Image Number 2 for United States Patent #5658149.
A device is described which is useful for providing a dedicated access channel to the root canal of a tooth. The device, which is the frustum of a cone, has a hollow interior passageway adapted to receive and loosely accommodate the shank of a standard assortment of endodontic files. The vertical length of the cone is approximately 10 mm to 15 mm. The wider end of the conical device has an outer diameter of approximately 2.5 millimeters. In practice, the orifice of a root canal is exposed by drilling an access cavity. An appropriately sized endodontic file is selected which will fit within the orifice of the canal. The conical device is slid over the endodontic file until the wider end of the cone is adjacent to the file handle. The file tip is then inserted into the root canal, and the conical device is slid down the shaft of the file until it is brought to bear against the floor of the access cavity with the narrow end of the conical device juxtaposed to the exposed orifice of the root canal. A projected canal matrix material is carefully injected around the endodontic file and the entire access cavity is filled with a suitable self-curing matrix material, such as glass ionomer, to the biting surface. After the matrix solidifies, the file and conical device are removed leaving a conical access channel to the canal orifice.