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There is a lot of
confusion regarding intraoral digital dental sensors technology.
We thought it would be helpful to educate doctors on dental sensors in the
market.
Sensor Design
All current generation sensors use the same general components in an
assembly that is essentially a sandwich. The components that make up the
“sandwich” are: 1) Scintillator (the best are CSi cesium iodide) this
converts the xray photons to light that the sensor can recognize. 2) FOP
– fiber optic plate – This filters the light and directs it to the sensor
3) CMOS sensor – its pixels are aligned in a grid to absorb the light
according to the density of the substance that the photons are
penetrating. 4) Analog to digital convertor which converts the pixel well
information to digital information that the computer translates into an xray.
In the design of this
“sandwich” some manufacturers have put the A to D convertor in a separate
module attached to the sensor (SuniRay2, Schick 33) while others have put
all of the components into the head of the digital dental sensor
(e.g. Dexis, Gendex, E2V).
Inactive Area
All sensors have some degree of inactive area as the case that encloses
the digital dental sensor does not allow edge to edge imaging. Some
digital dental sensors have a little more or a little less inactive area.
Having less casing means more active area but it means less internal
cushioning and more likely hood of a drop on a hard surface causing
internal damage. This is a known trade-off in sensor manufacturing
because the closer the internal sensor dimensions are to the external case
dimensions the less cushioning can be used to protect the sensor.
USB Connection
If you are getting a sensor that terminates in a USB Male connection
than you definitely want to use a 6″ USB extension to preserve the
life of the original USB connector. USB Male which is the terminating plug
on about 80% of today’s sensors has a connect/disconnect life of 1500
cycles. If you are not using an extension you will eventually wear out the
factory plug. Some digital dental sensor manufacturers do not offer a
repair or replacement (e.g Dexis) so you want to preserve that connection
from day one. Extensions can be purchased on Amazon for less than $3 each.
It will be the best and cheapest way to preserve the life of the sensor.
Sensor Failure
The most common sensor damage, when the sensor looks perfect on the
outside, is compression damage to the internal components of the sensor.
If you plan on taking occlusal xrays on kids makes sure that a cotton
roll or stick is placed in the molar region so the child cannot bite on
the face of the sensor. The sensor face can deflect enough (with biting
pressure) to compress the internal components and ruin the sensor. A drop
on a hard surface can cause cracking of the FOP or delamination of the
internal components. It is imperative that every staff member is aware of
the fragile nature of sensors to insure proper handling.
Another common failure point is where the cable meets the sensor.
Proper positioning and the use of holders will greatly reduce failures
from cable malfunctions. Always make sure that the cable is exiting the
mouth without being bitten on. Also, avoid flexing the cable in awkward
positions that put undue stress on the cable. Most sensors today have the
possibility for cable replacement but it is a significant cost. Also, the
sensor needs to be opened up, so there is no guarantee that the cable
replacement will not cause other issues. The best bet is to make sure that
every staff member understands correct positioning.
Proper Exposure
In testing many different sensors with a testing phantom designed for
objective comparison, I can say that when today’s sensors are properly
exposed and filtered there is not a significant diagnostic difference from
one to the next.
Price
Despite there not being a significant difference in design, durability,
or warranty, there is a significant difference in price. The big supply
house digital dental sensors (Schein – Dexis, Patterson Schick 33 &
Carestream – RVG Sensors) are $10K 12K per sensor. Dental
imaging technology companies (Dental TI, Masterlink, Sota, ImageWorks and
others) sell sensors that average between $4900 – $5900.
Sensor Manufacturer
There are just a handful of manufacturer’s that make digital dental
sensors and internal components for all the sensors on the market. All
sensors manufactured by E2V out of France are the EXACT same. The
exception being the XDR sensor that has a slightly different case design.
These sensors that are the EXACT same (BelSensor Gold, DreamSensor, Clio,
QuickRay) with the only difference being the name on the case.
Image Quality
Image quality is influenced by many factors but the three most
important are: 1) Correct xray exposure each head should have different
settings for anterior and posterior xrays and small and large patients.
2) Correct and consistent positioning. Maintaining consistent distance as
well as a perpendicular relationship (whenever possible) between the beam
and the sensor face will give the most consistent results. 3) Post
processing filters to adjust contrast/brightness and sharpness to the
preferences of the end user.
Imaging Software
A good starting point in narrowing the sensor field is determining the
imaging software that you will be using. Software like Apteryx’s
XrayVision 4 allows for the use of nearly any digital dental sensor on the
market. Other software will limit connection unless the sensor offers a
twain driver. One sensor, the Clio Sensor, offers native integration into
Dexis 10. If you are not locked into a particular software you can download
a 30 day fully functioning trial from Apteryx. You can use the software to
compare different sensors that you may be considering. You will be able to
test the results that you get from each sensor in your office.
Some dealers will send a sensor for this kind of evaluation.
X-Ray Heads
If you have older AC xray heads you probably will sacrifice a little
image quality. Newer DC heads can deliver a more optimal exposure than
older heads. If you are in doubt of the quality of your existing heads it
is a good idea to get assurance from the vendor prior to making the
investment in digital dental sensors. In general lower KV works better
with digital xray as it returns more gray scale information.
These are some of the considerations that we at Masterlink recommend taking into account when “going digital”. If your office would like assistant or has questions about going digital. Please feel free to give our office a call at 1.800.672.5733.
