使用传统（两件式）与金属注射成型托槽进行固定正畸治疗对头发中镍和铬含量的影响：一项双盲随机临床试验。

Effects of fixed orthodontic treatment using conventional (two-piece) versus metal injection moulding brackets on hair nickel and chromium levels: a double-blind randomized clinical trial.

作者信息

Khaneh Masjedi Mashallah, Haghighat Jahromi Nima, Niknam Ozra, Hormozi Elham, Rakhshan Vahid

机构信息

Department of Orthodontics, Faculty of Dentistry, Ahvaz Jundishapur University of Medical Sciences, Iran.

Department of Orthodontics, Faculty of Dentistry, Ahvaz Jundishapur University of Medical Sciences, Iran,

出版信息

Eur J Orthod. 2017 Feb;39(1):17-24. doi: 10.1093/ejo/cjw017. Epub 2016 Mar 11.

DOI:10.1093/ejo/cjw017

PMID:26969422

Abstract

INTRODUCTION

Although nickel and chromium are known as allergen and cytotoxic orthodontic metals, very few and controversial studies have assessed the effect of orthodontic treatment on their systemic levels especially those reflected by their best biomarker of exposure, hair. Additionally, metal injection moulding (MIM) brackets are not studied, and there is no study on systemic ion changes following their usage.

METHODS

In this double-blind randomized clinical trial, scalp hair samples of 24 female and 22 male fixed orthodontic patients [as two groups of conventional (two-piece) versus MIM brackets, n = 23×2] were collected before treatment and 6 months later. Randomization was carried out using a computer-generated random number table. The patients, laboratory expert, and author responsible for analyses were blinded of the bracket allocations. Hair nickel and chromium levels were measured using atomic absorption spectrophotometry. The effects of treatment, bracket types, gender, and age on hair ions were analysed statistically (α = 0.05, β ≤ 0.02).

RESULTS

In both groups combined (n = 46), nickel increased from 0.1600±0.0890 µg/g dry hair mass (pre-treatment) to 0.3199±0.1706 (6th month). Chromium increased from 0.1657±0.0884 to 0.3066±0.1362 µg/g. Both of these increases were significant (paired t-test, P = 0.0000). Bracket types, age, and gender had no significant influence on ion levels (P > 0.05). ANCOVA indicated different patterns of chromium increases in different genders (P = 0.033) and ages (P = 0.056).

LIMITATIONS

Sample size determination should have accounted for the grouping as well.

CONCLUSION

Hair nickel and chromium levels might increase about 185-200% after 6 months. They might not be affected by bracket types. Gender and age might not influence the baseline or 6th-month levels of both metals. Gender might however interact with orthodontic treatment, only in the case of chromium.

REGISTRATION

The research is registered offline (thesis) and online (IR.AJUMS.REC.1394.516).

PROTOCOL

The protocol was pre-determined before any experiments begin.

FUNDING

The study was self-funded by the authors.

摘要

引言

尽管镍和铬被认为是正畸金属中的过敏原和具有细胞毒性的物质，但很少有研究且研究结果存在争议，这些研究评估了正畸治疗对其全身水平的影响，尤其是通过其最佳暴露生物标志物——头发所反映的水平。此外，金属注射成型（MIM）托槽尚未得到研究，也没有关于使用MIM托槽后全身离子变化的研究。

方法

在这项双盲随机临床试验中，收集了24名女性和22名男性固定正畸患者（分为传统（两件式）托槽组和MIM托槽组，每组n = 23）治疗前和6个月后的头皮毛发样本。使用计算机生成的随机数表进行随机分组。患者、实验室专家以及负责分析的作者均对托槽分配情况不知情。采用原子吸收分光光度法测量头发中的镍和铬水平。对治疗、托槽类型、性别和年龄对头发离子的影响进行统计学分析（α = 0.05，β ≤ 0.02）。

结果

两组患者（n = 46）的镍含量从治疗前干发质量的0.1600±0.0890 μg/g增加到第6个月时的0.3199±0.1706 μg/g。铬含量从0.1657±0.0884 μg/g增加到0.3066±0.1362 μg/g。这两种增加均具有统计学意义（配对t检验，P = 0.0000）。托槽类型、年龄和性别对离子水平无显著影响（P > 0.05）。协方差分析表明，不同性别（P = 0.033）和年龄（P = 0.056）的铬增加模式不同。