|Year : 2021 | Volume
| Issue : 1 | Page : 71-75
Comparison of friction coefficient and surface roughness on stainless steel nickel titanium, and nickel-titanium copper wires to standard edgewise brackets: An experimental in vitro study
Yuniar Elsa Dwinuria, Dimas Iman Nugroho, Jusuf Sjamsudin, Ida Bagus Narmada
Department of Orthodontic, Faculty of Dental Medicine, Universitas Airlangga, Surabaya, Indonesia
|Date of Submission||13-Feb-2020|
|Date of Decision||27-Apr-2020|
|Date of Acceptance||20-Aug-2020|
|Date of Web Publication||28-Jan-2021|
Prof. Dr. Ida Bagus Narmada
DDS, Department of Orthodontic, Faculty of Dental Medicine, Universitas Airlangga, Jalan Mayjen Prof. Dr. Moestopo 47 Surabaya.
Source of Support: None, Conflict of Interest: None
Aim: The aim of this study was to investigate the friction and the difference in the roughness of the wire on the standard edgewise bracket. Materials and Methods: This was an experimental laboratory study with a posttest only control group design. The number of samples in this research was 21. The samples were divided into three groups (n = 7) consisting of 0.016′′ x 0.022′′ stainless steel archwire (SS group), 0.016′′ x 0.022′′ nickel-titanium archwire (NiTi group), and 0.016′′ x 0.022′′ nickel-titanium copper archwire (NiTiCu group). The bracket used in each group is standard edgewise slot 0.018. Friction coefficient test was conducted by creating an examination tool from acrylic to fixate the bracket with a size of 2cm x 5cm. The bracket was then attached using glue (polyvinyl acetate) and the archwire was fixated to the bracket using power O. After the friction test, three samples were taken from each group to be tested morphology and topography of each type using scanning electron microscope (SEM). Statistical analysis used in this research is using one-way analysis of variance (ANOVA) to find out the comparison of variables and Tukey’s honest significant difference (HSD) to find out the comparison between three groups (P < 0.05). Results: The lowest friction coefficient was found in SS archwire, which consecutively followed by NiTiCu and NiTi. The smoothest archwire surface observed by SEM was SS, followed by NiTiCu and NiTi. Conclusion: SS wire has the smoothest archwire surface and the lowest frictional force, so it is well used for the teeth movement in space closing on edgewise bracket.
Keywords: Dental Medicine, Friction Coefficient, Nickel Titanium, Nickel-Titanium Copper, Stainless Steel
|How to cite this article:|
Dwinuria YE, Nugroho DI, Sjamsudin J, Narmada IB. Comparison of friction coefficient and surface roughness on stainless steel nickel titanium, and nickel-titanium copper wires to standard edgewise brackets: An experimental in vitro study. J Int Oral Health 2021;13:71-5
|How to cite this URL:|
Dwinuria YE, Nugroho DI, Sjamsudin J, Narmada IB. Comparison of friction coefficient and surface roughness on stainless steel nickel titanium, and nickel-titanium copper wires to standard edgewise brackets: An experimental in vitro study. J Int Oral Health [serial online] 2021 [cited 2021 Mar 5];13:71-5. Available from: https://www.jioh.org/text.asp?2021/13/1/71/308369
| Introduction|| |
Orthodontic treatment is a discipline in dentistry focusing in the functional and facial aesthetic enhancement. The uses of aesthetic wires have increased in orthodontic treatment because of the increased number of patients who require good aesthetic as a prerequisite of their treatment. A massive development has occurred in the orthodontic field for several decades. Numerous inventions and productions of recent high-technology materials create various orthodontic appliances with different properties and characteristics, resulting in specific advantages and disadvantages on each orthodontic appliance depending on the clinical purpose. Orthodontic bracket and archwire are the important part of orthodontic treatment, as orthodontic bracket can conduct the force from wire to the structure of tooth and periodontal complex, which stimulates the tooth movement.
Archwires made from metal such as stainless steel (SS), nickel titanium (NiTi), and nickel-titanium copper (NiTiCu) are commonly used. In orthodontic treatment, SS wire type 18%–8% (18% chrome and 8% nickel) is usually used, whereas NiTi metal often contains an equal atomic presentation of nickel and titanium, with 51.3%–57% nickel and 43%–48.7% titanium. NiTiCu archwire has 5.5%–6.9% of copper metal.
The surface topography of the orthodontic archwires is an essential property, having the ability to influence the mechanical characteristics, the appearance, corrosion, and their biocompatibility. The result of the surface structure depends on several factors including the alloy used in manufacturing, the complex manufacturing process, and the finishing treatment of the surface.
