tension of different concentrations of sodium hypochlorite
solutions on radicular dentine permeability. Brazilian Dental Journal 3, 38–40.
Sirtes G, Waltimo T, Schaetzle M, Zehnder M (2005) The effects of temperature on
sodium hypochlorite short-term stability, pulp dissolution capacity, and antimicrobial
efficacy. Journal of Endodontics 31, 669 –71.
Sjögren U, Figdor D, Persson S, Sundqvist G (1997) Influence of infection at the time
of root filling on the outcome of endodontic treatment of teeth with apical
periodontitis. International Endodontic Journal 30, 297-306.
Stojicic S, Zivkovic S, Qian W, Zhang H, Haapasalo M (2010) Tissue dissolution by
sodium hypochlorite: effect of concentration, temperature, agitation, and surfactant.
Journal of Endodontics 36, 1558–62.
Page 17 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Tay FR, Gu LS, Schoeffel GJ, Wimmer C, Susin L, Zhang K, Arun SN, Kim J, Looney
SW, Pashley DH (2010) Effect of vapor lock on root canal debridment by using a side-
vented needle for positive pressure irrigant delivery. Journal of Endodontics 36, 745-50.
Tyuzyo K (1960) On the relation between viscosity and critical micelle concentration of
detergent solutions. Kolloid-Zeitschrift 175, 40-9.
Viswanath DS (2007) Viscosity of liquids: Theory, Estimation, Experiment, and Data.
pp. 1-8. Ed Springer.
Page 18 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Figure Legend
Figure 1 Relationship between dynamic viscosity µ (mPa .s) and concentrations of
surfactants Benzalkonium Chloride (CBAK), Tween 80 (CTW) and Triton X-100 (CTR)
for low concentrations (from 0 to 10%) mixed with 2.4% NaOCl at 37°C.
Page 19 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Table 1. Comparison of mean viscosity, µ ± standard deviation (mPa.s)
according to NaOCl concentration and temperature (22 or 37°C), and corresponding
mean Reynolds number ± standard deviation calculated for two values of the root canal
diameter.
CNaOCL µ (mPa.s)
37°C
Reynolds number for a root canal diameter of
0.45mm
Reynolds number for a root canal diameter of
0.70mm
µ (mPa.s)
22°C
Reynolds number for a root canal diameter of
0.45mm
Reynolds number for a root canal diameter of
0.70mm
0.6% 1.15 ± 0.009 h
379 244 1.202 ± 0.007 d 363 233
1.2% 1.152 ± 0.006 h 378 243 1.213 ± 0.006
c 359 231
2.4% 1.186 ± 0.008 g 368 236 1.224 ± 0.006
c 356 229
4.8% 1.245 ± 0.008 f 350 225 1.298 ± 0.007
b 336 216
9.6% 1.312 ± 0.01 e
332 214 1.772 ± 0.01 a 246 158
Page 20 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Table 2. Comparison of mean viscosity, µ ± standard deviation (mPa.s)
according to benzalkonium chloride concentrations (CBAK) mixed with 2.4% NaOCl at
37°C and corresponding mean Reynolds number ± standard deviation calculated for
two values of the root canal diameter.
CBAK
µ (mPa.s)
Reynolds number for a root canal diameter of 0.45mm
Reynolds number for a root canal diameter of 0.70mm
0% control 1.186 ± 0.008 a 368 236
0.004% 1.179 ± 0.005 a 370 238
0.008% 1.18 ± 0.009 a 369 237
0.5% 1.18 ± 0.006 a 369 237
1% 1.18 ± 0.008 a 369 237
3.125% 1.203 ± 0.004 a 362 233
6.25% 1.38 ± 0.004 b 316 203
12.5% 2.081 ± 0.008 c 209 135
Page 21 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Table 3. Mean viscosity, µ ± standard deviation (mPa.s) according to Tween
80 concentrations (CTW) mixed with 2.4% NaOCl at 37°C and corresponding mean
Reynolds number ± standard deviation calculated for two values of the root canal
diameter.
