Abstract: The method provides a means for a dentist to record the shape in situ of teeth prepared for repair. During a search mode, a high resolution grey scale image is presented on a monitor. The scan head is positioned over the prepared cavity, using this visual feedback. A trigger initiates actual 3D data acquisition, which is accomplished in a fraction of a second using an active triangulation principle. The result is stored in congruent memory banks in the form of a 3D profile and a pseudoplastic grey scale image representing the back-scattered contrast. The pseudoplastic contrast image is displayed instantaneously on the monitor. The point to point relationship between the pseudoplastic grey scale image and the 3D profile allows use of the grey scale display as a drawing plane for operator data verification and editing.

Abstract: A method and apparatus for machining a custom-shaped dental restorative part from a blank of dental material yield the entire part in a single operation, and include a workpiece being mounted on a support member which facilitates rotation and axial movement of the workpiece. A separating disk is used for almost the entire machining operation, and an additional tool in the shape of a burr can optionally be provided to shape more elaborate pieces. The disk and burr are supported by a tool holder which is supported for movement parallel to and rotationally about an axis. The disk and burr are powered by a closed loop fluid supply arrangement. A tool velocity sensing scheme is utilized for adaptive feed and to compensate for tool wear. The machining mechanism and associated control circuitry are enclosed in a common cabinet so as to provide a mobile unit suitable for use in a dentist's office.

Abstract: A blank adapted for use in custom fabrication of an implant for dental restoration includes first and second joined parts. The first part is made of the raw material of the ultimate implant, whereas the second part can be made of a different material. The second part is shaped to facilitate a positive support of the blank in a milling machine, and is preferably equipped with a code-bearing surface which permits information about the physical properties of the blank to be sensed by the machine. In a preferred realization, the first part is made from ceramic silica and the second part from aluminum, and the two are bonded by an acrylic glue.

Abstract: The surface characteristics of an organ that needs restoration, for example, a tooth which has been prepared for an inlay insertion, are read by means of a noncontact scan-head. The three-dimensional shape parameters of the implant required to restore the tooth in function and appearance are computed on the basis of the recorded contour data. These parameters are then used in a program sequence which controls a milling, cutting or erosive process in order to manufacture the restorative inlay while the patient waits.

Abstract: A scanner includes a scan head having a linear array of transducers Xn, and a transmitter 106 which excites the transducers in response to transmit signals TRn from a reference generator 110 so that the transducers emit a plurality of successive bursts of ultrasonic energy, each burst producing a transmitted beam which is steered and focused along a radially-extending scan line. To effect received beam steering and focusing, received signals Sn from the transducers are supplied to a processor 112 along with associated in-phase binary reference signals bn(R) and quadrature binary reference signals bn(I). The received signal is multiplied by a reference signal and the product is integrated for a specific time duration whose time occurrence is used to steer and focus the beam.

Abstract: An identification plate of gold alloy is inserted in a small blind hole drilled into the crown of a tooth. The hole is then filled with a durable filler which hardens around the plate to embed it in a durable, heat resistant filling. The filling material can be colored so that it is readily located when identification is desired. For making the identification, the filler is dissolved away to leave the plate, which can be read by means of optical magnification.Also disclosed is an electrical device especially adapted for providing plate blanks with the desired identifying information.

Abstract: A method and apparatus for determining a change of the flow state of a flowable substance by transmitting ultrasonic or ultrasound waves of constant frequency to a spatial region of the substance, receiving ultrasonic waves backscattered by the substance, converting the backscattered ultrasonic waves into a primary signal which is amplitude- and phase-modulated in accordance with the backscattering and demodulating the primary signal in order to obtain a modulation signal. This modulation signal can be divided into a spectrum of signal components of different frequency and possessing pseudo periods which are defined as the time intervals between successive momentary values of the modulation signal, such momentary values corresponding to one another. The time duration corresponding to a predetermined number of pseudo periods is compared with a predetermined time duration.

Abstract: A method of, and apparatus for, testing the hardness of a material by means of an impact device wherein an impact body having a test tip or point which is either integrated, e.g., connected with, or separate from, the impact body is brought to impact against the material to be tested. There is determined the velocity of the impact body and/or the test tip both directly before and after impact, and there is then formed a characteristic value from both velocities which is utilized as criterion for the hardness of the material.