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ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XV, Issue III, March 2026
Study on the Influence of Cinnamon Powder on the Corrosion
Resistance of 21K Gold Alloy in Artificial Saliva in the Presence of
Cinnamon Powder
Dr. A. Krishnaveni
1*
, Dr. S. Manimekalai
2
1
Department of Chemistry, Yadava College, Affiliated Madurai Kamaraj University Madurai – 625 014,
India.
2
Department of Chemistry, Yadava College, Affiliated Madurai Kamaraj University Madurai – 625 014,
India
*Corresponding Author
DOI:
https://doi.org/10.51583/IJLTEMAS.2026.150300008
Received: 14 March 2026; Accepted: 19 March 2026; Published: 01 April 2026
ABSTRACT
Corrosion resistance is a critical factor influencing the long-term performance and biocompatibility of dental
and biomedical alloys. This study explores the corrosion behaviour of 21K gold alloy and other metallic
materials in artificial saliva both in the presence and absence of cinnamon powder. Cinnamon, a common natural
flavouring agent used in food and oral care products contains bioactive compounds that may alter the
electrochemical environment of the oral cavity. Corrosion testing was performed using potentiodynamic
polarisation and electrochemical impedance spectroscopy (EIS) to evaluate the electrochemical stability of the
materials. The results indicated that the presence of cinnamon powder enhances the corrosion resistance of 21K
gold alloy. These findings suggest that the dietary or therapeutic use of cinnamon powder could influence the
durability and performance of metallic dental and orthodontic devices.
Keywords: Corrosion, Artificial Saliva, Cinnamon Powder, 21K Gold Alloy, Polarisation study, and AC
impedance spectra.
INTRODUCTION
Once implanted, metals and alloys are exposed to various body fluids and may undergo corrosion in this
biological environment. The corrosion resistance of different alloys in bodily fluids has been extensively studied
by numerous researchers. For example, B.I. Johansson et al. investigated the corrosion behaviour of dental
copper, nickel, and gold alloys in artificial saliva and saline solutions over four weeks. Their study revealed that
copper and beryllium-containing nickel alloys exhibited significant surface degradation whereas high-gold
alloys demonstrated superior stability
.
D. Brune et al. investigated the corrosion behaviour of gold alloys and titanium in artificial saliva, focusing on
the release of metal ions during extended immersion. Their findings provide valuable baseline data on the
behaviour of gold and its alloys in artificial saliva. Tzu-Hsin Lee et al. highlighted the impact of fluoride as a
recurring factor in corrosion studies, noting that the presence of fluoride in artificial saliva significantly reduces
the corrosion resistance of Ni-Ti and other dental alloys. Additionally, Aggryppyne Keyne Oberta Sembiring et
al. studied the use of cinnamon bark extract as a natural corrosion inhibitor for iron. Their results showed that
compounds from cinnamon bark can form complexes with Fe(III) at the metal surface, thereby reducing
corrosion rates.
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Orthodontic wires, such as SS 18/8, Ni–Cr, Ni–Ti. Doctors commonly use SS316 and 22 K gold to correct the
alignment of teeth. These wires are exposed to corrosion in a saliva environment. In addition, they are affected
by corrosive agents present in food, beverages, candies, and orally administered tablets.
The present study investigates the effect of cinnamon powder on the corrosion resistance of 21K gold in artificial
saliva using electrochemical techniques, including polarisation and AC impedance spectroscopy.
EXPERIMENTAL METHODS
Preparation of the metal specimens
A thin wire of 21K gold alloy was used as the test material in this work. 21K gold alloy consists of 21 parts of
pure gold, and the remaining two parts are copper and zinc. The added metals make the texture of 21K gold
harder and thereby more durable for making jewellery.
The 21K gold alloy was compressed using a Teflon rod. The samples were polished to a mirror finish and used
for electrochemical studies. The metal specimens encapsulated in a Teflon rod were immersed in artificial saliva
( ISO standard ISO 3160-2) whose composition was as follows: 0.4g/l of KCl, 0.4g/l of NaCl, 0.906g/l of
CaCl
2
.2H
2
O, 0.690g/l of NaH
2
PO
4
.2H
2
O, 0.005g/l Na
2
S.9H
2
O and 1g/l of urea (Fusayama Meyer artificial
saliva, with the pH of the artificial saliva being approximately 6.9.
Preparation of Cinnamon powder:
About 0.5 g of cinnamon powder was accurately weighed and powdered.
Fig 1 cinnamon powder
Composition
Cinnamon contains a range of resinous compounds, including cinnamaldehyde, cinnamate, cinnamic acid, and
other essential oils.