CTW µ (mPa.s)
Reynolds number for a root canal diameter of 0.45mm
Reynolds number for a root canal diameter of 0.70mm
0% control 1.186 ± 0.008 a 368 236
0.0015% 1.184 ± 0.005 a 368 237
0.003% 1.172 ± 0.01 a 372 239
0.006% 1.157 ± 0.004 a 377 242
0.02% 1.123 ± 0.004 a 388 250
0.04% 1.130 ± 0.009 a 386 248
0.0625% 1.135 ± 0.005 a 384 247
0.12% 1.151 ± 0.007 a 379 243
0.24% 1.153 ± 0.006 a 378 243
0.45% 1.172 ± 0.004 a 372 239
0.9% 1.173 ± 0.001 a 372 239
1% 1.182 ± 0.007 a 369 237
1.2% 1.191 ± 0.005 a 366 235
6% 1.196 ± 0.005 a 365 234
15% 2.529 ± 0.008 b 172 111
20% 3.983 ± 0.009 c 109 70
25% 4.943 ± 0.009 d 88 57
Page 22 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Table 4. Mean viscosity, µ ± standard deviation (mPa.s) according to Triton X-
100 concentrations (CTR) mixed with 2.4% NaOCl at 37°C and corresponding mean
Reynolds number ± standard deviation calculated for two values of the root canal
diameter.
CTR
µ (mPa.s)
Reynolds number for a root canal diameter of 0.45mm
Reynolds number for a root canal diameter of 0.70mm
0% control 1.186 ± 0.008 a 368 236
0.000035% 1.176 ± 0.006 a 371 238
0.00007% 1.173 ± 0.009 a 372 239
0.0001428% 1.144 ± 0.005 b 381 245
0.00386% 1.146 ± 0.009 b
380 245 0.125% 1.147 ± 0.012
b 380 244
0.25% 1.156 ± 0.005 b 377 242
0.5% 1.161 ± 0.005 a 375 241
0.8% 1.168 ± 0.004 a 373 240
1% 1.181 ± 0.007 a 369 237
3.12% 1.181 ± 0.008 a 369 237
6.25% 2.375 ± 0.008 c 184 118
15% 6.012 ± 0.02 d
73 47 20 % 18.426 ± 0.06
e 24 15
25 % 24.218 ± 0.06 f 18 12
Page 23 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
Figure 1. Relationship between dynamic viscosity µ (mPa .s) and
concentrations of surfactants Benzalkonium Chloride (CBAK), Tween 80 (CTW) and
Triton X-100 (CTR) for low concentrations (from 0 to 10%) mixed with 2.4% NaOCl at
37°C.
Page 24 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
A. COPYRIGHT
1. The Contributor assigns to Wiley-Blackwell, during the full term of copy-right and any extensions or renewals, all copyright in and to the Contribution,and all rights therein, including but not limited to the right to publish, repub-lish, transmit, sell, distribute and otherwise use the Contribution in whole or inpart in electronic and print editions of the Journal and in derivative worksthroughout the world, in all languages and in all media of expression nowknown or later developed, and to license or permit others to do so.
2. Reproduction, posting, transmission or other distribution or use of the finalContribution in whole or in part in any medium by the Contributor as permit-ted by this Agreement requires a citation to the Journal and an appropriatecredit to Wiley-Blackwell as Publisher, and/or the Society if applicable, suitablein form and content as follows: (Title of Article, Author, Journal Title and Volume/Issue, Copyright © [year], copyright owner as specified in the Journal).Links to the final article on Wiley-Blackwell’s website are encouraged whereappropriate.
B. RETAINED RIGHTS
Notwithstanding the above, the Contributor or, if applicable, the Contributor’sEmployer, retains all proprietary rights other than copyright, such as patentrights, in any process, procedure or article of manufacture described in theContribution.
C. PERMITTED USES BY CONTRIBUTOR
1. Submitted Version. Wiley-Blackwell licenses back the following rights tothe Contributor in the version of the Contribution as originally submitted forpublication:
a. After publication of the final article, the right to self-archive on the Con-tributor’s personal website or in the Contributor’s institution’s/employer’sinstitutional repository or archive. This right extends to both intranets andthe Internet. The Contributor may not update the submission version orreplace it with the published Contribution. The version posted must containa legend as follows: This is the pre-peer reviewed version of the followingarticle: FULL CITE, which has been published in final form at [Link to finalarticle].
b. The right to transmit, print and share copies with colleagues.
