The present study analyzes the orthodontic nickeltitanium alloy with orthodontic shape memory (Niti GAC arches, Nitinol 3M arches, Beta Titanium 3M arches) from the viewpoint of its cytotoxicity. Apart from the intrinsic toxicity of the metals upon cells, corrosion may dramatically alter the behaviour of alloys, as evidenced by the in vitro and in vivo studies developed in the field. Due to the high and variable nickel content, its is possible that, at least theoretically, the released ions should produce as a result of intraoral corrosion secondary effects, which makes necessary to assert the cytotoxicity of NiTi alloys prior to their safe utilizationor in the oral cavity of children and young patients.
Evaluation of cell morphology and determination of cell viability, following exposure to the 3 types of orthodontic materials, evidenced no toxic reactions. Several problems are still to be elucidated, related to the consequences of the surface conditions, of the dissolution and in vivo release of the nickel ions after a longer treatment, of the accumulations of ion traces, of the response of the dental-periodontal tissues, of the effects manifested at cell and molecular level. Apart from the intrisic toxicity of metals upon cells, corrosion may dramatically influence the behaviour of alloys under in vitro conditions, comparatively with the in vivo ones, the nitinol samples being biologically safe.
- cell cultures
- orthodontic alloys