Benefits of cinnamon powder
Manages Blood Sugar and Diabetes: Cinnamon improves insulin sensitivity and helps lower blood glucose
levels, which is particularly beneficial for individuals with Type 2 diabetes. Heart Health Support: It helps reduce
"bad" LDL cholesterol, triglycerides, and blood pressure, while maintaining "good" HDL cholesterol. High
Antioxidant Content: It contains potent antioxidants that protect the body against oxidative stress and free radical
damage. Anti-inflammatory Properties: Its active compounds help fight inflammation, which can alleviate
conditions like joint pain and muscle aches. Weight Management: Cinnamon can help curb cravings, reduce
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hunger, and speed up metabolism. Improves Digestion: Known to reduce symptoms of gas, bloating and
indigestion. Cognitive Function: Studies suggest it may help protect brain health and reduce the risk of
neurodegenerative diseases.
Electrochemical Study
In the present study, the corrosion resistance of 21K gold alloy immersed in artificial saliva was evaluated in the
absence and presence of cinnamon powder using polarization studies and AC impedance spectroscopy.
Polarization measurements were conducted using a CHI Electrochemical Workstation (model 604E).
Polarization study
Polarization studies were conducted using a three-electrode cell setup (Figure 2), with a saturated calomel
electrode (SCE) as the reference electrode, platinum as the counter electrode and a 21K gold alloy as the
working electrode. From these studies, key corrosion parameters were obtained, including the corrosion
potential (Ecorr), corrosion current density (Icorr), anodic (ba) and cathodic (bc) Tafel slopes, and linear
polarization resistance (LPR) values.
Figure 2. Three-electrode cell assembly
AC impedance spectra
In the present study the same instrument and setup used for the polarization measurements were employed to
record the AC impedance spectra. A stabilization period of 5-10 min was allowed for the system to reach a
steady-state open circuit potential. The real (Z′) and imaginary (Z″) components of the cell impedance were
measured in ohms over a range of frequencies.
Impedance spectra were recorded with the following parameters: initial potential E(v) = 0, high frequency =
1×10⁵ Hz, low frequency = 1 Hz, amplitude = 0.005 V, and a quiet time of 2s. From the Nyquist plots, the
transfer resistance (Rₜ) and double-layer capacitance (Cdl) were determined, while Bode plots were used to
obtain the impedance.
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RESULTS AND DISCUSSION
The present investigation aimed to evaluate the corrosion resistance of orthodontic wire made from 21 K alloy
in artificial saliva both in the absence and presence of cinnamon powder, using electrochemical techniques such
as polarization studies and AC impedance spectroscopy.
Polarization study
The influence of cinnamon powder on the corrosion resistance of the 21K gold alloy in artificial saliva (AS)
was investigated using a polarization study. The Polarization curves of the 21K gold alloy in the AS solution
in the absence and presence of cinnamon powder, are shown in Figure 3. The corrosion parameters are listed
in Table 1. The corrosion parameters are compared in Figure 4-5.
Table 1: Corrosion Parameters of 21K gold alloy immersed in artificial saliva in the absence and presence of
cinnamon powder obtained by polarization study.
Metal
System
E
corr
mV vs SCE
b
c
mV/decade
b
a
mV/decade
LPR
Ohm cm
2
I
corr
A/0.00785 cm
2
21K gold
alloy
Artificial
saliva
-0.227
3.140
1.786
435713
2.026x10
−7
21K gold
alloy
Artificial
saliva +
Cinnamon
powder
-0.206
5.325
4.618
437277
1.023 X10
-8
Figure 3. Polarization curves of 21K Gold alloy immersed in various test solution AS
b) AS+cinnamon powder
b
a
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Figure 4. Comparison of LPR values of 21K gold alloy immersed in artificial saliva (AS) in the presence and
absence of cinnamon powder
Figure 5. Comparison of Icorr values of 21K Gold alloy immersed in artificial saliva (AS) in the presence
and absence of cinnamon powder.
Correlation of corrosion parameters obtained by Polarization Study is shown in Scheme A.
0
0.5
1
1.5
2
2.5
2.026×10
-8
1.023×10
-8
Ic
AS AS+Cinnamon powder
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Scheme A. Correlation among corrosion parameters in polarization study.
Based on these concepts, it can be observed from Table 1 that in the presence of cinnamon powder, the corrosion
resistance of the 21K gold alloy in AS increases. This is revealed by the fact that, in the presence of cinnamon
powder the LPR value of the 21 K gold alloy increases (Figure 3) and the corrosion current decreases (Figure
3).
Implication
The corrosion resistance of the 21K gold alloy in artificial saliva increased in the presence of cinnamon powder.
