Root canal therapy is one of the main treatment options for endodontic diseases in which an effective irrigation is key to a successful therapy. In the present paper, the irrigation flow inside an instrumented root canal is numerically investigated, and then the effect of inflow temperature on the irrigation is analyzed based on the computational fluid dynamics results. The magnitude of the shear stress and its corresponding coverage of the irrigation flow on the wall is adopted to characterize the clean efficiency. The axial velocity is used to represent the replacement of local flow field, which stands for the capability to carry away the cleaning residue. Results show that the effective area that the shear stress covers on the root canal wall behind the needle outlet is usually larger than that in front of the outlet, and both the effective coverage of the shear stress and the replacement of the irrigant are improved when the velocity increases. It is convinced that the critical shear stress, namely, the lowest shear stress required to peel off the smear layer on the root canal wall, decreases with the increase in the temperature. Although no apparent variation of the shear stress on the wall can be observed while improving the inflow temperature, the effective surface to be cleaned is improved to some extent because of the decrease in the critical shear stress. Meanwhile, the power consumption is reduced obviously. If the input power remains constant when the temperature increases, both the shear stress on the wall and the replacement are significantly improved besides the decrease in the critical shear stress. This means both the clean efficiency on the wall and the clearing capability (namely replacement) in local flow field are significantly promoted.

1.
T. N.
Aniketh
,
M.
Idris
,
I. B.
Geeta
,
K. J.
Nandakishore
, and
S. A.
Kareem
, “
Root canal irrigants and irrigation techniques: A review
,”
J. Evol. Med. Dent. Sci.
4
(
27
),
4694
4700
(
2015
).
2.
B.
Radomir
,
P.
Jelena
,
Ž.
Slavoljub
,
M.
Aleksandar
,
N.
Marija
, and
G.
Jovanka
, “
Ultrastructural analysis of uninstrumented root canal areas following various irrigation regimens
,”
Stomatol. Glas. Srb.
63
(
2
),
57
62
(
2016
).
3.
Z.
Mohammadi
,
H.
Jafarzadeh
,
S.
Shalavi
, and
J. I.
Kinoshita
, “
Unusual root canal irrigation solutions
,”
J. Contemp. Dent. Pract.
18
(
5
),
415
420
(
2017
).
4.
C.
Boutsioukis
,
T.
Lambrianidis
, and
E.
Kastrinakis
, “
Irrigant flow within a prepared root canal using various flow rates: A computational fluid dynamics study
,”
Int. Endod. J.
42
,
144
155
(
2009
).
5.
G.
Faria
,
K. S.
Viola
,
H.
Coaguila-Llerena
,
L. R. A.
Oliveira
,
R. T.
Leonardo
,
A. J.
Aranda-García
 et al, “
Penetration of sodium hypochlorite into root canal dentine: Effect of surfactants, gel form and passive ultrasonic irrigation
,”
Int. Endod. J.
52
(
3
),
385
392
(
2018
).
6.
A. C. S.
Druttman
and
C. J. R.
Stock
, “
An in vitro comparison of ultrasonic and conventional methods of irrigant replacement
,”
Int. Endod. J.
22
(
4
),
174
178
(
1989
).
7.
K.
Gulabivala
,
B.
Patel
,
G.
Evans
, and
Y.-L.
Ng
, “
Effects of mechanical and chemical procedures on root canal surfaces
,”
Endod. Top.
10
,
103
122
(
2005
).
8.
C.
Boutsioukis
,
C.
Gogos
,
B.
Verhaagen
,
M.
Versluis
,
E.
Kastrinakis
, and
L. W. M.
Van der Sluis
, “
The effect of root canal taper on the irrigant flow: Evaluation using an unsteady computational fluid dynamics model
,”
Int. Endod. J.
43
,
909
916
(
2010
).
9.
C.
Boutsioukis
,
C.
Gogos
,
B.
Verhaagen
,
M.
Versluis
,
E.
Kastrinakis
, and
L. W. M.
Van der Sluis
, “
The effect of apical preparation size on irrigant flow in root canals evaluated using an unsteady computational fluid dynamics model
,”
Int. Endod. J.
