Effect of Ionizing and Non-ionizing Radiation On Amalgam, Composite and Zirconomer Based Restorations

Dear Editor,

With great interest we read the article by Patel et al., entitled “An invitro Evaluation of Microleakage of Posterior Teeth Restored with Amalgam, Composite and Zirconomer–A Stereomicroscopic Study” [1] that is published in the July issue of the Journal of Clinical and Diagnostic Research (Vol-9(7): ZC65-ZC67, 2015). In this article, the authors performed an in vitro stereomicroscopic study to evaluate the microleakage of posterior teeth restored with amalgam, composite and zirconomer. In their study, cavities prepared on the occlusal surface, were restored with amalgam, composite and zirconomer. These researchers reported that based on their findings, zirconomer revealed the highest level of microleakage compared to composite and amalgam. The microleakage of composite was moderate and amalgam showed the minimum level of microleakage. This paper seems to have a serious shortcoming. Substantial evidence shows that in the studies on microleakage of amalgam, the challenging issue of exposure to different sources of electromagnetic fields (e.g. Wi-Fi, mobile phones and mobile base stations, or even electrical household appliances such as hair dryers, electric shavers and vacuum cleaners) and their effects on enhanced microleakage should be taken into account. Over the past several years, our lab at the Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC) has performed extensive experiments on the health effects of exposure of animal models and humans to different sources of electromagnetic fields (EMFs) such as cellular phones [2–9], mobile base stations [10], mobile phone jammers [11], laptop computers [12], radars [3], dentistry cavitrons [13] and MRI [14,15]. Our first report on the role of exposure to MRI or microwave radiation emitted by mobile phones in enhancing the release of mercury from dental amalgam restoration was published in 2008 [8]. Due to some limitations in this early study, we have recently investigated the effect of exposure to relatively stronger magnetic fields (0.25 T in our previous report versus 1.5 T in our recent study). Interestingly, this study confirmed our previous findings that the release of mercury from amalgam fillings can be enhanced by exposure to EMFs [16]. We have also shown that some of the papers which reported no increased release of mercury after MRI, may have some methodological flaws [17]. On the other hand, microleakage studies also provide further evidence that supports the biologically detrimental effect of MRI on increasing the microleakage of dental amalgam fillings [18,19]. As there is no reports indicating that exposure of other filling materials such as composites to EMFs enhances the microleakage, we believe that the significant role of rapidly increasing exposure to EMFs in increasing amalgam microleakage is not addressed in the study of Patel et al., In this light, to obtain more reliable results, the comparison of microleakage of amalgam and non-amalgam filling materials should be performed in both presence and absence of EMFs. We hope that these comments will provide evidence for broader understanding of the challenging issue of enhanced dental amalgam microleakage due to exposure to EMFs.

[1]. Patel MU, Punia SK, Bhat S, Singh G, Bhargava R, Goyal P, An invitro Evaluation of Microleakage of Posterior Teeth Restored with Amalgam, Composite and Zirconomer–A Stereomicroscopic Study J Clin Diagn Res 2015 9(7):ZC65-67.  [Google Scholar]

[2]. Mortazavi SMJ, Motamedifar M, Namdari G, Taheri M, Mortazavi AR, Shokrpour N, Non-Linear Adaptive Phenomena which Decrease the Risk of infection after Pre-Exposure to Radiofrequency Radiation, Dose-Response 01/2013; (in press)   [Google Scholar]

[3]. Mortazavi SMJ, Taeb S, Dehghan N, Alterations of Visual Reaction Time and Short Term Memory in Military Radar Personnel Iranian J Publ Health 2013 42:428-35.  [Google Scholar]

[4]. Mortazavi SMJ, Rouintan MS, Taeb S, Dehghan N, Ghaffarpanah AA, Sadeghi Z, Ghafouri F, Human short-term exposure to electromagnetic fields emitted by mobile phones decreases computer-assisted visual reaction time Acta Neurologica Belgica 2012 112:171-75.  [Google Scholar]

