Maybe not? We already have a variety of metals in our bodies, and cells already interact with them as needed and filtering them if not. (I'm obviously being very generic here. Heavy metals are an obvious exception to this.)

Meanwhile, biology has no idea what plastic is and it seems like our bodies have a hard time filtering it out.

Sorry if you were joking and I missed it.

Metals, yes. Metal shavings can have sharp edges, which may not do good things to the inside of your mouth (nor to your GI track if you swallow them).