Resorbability

For materials to exert biological activity, they need to dissolve/dis-integrate in the tissues. Most endodontic materials are removed from connective tissues if (dis-)placed there (Above left: calcium hydroxide in the tissue; right: one month later calcium hydroxide has been resorbed off).

The resorptive process may be dependent on the nature of the material. Calcium hydroxide in the tissue is often associated with giant cells. AH26 is seen as small fragments in and around macrophages within a large zone of inflammation, which subsides rapidly when the material sets. ZnO-based materials are also associated with macrophages and neutrophils.

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