43
,
874
881
(
2010
).
10.
C.
Boutsioukis
,
T.
Lambrianidis
,
B.
Verhaagen
,
M.
Versluis
,
E.
Kastrinakis
,
P. R.
Wesselink
, and
L. W. M.
van der Sluis
, “
The effect of needle-insertion depth on the irrigant flow in the root canal: Evaluation using an unsteady computational fluid dynamics model
,”
J. Endod.
36
,
1664
1668
(
2010
).
11.
T. S.
Vinothkumar
,
S.
Kavitha
,
L.
Lakshminarayanan
,
N. S.
Gomatbi
, and
V.
Kumar
, “
Influence of irrigating needle-tip designs in removing bacteria inoculated into instrumented root canals measured using single-tube luminometer
,”
J. Endod.
33
,
746
748
(
2007
).
12.
C.
Boutsioukis
,
B.
Verhaagen
,
M.
Versluis
,
E.
Kastrinakis
,
P. R.
Wesselink
, and
L. W. M.
van der Sluis
, “
Evaluation of irrigant flow in the root canal using different needle types by an unsteady computational fluid dynamics model
,”
J. Endod.
36
,
875
879
(
2010
).
13.
F.
Bukiet
,
T.
Soler
,
M.
Guivarch
,
J.
Camps
,
H.
Tassery
,
F.
Cuisinier
, and
N.
Candoni
, “
Factors affecting the viscosity of sodium hypochlorite and their effect on irrigant flow
,”
Int. Endod. J.
46
,
954
961
(
2013
).
14.
C. E.
Loo
and
J.
Bridgwater
, “
Theory of thermal stresses and deposit removal
,”
Powder Technol.
42
,
55
65
(
1985
).
15.
D.
Dong
,
J.
Zhang
,
Z.
Wu
, and
L. I.
Zhuo
, “
The influencing factors on the critical shear stress of thermal hydrolyzed sludge
,”
Acta Sci. Circumstantiae
38
(
2
),
553
559
(
2018
).
16.
C.
Poggio
,
M.
Ceci
,
R.
Beltrami
,
M.
Colombo
, and
A.
Dagna
, “
Viscosity of endodontic irrigants: Influence of temperature
,”
Dent. Res. J.
12
,
425
(
2015
).
17.
G.
Velayutham
,
A.
Priyanka
,
K. A.
Pradeep
, and
N. L.
Lakshmi
, “
Influence of temperature and concentration on the dynamic viscosity of sodium hypochlorite in comparison with 17% EDTA and 2% chlorhexidine gluconate: An in vitro study
,”
J. Conservative Dent.
17
,
57
60
(
2014
).
18.
G. W.
Zou
, “
Fluid mechanics and physical properties of fluids
,” in
Viscous Fluid Dynamics
, edited by
G. W.
Zou
(
National Defense Industry Press
,
Beijing, China
,
2013
), pp.
41
76
.
19.
L.
Giardino
,
Z.
Mohammadi
,
R.
Beltrami
,
C.
Poggio
,
C.
Estrela
, and
L.
Generali
, “
Influence of temperature on the antibacterial activity of sodium hypochlorite
,”
Braz. Dent. J.
27
,
32
36
(
2016
).
20.
L.
Zou
,
Y.
Shen
,
W.
Li
, and
M.
Haapasalo
, “
Penetration of sodium hypochlorite into dentin
,”
J. Endod.
36
,
793
796
(
2010
).
21.
S.
Frais
,
Y.-L.
Ng
, and
K.
Gulabivala
, “
Some factors affecting the concentration of available chlorine in commercial sources of sodium hypochlorite
,”
Int. Endod. J.
34
,
206
215
(
2001
).
22.
G.
Sirtes
,
T.
Waltimo
,
M.
Schaetzle
, and
M.
Zehnder
, “
The effects of temperature on sodium hypochlorite short-term stability, pulp dissolution capacity, and antimicrobial efficacy
,”
J. Endod.
31
,
669
671
(
2005
).
23.
T. S.
Rosenkrantz
and
W.
