System for protection of soft tissues against a teeth whitening substance

An appliance for controlling an application of peroxide or other teeth whitening substance to a user's teeth, the appliance comprising:

• a source of light;
• a system for directing the light from the source of light through an optical fiber within an active bristle on an appliance brushhead to a surface in the mouth which is either a tooth or a gum region;
• a detection system for determining a selected characteristic of a returning reflected light from the mouth surface via the optical fiber within the active bristle, wherein one aspect of the characteristic indicates that the returning reflected light is reflected from a tooth and another aspect of the characteristic indicates that the returning reflected light is reflected from a gum region;
• and
• a control circuit for (i) activating the tooth whitening substance if the characteristic is the one aspect, and (ii) not activating the tooth whitening substance if the characteristic is the another aspect, wherein the control circuit activates the tooth whitening substance by sending an electrical signal to an electrochemical active region on the (a) the active bristle, through which the returning reflected light is returned, or (b) a bristle fiber, adjacent thereto.