2. Accepted Version. Re-use of the accepted and peer-reviewed (but notfinal) version of the Contribution shall be by separate agreement with Wiley-Blackwell. Wiley-Blackwell has agreements with certain funding agencies governing reuse of this version. The details of those relationships, and otherofferings allowing open web use, are set forth at the following website:http://www.wiley.com/go/funderstatement. NIH grantees should check thebox at the bottom of this document.
3. Final Published Version. Wiley-Blackwell hereby licenses back to the Contributor the following rights with respect to the final published version ofthe Contribution:
a. Copies for colleagues. The personal right of the Contributor only to sendor transmit individual copies of the final published version in any format tocolleagues upon their specific request provided no fee is charged, and further-provided that there is no systematic distribution of the Contribu-tion, e.g. posting on a listserve, website or automated delivery.
b. Re-use in other publications. The right to re-use the final Contribution orparts thereof for any publication authored or edited by the Contributor(excluding journal articles) where such re-used material constitutes lessthan half of the total material in such publication. In such case, any modifi-cations should be accurately noted.
c. Teaching duties. The right to include the Contribution in teaching ortraining duties at the Contributor’s institution/place of employment includ-ing in course packs, e-reserves, presentation at professional conferences,in-house training, or distance learning. The Contribution may not be usedin seminars outside of normal teaching obligations (e.g. commercial semi-nars). Electronic posting of the final published version in connection withteaching/training at the Contributor’s institution/place of employment ispermitted subject to the implementation of reasonable access controlmechanisms, such as user name and password. Posting the final publishedversion on the open Internet is not permitted.
d. Oral presentations. The right to make oral presentations based on theContribution.
4. Article Abstracts, Figures, Tables, Data Sets, Artwork and SelectedText (up to 250 words).
a. Contributors may re-use unmodified abstracts for any non-commercialpurpose. For on-line uses of the abstracts, Wiley-Blackwell encourages butdoes not require linking back to the final published versions.
b. Contributors may re-use figures, tables, data sets, artwork, and selectedtext up to 250 words from their Contributions, provided the following conditions are met:
(i) Full and accurate credit must be given to the Contribution.(ii) Modifications to the figures, tables and data must be noted.
Otherwise, no changes may be made.(iii) The reuse may not be made for direct commercial purposes, or for
financial consideration to the Contributor.(iv) Nothing herein shall permit dual publication in violation of journal
ethical practices.
COPYRIGHT TRANSFER AGREEMENT
Date: Contributor name:
Contributor address:
Manuscript number (if known):
Re: Manuscript entitled
(the “Contribution”)
for publication in (the “Journal”)
published by (“Wiley-Blackwell”).
Dear Contributor(s):Thank you for submitting your Contribution for publication. In order to expedite the editing and publishing process and enable Wiley-Blackwell to disseminate your Contribution to the fullest extent, we need to have this Copyright Transfer Agreement signed and returned as directed in the Journal’sinstructions for authors as soon as possible. If the Contribution is not accepted for publication, or if the Contribution is subsequently rejected, this Agreement shall be null and void. Publication cannot proceed without a signed copy of this Agreement.
CTA-A
03/02/2013 BUKIET
Labo. biol. santé et Nanosciences, UFR Odonto. de Montpellier 1, 545 Av du Prof J.L. Viala, 34193, Montpellier Cedex 5, France.
Factors affecting the viscosity of the root canal irrigant sodium hypochlorite and their effect on irrigant flow
The INTERNATIONAL ENDODONTIC JOURNAL
"WILEY-BLACKWELL"
Contribution
Page 25 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review
D. CONTRIBUTIONS OWNED BY EMPLOYER
1. If the Contribution was written by the Contributor in the course of the Contributor’s employment (as a “work-made-for-hire” in the course ofemployment), the Contribution is owned by the company/employer whichmust sign this Agreement (in addition to the Contributor’s signature) in thespace provided below. In such case, the company/employer hereby assigns toWiley-Blackwell, during the full term of copyright, all copyright in and to theContribution for the full term of copyright throughout the world as specified inparagraph A above.
