I claim the ornamental design for a teeth model fixing pin, as shown and described.
FIG. 1 is a front perspective view of the teeth model fixing pin;
FIG. 2 is a front side view thereof;
FIG. 3 is a rear side view thereof
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plane view thereof;
FIG. 7 is a bottom plane view thereof;
FIG. 8 is a reference figure of a front perspective view showing the state of combining the teeth model fixing pin with a sleeve and an end cap in use; and,
FIG. 9 is a reference figure of a front exploded perspective view showing the state of combining the teeth model fixing pin with a sleeve and an end cap in use.
The broken lines in the drawings form no part of the claimed design.