Focus question

“What is the general overview of the risks and stability associated with titanium materials?”

Literature search

This review was prepared using data collected from until November 2018 through a keyword online search using MEDLINE (PubMed), Embase, Cochrane Library, and Google Scholar. Additional data were gathered for the necessary detailed parts using keywords including titanium toxicity, titanium alloy toxicity, titanium implant toxicity, and yellow nail syndrome; a total of 4213 articles were searched.

Inclusion criteria

We searched the toxicity of titanium through a division into four categories: the toxicity of titanium, the toxicity of titanium alloys, the toxicity of titanium implants, and diseases related to titanium.

Exclusion criteria

The exclusion criteria were as follows: non-English publications and duplicated articles.

Screening

In order to investigate the relevance of the main topic with recent studies, we collected the data from 1991 to November 2018 and keywords were also limited to “titanium toxicity human,” “titanium alloy toxicity human,” “titanium implant toxicity,” “titanium corrosion,” and “yellow nail syndrome titanium”; thus, 1820 articles were found. Additionally, another 464 articles that were found from the “titanium implant corrosion” keyword and another 84 articles that were found from the “titanium implant allergy” keyword were further identified and included in the “toxicity of titanium implant” category.

Data extraction

Based on these data, we divided the summarized data into one of four categories: the toxicity of titanium, the toxicity of titanium alloys, the toxicity of titanium implants, and diseases related to titanium.