FIG. 1 is a front view of a head portion of a toothbrush according to my new design;
FIG. 2 is a right side view thereof, the left side view being a mirror image thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a front perspective view thereof;
FIG. 7 is a rear perspective view thereof;
FIG. 8 is a close up right-side view of the head portion thereof;
FIG. 9 is a close up rear view of the head portion thereof; and,
FIG. 10 is a close up rear perspective view of the head portion thereof.
The broken lines showing the bristle and handle structures illustrate environment of the head portion of a toothbrush that forms no part of the claimed design.