The present invention relates to a method for reducing or eliminating loss of minerals from the enamel and dental hypersensitivity against temperature changes, in particular when caused by the bleaching of teeth with products containing hydrogen peroxide or other oxidizing agents. The output of one mixer is coupled, so as to form a feedback path, to a frequency divider circuit whose first output is coupled to the second input of the first mixer. The frame is arranged by at least one cross component formed out of sheet metal into a box-type structure, the cross component extending substantially across the entire width of the web. The insert is formed by standard sintering practices, followed by the chemical removal of the binder phase from the surface and near surface regions of the insert. In yet another embodiment, a semiconductor memory device can include a memory array with amplifiers that include dual-gate transistors, as well as associated calibration circuitry. The outside surface of the front neck portion and the outside surface of the extension shaft are now the adhesive surface for the dual step insert, which is adhesively coupled into the arrow shaft.