The functionality of CaviTAU®

CaviTAU® Basis- und Handgerät

Ultrasound based imaging has been a safe and minimally invasive technology in medicine since the 1940’s. CaviTAU® does not use the standard ultrasound technique, which evaluates the range or background of reflected sound signals, but instead picks up sound waves that remain after the sound has completely traversed the bone. This technique is based on the fact that sound penetrates dry and solid bone tissue faster than water (or liquid fat in fat cells) or softened bone tissue. Therefore, fatty-degenerative osteonecrotic and osteolytic osteopathies (FDOJ/“NICO”), with many hollow, air-filled cavities and dry and fibrous medullary changes can be detected with CaviTAU®. CaviTAU® is thus a safe and effective imaging test method for alveolar cancellous bone.

Quick detection and localization of cavitators

CaviTAU® relates to detecting and locating dental cavitations in jawbones using Through-Transmission Alveolar Ultrasonography (TAU). CaviTAU® generates an ultrasound pulse and passes the pulse through the jawbone. The pulse is detected and monitored subsequently by an ultrasound receiving unit. Attenuations of the amplitude of the pulse are indicative for pathological changes in the jawbone. The results are displayed on a color monitor, showing different colors according to different degrees of attenuation (Figure 1 and 2).

Figure 1: Detailed colour schemes of anatomical structures with different densities in new CaviTAU® in upper jawbone
Figure 2: Detailed colour schemes of anatomical structures with different densities in new CaviTAU® in lower jawbone
Figure 3: Figure 3 shows the new CaviTAU® dashboard, which is not explained in details here. Remarkable is the integration of patient`s actual OPG to ensure orientation during the enoral measuring. Each single area is enlarged and displayed on right upper for detailed interpretation of bone density. All 2D graphs can be presented in 3D format and tilted and zoomed.
Normally, ultrasound is reflected from the cortical bone (outer bone layer of the jawbone), so CaviTAU® operates at a specific frequency of 2.5 – 2.75 MHz to penetrate the cortex. CaviTAU® measures the attenuation in the speed of sound after the passage of the fatty-degenerative areas of a cavity bladder with osteolysis / osteonecrosis.

A computer evaluates the speed and strength of the generated sound after it has traversed the bone. He transforms the signal into a three-dimensional color-coded picture. Thus, the picture is color-coded to make the strength of the destruction understandable to the patient as well:

GREEN = Healthy and solid bone and tooth structures
YELLOW / ORANGE = Median stage of chronic fatty degeneration of pine osteitis
RED = Greasy dissolved jawbone with bacteria, and toxins and extreme RANTES / CCL5 expression

In contrast to the precursor model “Cavitat”, the construction of CaviTAU® is designed in such due to the fixed coplanarity of the transmitter – located outside the mouth on the cheek – and the receiver – on the tongue or palate side within the mouth – objectively created measuring results are achieved. A manipulation of the position of transmitter and receiver by the user is excluded. The measurement itself is painless and only takes a short time. The intensive use of gel masses in the mouth is no longer necessary with CaviTAU®.

In men, it is important that no beard is present.

CaviTAU® device in use
CaviTAU® device in use
CaviTAU® cross view
CaviTAU® cross view

Brief description of CaviTAU®

Figure 4 shows the embodiment of the CaviTAU® handhold: The thick round element on the left, located below, is the ultrasonic transducer 2 and the thin round element is the ultrasonic receiver 3. Two arms connect to the handle on the right. An electrical cable in the rightmost position connects to the processing unit (not shown).
Figure 4: CaviTAU® measuring unit

One part of the measuring unit, preferably the transducer is either on the outside somewhere on the cheek or inside on the buccal side of the mouth whereas the receiver is to be positioned on the lingual or palatal side. In both cases the position of transducer and receiver is well defined in a safe and simple way. In most cases the flexibility of the cheek is sufficient to equalize existing anatomical peculiarities and still to be able to achieve coplanarity; if not, it is possible to use a semi-solid gel. It should be noted that the deviations from coplanarity occur only in one dimension whereas for the Cavitat Ultrasonograph the deviations occur routinely in all three dimensions.

