Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2013  |  Volume : 24  |  Issue : 3  |  Page : 298--301

Are more nickel ions accumulated in the hair of fixed orthodontic patients?


Mostafa Abtahi1, Arezoo Jahanbin1, Masoud Yaghoubi2, Habibollah Esmaily3, Hanieh Zare4,  
1 Department of Orthodontics, Mashhad University of Medical Sciences, Mashhad, Iran
2 Department of Orthodontics, Bojnord University of Medical Sciences, Mashhad, Iran
3 Department of Community and Public Health, Mashhad University of Medical Sciences, Mashhad, Iran
4 Dentist, Private Practice, Mashhad, Iran

Correspondence Address:
Arezoo Jahanbin
Department of Orthodontics, Mashhad University of Medical Sciences, Mashhad
Iran

Abstract

Background and Objectives : All elements existing in orthodontic alloys can be released to the oral cavity as corrosion products; therefore, they can accumulate in body tissues after systemic absorption. Among body tissues that can be evaluated for systemic absorption of nickel, in this study we used hair strands, because if nickel is absorbed systematically, it would accumulate in these strands over time. Furthermore, hair sampling is a non-invasive method, so the main aim of this study was the evaluation of nickel ions release into the hair strands of fixed orthodontic patients compared with the control group in a 4-month duration. Materials and Methods: In this clinical trial, the test group included 24 female patients between 12-20 years of age that were going to begin fixed orthodontic treatment. The control group consisted of their sisters in the same age range, who volunteered to participate in this study. Initial hair samples were taken from both groups at the beginning the study and immediately before setting up the fixed appliances in test group. The samples were taken from three different scalp sites including; frontal, vertex, and occipital areas. After 16 weeks, hair samples were taken from approximately the same scalp areas in both the groups. The samples were analyzed by atomic absorption spectrophotometer and data analyzed by Mann-Whitney test. Results: This study showed that there were significant differences in nickel levels before and after study for case (P = 0.004) and control groups (P = 0.012). The mean nickel concentration after four months was 0.382 ± 0.36 μg/g for controls and 0.673 ± 0.38 μg/g for the case group, which was significantly different (P = 0.002). Conclusion: The hair nickel concentrations significantly increased after insertion of fixed orthodontic appliances as compared with the control group.



How to cite this article:
Abtahi M, Jahanbin A, Yaghoubi M, Esmaily H, Zare H. Are more nickel ions accumulated in the hair of fixed orthodontic patients?.Indian J Dent Res 2013;24:298-301


How to cite this URL:
Abtahi M, Jahanbin A, Yaghoubi M, Esmaily H, Zare H. Are more nickel ions accumulated in the hair of fixed orthodontic patients?. Indian J Dent Res [serial online] 2013 [cited 2020 Jan 18 ];24:298-301
Available from: http://www.ijdr.in/text.asp?2013/24/3/298/117990


Full Text

Orthodontic appliances are made of different alloys and these appliances are required to remain in the oral cavity of a patient for a period of time. Unfortunately, enzymatic and microbiological characteristics of the oral cavity create a suitable environment for metal corrosion. Corrosion products consist of different elements such as nickel and chromium, which can be released in the oral cavity. [1],[2]

Great concerns have been aroused about allergic, cytotoxic, and even carcinogenic side effects of these metal ions, especially nickel. [3],[4],[5],[6],[7],[8]

Most orthodontic appliances are made of the nickel element. This is the most sensitizing agent in industrialized countries and is mostly associated with the wearing of jewelery and trinkets, and other objects made of stainless steel. Moreover, orthodontic treatments mainly concern youngsters, who are more prone to allergic reactions than adults. [9]

In toxicology and environmental sciences, markers of exposure to toxic metals, where the concentration of the toxicant is determined in in vivo tests, generally include sites of elimination or accumulation. Frequently, it is impossible to conduct measurements at the site of accumulation (internal organs - liver and kidneys) by noninvasive means. Therefore, it is recommended to use excretion routes to develop biological markers of exposure. [6]

According to the fact that all elements that exist in orthodontic alloys can be released into the oral cavity as corrosion products, it is quite rational to measure the nickel concentration in body tissues in order to evaluate its systemic absorption. [10]

Among body tissues that can be evaluated for systemic absorption of nickel, in our study we used hair strands, because if the nickel is absorbed systematically, it would accumulate in these strands over time. Furthermore, hair sampling is a noninvasive method, so the main aim of this study was the evaluation of nickel ions release into the hair strands of fixed orthodontic patients compared with the control group in 4-month duration.

