globally a positive or negative polarization corresponding to evoked times but it is interrupted by reversed polarity allowing the molecules to circulate into the tooth and eventually to emerge from steric or electric dead ends in fig8 according to a variant the thermal rise is brought about not by an electric resistor but by a circulation of water or any type of thermal vector in conduits 60 which pass through the gutter 1 by penetrating through an opening 67 and leaving through another one 68 this vector can be a liquid or a gas such as hot air it is obvious that this mounting does not impede the addition of the electrophoretic field in the example shown in this figure and corresponding to a possibility of implementation of the invention the field is carried by the gutter 1 itself which is made out of conductive material and the connection 27 28 can be seen under the conduits of the thermal vector the diagram of fig9 illustrates the successive operating steps in the case the molecules responsible for the coloring of the tooth are of positive loaded the non activated product is placed in a standard gutter 69 or made to measure the principle of activation or of acceleration of the.