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Corrosion depth and extent in bands … Keerthi VN et al
Journal of International Oral Health 2016; 8(4):451-454
Received: 19th November 2015 Accepted: 16th February 2016 Conflict of Interest: None
Source of Support: Nil
Original Research
Doi: 10.2047/jioh-08-04-08
Comparative Evaluation of Corrosion Depth and Extent between Pre-welded and Welded
Bands in Various Intraoral Simulated Conditions: An In Vitro Scanned Electron Microscope
Study
V Naga Keerthi1, K Pradeep Babu2, M Senthil Kumar3, Anoop Mathew4, Aniruddh Yashwant4, A Nanda Kumar5
Contributors:
1
Post-graduate Student, Department Orthodontics and
Dentofacial Orthopedics, Indira Gandhi Institute of Dental
Sciences, Puducherry, India; 2Reader, Department of Orthodontics
and Dentofacial Orthopedics, Indira Gandhi Institute of
Dental Sciences, Puducherry, India; 3Professor, Department
of Orthodontics and Dentofacial Orthopedics, Indira Gandhi
Institute of Dental Sciences, Puducherry, India; 4Senior Lecturer,
Department of Orthodontics and Dentofacial Orthopedics, Indira
Gandhi Institute of Dental Sciences, Puducherry, India; 5Professor,
Department of Orthodontics and Dentofacial Orthopedics,
Meenakshi Ammal Dental College, Chennai, Tamil Nadu, India.
Correspondence:
Dr. Keerthi VN. Department of Orthodontics and Dentofacial
Orthopedics, Indira Gandhi Institute of Dental Sciences, Puducherry,
India. Phone: +91-8675728458. Email: [email protected]
How to cite the article:
Keerthi VN, Babu KP, Kumar MS, Mathew A, Yashwant A,
Kumar AN. Comparative evaluation of corrosion depth and
extent between pre-welded and welded bands in various intraoral
simulated conditions: An in vitro scanned electron microscope
study. J Int Oral Health 2016;8(4):451-454.
Abstract:
Background: In orthodontic treatment multiple teeth are involved
by placing brackets and bands on the teeth, which provide tooth
movement. Earlier, banding was done on all the teeth in fixed
orthodontic treatment to correct the malaligned teeth which
prolongchairside time and has a badesthetic appearance. To
overcome this, brackets were introduced. Instead for molars, most
of the orthodontists use the molar band as it has better contact, and
high amount of force can be applied. The purpose of the study was
to compare the corrosion depth and extent of bands in customized
welded and pre-welded preformed molar bands in various intraoral
simulated conditions and to find the suitable welded band material
for molars.
Materials and Methods: The molar bands of Group A - Customized
welded molar bands (24 numbers) and Group B - Preformed molar
bands (24 numbers) were divided into six samples for each subgroup,
i.e., artificial saliva, artificial saliva with fluoride toothpaste, artificial
saliva with coffee, and artificial saliva with South Indian spices and
kept in the incubator. Incubator was set at the temperature of 37°C
for 72 h. After 72 h of incubation, all samples were removed from
the dietary medium, and the samples were dried using tissue paper
to remove the wet particles. Now, the samples from each group
were measured under scanned electron microscope to know the
corrosion depth and extent. All samples of all groups are examined
for corrosion depth and extent at the areas of attachment at ×100,
and the pictures are clicked automatically for further assessment.
Results: In both customized welded and preformed molar bands
expressed a statistically increased corrosion depth and extent in
samples immersed in artificial saliva with coffee when compared to
other dietary media. Pre-welded molar bands showed less amount
of corrosion when compared to welded molar bands.
Conclusion: In this study, pre-welded bands showed superior
quality with less corrosion compared to welded bands in all the
dietary media. Hence, pre-welded bands are advised for banding in
orthodontic treatment as it has less amount of corrosion.
Key Words: Dietary medium, GIMP, surface characteristics
Introduction
An individual needs orthodontic treatment mainly to achieve
normal occlusion and esthetic facial profile. Recently,
orthodontic treatment was more esthetic concerned to an
individual than form and function.1
Magill was the first person to introduce the plain band. Initially,
molar banding was done by welding the band using a spot welder
according to the tooth contour. This procedure consumes a lot of
clinical time for an orthodontist. To make life simpler, preformed,
pre-welded molar bands were introduced which was available
in the correct anatomical shape of molar teeth in various sizes.
