Nonbiologic material such as metal, ceramic, and plastic.

Alloplastic materials are often used when significant [[defect]]s 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.