Oh
, “
Cerebral blood flow velocity in infants with polycythemia and hyperviscosity: Effects of partial exchange transfusion with plasmanate
,”
J. Pediatr.
101
,
94
98
(
1982
).
24.
C.
Boutsioukis
,
B.
Verhaagen
,
M.
Versluis
,
E.
Kastrinakis
, and
L. W. M.
van der Sluis
, “
Irrigant flow in the root canal: Experimental validation of an unsteady computational fluid dynamics model using high-speed imaging
,”
Int. Endod. J.
43
,
393
403
(
2010
).
25.
R.
Franklin
,
L. S.
Gu
,
J.
Schoeffel
,
C.
Wimmer
,
L.
Susin
,
K.
Zhang
,
S. N.
Arun
,
J.
Kim
,
S. W.
Looney
, and
D. H.
Pasbley
, “
Effect of vapor lock on root canal debridement by using a side-vented needle for positive-pressure irrigant delivery
,”
J. Endod.
36
,
745
750
(
2010
).
26.
C.
Boutsioukis
,
E.
Kastrinakis
,
T.
Lambrianidis
,
B.
Verhaagen
,
M.
Versluis
, and
L. W. M.
van der Sluis
, “
Formation and removal of apical vapor lock during syringe irrigation: A combined experimental and computational fluid dynamics approach
,”
Int. Endod. J.
47
,
191
201
(
2014
).
27.
Y.
Gao
,
M.
Haapasalo
,
Y.
Shen
,
H.
Wu
,
B.
Li
,
N. D.
Ruse
, and
X.
Zhou
, “
Development and validation of a three-dimensional computational fluid dynamics model of root canal irrigation
,”
J. Endod.
35
,
1282
1287
(
2009
).
28.
Y.
Shen
,
Y.
Gao
,
W.
Qian
,
N. D.
Ruse
,
X.
Zhou
, and
H.
Wu
, “
Three-dimensional numeric simulation of root canal irrigant flow with different irrigation needles
,”
J. Endod.
36
(
5
),
884
889
(
2010
).
29.
D.
Šnjarić
,
Z.
Čarija
,
A.
Braut
,
A.
Halaji
,
M.
Kovačević
, and
D.
Kuiš
, “
Irrigation of human prepared root canal—Ex vivo based computational fluid dynamics analysis
,”
Croat. Med. J.
53
(
5
),
470
479
(
2012
).
30.
Y.
Ma
,
J.
Han
,
H.
Yu
, and
X.
Wang
, “
Computational fluid dynamics analysis of the flow of four irrigations in root canal
,”
Chin. J. Stomatol.
50
,
352
357
(
2015
).
31.
R.
Wang
,
Y.
Shen
,
J.
Ma
,
D.
Huang
,
X.
Zhou
,
Y.
Gao
, and
M.
Haapasalo
, “
Evaluation of the effect of needle position on irrigant flow in the C-shaped root canal using a computational fluid dynamics model
,”
J. Endod.
41
,
931
936
(
2015
).
32.
X.
Chen
,
Q. R.
Yang
,
R. H.
Wu
, and
Y.
Wang
, “
Numerical simulation and experimental study on defouling performance of solid-liquid two phase flow on heat transfer surface
,”
J. Chem. Eng. Chin. Univ.
31
,
818
826
(
2017
).
33.
H. Y.
Bi
, “
Fouling fluidized-removing and heat transfer enhancement technique on intake water and heat transfer of sewage-source heat pump system
,” Ph.D. thesis,
Dalian University of Technology
,
Dalian, China
,
2007
.
34.
M.
Hou
,
M.
Chen
,
L. I.
Lei
,
S.
Zhang
,
D.
Zhou
, and
W. U.
Ligeng
, “
Flushing methods, temperature and flushing time of sodium hypochlorite affect the clearance effect on the smear layer of root canal
,”
Chin. J. Tissue Eng. Res.
43
,
6918
6923
(
2015
).
35.
L.
Li
, “
Comparation the effectiveness of smear layer removal by the agitation techniques, the temperature and the agitation time of sodium hypochlorite
,” Ph.D. thesis,
Tianjin Medical University
,
Tianjin, China
,
2014
.
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