Black & white photograph
Above - lateral incisor, first bicuspid, and first molar showing vertical concavities on the cervical part of the crown, the floors of which could not be reached effectively by dental floss. Below - Same as above. After the mesial surfaces were completely marked with a red wax pencil, they were thoroughly cleansed with dental floss. The dark markings shown herein indicate the amount of wax that could not be thus reached by the floss. The cleansing value of bristles in such instances is quite obvious (See Figs. 324 and 325).
This work is dedicated to the Public Domain.