I agree with Richard. I was grinding my toenails down with a sanding drum on my Flexshaft several years ago, which caused the fungus to spread to more toenails and fingernails, but the really scary part was that I got the fungus in my lungs from breathing that dust. I was hospitalized for two weeks and could have died from the lung fungus. My doctor told me it was dangerous to even file the thickened nail down because that also causes the fungus to become airborn. The only thing you should use are nail clippers. He told me to dip the clippers in a 50/50 solution of bleach and water after clipping each nail to prevent the spread of the fungus. If the nails become painful because they are pinching in at the side, soak them in warm water with ACV or TTO twice a day to soften them. You can also cut out a notch at the curve to relieve the pressure. The nail surface will absorb any remedy you use, so there's really no need to file or grind them down.