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RAJIV GANDHI UNIVERSITY OF
HEALTH SCIENCES
MASTER OF DENTAL SURGERYORTHODONTICS AND
DENTOFACIAL ORTHOPAEDICS
2013
A.E.C.S. MAARUTI COLLEGE
OF
DENTAL SCIENCES
AND
RESEARCH CENTRE
NO. 108, HULIMAVU TANK BUND ROAD,
KAMMANAHALLI,
BANGALORE-560076.
RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES
KARNATAKA, BANGALORE
ANNEXURE -II
PROFORMA FOR REGISTRATION SUBJECT FOR DISSERTATION
1.
NAME OF THE
Dr. ANGEL MARY NAKKA
CANDIDATE
A.E.C.S. MAARUTI COLLEGE OF DENTAL
AND ADDRESS
SCIENCES AND RESEARCH CENTER,
NO 108, HULIMAVU TANK BUND ROAD,
HULIMAVU, BANGALORE-76
2.
NAME OF THE
A.E.C.S. MAARUTI COLLEGE OF DENTAL
INSTITUTION
SCIENCES AND RESEARCH CENTER,
BANGALORE-76
3.
COURSE OF STUDY AND
MASTER OF DENTAL SURGERY-
SUBJECT
ORTHODONTICS AND DENTOFACIAL
ORTHOPEDICS
4.
DATE OF ADMISSION
31.07.13
5.
TITLE OF THE TOPIC
ANALYSIS OF SURFACE
CHARACTERISTICS AND CORROSION
RESISTANCE OF ORTHODONTIC WIRES
IN ARTIFICIAL SALIVA - An In vitro Study
BRIEF RESUME OF THE INTENDED WORK:
6.1 NEED FOR THE STUDY:
Dental materials within the mouth interact continuously with
physiological fluids. Oral tissues are exposed to both chemical and
physical stimuli as well as metabolism of about 30 species of bacteria.
Yet for most part, oral tissues other than dental tissues remain healthy.
The pH of saliva varies from 5.2 to 7.8. Corrosion, the graded
degradation of materials by electrochemical attack, is of concern
particularly when orthodontic appliances are placed in the hostile
electrolytic environment provided by the human mouth.
Stainless steel has been mainly used material in orthodontics
since its introduction in 1932, with a wide range of applications in
both fixed and removable appliances. Nickel Titanium wires have
unique properties of shape memory and super elasticity and are
excellent for initial alignment. Beta Titanium offers a high desirable
combination of strength and springiness. It also has reasonably good
formability, which is lacking in Nitinol.
In this study , the dissimilarity in corrosion resistance and
surface characteristics of different orthodontic wires will be studied.
6.2 REVIEW OF LITERATURE
Robert D Barrett et al in 1993 conducted an in vitro study to
compare the corrosion rate of a standard orthodontic appliance consisting
of bands, brackets, and either stainless steel or nickel titanium arch wires.
The corrosion products analysed were nickel and chromium. Evaluation
was conducted with appliances immersed for 4 weeks in a prepared
artificial saliva medium at 370c. Ten identical sets appliances were used
on a maxillary arch with a full complement of teeth. Five sets were ligated
to nickel titanium arch wires. Nickel and chromium release was quantified
with the use of a flameless atomic absorption spectrophotometry. The
analysis of variance was used to determine if differences existed between
the nickel and chromium release according to arch wire type, as well as
with time(days 1,7,14,21,and 28).
The results indicate that (1) Orthodontic appliances release
measurable amounts of nickel and chromium when placed in artificial
saliva. 2) The nickel release reaches a maximum after approximately 1
week, then the rate of release diminishes with time. On the other hand,
chromium release increases during the first two weeks and levels off
during the subsequent two weeks. 3) The release rates of nickel or
chromium from stainless steel and Ni Ti arch wires are not significantly
different. 4) For both arch wires types, the release for nickel averaged 37
times greater than that for chromium. How much of these corrosive
products are actually absorbed by patients still needs to be determined 1.
Her Kim et al in 1999 conducted a study on corrosion of stainless
steel, nickel titanium, and titanium orthodontic wires. The purpose of this
study was to determine if there is a significant difference in corrosive
potential of stainless steel, nickel titanium, nitride coated Ni Ti, epoxy
coated nickel titanium and titanium orthodontic wires. Atleast two
specimens of each wire were subjected to potentiostatic anodic solution in
0.95NaCl solution with neutral pH at room temperature. Using a wenking
MP 95 potentiostat and electrochemical corrosion cell, the breakdown
potential of each wire was determined. Photography were taken of wire
specimens using scanning electron microscope, and surface changes were
quantatively evaluated. The breakdown potentials of stainless steel, two
nickel titanium wires, nitride coated nickel titanium, epoxy coated nickel
titanium and titanium were 400mv,300mv,750mv,300mv,1800mv and
>2000mv respectively. SEM (scanning electron microscope) photographs
revealed that some nickel titanium and stainless steel wire were
susceptible to pitting and localised corrosion.
