Tensile strength differences between nickel-titanium and titanium molybdenum alloy orthodontic archwire after immersion in detergent toothpaste

Hilda Fitria Lubis; Calvint

doi:10.4103/SDJ.SDJ_29_20

ORIGINAL ARTICLE

Year : 2020 | Volume : 4 | Issue : 3 | Page : 110-114

Tensile strength differences between nickel-titanium and titanium molybdenum alloy orthodontic archwire after immersion in detergent toothpaste

Hilda Fitria Lubis, Calvint
Department of Orthodontics, Faculty of Dentistry, University of Sumatera Utara, Indonesia

Date of Submission	05-Jul-2020
Date of Decision	13-Aug-2020
Date of Acceptance	17-Sep-2020
Date of Web Publication	17-Oct-2020

Correspondence Address:
Hilda Fitria Lubis
Kompleks Tasbi 2 Blok 4 No 85, Medan, North Sumatera
Indonesia

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/SDJ.SDJ_29_20

Abstract

Background: Titanium-based alloys, such as nickel-titanium (NiTi) and titanium molybdenum alloy (TMA), have gained immense popularity in the last decades. Some toothpaste ingredients can negatively affect orthodontic procedures. Objective: The objective of this study was to examine the differences in tensile strength between NiTi and TMA orthodontic wires after immersion in detergent toothpaste. Methods: Six treatment groups were established, with NiTi and TMA wires immersed in 25 g detergent toothpaste for 4, 8, and 12 h. Tensile strength measurements were carried out using a Tensilon RTF-1350 universal testing machine. Results: The P values of the NiTi and TMA wires were as follows: 0.000 after 4 h, 0.000 after 8 h, and 0.002 after 12 h. These results showed that there were significant differences between the tensile strength of NiTi and TMA orthodontic wires after immersion in detergent toothpaste for increasing periods of time. Conclusion: The tensile strength of NiTi wire was greater than the tensile strength of TMA archwire. However, detergent toothpaste did not have a significant effect on change in tensile strength of NiTi and TMA wire.

Keywords: Detergent toothpaste, nickel-titanium, tensile strength, titanium molybdenum alloy, wire

How to cite this article:
Lubis HF, Calvint. Tensile strength differences between nickel-titanium and titanium molybdenum alloy orthodontic archwire after immersion in detergent toothpaste. Sci Dent J 2020;4:110-4

How to cite this URL:
Lubis HF, Calvint. Tensile strength differences between nickel-titanium and titanium molybdenum alloy orthodontic archwire after immersion in detergent toothpaste. Sci Dent J [serial online] 2020 [cited 2020 Oct 22];4:110-4. Available from: https://www.scidentj.com/text.asp?2020/4/3/110/298440

Background

The aim of orthodontic treatment is to improve dental aesthetics, which can improve a person's quality of life by achieving ideal dental occlusion and dental relationships.^[1],[2],[3] Orthodontic treatment can be performed with removable, fixed, or combined appliances.^[3] Fixed orthodontic treatment has progressed quite significantly, especially in the orthodontic bracket system.^[4] One of the major considerations in fixed orthodontic therapy is the choice of wire.^[5] Titanium-based alloys have gained immense popularity in the last decades.^[6] Nickel-titanium (NiTi) with a composition of 55% nickel and 45% titanium was developed by Buechler in 1962. NiTi wires have excellent spring back with low load-to-deflection ratio and provide a desirable force level and good control of force magnitude.^[7],[8] In 1979, Goldberg and Burstone introduced a beta-titanium (β-Ti) alloy into orthodontic applications for the first time. β-Ti alloy is commercially available as titanium molybdenum alloy (TMA).^[9] TMA has a composition of 77.8% titanium, 11.3% molybdenum, 6.6% zirconia, and 4.3% zinc. It has a combination of good strength and flexibility.^[10] TMA is one of the alloys that is used widely in orthodontic treatment, but it is less popular than NiTi.

Orthodontic treatment patients are recommended to pay attention to oral hygiene by prescribing toothpastes to improve oral health. However, toothpastes can damage orthodontic wires in the oral environment.^[11] Toothpastes contain many important ingredients, such as abrasive ingredients, scouring agents, humectants, fluorides, tooth whiteners, water, flavoring ingredients, sweeteners, colloids, and detergents.^[12] Some of these ingredients can induce alterations when in proximity to metal, and these changes on the surface properties of orthodontic brackets may negatively affect orthodontic procedures.^[13]

Tensile strength can be defined as the maximum force a material can bear before breakage and rupture.^[14] The greater the tensile strength of the archwires, the better the mechanical properties of the archwires.^[15] Along with the release of elements from metals or alloys, corrosion of orthodontic wires can lead to roughening of the surface and weakening of the appliances, which can severely affect the ultimate strength of the material and lead to mechanical failure or even fracture of the orthodontic materials.^[9]