Hence, it was concluded that individuals fitted with orthodontic wires made of 21K gold alloy in artificial saliva
need not hesitate to take cinnamon powder orally.
AC Impedance spectra
The AC impedance spectra (Nyquist plot) of 21K gold immersed in artificial saliva are shown in Figure 6, and
the AC impedance spectra (3D Interaction) of 21K gold immersed in artificial saliva (AS) + cinnamon powder
are shown in Figure 7. The AC impedance spectra (Bode plot) of 21K gold immersed in artificial saliva are
shown in Figure 8, and the AC impedance spectra (Bode plot) of 21K gold immersed in artificial saliva (AS) +
Cinnamon powder are shown in Figure 9. The corrosion parameters are compared in Figures 10 and 11,
respectively. The corrosion parameters, such as the charge transfer resistance (R
t
) and double layer capacitance
(C
dl
) values, are listed in Table 2.
Table 2: Corrosion parameters of 21K gold alloy immersed in artificial saliva (AS) in the absence and presence
of Cinnamon powder obtained from AC impedance spectra.
Metal
System
Nyquist plot
Bode plot impedance log(Z/ohm)
R
t
ohm cm
2
C
dl
F/cm
2
21K Gold
alloy
Artificial saliva
21356
2.406X10
-10
5.340
21K Gold
alloy
Artificial saliva +
Cinnamon powder
160472
3.203X10
-11
5.220
CORROSION
RESISTANCE
INCREASES
LPR
INCREASES
CORROSION
CURRENT
DECREASES
POLARISATION STUDY
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Figure 6: AC impedance spectra of 21K gold alloy immersed in artificial saliva.
Figure 7: AC impedance spectra (3D Interaction) of 21K gold alloy immersed in artificial saliva (AS)+
Cinnamon powder
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Fig 8. The AC impedance spectra (Bode plot) of 21K gold alloy immersed in artificial saliva
Fig 9 AC impedance spectra (Bode plot) of 21K gold alloy immersed in artificial saliva (AS)+ Cinnamon powder
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Figure 10. Comparison of Rt values of 21K gold alloy immersed in AS and AS+ cinnamon powder
Figure 11. Comparison of C
dl
values of 21K gold alloy immersed in AS and AS+ cinnamon powder
As shown in Table 2, in the presence of cinnamon powder, the corrosion resistance of the 21K gold alloy in
artificial saliva increased. This is revealed by the fact that in the presence of cinnamon powder, the R
t
value
increased and the C
dl
value decreased.
AC impedance spectra (Bode plot) of 21K gold alloy immersed in artificial saliva (AS)+ Cinnamon powder in.
21356
160472
0 20000 40000 60000 80000 100000 120000 140000 160000 180000
1
2
3
4
5
6
comparision of Rt value
2.406×10
-10
3.203×10
-11
0
0.5
1
1.5
2
2.5
3
3.5
Comparison of Cdl value
AS+Cinnamon powder
AS
AS
AS+cinnamon powder
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The Rt value was 21356. The double-layer capacitance (C
dl
) was 2.413 × 10
-11
. These observations indicate
that the protective film formed on 21K gold alloy was more stable. It can withstand the attack of aggressive ions
present in the AS.
The Rt value was 160472. The double-layer capacitance (C
dl
) was 3.1781X10
-11
. These observations indicate
that the corrosion resistance of 21 Karat gold in AS increased in the presence of cinnamon powder. The film
formed on the metal surface prevented electron loss from the metal. The presence of the film caused the charge
transfer resistance to increase and decreased the double-layer capacitance value.
Implication
Patients who use 21K gold alloy orthodontic wires can consume cinnamon powder, as the corrosion resistance
of 21K gold alloy metal increases in the presence of cinnamon powder.
SUMMARY AND CONCLUSIONS
The corrosion resistance of 21K gold alloy in artificial saliva (AS), in the absence and presence of cinnamon
powder, was investigated using polarisation studies and AC impedance spectra. The corrosion resistance of the
21 K gold alloy in artificial saliva increased in the presence of cinnamon powder. This was revealed by an
increase in the LPR value, an increase in the Rt value, a decrease in the corrosion current, and a decrease in the
double-layer capacitance value. Hence, it was concluded that people fitted with orthodontic wires made of 21K
gold alloy in artificial saliva need not hesitate to take cinnamon powder orally. (
Table 3).
Table 3. Summary of the study
Corrosion parameters
Artificial Saliva (AS)
AS+ cinnamon powder (increases/decreas
LPR
435713
437277 (increases)
Rt
21356
160472 (increases)
Corrosion Current
2.026 x 10
-7
1.023 x 10
-8
(decreases)
Double-layer Capacitance
2.406×10
-10
3.203×10
-11
(decreases)
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