Copper makes up about 2% of a regular dental Amalgam filling, and those do wear down over the years.
Some sites claim Vitamin C in amounts of 4 g= 4000 mg per day will flush out copper and other heavy metals.
The heavy metals do their damage by, among other ways, acting as a free radical-generating station 24/7.
So Vitamin C as a water soluble will quench a good part of those, altho it has a short acting time in the body.
Some people note that their headaches either go away or lessen greatly within 30-60 minutes of taking a large dose of C about 2000 mg in water. This is likely because it really is fixing the cause of which the headache is the symptom.