A study conducted by Brindha et al. evaluating tensile strength and surface topography of orthodontic wire after infection control procedures found that sterilization/disinfection procedures have an effect of increasing the tensile strength of stainless steel orthodontic wire and TMA.^[16] A study by Singh et al. found that the heat sterilization and cold with dry heat method, autoclave, ethylene oxide, and glutaraldehyde did not have a significant effect on orthodontic stainless steel wire but had a significant effect on NiTi and TMA orthodontic wires.^[17]

This study used NiTi and TMA orthodontic archwires immersed in detergent toothpaste for 4, 8, and 12 h. The duration used was obtained from the calculation of the average time needed to brush teeth, which is 2 min, with brushing frequency twice a day, then calculated into 2, 4, and 6 month periods. The purpose of this study was to determine the differences in tensile strength between NiTi and TMA orthodontic wires after immersion in detergent toothpaste.

Materials and Methods

This experimental laboratory research study used a comparative design. The materials used were HPAI nonfluoride detergent toothpaste (Miswak Utama, Bangil, Indonesia) containing sodium lauroyl sarcosinate, 24 pieces of NiTi orthodontic archwires (American Orthodontics, Sheboygan, USA), and 24 pieces of TMA orthodontic archwires (American Orthodontics, Sheboygan, USA) with 0.016 × 0.022 inches diameter and 15 cm length. The samples were divided into six treatment groups consisting of eight samples for each treatment group:

Group A: NiTi archwires immersed in 25 g detergent toothpaste and stored in an incubator at 37°C for 4 h
Group B: NiTi archwires immersed in 25 g detergent toothpaste and stored in an incubator at 37°C for 8 h
Group C: NiTi archwires immersed in 25 g detergent toothpaste and stored in an incubator at 37°C for 12 h
Group D: TMA archwires immersed in 25 g detergent toothpaste and stored in an incubator at 37°C for 4 h
Group E: TMA archwires immersed in 25 g detergent toothpaste and stored in an incubator at 37°C for 8 h
Group F: TMA archwires immersed in 25 g detergent toothpaste and stored in an incubator at 37°C for 12 h

After being immersed and dried, each treatment group was tested to evaluate tensile strength using a universal testing machine (Tensilon RTF-1350; AND, Tokyo, Japan) operated with a 0.5 mm/s crosshead speed.

Statistical analysis

The data were analyzed using SPSS version 20 (IBM, New York, USA). The normality test was performed using the Shapiro–Wilk test. The Mann–Whitney U test and t-test bivariate analysis test were carried out to evaluate the tensile strength differences between the NiTi and TMA orthodontic archwires after immersion in detergent toothpaste. One-way ANOVA multivariate analysis and the Kruskal–Wallis test were used to evaluate the tensile strength mean value differences of the NiTi and TMA orthodontic archwires after being immersed in detergent toothpaste for 4, 8, and 12 h.

Results

The average tensile strength of NiTi wire was greater than that of TMA wire. In the NiTi group, the highest tensile strength was found at immersion for 4 h, while the lowest tensile strength was found at immersion for 12 h. In the TMA group, the highest tensile strength was found at immersion for 4 h, while the lowest tensile strength was found at immersion for 12 h. The average tensile strength of each group is presented in [Table 1].

Table 1: Tensile strength mean values and standard deviations of nickel-titanium and titanium molybdenum alloy orthodontic archwires for each group

Click here to view

The results of the Shapiro-Wilk normality test showed that the data distribution was normally distributed for the tensile strength measurements of the NiTi orthodontic wire in group A and group B; however, the data in group C were not normally distributed (P = 0.024). The data distribution was normally distributed for the tensile strength measurements of TMA orthodontic wire in all groups. Therefore, the Kruskal-Wallis test was used to evaluate the NiTi groups, while the TMA groups were evaluated using the one-way ANOVA test [Table 2].

Table 2: Independent t-test results of the tensile strength of nickel-titanium and titanium molybdenum alloy orthodontic wire after immersion in detergent toothpaste for 4, 8, and 12 h

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The significance test results for NiTi and TMA orthodontic archwire indicate that there was no significant difference between the tensile strength of NiTi orthodontic wire after immersion in detergent toothpaste for 4, 8, and 12 h (P = 0.636) using the Kruskal-Wallis test. Similarly, there was no significant difference between the tensile strength of TMA orthodontic wire after immersion in detergent toothpaste for 4, 8, and 12 h (P = 0.538) using the one-way ANOVA test.

The tensile strength differences between NiTi and TMA orthodontic archwires were statistically significant. The results of this study indicate that the tensile strength of NiTi orthodontic wires was greater than that of TMA orthodontic wires after immersion in detergent toothpaste for 4, 8, and 12 h. Based on these tests, it can be concluded that there is a significant difference between the tensile strengths of NiTi and TMA orthodontic wires after immersion in detergent toothpaste.

