The invention relates to a dental composition comprising a hardenable powder to be used in a process for retraction of dental tissue. The described coupling method employs infrared signals communicated along a nano-scale resonant semiconductor waveguide between for example PIN diode signal transducers. There is a connection electrically connected to outputs of the transformer to provide power at the second voltage level. A resistor applies the second rectified voltage to a first capacitor that stores the first voltage.