 Materials and Methods



In this study, the test group included 24 female patients between 12-20 years of age that were going to begin fixed orthodontic treatment. The control group consisted of their sisters in the same age range of the test group, who volunteered to participate in this study. Informed consent was filled by every case or their parents if they were under 18 years old, and the protocol was approved by Ethics Committee of Mashhad University of Medical Sciences.

Both groups were in permanent dentition and had 4-6 amalgam fillings. Furthermore, in test group, the treatment plan consisted of four permanent teeth extraction. Test group was not treated by transpalatal arch, lingual arch or headgear. Both groups had not used hair color products before the beginning of the study, and were requested not to use hair color and not to get a haircut until the end of study.

Standard edgewise stainless steel brackets (Dentaurum Company, Inspringen, Germany) with the slot size of 0.018 inch were used for test group, and 0.014 inch Ni-Ti arch wires (Dentaurum Company, Inspringen, Germany) were inserted into the bracket slots for initiating teeth alignment. After 16 weeks, hair samples were taken from approximately the same scalp areas by the same method as in the initial stage.

Initial hair samples were taken from both groups at the beginning the study and immediately before setting up the fixed appliances in the test group. The samples were taken from three different scalp sites including the frontal, vertex, and occipital area. By using a sterilized scissors, some hair was cut off from exactly root hair. After cutting hair, with the help of a 100 cm glass slab, we cut extra hair away from the hair root to make the size of each hair sample equal to the slab length. This action was repeated in the three mentioned areas, until the sum of hair samples reached 0.5 gram.

The hair samples were weighed into 50 ml plastic tubes and washed with acetone followed by 0.01% Triton solution, according to the procedures previously recommended by the Hair Analysis Standardization Board. [10] The samples were dried in an oven at 80 ± 5°C. In all the cases, the dried hair samples were kept into pre-cleaned and labelled polyethylene vials. All the chemicals used were supplied by Merck (Darmstadt, Germany).

Ten ml concentrated HNO 3 and 10 ml of perchloric acid were added and kept for 2 hours prior to ultrasonic stirring. In each tube, 2 ml of ultrapure water (ELGA, Bucks, UK) was added and the tubes were placed inside the water-bath for 60 minutes. At the end of experiment, the solutions in the tubes were centrifuged at 3000 rpm for 10 min and the acid liquid phase was separated with a Pasteur pipette. A 2 ml volume of ultrapure water was added to clean the solid residue twice and the mixture was centrifuged again at 3000 rpm for 10 minutes. The liquid phase was again separated with a pipette and combined with the acid leachate. The solution was finally made up to 25 ml with ultrapure water and placed into a polyethylene bottle at 4°C. The samples were analyzed by atomic absorption spectrometry (Varian Atomic Absorption Spectrometer Series AA240 FS) [Table 1].{Table 1}

Data analysis was done in two groups using Mann-Whitney test. Significance levels for statistical test were predetermined at a probability value of 0.05 or less. All analyses were performed with SPSS software (version 11, SPSS Inc., Chicago, IL).

 Results



The mean value for nickel concentration at the beginning of the study for the case group was 0.350 ± 0.40 μg/g and for the control group was 0.245 ± 0.31 μg/g. Both groups were compared by Mann-Whitney test. There was no significant difference in hair nickel concentration of both groups at baseline before setting up the case group with fixed orthodontic appliances. (P = 0.17) [Table 2] and [Figure 1].{Table 2}{Figure 1}

After 16 weeks from setting up the fixed orthodontic appliances in the case group, nickel concentrations were analyzed again. The mean nickel concentration after four months was 0.382 ± 0.36 μg/g for the control group and 0.673 ± 0.38 μg/g for the case group that showed significant differences (P = 0.002).

