FIG. 1 is a perspective view as seen from the front and left side of a toothbrush refill showing our new design;

FIG. 2 is a left side view of the toothbrush refill of FIG. 1;

FIG. 3 is a right side view of the toothbrush refill of FIG. 1;

FIG. 4 is a front view of the toothbrush refill of FIG. 1;

FIG. 5 is back view of the toothbrush refill of FIG. 1;

FIG. 6 is an enlarged top view of the toothbrush refill of FIG. 1; and,

FIG. 7 is an enlarged bottom view of the toothbrush refill of FIG. 1.

The broken lines illustrate portions of the toothbrush refill that form no part of the claimed design.