The Semi-Solid Gel in new CaviTAU®

A semi-solid gel is placed between receiver and alveolar ridge. The sound velocity in this gel should be in the same range as that of soft tissue i.e. 1460 – 1615 m/s and the gel should have a sound attenuation from 0,3-1,5 dB/cm (1 MHz) so that the acoustical measurements of the properties of the jawbone are not impeded. The haul-off speed for spontaneous resilience should be at most 80 mm/sec. Appropriate semi-solid gels must be soft, very resilient and very flexible so that a complete contact of the semi-solid gel with the receiver and the alveolar ridge can be secured; the absence of air bubbles within the semi-solid gel used can be checked by visual inspection. Because of the flexibility of the gel it is also possible to adjust the position of the measuring unit without disturbing the contact of the gel and without disturbing the measurements. The semi-solid property of the gel prevents that the gel disappears before or during the measurement. Semi-solid gels with such characteristics are commercially available, e.g. the Sonogel Sonokit soft, article number 6510 and 6520, marketed by Sonogel Vertriebs-GmbH in Bad Camberg, Germany. It is a styrenic block copolymer with a hydrogenated midblock of styrene-ethylene/butylene-styrene or styrene-ethylene/propylene-styrene and belongs to the compound class of thermoplastic elastomers. The semi-solid gel can be used as such and is inserted between receiver and alveolar ridge to perform the measurements. For this purpose a block of the gel is cut at the narrow side to create a little pocket into which the receiver can be inserted; the use of a very small amount of a lubricant, e.g. the formerly used ultrasonic gel or water facilitates the insertion of the receiver. After elimination of any air bubbles between the receiver and the semi-solid gel the measuring unit is ready for use. In case of complicated anatomical conditions it can be reasonable to use the semi-solid gel on the cheek, i.e. outside of the mouth, as well. This works well for the mandibula, whereas for the maxilla some practical skills are necessary to keep the gel in place. The size of the piece of the semi-solid gel used should large enough to safely cover all relevant parts needed for the measurements. For hygienic and for economic reasons the use of single-use covers is provided which advantageously keep the measuring device reusable. Furthermore, the single-use cover does not interfere with the flexible properties of the media used and therefore, as often found in ultrasonic measurements, a non-elastic but flexible plastic film is used, being filled inside with a very small amount of a suitable lubricant, e.g. a usual ultrasound gel so that the measuring device can move freely inside of the cover. The use of a further single-use cover is not essential when the flexible cover itself is used as a single-use article. In new CaviTAU® one or more light-emitting diodes (LEDs) are provided in order to improve the position recognition of the receiver (see Figure 5).
Figure 5: LEDs at the enoral ultrasonic receiver

Calibration and functional test

The arrangement of the measuring unit in a defined geometry allows an easy test of the functionality and calibration of the apparatus. Immersing completely the measuring unit in water, gradually moving the unit through the surface of the water and finally placing the unit entirely in air, while continuously sending ultrasonic signals through the unit, allows the assessment of the functionality of the apparatus. Water and air give very different signals and their expected occurrence, particularly when the measuring unit is moved through the boundary between water and air, allows the proof of the correct functioning of the piezoelectric elements. This check should be performed every time before use.

Detailed Description of new CaviTAU®

New CaviTAU® comprise a flexible strip configured to measure a force applied to at least one of the arms and wherein CaviTAU® is configured to provide an indication of the measured force by visual and/or audible means. By preferably locating a flexible strip in the arm of the apparatus coupled to the ultrasonic receiver, this prevents excessive force from being applied to the gel interface between the ultrasonic transducer and ultrasonic receiver. In response to the measured force exceeding or falling below one or more predetermined thresholds, CaviTAU® is configured to provide an indication according to the value of measured force.

CaviTAU® comprises a multiplexer or means configured to multiplex the analogue signal data generated by the ultrasonic receiver. The amplification means and/or the multiplexing means is preferably located in the arm to which the ultrasonic receiver is coupled and in close proximity to the ultrasonic receiver in order to improve signal-to-noise ratio i.e. to reduce error.

CaviTAU® comprises a transmitter or means to transmit the multiplexed analogue signal data to a discrete main unit that is separate from but associated for further processing of the signals. Due to the multiplexing, the number of transmission means from the apparatus to the main unit is beneficially smaller than the number of active piezoelectric elements in the ultrasonic receiver. By multiplexing the analogue signal data received simultaneously from a plurality of all the active piezoelectric elements (e.g. 96 elements), in a wired example i.e. when the transmission means comprises a plurality of cables, the apparatus advantageously reduces the number of cables required for transmitting the preprocessed signal data to the main unit (e.g. 8 cables as opposed to 96) and thereby enables serial transmission and processing of the signal data.

CaviTAU® transmits the amplified and multiplexed analogue signal data to a main unit associated with the apparatus concurrently with digitalising the signal data; partially processing the digital signal data; storing the partially processed signal data in a memory; and transmitting the partially processed digital signal data to a software application for final processing and subsequent transmission to a display unit associated with the apparatus.

CaviTAU® includes a step of displaying the further processed data by associating different signal strengths with at least one of: a grayscale comprising different tones, one or more colour schemes (see Figure 1 and 2) comprising different colours and a graph, preferably wherein signal data for unproblematic zones are displayed with reduced coloured areas whilst data indicating peculiarities are displayed as large areas. By providing one or more grayscale/colour schemes, this aids a user with recognition of relevant data. Furthermore, displaying the signal data in a form of graph enables quick analysis. Such a graph can be presented in 3D format (see Figure 3).

More informations about CaviTAU®