Also, this study showed that there were significant differences in hair nickel concentration of baseline and after four months for cases (P = 0.004) and controls (P = 0.012).

[Figure 1] shows nickel concentration in case and control groups in observation period. On the basis of it, nickel concentration in both groups increases but in case group this increase is more rapid.

 Discussion



Nickel is the most common contact allergen affecting females in Europe and the USA. [11]

The data provided by the literatures are contrasting concerning the role of orthodontic appliances in contact allergies due to nickel release. Cases of contact allergic dermatitis were frequently reported in the literature and were related to hooks, loops of face bows and cervical headgears. [12],[13],[14] According to increasing intention in orthodontic treatment in individuals, there is great concern about nickel containing appliances. Therefore, many researchers have investigated nickel release and its absorption in body tissues. They have followed the nickel footprint in saliva, blood serum, dental plaque, urine, epithelial cells of oral mucosa, and finally in the hair strands of orthodontic patients. Of course, there are some in vitro studies about nickel release from orthodontic appliances, but contrasting results have been reported in the literatures. Our aim was to plan an exact study and gather evidence about probable nickel levels absorbed by body tissues and its significance in comparison with dietary nickel intake.

In this study, 24 females who were going to be treated with fixed orthodontic appliances participated as the test group, and their sisters (N = 24) with no previous orthodontic treatment participated as the control group. Both groups were corresponding in sex, age, and environment in order to maximize the similarity in both groups since nickel can be absorbed by diet.

This study showed nickel concentration in test group increased approximately two times greater than controls, and Mann-Whitney test revealed significant changes in both groups after four months.

Nickel hair levels correlate with chronic exposures and ingestion. Furthermore, hair is sensitive to external contamination with Ni. Some shampoos and many hair perm dye bleach products place Ni into the hair. Although we emphasized to our samples not to use any hair color in study period, but they may use hair accessories in this duration and this may be the reason of Ni increase in control group after four months.

Our result was not in agreement with the study of Levrini, who did not find any significant difference in nickel concentration between the test and control groups. However, Levrini measured nickel levels in both groups only one time, so any changes in nickel levels caused by dietary intake could not be traced. [15]

Several authors believe that nickel levels in orthodontic patients differ from controls, while others believe that there is no significant difference in the nickel content of the body between test and control samples. [16],[17],[18],[19],[20],[21],[22]

In this regard, Bishara et al. measured nickel concentrations in the blood of 31 orthodontic patients in three different time periods. They concluded that patients with full banded and bonded orthodontic appliances did not show either a significant or consistent increase in nickel blood levels during the first four to five months of orthodontic therapy. [23]

However, Ağaoğlu et al. evaluated the concentrations of nickel and chromium ions in salivary and serum samples from patients treated with fixed orthodontic appliances. They concluded that fixed orthodontic appliances released measurable amounts of nickel and chromium when placed in the mouth, but this increase did not reach toxic levels for nickel and chromium in the saliva and serum. [24]

Two factors determine the toxic effects of a material. These are exposure time and its concentration. Most of the potentially toxic substances are not easily soluble in tissue fluids, so the potentially toxic products do not have enough time to distribute in the body tissues. Some authors believe that if there are low concentrations of these toxic substances, the body tissues can transfer and neutralize them. On the other hand, some authors believe that there is no threshold for the harmful effects of these toxic elements. Investigating systemic changes due to biological effects of different materials if not impossible is very difficult. Most evidences on biocompatibility of materials are gained through indirect observations. [6]

 Conclusion



This study proved most orthodontic appliances can release nickel during orthodontic period and this nickel can be absorbed systematically by body tissues such as hair. Moreover, the investigation showed despite there was no significant difference in hair nickel concentration between case and control groups before setting up the fixed orthodontic appliances, nickel concentration in the case group after four months was two times greater than controls and differences was significant.

So, continued follow-up and large sample of patients is needed to determine the patterns and the long-term significance of nickel release in the hair of orthodontic patients.