The results indicate that corrosion occured readily in stainless steel.
Variability in breakdown potential of Ni-Ti alloy wires differed across
Vendor wires. The nitride coating did not effect the corrosion of the alloy,
but epoxy coating decreased corrosion .Titanium wires and epoxy coated
Ni-Ti wires exhibited the least corrosive potential2.
Her Hsiung Huang in 2005 conducted an in vitro study
to investigate variation in corrosion resistance of commercial Ni Ti dental
orthodontic wires from different manufactures using the fast electro
chemical technique. The linear polarization test was used to evaluate the
corrosion resistance, in terms of polarization resistance (Rp), of as
received commericial Ni-Ti wires in acidic saliva at 37oc. One way
analysis of variance was used to analyse Rp with the wire manufacturer as
the variable factor. Atomic force microscope was used to analyse three
dimensional surface topography and roughness (Ra). Electron
spectroscopy for chemical analysis was used to identify the chemical
structure of passive film on the Ni Ti wires.
The results showed that Ni-Ti wires from different manufactures had a
statistically significant difference in R p(P< .001). Different surface
topography was present among the tested Ni Ti wires, whereas the same
surface chemical structure was observed for the tested Ni Ti wires. The
surface roughness of the commercial Ni Ti wires with similar surface
chemical structure does not correspond with the difference in corrosion
resistance3.
Mau-Chin Lin et al in 2006 conducted a study to investigate
the variation in corrosion resistance of commercial stainless steel brackets
with different brands and types for the same application, using the
electrochemical technique. The linear polarization test was used to
evaluate the corrosion resistance, in terms of polarization resistance (Rp)
of as-received commercial SS brackets in acidic artificial saliva. A twoway analysis of variance was used to analyse the Rp with the factors of
band and type. A scanning electron microscope and an atomic force
microscope were used to analyse the surface morphology and roughness,
respectively. The x-ray photoelectron spectroscopy was used to identify
the chemical composition of the passive film on SS brackets.
The results showed that different brands of SS brackets had a
statistically significant difference in Rp (P<.0001), whereas there was no
statistical difference between the bracket type (“Roth” and standard)
(P=.27). Different surface topography, including surface roughness and
defect, was present among the tested SS brackets. The same passive film
structure, containing Cr2O3/Fe2O3 with small amounts of NiO, was
observed on all SS brackets. The surface topography of the commercial
SS brackets with identical surface passive film structure did not
correspond with the difference in corrosion resistance6.
Tzu-Hsin Lee et al in 2010 conducted a study to test the
hypothesis that different nickel- titanium arch wires may have dissimilar
corrosion resistance in a fluoride containing oral environment. In this
study they have done linear polarization test and fast electrochemical
technique to evaluate the corrosion resistance, in terms of polarization
resistance (Rp), of four different commercial Ni-Ti wires in artificial
saliva (pH 6.5) with various NaF concentrations (0%,0.01%,0.1%,0.25%
and 0.5%). Two-way analysis of variance was used to analyse Rp with the
factors of arch wire manufacturer and NaF concentration. Surface
characterizations of arch wires were analyzed using scanning electron
microscopy,
atomic
force
microscopy
and
x-ray
photoelectron
spectroscopy.
The results showed that both arch wire manufacturer and NaF
concentration had a significant influence on Rp of Ni Ti wires. Different
surface topography was present on the test Ni-Ti wires that contained the
similar surface chemical structure. The surface topography did not
correspond to the difference in corrosion resistance of the Ni-Ti wires.
Increasing the NaF concentration in artificial saliva resulted in decrease in
Rp, or corrosion resistance in 0.5% NaF containing environment4.
Manu Krishnan et al in 2013conducted an in vitro study to compare the
corrosion behavior of commercially available surface modified nickel
titanium arch wires with respect to a conventional Ni-Ti and to evaluate
its association with surface characteristics .Five types of surface modified
arch wires and a conventional Ni-Ti arch wire all from different
manufacturers, were evaluated for their corrosion resistance from
breakdown potential in an anodic polarization scan in ringers solution
.Surface characteristics were determined from scanning electron
microscope ,atomic force microscope and energy dispersive analysis.
One-way analysis of variance and post hoc Duncan’s multiple range tests
were used to evaluate statistical significance.
According to the results surface modified Ni-Ti wires showed
significant improvement in corrosion resistance and reduction in surface
roughness values5.
6.3 AIM OF THE STUDY;
To evaluate surface characteristics and corrosion resistance of four
different orthodontic arch wires in artificial saliva.
6.4 OBJECTIVES OF THE STUDY;
1) To do surface analysis of orthodontic wires using scanning
electron
microscope
(SEM)
and
Atomic
force
microscope(AFM).
2) To evaluate corrosion resistance of orthodontic wires using
salt spray testing chamber.
