If you intentionally cut bread slices with a meat knife, can you then eat that slice of bread with dairy products?
1 Answer
In the Shulchan Aruch it was generally assumed that knives had some amount of residue on them, so the answer would be a simple "no."
I know rabbis who you'd consider "modern Orthodox" who feel this still applies today -- if you look carefully at the serrations -- so the answer would still be "no." I know other rabbis who you'd consider "ultra-Orthodox" who have said today's knives are cleaner (thank you, modern detergent technology, and stainless steel) so there may be more room for leniency.
So take a very careful look at the knife, then ask your local rabbi.