References

1Powers JM, Sakuguchi RL. CRAIG's Restorative Dental Material. USA: Mosby Elseveir; 2006. p. 396.
2Matasa CG. Orthodontic attachment corrosion susceptibilities. J Clin Orthod 1995;29:16-23.
3Grimsdottir MR, Hensten-Pettersen A, Kullmann A. Cytotoxic effect of orthodontic appliances. Eur J Orthod 1992;14:47-53.
4Bumgardner JD, Lucas LC. Cellular response to metallic ions released from nickel-chromium dental alloys. J Dent Res 1995;74:1521-7.
5Sakai T, Takeda S, Nakamura M. The effects of particulate metals on cell viability of osteoblast-like cells in vitro. Dent Mater J 2002;21:133-46.
6Kerosuo H, Kullaa A, Kerosuo E, Kanerva L, Hensten-Pettersen A. Nickel allergy in adolescents in relation to orthodontic treatment and piercing of ears. Am J Orthod Dentofacial Orthop 1996;109:148-54.
7Janson GR, Dainesi EA, Consolaro A, Woodside DG, de Freitas MR. Nickel hypersensitivity reaction before, during, and after orthodontic therapy. Am J Orthod Dentofacial Orthop 1998;113:655-60.
8Marigo M, Nouer DF, Genelhu MC, Malaquias LC, Pizziolo VR, Costa AS, et al. Evaluation of immunologic profile in patients with nickel sensitivity due to use of fixed orthodontic appliances. Am J Orthod Dentofacial Orthop 2003;124:46-52.
9Faccioni F, Franceschetti P, Cerpelloni M, Fracasso ME. In vivo study on metal release from fixed orthodontic appliances and DNA damage in oral mucosa cells. Am J Orthod Dentofacial Orthop 2003;124:687-93.
10Pereira ML, Silva A, Tracana R, Carvalho GS. Toxic effects caused by stainless steel corrosion products on mouse seminiferous cells. Cytobios 1994;77:73-80.
11Staekjaer L, Menne T. Nickel allergy and orthodontic treatment. Eur J Orthod 1990;12:284-9.
12Burden DJ, Eedy DJ. Orthodontic headgear related to allergic contact dermatitis: A case report 1991;170:447-8.
13Dickson G. Contact dermatitis and cervical headgear. Br Dent J 1983;155:112.
14Greig DG. Contact dermatitis reaction to metal buckle on a cervical headgear. Br Dent J 1983;155:61-2.
15Levrini L, Lusvardi G, Gentile D. Nickel ions release in patients with fixed orthodontic appliances. Minerva Stomatol 2006;55:115-21.
16Menzes LM, Quintao CA, Boloqnese AM. Urinary excretion levels of nickel in orthodontic patients. Am J Orthod Dentofacial Orthop 2007;131:635-8.
17Amini F, Borzabadi Farahani A, Jafari A, Rabbani M. In vivo study of metal content of oral mucosa cells in patients with and without fixed orthodontic appliances. Orthod Craniofac Res 2008;11:51-6.
18Fors R, Persson M. Nickel in dental plaque and saliva in patients with and without orthodontic appliances. Eur J Orthod 2006;28:292-7.
19Matos de Souza R, de Menezes L. Nickel, chromium and iron levels in the saliva of patients with simulated fixed orthodontic appliances. Angle Orthod 2008;78:345-50.
20Kerosuo H, Moe G, Hensten-Pettersen A. Salivary nickel and chromium in subjects with different types of fixed orthodontic appliances. Am J Orthod Dentofacial Orthop 1997;111:595-8.
21Petoumenou E, Arndt M, Keiliq L, Reimann S, Hoederath H, Eliades T, et al. Nickel concentration in the saliva of patients with nickel-titanium orthodontic appliances. Am J Orthod Dentofacial Orthop 2009;135:59-65.
22Singh DP, Sehgal V, Pradhan KL, Chandna A, Gupta R. Estimation of nickel and chromium in saliva of patients with fixed orthodontic appliances. World J Orthod 2008;9:196-202.
23Bishara SE, Barret RD, Selim MI. Biodegradation of orthodontic appliances. Part 2. Changes in blood level of nickel. Am J Orthod Dentofacial Orthop 1993;103:115-9.
24Aðaoðlu G, Arun T, Izgi B, Yarat A. Nickel and chromium levels in the saliva and serum of patients with fixed orthodontic appliances. Angle Orthod 2001;71:375-9.