Should titanium miniplates be removed after bone healing is complete?

A prospective study of 32 patients was performed to analyze black pigmentation in the soft tissue covering titanium miniplates. This soft tissue was compared with the soft tissue covering Champy stainless steel plates. All plates were removed 8 months after application. Macroscopically visible pigmentation was found in 25.6% of the soft tissue covering titanium miniplates and in none of the soft tissue covering Champy stainless steel plates. Microscopically visible pigmentation was found in 71.8% of the soft tissue covering titanium miniplates and in 65.3% of the soft tissue covering Champy stainless steel plates. Energy-dispersive x-ray analysis of the soft tissue covering titanium miniplates revealed only the presence of titanium dioxide. In the soft tissue near Champy stainless steel plates, chromium, nickel, iron, and molybdenum were found. Electron microscopy showed titanium dioxide to be mainly deposited between the collagen fibers, whereas stainless steel particles were mainly found in giant cells.