I often interchange Nokia power supplies, without doing any harm (so far...).
BUT, before doing so, see if you can verify that the 2 power supplies output the same voltage. Normally that information will be written on the power supply (it's usually something like 3.6v or 3.7v). I have a feeling that a difference of 0.1 of a volt or so *probably* wouldn't cause problems... but then you might be starting to push your luck...
If they output (roughly) the same voltage, then you should check the power rating (guessing here, but it's usually a few 100 mA or so). If the power ratings are the same (OR the 8210 charger has a HIGHER power rating (remember that's the figure with mA after it)), then you *should* be good to go.
HOWEVER, don't call me if you end up frying your phone... (ha ha)