Association of dental amalgam fillings with neurodegenerative diseases (multiple sclerosis and alzheimer's disease): Systematic review and Meta-analysis

Abstract

Introduction: Mercury is a neurotoxin element that is released from dental amalgam restorations. Since circumstantial evidence exists that the pathology of neurodegenerative diseases including Alzheimer (AD) and multiple sclerosis disease (MS) might be in part caused or exacerbated by inorganic mercury, we conducted a systematic review and meta-analysis using a comprehensive search strategy. Materials & Methods: A systematic search of resources to investigate the association between dental amalgam and Ms and AD from Google scholar, PubMed, Embase, Cochrane, Scopus, Proquest, Ovid and Web of science was completed. Studies were screened according to a pre-defined protocol. Two individuals independently assessed the quality of the articles. Endnote X5 resource management software was used to organize, study titles and abstracts as well as identify duplicates. Finally, 6 articles were included in the meta-analysis. A random effect model was also used to perform the meta-analysis. Results: Mean difference of restoration numbers between two groups was (Pooled Mean difference = 0.58, 95% CI: 0.33-0.83, p-value <0.001) with greater numbers in MS patients. The pooled OR for the risk of MS among amalgam users was 1.02 (95% CI, 0.86-1021, p=0.81) with a slight non statistically significant increase between amalgam use and MS risk. In the case of Alzheimer's disease, due to the limited number of previous studies, only previous studies were reviewed. Conclusion: Although a suggestive elevated risk was found for those individuals with a large number of dental amalgams, the difference between cases and controls was not statistically significant. It seems that the number of amalgam fillings are among the factors associated with MS disease.