Weld and preformed molar bands were supposed to have same
characteristics and properties. The problem usually encountered
with orthodontist was detachment of welded attachments from
the bands which prolongs the treatment time. Bands and buccal
tube have their own physical and mechanical properties, but
they are kept under stress in an oral environment which includes
saliva, food substances, and masticatory force. This leads to
detachment of welded attachment which was mainly due to
corrosion. Hence, corrosion influences orthodontic treatment.2
Corrosion of the welded attachment is nothing but the
degradation of the material by chemical reaction of the food
substance in the mouth. Corrosion degrades the strength and
appearance of the material.2 The attachment of the buccal
tube with the molar band should be strong to resist the force
of the wire. Hence, the purpose of the study was to compare
the corrosion characteristics and properties of welded and
preformed molar bands in various dietary media.
Aims and objectives
The aim of the study was to compare the corrosion depth and
extent of welded and pre-welded molar bands in various dietary
451
Corrosion depth and extent in bands … Keerthi VN et al Journal of International Oral Health 2016; 8(4):451-454
media such as artificial saliva, fluoride toothpaste with artificial
saliva, coffee with artificial saliva, and South Indian spices with
artificial saliva; and the objective was to assess the corrosion
depth and extent in pre-welded and welded molar bands in
various above-mentioned dietary media.
The samples were placed on the specimen stand under the
bell jar. The membrane samples were covered with gold (gold
ion sputtering) by setting the air pressure under the bell jar to
0.2 tor, voltage to 1.2 kV and the current to 10 mA for 10-15 min.
Each sample after gold ion sputtering, the specimen stage was
cleaned with acetone and the gold ion sputtered samples the
mounted on the specimen stage using conductive glue. The
mounted ion sputtered membrane samples were placed in the
SEM for characterization.
Materials and Methods
The present in vitro study was designed to compare the
welded and pre-welded preformed bands for molars in
artificial saliva with dietary substances to know the surface
characteristics. The customized welded molar bands
(24 numbers), band material from rocky mountain, and
buccal tube from American Orthodontics were taken and
welded the buccal tubes in the band using a spot welder
and pre-welded molar bands (24 numbers - American
Orthodontics)were exposed to artificial saliva, artificial saliva
mixed with fluoride toothpaste, artificial saliva mixed with
coffee, and artificial saliva mixed withSouth Indian spices to
find the corrosion depth and extent.
All samples of all the groups were examined for corrosion depth
and extent at the areas of attachment at ×100 and the pictures
was clicked automatically for further assessment.
Results
In this study, the pre-welded and welded molar bands were
placed in four different dietary media (artificial saliva, artificial
saliva mixed with fluoride toothpaste, artificial saliva with
coffee, and artificial saliva with South Indian spices) to detect
the corrosion depth and extent of the bands by scanned
electron microscopy.
Artificial saliva of 400 ml was prepared in biochemistry
laboratory and divided into two parts, Artificial saliva and the
dietary medium, were same for both the groups; hence, the
medium wasprepared simultaneously. Artificial saliva and
dietary medium were taken in the proportion of 10:1 ratio,
i.e., 1 g of each dietary medium was diluted in 100 ml of artificial
saliva, and it was equally divided for both the groups.
Comparing welded molar bands [1] and pre-welded molar
bands [2], statistically, it denoted that there was a significant
difference between welded molar bands [1] and pre-welded
molar bands [2] Mean value showed that there was a higher
amount of corrosion depth and extent in 1 when compared
with 2. While comparing all the four dietarymedia, welded
bands in artificial saliva with coffee showed a higher amount of
corrosion depth and extent followed by the medium of artificial
saliva with fluoridated toothpaste, artificial saliva with South
Indian spices, and artificial saliva (Table 1).
Now, the prepared ingredients were kept in separate 100 ml
beaker for each subgroup (Figure 1). The molar bands of
Group A (24 numbers) and Group B (24 numbers) and divided
into six samples for each subgroup and kept in the incubator
at the temperature of 37°C for 72 h. After 72 h of incubation,
all the samples was removed from the dietary medium and
making the samples to dryusing tissue paper to remove the wet
particles. Now, the samples from each group were measured
under scanned electron microscope (SEM) to know the
corrosion depth and extent.
