The loop (38) of the gingiva holding string (32) forms two ends (34, 36) firmly coupled to the application handle (18). The abutting loop end parts close the loop, which is placed round the tooth, with the string deposited on the gum tissue. Then the loop is tightened by turning the handle and consequent string twisting. Then the loop is compressed between the tooth and the gum tissue. Pref. the handle is cylindrical and has a front face (20), on which the loop ends are fastened. The front face may contain an insert (26) and an enlarged recess (22) for the insert.