[5]. Mortazavi SMJ, Mosleh-Shirazi MA, Tavassoli AR, Taheri M, Mehdizadeh AR, Namazi SAS, Increased Radioresistance to Lethal Doses of Gamma Rays in Mice and Rats after Exposure to Microwave Radiation Emitted by a GSM Mobile Phone Simulator Dose-response: a publication of International Hormesis Society 2013 11:281-92.  [Google Scholar]

[6]. Mortazavi S, Mosleh-Shirazi M, Tavassoli A, Taheri M, Bagheri Z, Ghalandari R, A comparative study on the increased radioresistance to lethal doses of gamma rays after exposure to microwave radiation and oral intake of flaxseed oil Iranian Journal of Radiation Research 2011 9:9-14.  [Google Scholar]

[7]. Mortazavi SMJ, Habib A, Ganj-Karimi AH, Samimi-Doost R, Pour-Abedi A, Babaie A, Alterations in TSH and Thyroid Hormones Following Mobile Phone Use OMJ 2009 24:274-78.  [Google Scholar]

[8]. Mortazavi SMJ, Daiee E, Yazdi A, Khiabani K, Kavousi A, Vazirinejad R, Mercury release from dental amalgam restorations after magnetic resonance imaging and following mobile phone use Pakistan Journal of Biological Sciences 2008 11:1142-46.  [Google Scholar]

[9]. Mortazavi SMJ, Ahmadi J, Shariati M, Prevalence of subjective poor health symptoms associated with exposure to electromagnetic fields among University students Bioelectromagnetics 2007 28:326-30.  [Google Scholar]

[10]. Mortazavi SMJ, Safety Issue of Mobile Phone Base Stations Journal of biomedical physics & engineering 2013 3:1-2.  [Google Scholar]

[11]. Mortazavi SMJ, Adaptive responses after exposure to cosmic and natural terrestrial radiation Indian Journal of Radiation Research 2004 :104-12.  [Google Scholar]

[12]. Mortazavi SMJ, Tavasoli AR, Ranjbari F, Moamaei P, Effects of Laptop Computers’ Electromagnetic Field on Sperm Quality Journal of Reproduction and Infertility 2011 11:251-58.  [Google Scholar]

[13]. Mortazavi SM, Vazife-Doost S, Yaghooti M, Mehdizadeh S, Rajaie-Far A, Occupational exposure of dentists to electromagnetic fields produced by magnetostrictive cavitrons alters the serum cortisol level Journal of natural science, biology, and medicine 2012 3:60-64.  [Google Scholar]

[14]. Mortazavi SM, Daiee E, Yazdi A, Khiabani K, Kavousi A, Vazirinejad R, Mercury release from dental amalgam restorations after magnetic resonance imaging and following mobile phone use Pakistan journal of biological sciences: PJBS 2008 11:1142-46.  [Google Scholar]

[15]. Mortazavi SMJ, Neghab M, Anooshe SMH, Bahaeddini N, Mortazavi G, Neghab P, High-field MRI and Mercury release from dental amalgam fillings THEIJOEM 2014 5:101-05.  [Google Scholar]

[16]. Mortazavi SMJ, Neghab M, Anoosheh SMH, Bahaeddini N, Mortazavi G, Neghab P, High-field MRI and Mercury release from dental amalgam fillings International Journal of Occupational and Environmental Medicine 2014 5:101-5.  [Google Scholar]

[17]. Mortazavi SMJ, Mortazavi G, Effects of X-rays and magnetic resonance imaging on mercury release from dental amalgam into artificial saliva Oral Radiol 2014 :1-2.  [Google Scholar]

[18]. Shahidi SH, Bronoosh P, Alavi AA, Zamiri B, Sadeghi AR, Bagheri MH, Javadpour S, Effect of magnetic resonance imaging on microleakage of amalgam restorations: an invitro study Dento maxillo facial radiology 2009 38:470-74.  [Google Scholar]

[19]. Yilmaz S, Misirlioglu M, The effect of 3 T MRI on microleakage of amalgam restorations Dento maxillo facial radiology 2013 42:20130072  [Google Scholar]