Discussion

Orthodontic wire is one of the orthodontic appliances that is designed to apply force to mispositioned teeth and move them into the ideal arch with proper occlusion.^[8] Orthodontic wires used in the oral cavity for a long period of time are exposed to various conditions, such as saliva, temperature, and acidic environment, which can cause corrosion and the release of metal ions in the oral cavity.^[9],[18] Along with the release of elements from metals or alloys, corrosion of orthodontic wires can lead to roughening of the surface, weakening of the appliances, and fracture of the orthodontic materials.^[9]

[Table 1] shows a decrease in tensile strength of NiTi and TMA orthodontic archwires after immersion in detergent toothpaste for 4, 8, and 12 h, but this decrease was not statistically significant. The results of this study are consistent with research by Brandao et al., which found no significant differences in the release of titanium, chromium, nickel, and iron ions in orthodontic brackets immersed in various types of toothpaste.^[19]

The tensile strength of orthodontic archwires determines the maximum force that can be distributed by the archwires when used as springs to move teeth.^[15] Changes in tensile strength can be caused by corrosion.^[9] The protective oxide layer is susceptible to both mechanical and chemical disruption, and it can slowly dissolve as the metal is exposed to oxygen from the surrounding medium. Acidic conditions and fluoride-containing products can contribute to these processes.^[9],[20]

Daily use of toothpaste can cause corrosion of orthodontic wires.^[11] Some of the ingredients in toothpaste can cause changes in metal.^[13] Inorganic components in toothpaste, such as phosphate, sodium, and potassium, act as an electrolyte medium, which can trigger electrochemical reactions. Electrochemical reactions are reactions that occur at the anode (oxidation occurs) and cathode (reduction occurs), in which metal ions act as anodes and H⁺ ions from the electrolyte medium act as cathodes.^[20],[21]

Nonfluoride detergent toothpaste was used in this study because it contains certain ingredients, such as sodium lauroyl sarcosinate, sodium saccharin, and sodium benzoate, which can lead to the release of ions due to the presence of sodium ions, which triggers electrochemical reactions. Calcium carbonate (CaCO₃) in detergent toothpaste is also known to cause changes in the mechanical properties of materials. According to Wasono et al., sodium chloride (NaCl), calcium sulfate (CaSO₄), calcium carbonate (CaCO₃), and dissolved oxygen can affect the corrosion process in materials. Chloride, sulfate, and carbonate ions are capable of attacking metal surfaces and thereby causing metal corrosion to occur.^[21]

In NiTi and TMA orthodontic wires, the loss of metal ion stabilization begins with the breakdown of the passive titanium oxide layer (TiO₂) as the initial wire defense barrier. After the dissolution of the passive titanium layer as a protector, the nickel ions in NiTi orthodontic wires are then oxidized and released.^[22] The ionic constituents of TMA orthodontic wires, such as zirconia and zinc, that serve to increase the strength of the wire are also released.^[10] Release of the metal constituent ions causes a decrease in NiTi and TMA orthodontic archwire tensile strength.

Changes in the tensile strength of NiTi and TMA orthodontic archwires after immersion in detergent toothpaste for 4, 8, and 12 h demonstrated that the longer the wire was exposed to detergent toothpaste, the lower the value of the tensile strength. However, the difference in tensile strength was not statistically significant. The non-fluoride detergent toothpaste used in this study had little effect on the mechanical properties of NiTi and TMA orthodontic wires, specifically tensile strength.

The results of this study present a significant difference in tensile strength between NiTi and TMA orthodontic archwires after immersion in detergent toothpaste. This study also demonstrated that the tensile strength of NiTi was greater than that of TMA. The difference in tensile strength occurs because NiTi has better flexibility compared to TMA. NiTi has a higher elastic limit value and lower modulus of elasticity compared to TMA.^[23] Another factor that influences the difference in orthodontic archwire tensile strength between NiTi and TMA is the presence of nickel ions in NiTi, which are not found in TMA. Nickel ions are useful in increasing hardness, resisting heat, and providing flexibility to the wire.^[2] Several further studies using a scanning electron microscope are needed to see the effect of detergent toothpaste on the surface structure of NiTi and TMA orthodontic wires.