Discussion
Bands attached with buccal tubes, when adapted to the molar
teeth get exposed to the oral environments such as saliva, food
substances, masticatory forces, wires, temperature variations,
and forces derived active components. Although these factors
may directly result in detachment mostly due to the corrosion
which was resultant of the above factors that might cause
detachment.
In general, the molar band was welded using a spot welder
after adapting to the tooth contour. Corrosion of the welded
Table 1: Values obtained in SEM for corrosion depth in welded and
pre‑welded bands.
Medium
Welded [1] (µm) Pre‑welded [2] (µm)
Artificial saliva
Artificial saliva with
fluoridated toothpaste
Artificial saliva with coffee
Artificial saliva with
South Indian spices
Figure 1: Samples immersed in thedietary medium.
SEM: Scanning electron microscope
452
2723.3
4585
2195
3661.6
4843.3
4285
4003.3
3175
Corrosion depth and extent in bands … Keerthi VN et al
Journal of International Oral Health 2016; 8(4):451-454
attachment was the degradation of the material by chemical
reaction of the food substance in the oral cavity. Corrosion
reduces the strength of the material. The attachment of the
buccal tube with molar band should be strong to resist the
force of wires, active attachments, masticatory forces and
corrosion.3,4
GIMP was used to see the exact information of the measured
items on the image. All the images were measured with the
unit of µm. Babaloukas et al. in Journal of Microscopy 2010
used GIMP software to evaluate correction of vignetting on
medical microscopic images.8
In comparing the samples between customized welded and
preformed molar bands, the welded molar band has more
amount of corrosion than pre-welded molar bands. In welded
molar band, the contouring of the band according to the
tooth surface may lead to abrasion, surface roughness for
the attachment of the buccal tube which might increase the
corrosion depth and extent than pre-welded molar bands.
These molar bands were manually made which does not have
control over the spot welding like preformed molar bands, in
which interior was micro-etched to increase bond strength and
retention. The preformed band has been shaped according
to the tooth anatomy for proper retention. Preformed molar
bands were strong enough to avoid wall collapses while being
malleable which led to less amount of corrosion than the
welded molar bands.9
The dietary media used in this study was most common food
substances consumed in day-to-day life in South India. As these
are commonly consumed food substances, we need to evaluate
their effects on the bands, buccal tubes, and surrounding
structures in orthodontic patients.5
This study consisted of two groups, welded molar bands
and preformed molar bands, in which the corrosion depth
and extent were evaluated. Four dietary media selected were
artificial saliva (A), artificial saliva with fluoride toothpaste (B),
artificial saliva with coffee (C), and artificial saliva with South
Indian spices (D). Each medium was taken in a beaker. The
numbers of samples in each group were 24. Six bands were
immersed in each dietary media, and the beakers were placed
in incubator at the temperature of 37°C for 72 h.6
Among all the four dietary media, artificial saliva mixed with
coffee showed more amount of corrosion comparatively.
Coffee is slightly acidic (pH 5.0-5.1) which have a stimulating
effect on humans because of its caffeine content. Acidic content
of coffee may lead to corrosion of orthodontic appliances.
Harzer et al., in 2001, stated that the corrosive properties of
brackets in fluoride containing toothpaste (Gel Kham) and
tea during orthodontic treatment using light and scanning
microscopy.10 The second higher amount of corrosion was
seen in the medium of artificial saliva with fluoride toothpaste.
When fluoride toothpastewas used in orthodontic patients, it
may influence the surface characteristics of the orthodontic
material.10,11 According to these studies, fluoride toothpaste
and coffee may influence the bands, buccal tubes, and other
orthodontic materials and also affects the orthodontic
treatment.10
Scanned electron microscopy was used to analyze the
corrosion depth of the band. The samples were placed on the
specimen stand under the bell jar. The membrane samples
are covered with gold (gold ion sputtering) by setting the air
pressure under the bell jar to 0.2 tor, the voltage to 1.2 kV and
the current to 10 mA for 10-15 min. Each sample after gold
ion sputtering, the specimen stage was cleaned with acetone
and the gold ion sputtered samples are then mounted on
the specimen stage using conductive glue. The mounted ion
sputtered membrane samples were placed in the SEM for
characterization.7
The samples of all groups (Group A and Group B) are
examined for surface characteristics at the areas of attachment
at ×100, and the images are clicked automatically for further
assessment (Figure 2).
