Abstract: The method for joining a metal foil with a synthetic material foil comprises unwinding both materials from a supply roll each, and subjecting the synthetics foil, prior to the application of an adhesive, to a corona discharge on a narrow border region. The metal foil and the synthetic material foil are then pressed together and irradiated by ultraviolet radiation causing polymerization of the adhesive. The composite foil material thus obtained is transferred to a further processing station. There the dental matrix can be punched out of such a composite sheet material, having a high tensile strength, whose metal portion can easily be inserted between two adjacent teeth whereas the transparent synthetic material part allows light curing of the dental filling material.

Abstract: The cup to be used as a paste carrier for dental hygienic consists of a rubber elastic material and can be driven for rotation by a hand piece. The cup comprises a paste receiving part, the inner side enlarging towards its open edge as well as the outer side of the cup enlarging towards its open edge comprising spiraled ribs which are running in the opposite direction to the rotational direction of the hand piece. The structure on the inner side of the paste receiving part allows a continuous supply of paste and a cooling of the cup, and the structure of the outer side of the cup prevents a bale formation of the mucous and guarantees an effective cooling of the cup.

Abstract: In a tensioning gripper with a ring and a coaxially arranged rotary pin, both the ring and the pin are provided with a slot suitable for receiving a matrix to be tensioned. The slot of the rotary pin has a symmetry plane parallel to the longitudinal axis of the rotary pin. The sides of the slot are composed by two angled portions which are arranged symmetrically on both sides of the symmetry plane and both portions converge towards the longitudinal axis of the rotary pin, the two vertices of the portions being opposite and adjacent one another. Such a slot allows easy introduction and gripping of the matrix until, by rotating the pin, the matrix is held and tensioned.

Abstract: A flexible spindle suitable for transmitting a torque as well as an axial thrust is constituted by a plurality of helical spirals of wire all of the same length. Each spiral has opposite winding directions to the winding direction of the adjacent spirals and the outer diameter of each spiral is equal to the inner diameter of the spiral which surrounds it. The terminal ends of the spirals are assembled integrally with each other and with the terminal ends of a flexible member situated inside the innermost spiral. Each sprial has a length which is equal to that of the other spirals as measured along their axis when these are in their bent operating position and under those conditions under which they are designed to transmit torque and thrust, with the flexible spindle resulting not to be radially or longitudinally deformable when under stress, thus transmitting the forces without loss.

Abstract: The ablator is made with synthetic resins reinforced so as to resist the mechanical stresses of flexion and abrasion. The resins are reinforced with metallic or non-metallic fibers totally incorporated in them, and are reinforced against wear due to abrasion by a modification in their surface molecular structure by means of a process of ionic implantation or similar procedures. Preferably, the synthetic resins used belong to the group of polyarylamides which exhibit better characteristics of mechanical resistance and of the duration of the sharpened edge of the ablator.