In combination a mouth guard and a temperature sensor which includes a plastic molded mouth guard including a mouth portion, a bite portion and a gum shield. The mouth guard molded with a dispersion of an over temperature color plastic and a normal color plastic, such that the mouth guard displays a combination of the normal color and the over temperature color. The normal color plastic contains a thermo chromatic ink based coloring which transforms the normal color portion of the dispersion to second color at a preselected transformation temperature. The transformation temperature is selected to indicate over heating of the human body by transformation of the mouth guard from the combination of the normal color and the over temperature color to a combination of the second color and the over temperature color.