Conclusion

There was a significant difference between the tensile strength of NiTi and TMA orthodontic wire after immersion in detergent toothpaste. The tensile strength of NiTi archwire was greater than the tensile strength of TMA archwire. However, detergent toothpaste did not have a significant effect on changes in the tensile strength of NiTi and TMA orthodontic archwires.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Graber L, Vanarsdall R, Vig KW, Huang GJ. Orthodontics: Current principles and techniques. 6^th ed.. Philadelphia: Mosby; 2017.
2.	Kharbanda OP. Orthodontics diagnosis and management of malocclusion and dentofacial deformities. 1^st ed. Chennai: Elsevier; 2009.
3.	Setyowati P, Ardhana W. Perawatan maloklusi kelas III dengan hubungan skeletal kelas III disertai makroglosia menggunakan alat ortodontik cekat teknik Begg. Dent J (Maj Ked Gigi) 2013;20:184-91.
4.	Andryani S, Nazruddin, Bahirrah S. The effect of different bracket types on orthodontic treatment evaluated with the objective grading system. Sci Dent J 2019;9:9-16.
5.	Hepdarcan SS, Yilmaz RB, Nalbantgil D. Which orthodontic wire and working sequence should be preferred for alignment phase? A review. Turk J Orthod 2016;29:47-50.
6.	Juvvadi SR, Kailasam V, Padmanabhan S, Chitharanjan AB. Physical, mechanical, and flexural properties of 3 orthodontic wires: An in-vitro study. Am J Orthod Dentofacial Orthop 2010;138:623-30.
7.	Chang HP, Tseng YC. A novel β-titanium alloy orthodontic wire. Kaohsiung J Med Sci 2018;34:202-6.
8.	Pandis N, Bourauel CP. Nickel-titanium (NiTi) arch wires: The clinical significance of super elasticity. Semin Orthod 2010;16:249-57.
9.	Castro SM, Ponces MJ, Lopes JD, Vasconcelos M, Pollmann MC. Orthodontic wires and its corrosion the specific case of stainless steel and beta titanium. J Dent Sci 2015;10:1-7.
10.	Arifiani P, Siregar E. Karakteristik kawat TMA (titanium molybdenum alloy) dan penggunaannya dalam perawatan ortodonti. MKGK Clin Dent J 2016;2:163-71.
11.	Souza R, Chatrree A, Rajendran S. Stainless steel alloys for dental application: corrosion behaviour in the presence of toothpaste vicco. Der Pharma Chem 2017;9:25-31.
12.	Roslan AN, Sunariani J, Irmawati A. Penurunan sensitivitas rasa manis akibat pemakaian pasta gigi yang mengandung sodium lauryl sulphate 5%. Jurnal PDGI 2009;58:10-3.
13.	Nik TH, Hosshmand T, Farhadifard H. Effect of different types of toothpaste on frictional resistance between orthodontic stainless steel bracket and wire. J Dent (Tehran) 2017;14:275-81.
14.	Aminian A, Nakhaei S, Agahi RH, Rezaeizade M, Aliabadi HM, Heidarpour M. Evaluation of the effect of different stretching patterns on force decay and tensile properties of elastomeric ligatures. Dent Res J (Isfahan) 2015;12:589-95.
15.	Fatimah DI, Anggani HS, Ismah N. Effect of fluoride mouthwash on tensile strength of stainless steel orthodontic archwires. J Phys Conf Ser 2017;884:1-5.
16.	Brindha M, Kumaran NK, Rajasigamani K. Evaluation of tensile strength and surface topography of orthodontic wires after infection control procedures: Anin vitro study. J Pharm Bioallied Sci 2014;6:44-8.
17.	Singh S, Pai VS, Amrita N. The effects of hot and cold sterilization on the tensile strength of orthodontic wires (An in-vitro study). Virtual J Orthod 2011;9:1-8.
18.	Jamillian A, Moghaddas O, Toopchi S, Perillo L. Comparison of nickel and chromium ion released from stainless steel and NiTi wires after immersion in Oral B, Orthokin and artificial saliva. J Contemp Dent Pract 2014;15:403-6.
19.	Brandao GA, Simas RM, Almeida LM, Silva JM, Meneghim MC, Preira AC, et al. Evaluation of ionic degradation and slot corrosion of metallic brackets by action of different dentifrices. Dent Press J Orthod 2013;18:86-93.
20.	House K, Sernetz F, Dymock D, Sandy JR, Ireland AJ. Corrosion of orthodontic appliances-should we care? Am J Orthod Dentofacial Orthop 2008;133:584-92.
21.	Wasono NP, Assa YA, Anindita PS. Pelepasan ion nikel dan kromium bracket stainless steel yang direndam dalam minuman isotonik. Pharmacon 2016;5:158-63.
22.	Mawaddah CA, Devi LS, Prijatmoko D. Perbedaan defleksi kawat ortodonti nikel-titanium dan niti epoxy resin coated pada perendaman dalam saliva buatan dan minuman berkarbonasi. J Pustaka Kesehatan 2016;4:519-24.
23.	Ferreira MA, Luersen MA, Borges PC. Nickel-titanium alloys: A systematic review. Dental Press J Orthod 2012;17:71-82.