7 MATERIALS AND METHOD
7.1 SOURCE OF DATA
 Stainless steel wire(SS )
 Nickel – Titanium(Ni-Ti)
 Beta – Titanium(β-Ti)
 Titanium molybdenum alloy(TMA)
 Scanning electron microscope-used to observe surface
morphologies of orthodontic wires.
 Atomic force microscope-to evaluate three dimensional
surface roughness.
 Salt spray testing chamber-used to evaluate corrosion
resistance.
 X-ray
photoelectron
spectroscopy-outermost
chemical analysis of orthodontic wires.
surface
7.1. METHOD OF COLLECTION OF DATA / METHODOLOGY
40 arch wires will be tested in this study. The samples will be divided
into 4 groups.
 Group I
It consists of 5 upper and 5 lower stainless steel wires of 0.016”
with ovoid arch form immersed in artificial saliva.
 Group II
It consists of 5 upper and 5 lower Ni-Ti wires of 0.016” with
ovoid arch form immersed in artificial saliva.
 Group III
It consists of 5 upper and 5 lower Beta titanium wires of 0.016”
with ovoid arch form immersed in artificial saliva.
 Group IV
It consists of 5 upper and 5 lower titanium-molybdenum wires of
0.016” with ovoid arch form immersed in artificial saliva.
1. A scanning electron microscope (SEM), (S 3000N, Hitachi,
Tokyo, Japan) will be used to observe surface morphologies of
orthodontic wires.
2. The scanning electron microscope (SME) examination will be
performed at a magnification of 1200x and with area size about
125x 80µm.
3. A three dimensional surface roughness (Ra) will be evaluated
using atomic force microscope (AFM) with the detection limit
close to atomic size.
4. The atomic force microscope (AFM) analysis carried with the
area size of 20 x 20 µm, and two areas were examined for each
type of wire.
5. The outer most surface chemical analysis of the passive film on
the surface of the orthodontic wires assessed from x-ray photo
electron spectroscopy(XPS).
 For XPS analysis two spots analyzed for each type of
wire.
6. A salt chamber used to perform linear polarization test for
corrosion resistance.
7. Appropriate statistical analysis tests will be carried out to
evaluate the significance of different parameters with regard to
surface analysis and corrosion resistance.
7.2 INCLUSION CRITERIA
- Not applicable.
7.3 EXCLUSION CRITERIA
- Not applicable.
7.4 DOES THE STUDY REQUIRE ANY INVESTIGATION /
INTERVENTION TO BE CONDUCTED ON PATIENT OR
OTHER HUMAN OR ANIMAL?
- No.
7.5 HAS ETHICAL CLEARANCE BEEN OBTAINED FROM
THE INSTITUTION?
-Yes
8. LIST OF REFERENCES
8.1 JOURNAL REFERENCES:1) 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; 8-14).
2) Kim H, Johnson JW> Corrosion of stainless steel, nickel titanium,coated
nickel titanium, and titanium orthodontic wires. (Angle Orthod. 1999;69;3944).
3) Huang HH. Variation in corrosion resistance if Ni Ti wires from different
manufacturers. (Angle Orthod. 2005;75,75;569-573).
4) Tzu-Hsin Lee; Ta- Ko Huang; Shu-Yuan Lin; Li-Kia Chen; Ming-Yung
Chou; Her Hsuing Huang. (Angle Orthod 2010;80;3;547-553).
5) Manu Krishnan; Saraswathy Seema; A Vinod Kumar; N Parvatha Varthini;
Kalathil Sukumaran; Vasant R Pawar; Vimal Arora.(Angle
Orthod.0000;00:000-000)
6) Mau-Chin Lin;Sheng-Cheih Lin;Tzu-Hsin Lee;Her Hsiung Huang(Angle
Orthod 2006;76:322-329)
9. SIGNATURE OF CANDIDATE
This study will help us in choosing more
10. REMARKS OF GUIDE
biocompatible wires.
11.1 NAME AND DESIGNATION
DR.C.S. RAMACHANDRA
OF GUIDE
PROFESSOR
DEPARTMENT OF ORTHODONTICS
AECS MAARUTI COLLEGE OF
DENTAL SCIENCES AND RESEARCH
CENTRE, BANGALORE.
11.2 SIGNATURE OF GUIDE
11.3 NAME AND DESIGNATION
Dr. N. SHAM BHAT
OF
PROFFESOR
CO-GUIDE
DEPARTMENT OF ORTHODONTICS
AECS MAARUTI COLLEGE OF
DENTAL SCIENCES AND RESEARCH
CENTRE, BANGALORE.
11.4 SIGNATURE OF CO-GUIDE
11.5 HEAD OF DEPARTMENT
DR . C.S. RAMACHANDRA
PROFESSOR AND HEAD
DEPARTMENT OF ORTHODONTICS
AECS MAARUTI COLLEGE OF
DENTAL SCIENCES AND RESEARCH
CENTRE, BANGALORE.
11.6 SIGNATURE
12.1 REMARK OF THE
CHAIRMAN / PRINCIPAL
12.2 SIGNATURE
Helps in better care of the patients.