Friction is a force, which opposes the motion of a surface in relation to other force and works in the opposite direction to the desired movement. Frictional force happened during sliding mechanics is a challenge to orthodontist as high frictional force can decrease the treatment effectivity by decreasing the tooth movement effectivity and inflict a problem in orthodontic anchorage. During sliding movements of teeth, the wire edges contact the bracket angles and a frictional force will develop that compete with normal tooth movements and decrease the magnitude of applied orthodontic forces. One of the main focus in enhancing tooth movement is by reducing frictional force between archwire and bracket.
Sliding mechanics is commonly used in cases of tooth extractions, problems of discrepancy between the dental arches, and when there is severe crowding in the dental arch. The main disadvantage of this mechanics is the frictional force generated between the bracket and archwire during orthodontic movement. Various factors may influence the frictional resistance, such as the composition of the brackets, archwires and ties, condition of the surface of arches, bracket slots, wire cross-section, torque at the interface between the archwire and bracket, type of bracket, saliva, and influence of oral functions., Therefore, attention must be paid to the choice of materials in each treatment plan.
The aim of this study was to investigate the frictional coefficient and surface roughness difference in SS, NiTi, and NiTiCu orthodontic archwire in standard edgewise bracket.
| Materials and Methods|| |
Setting and design
This was an experimental laboratory study with posttest only control group design. This study was conducted at the Research Center of Faculty of Dental Medicine, Universitas Airlangga and Material and Metalurgy, Industrial Technic Faculty, Institute of Technology Sepuluh November Surabaya (ITS) from August 2017 to February 2018. The sample was selected blind randomly and the sample size was determined by using the Lameshow’s sample size formula.
The sample was divided into three groups (n = 7) consisting of 0.016′′ x 0.022′′ SS archwire (American Orthodontic, Washington) (SS group), 0.016′′ x 0.022′′ NiTi archwire (American Orthodontic) (NiTi group), and 0.016′′ x 0.022′′ NiTiCu archwire (American Orthodontic) (NiTiCu group). The bracket used in each group is standard edgewise slot 0.018 (American Orthodontic).
Friction coefficient test was conducted by creating an examination tool from acrylic to fixate the bracket with a size of 2cm x 5cm. The bracket was then attached using glue (polyvinyl acetate) and the archwire was fixated to the bracket using power O (American Orthodontic). The calculation of frictional force in each sample was done in dry condition by using an autograph machine (Shimadzu, Kyoto, Japan).
Morphology and topography examination was done by using scanning electron microscope (SEM) (Jeol, Tokyo, Japan). In three samples on each group, after the friction coefficient test was done.
The data recorded were presented in mean ± standard deviation (SD) and analyzed with the Statistical Package for the Social Sciences (SPSS) software program, version 16.0 (IBM Corporation, Chicago, IL, USA) using one-way analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) to observe the difference of friction coefficient on each group (P < 0.05).
| Results|| |
This study was conducted using SS, NiTi, and NiTiCu archwire with the size of 0.016′′ x 0.022′′ as the samples. [Table 1] presents the mean of friction coefficient on each group, which showed that NiTi archwire has a significantly higher friction coefficient compared to NiTiCu and SS archwires, with the lowest coefficient found in SS archwires (P = 0.000) [Figure 1]. [Table 2] shows that there is a significant difference between three groups.
|Table 2: Tukey HSD test results on the frictional force of the SS, NiTi, and NiTiCu|
Click here to view
The result of the surface analysis presented in [Figure 2]A shows a smooth surface of SS archwire, which was received before treatment. A different result was observed in the surface of SS archwire after the treatment with a slight horizontal groove and scratches was found, as presented in [Figure 2]B.
A smooth surface with little striations was found in NiTi archwire before treatment [Figure 3]A, whereas after the treatment [Figure 3]B an alteration on its topography could be seen through the appearance of horizontal grooves and scratches, which was more abrasive compared to those found in SS archwire.