2. In addition to the rights specified as retained in paragraph B above and therights granted back to the Contributor pursuant to paragraph C above, Wiley-Blackwell hereby grants back, without charge, to such company/employer, itssubsidiaries and divisions, the right to make copies of and distribute the finalpublished Contribution internally in print format or electronically on the Com-pany’s internal network. Copies so used may not be resold or distributed externally.However the company/employer may include information and text from theContribution as part of an information package included with software orother products offered for sale or license or included in patent applications.Posting of the final published Contribution by the institution on a public accesswebsite may only be done with Wiley-Blackwell’s written permission, and paymentof any applicable fee(s). Also, upon payment of Wiley-Blackwell’s reprint fee,the institution may distribute print copies of the published Contribution externally.
E. GOVERNMENT CONTRACTS
In the case of a Contribution prepared under U.S. Government contract orgrant, the U.S. Government may reproduce, without charge, all or portions ofthe Contribution and may authorize others to do so, for official U.S. Govern-
ment purposes only, if the U.S. Government contract or grant so requires. (U.S.Government, U.K. Government, and other government employees: see notesat end)
F. COPYRIGHT NOTICE
The Contributor and the company/employer agree that any and all copies ofthe final published version of the Contribution or any part thereof distributedor posted by them in print or electronic format as permitted herein will includethe notice of copyright as stipulated in the Journal and a full citation to theJournal as published by Wiley-Blackwell.
G. CONTRIBUTOR’S REPRESENTATIONS
The Contributor represents that the Contribution is the Contributor’s originalwork, all individuals identified as Contributors actually contributed to the Con-tribution, and all individuals who contributed are included. If the Contributionwas prepared jointly, the Contributor agrees to inform the co-Contributors ofthe terms of this Agreement and to obtain their signature to this Agreement ortheir written permission to sign on their behalf. The Contribution is submittedonly to this Journal and has not been published before. (If excerpts from copy-righted works owned by third parties are included, the Contributor will obtainwritten permission from the copyright owners for all uses as set forth in Wiley-Blackwell’s permissions form or in the Journal’s Instructions for Contributors,and show credit to the sources in the Contribution.) The Contributor also warrants that the Contribution contains no libelous or unlawful statements,does not infringe upon the rights (including without limitation the copyright,patent or trademark rights) or the privacy of others, or contain material orinstructions that might cause harm or injury.
CHECK ONE BOX:
Contributor-owned work
Contributor’s signature Date
Type or print name and title
Co-contributor’s signature Date
Type or print name and title
Company/Institution-owned work
Company or Institution (Employer-for-Hire) Date
Authorized signature of Employer Date
U.S. Government work Note to U.S. Government EmployeesA contribution prepared by a U.S. federal government employee as part of the employee’s official duties, orwhich is an official U.S. Government publication, is called a “U.S. Government work,” and is in the publicdomain in the United States. In such case, the employee may cross out Paragraph A.1 but must sign (in theContributor’s signature line) and return this Agreement. If the Contribution was not prepared as part of theemployee’s duties or is not an official U.S. Government publication, it is not a U.S. Government work.
U.K. Government work Note to U.K. Government Employees(Crown Copyright) The rights in a Contribution prepared by an employee of a U.K. government department, agency or other
Crown body as part of his/her official duties, or which is an official government publication, belong to theCrown. U.K. government authors should submit a signed declaration form together with this Agreement.The form can be obtained via http://www.opsi.gov.uk/advice/crown-copyright/copyright-guidance/publication-of-articles-written-by-ministers-and-civil-servants.htm
Other Government work Note to Non-U.S., Non-U.K. Government EmployeesIf your status as a government employee legally prevents you from signing this Agreement, please contactthe editorial office.
NIH Grantees Note to NIH GranteesPursuant to NIH mandate, Wiley-Blackwell will post the accepted version of Contributions authored by NIHgrant-holders to PubMed Central upon acceptance. This accepted version will be made publicly available 12 months after publication. For further information, see www.wiley.com/go/nihmandate.
ATTACH ADDITIONAL SIGNATURE
PAGES AS NECESSARY
(made-for-hire in thecourse of employment)
CTA-A
Bukiet frédéric, DDS
03/02/2013
03/02/2013
Page 26 of 26
International Endodontic Journal
International Endodontic Journal
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
Top Related