The Truth About Digital Dental Sensors

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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.

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.