Electric Field and SAR Distribution in the Vicinity of Orthodontic Brace Exposed to the Cell Phone Radiation

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Jovanovic DB, Krasic DD, Stankovic VB, Cvetkovic, NN, Vuckovic DD. Electric Field and SAR Distribution in the Vicinity of Orthodontic Brace Exposed to the Cell Phone Radiation. Applied Computational Electromagnetics Society Journal 34(12):1904-1914. Dec 2019.

Abstract
The aim of this study is to investigate the impact of orthodontic brace on the electric field distribution and amount of the absorbed energy from the cell phone within the teeth. A comparative analysis of the models (child and adult) with and without brace has been carried out due to different morphological and tissue characteristics of child’s and adult’s head. The 3D realistic models of the child’s and adult’s head, with the jaw having the orthodontic brace, have been designed. The shapes and features of the child and adult head model, as well as the distance between the electromagnetic source and the exposed object, have an important role in the evaluation of the Specific Absorption Rate (SAR). The applied procedure is based on the numerical solution of the electromagnetic waves propagation equations. The numerical analysis has been performed at the frequency of 3G (0.9GHz). The obtained results are represented within the teeth positioned on the side of the electromagnetic radiation source. Based on the obtained results, one can conclude that the presence of orthodontic brace affects the increase of electric field and SAR within the teeth.

Excerpts
“According to previous studies, one can find that the metal objects can significantly increase the amount of absorbed energy. The authors in [1] have found that the SAR values can be several times greater in the presence of metal object. The effect of electromagnetic radiation from mobile phone on nickel release from orthodontic brackets has been taken into consideration in study [2]. It is found that the concentration of nickel in the artificial saliva in the exposure group was significantly higher than that of the control group. The level of the nickel released in this investigation was far below the toxic level but maybe enough that can lead to allergic reaction in humans. One of the previously studies [3] reported the involuntary movements of the subjects, which had gold (metal) alloy dental inlay, caused by electromagnetic waves.”
“It is evident that the value of the electric field is significantly greater in the presence of an orthodontic brace for both models. Based on the results shown in Figs. 6-8, as well as the results given in Table 3, the overall conclusion is that the presence of an orthodontic brace increases the electric field strength within the teeth.
Also it is noticeable that the electric field strength in the case of a child is higher comparing to the adult case.”
“Since the referent value for the electric field, prescribed by adequate standards at 0.9 GHz, is 41 V/m, comparing the results obtained by numerical calculation with values prescribed by safety standards, it is evident that obtained results exceed the referent levels inside all teeth in both models (with and without the orthodontic brace). However, it should be kept in mind that in the case of model with orthodontic brace the values are many times greater than the allowable values.”
“Regarding the obtained results for SAR within the teeth, in the presence of an orthodontic brace, a significant increase in the amount of absorbed energy can be observed. The maximum of SAR1g occurs in the tooth No. 6 in the case of a child (2.46 W/kg). This value is about 65% higher comparing to the adult with orthodontic brace and 45% higher comparing to the results obtained for a child without orthodontic brace. In this tooth and tooth No. 5, the SAR1g overcomes the safety values but only in the case of child in the presence of the orthodontic brace. The amount of absorbed energy inside the other teeth satisfies basic restriction. However, the increase in the amount of absorbed energy in the presence of an orthodontic brace is not negligible.”
“Based on the obtained results, one can conclude that the presence of orthodontic brace causes increase of electric field and SAR within the teeth. In some cases, those values overcome referent limits for electric field strength, i.e., safety limits for SAR values.”
“Because of the mentioned before and the fact that each standard contains specific safety limits of exposure to electromagnetic fields but they have been developed based on the research for adults, it should be established if they are sufficiently valid also in case of children.
The future researches should be focused on the impact of orthodontic brace on the electric field strength and amount of absorbed energy at the frequency of LTE-4G, and the latest generation of mobile networks – 5G.”

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