From [Figure 4]A, irregular cavities are found in the surface of NiTiCu which was received before the treatment, whereas [Figure 4]B shows topographical changes in NiTiCu surface after the treatment in the form of an irregular, wavy surface with faint scratches compared to before the treatment.
| Discussion|| |
The use of rectangular archwire in this study was to produce static frictional force during the space closing process or sliding mechanics. This sliding mechanic movement will produce friction between bracket and the archwire. The lower the frictional force, the better the result as smoother wire movement is produced. Friction between bracket and archwire could reduce the force up to 50%; thus, a low friction coefficient of archwire and bracket is desired. The result of this study showed that SS archwire has the lowest frictional force compared to NiTi and NiTiCu. This was in accordance with the study by Alfonso which stated that SS archwire has a lower frictional force than NiTi. The low frictional force of SS was due to it has the smoothest surface compared to the other titanium alloys. A study conducted by Kumar et al. also showed that SS archwire had a smoother surface compared to titanium metal alloy (TMA) at ×1000 magnification; SS archwire has the smoothest surface compared to NiTi and NiTiCu archwires.
NiTiCu archwire has a higher friction coefficient compared to SS archwire but lower than NiTi archwire. The addition of copper (Cu) in NiTi results in better stability compared to NiTi. NiTi archwire has a limitation as the force applied by NiTi archwire to the bracket is relatively lower, which leads to longer treatment duration. Composition addition can affect the shape memory of the archwire. The addition of Cu can improve the shape memory property of an alloy and minimalize the limitation of NiTi archwire. In addition, the addition of Cu in NiTi archwire can reduce the loading stress and increase the unloading stress, which increases the tooth movement effectivity during orthodontic treatment. The SEM observation of NiTiCu surface showed an irregular, wavy surface with faint to no visible scratches.
In contrast, NiTi archwire has the highest friction coefficient compared to SS and NiTiCu. This result was supported by Choi et al., which confirmed that NiTi archwire has the highest frictional force compared to SS archwire due to its high spring back characteristic. NiTi archwire has the ability to return to its original shape in higher temperatures. This material showed two specific characteristics: shape memory alloy (SMA) and superelastic effect (SE). Both effects were manifested by martensitic phase transformation caused by temperature changes (shape memory) or SE resulting in microstructure changes. The austenitic phase is stable in high temperature and low force, whereas the martensitic phase is stable in low temperature and high force. Both phases have a different crystal structure. The austenitic phase has a body-centered cubic crystal structure, whereas the martensitic phase has a crystal monoclinic structure. SMA enables the alloy to return to its original shape when heated above austenitic finished. SMA attains its original shape by transforming to the austenitic phase. In contrast to SS archwire, NiTi archwire has a large amount of evenly distributed pores with a rough surface. There was a correlation between the surface roughness and frictional force of archwire and bracket. In this study, NiTi archwire has higher surface roughness than NiTiCu archwire, whereas SS archwire was the lowest. This study was consistent with the previous study conducted with a similar result.
One of the main focuses in enhancing tooth movement is by reducing frictional force between archwire and bracket. In this research, SS had the smoothest surface roughness so it had the lowest friction coefficient compare to NiTi and NiTiCu. The lowest friction coefficient was found in SS archwire, which consecutively followed by NiTiCu and NiTi. The smoothest archwire surface observed by SEM was SS, followed by NiTiCu and NiTi.
In the future, NiTiCu could be an alternative that is used in the sliding mechanism because had the flexibility and lower coefficient than usual NiTi wire. Frictional force happened during sliding mechanics is a challenge to orthodontist as high frictional force can decrease the treatment effectivity by decreasing the tooth movement effectivity and inflict a problem in orthodontic anchorage. During sliding movements of teeth, the wire edges contact the bracket angles and a frictional force will develop that compete with normal tooth movements and decrease the magnitude of applied orthodontic forces.,
The limitation of this research is that each wire should be tested in each stage of orthodontic treatment. Choosing the right material is necessary to increase treatment effectivity and shorten treatment times.
| Conclusion|| |
The lowest friction coefficient was found in SS archwire, which consecutively followed by NiTiCu and NiTi. The smoothest archwire surface observed by SEM was SS, followed by NiTiCu and NiTi. SS archwire is suitable to be used during space closing step when a proper teeth alignment has been achieved due to its low frictional force. This study only in vitro, in the future, clinical trial about the use of each wire should be tested in each stage of orthodontic treatment. Choosing the right material is necessary to increase treatment effectivity and shorten treatment times.
The author would like to thank the Institute of Technology Sepuluh November (ITS) and Faculty of Dental Medicine, Universitas Airlangga Surabaya for supporting our study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
YED, DIN, JS, IBN: study conception, data collection, data acquisition and analysis, data interpretation, manuscript writing, all the authors approved the final version of the manuscript for publication
Ethical policy and institutional review board statement
Nil (in vitro study).
Patient declaration of consent
Nil (in vitro study).
Data availability statement
Available on request from [email protected]
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]