The ornamental design for a dual-sided toothbrush, as shown and described herein.
FIG. 1 illustrates a front perspective view of a dual-sided toothbrush.
FIG. 2 illustrates a top view of the dual-sided toothbrush.
FIG. 3 illustrates a bottom view of the dual-sided toothbrush.
FIG. 4 illustrates a right-side view of the dual-sided toothbrush.
FIG. 5 illustrates a left-side view of the dual-sided toothbrush.
FIG. 6 illustrates a front view of the dual-sided toothbrush; and,
FIG. 7 illustrates a rear view of the dual-sided toothbrush.
The features shown in broken lines in the drawings illustrate portions of the article of manufacture in which the design is embodied or to which it is applied that form no part of the claim.