The new generation of biocompatible radicular pivots of the Alexa II zirconium type represents a considerable technical improvement: Without troubling the usual operation process, it is now possible to substitute a metallic pivot with a zirconium-made pivot. The recorded failures in the radicular reconstruction done with the help of metallic pivots were most of the time due to the consecutive radicular and transradicular reaches to the migration of ions through the roots, as had already been demonstrated by Sandhaus (1966), Söremark (1971) and Wirtz (1973).

The realisation of the studies on migration was achieved thanks to the electronic microscope examination of histological cuts and to the spectrophotometry of atomic absorption of the extracted roots, which macroscopically presented blue-greyish stains up on their apical part. An A P.I.X.E probe also allowed the verification of the presence of dissolved metals, not only in the root but also at a certain distance of the latter.

The harmfulness of the product of degradation extended itself far beyond the insertion zone. Some pathologic troubles were caused by the metallic dissolution, on the local plan as well as the general one.

The bio ceramic made of zirconium Alex II goes much further than the simple replacement of the electro galvanic materials: it opens the way to unseen therapeutic possibilities.

The new sintering technologies allowed the obtainment of a bioceramic, the properties of which are the following:

- Absence of toxicity
- Resistance to acids and alkalis
- Resistance to high temperatures
- Resistance to corrosion
- Resistance to wear with a very low coefficient of crumbling. III Great hardness
- Improved resistance to the flexion of traction forces
- Electric neutrality, avoiding this way the metallic-migration-related pathologies
- Absence of bimetallism between different alloys
- Radio-opacity
- Perfect retention in the radicular well
- Adaptability: great choice of sizes
- Diversity in the employment