Financial terms were not disclosed.
Dr. Fresh LLC makes toothbrushes, floss, toothpaste and other oral care products. Its brands include Binaca, Orazyme, Firefly and items sold under its namesake brand.
The deal does not include Reach brand floss or other interdental products.
McNeil-PPC's parent company is Johnson & Johnson.
Dr. Fresh is based in Buena Park, Calif.
Johnson & Johnson is based in New Brunswick, N.J. Its stock added 6 cents to $71 in premarket trading on Tuesday.