The release of mercury (Hg++) from dental amalgams can induce oxidative stress and contribute to cognitive impairments in patients with long-term dental amalgams. Furthermore, the presence of mercury and aluminium could accelerate the progression of neurological diseases.

Conversely, titanium alloy (Ti 6Al-4V) is a biocompatible biomaterial of interest in the field of odontology. Although titanium is generally considered safe for patients, recent studies have revealed certain adverse effects associated with this material. However, the link between selenium deficiency and accumulation of heavy metals (mercury and aluminium) and depression has not been elucidated in patients with long-term dental titanium implants and/or amalgam fillings (at least 15 years in the mouth).

Our aim is to determine whether a selenium deficit could increase mercury and aluminium accumulation in patients with long-term titanium and dental implants (A + I group, n = 57) as compared to their levels in participants with long-term dental amalgams alone (A group, n = 55), and control subjects (without dental biomaterials, n = 30). To achieve this, we compared Se/Hg++ and Se/Al ratios in hair samples via ICP-MS spectrophotometry between A+I, A, and control groups, while a Beck's test was performed to assess possible differences in depressive behaviour.

In our study, A+I patients had lower Se/Hg²⁺ and Se/Al ratios than the A group. This suggests that titanium contributes to selenium depletion, which indirectly leads to Hg²⁺ or Al tissue accumulation in participants with long-term titanium and dental amalgam fillings. As heavy metals contribute to Alzheimer's disease pathology, selenium supplementation could reduce their accumulation in patients with long-term dental biomaterials.

Conclusion: Patients with long-term titanium and dental amalgam fillings have selenium levels that contribute to mercury and aluminium accumulation.