Nonbiologic material such as metal, ceramic, and plastic.

Alloplastic materials are often used when significant defects exist. Benefits include no donor site morbidity, relative ease of use, limitless supply, and predictable durability. Depending on the type of alloplast, limitations include a persistent risk of extrusion and infection.

Of particular interest in relation to cranioplasty is the ability of the material to provide neuroprotection.