Compared to the medium of artificial saliva mixed with fluoride
toothpaste, corrosion is less in the customized welded bands
when immersed in the medium of artificial saliva with South
Indian spices. The pH of South Indian spices was 9.5-10 which
was more alkaline. If the South Indian spices were in contact
with the orthodontic appliances for a longer duration, it might
lead to corrosion of the appliances.12 Artificial salivary medium
produced the least amount of corrosion. Factors such as pH of
artificial saliva (6.75) and temperature might affect the physical
properties of the material.13
The limitation of the study was described, as the study was done
in stimulated environment and in control temperature, values
obtained cannot be applied to the conditions encountered in
the actual oral environment, as the more complex mechanism
was involved in the oral cavity such as occlusal forces, tooth
Figure 2: Image obtained using scanned electron microscope.
453
Corrosion depth and extent in bands … Keerthi VN et al Journal of International Oral Health 2016; 8(4):451-454
movement, temperature variation, and presence of microorganisms.
Am J Orthod Dentofacial Orthop 2008;133(4):584-92.
5. Ardeshna AP, Vaidyanathan TK. Colour changes of
orthodontic elastomeric module materials exposed to
in vitro dietary media. J Orthod2009;36(3):177-85.
6. Barrett RD, Bishara SE, Quinn JK. Biodegradation of
orthodontic appliances. Part I. Biodegradation of nickel
and chromium in vitro. Am J Orthod Dentofacial Orthop
1993;103(1):8-14.
7. Bhad WA, Hazarers PV. Scanning electron microscopic
study and shear bond strength measurement with 5% and
37% phosphoric acid. AJODO1995;108(4):410-4.
8. Babaloukas G, Tentolouris N, Liatis S, Sklavounou A,
Perrea D. Evaluation of three methods for retrospective
correction of vignetting on medical microscopy images
utilizing two open source software tools. J Microsc
2011;244(3):320-4.
9. Graber LW, Vanarsdall RL, Vig KW. Orthodontics:
Current Principles and Techniques, 4 thed. St. Louis:
Elsevier; 2005.
10.Harzer W, Schröter A, Gedrange T, Muschter F.
Sensitivity of titanium brackets to the corrosive influence
of fluoride-containing toothpaste and tea. Angle Orthod
2001;71(4):318-23.
11.Kassab EJ, Gomes JP. Assessment of nickel titanium and
beta titanium corrosion resistance behavior in fluoride and
chloride environments. Angle Orthod 2013;83(5):864-9.
12.Dos Santos AA, Pithon MM, Carlo FG, Carlo HL,
de Lima BA, Dos Passos TA, et al. Effect of time and pH
on physical-chemical properties of orthodontic brackets
and wires. Angle Orthod2015;85:298-304.
13. Edwards IR, Spary DJ, Rock WP. The effect upon friction
of the degradation of orthodontic elastomeric modules.
Eur J Orthod 2012;34(5):618-24.
Different orthodontic materials react unusually in the oral
cavity to various dietary media. These products exhibit
several physical and structural changes when subjected to
variousdietary media. These changes could influence the
biomechanics directly or indirectly, so the material utilized for
the orthodontic treatment should have minimal changes in the
oral cavity during orthodontic treatment. The purpose of the
study was to identify the materials which are least vulnerable
to changes when exposed to different dietary media.
Conclusion
In this study,preformed bands showed superior quality with
less corrosion compared to customized welded bands in all
the dietary media. The various dietary media used in the study
had a significant effect on the molar bands, in which coffee had
a severe effect on corrosion due to its pH levels followed by
fluoride toothpaste. Hence, less consumption of coffee and
less usage of fluoride toothpaste in orthodontic patients was
recommended.
References
1. Proffit WR, Fields HW, Sarver DM. Contemporary
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2. Krishnan V, Kumar KJ. Weld characteristics of orthodontic
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3. Anusavice KJ. Philip’s Science of Dental Materials, 11th ed.
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4. House K, Sernetz F, Dymock D, Sandy JR, Ireland AJ.
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