Allergic reactions and nickel-free braces: a systematic review

Nickel-free braces have gained popularity as a viable alternative for patients who are allergic to nickel. The purpose of this systematic review was to determine whether evidence exists to justify the use of nickel-free brackets in orthodontic patients who are allergic to nickel. An electronic search was performed using 7 databases (MEDLINE, BBO, LILACS, Web of Science, EMBASE, BIREME and Cochrane Library), without restriction regarding year or language, with supplemental manual searching of the references of retrieved articles. The search strategy produced 89 papers. The data extraction and quality score of each paper were evaluated independently by two reviewers, once each. After selection based on the eligibility criteria, four papers, including 2 controlled clinical trials and 2 clinical trials, qualified for the final analysis. Quality assessment of the included articles was also performed. Nickel-free braces (Ni content - 2% max.) seem to represent a viable alternative for orthodontic patients who are allergic to nickel. However, further in vivo studies, considering the immunology characteristics of patients, are needed to determine the clinical implications of the findings of this study.