Two main types of digital systems are available today:
DR systems include a “sensor” and software, and are used with an existing dental X-ray machine and computer. The sensor is connected via USB cable to a computer, and is placed in the patient’s mouth and positioned like ordinary dental film. (show image of the X-Ray generator and a film in a dog’s mouth like in positioning guide) The largest sensor size currently available approximates the size of #2 dental film. Images are viewed in seconds, and may be digitally manipulated to heighten detail and minimize re-takes. The sensors are the most expensive part of the system, and although they are quite durable, care must be taken to prevent damage.
CR systems involve the use of “phosphor screens”, which look similar to ordinary dental film. After exposure, the screens are fed into a scanner, which gives you an image in around one minute. The phosphor screens are exposed to bright light to erase the prior image, and can be re-used hundreds of times. This type of system is more expensive, but does have the advantage of being able to produce larger #4 films.
The chart below compares various features of DR and CR systems. DR systems are currently more popular due to the speed with which you can obtain images.
|System Type||Hard Wired Sensor (DR)||Phosphor Screen (CR)|
|Sensor used||Hard wired sensor (CCD or CMOS) attached to the USB port of the computer||Radio-sensitive screens in plastic sleeves|
|Number of use until replacements||Indefinite||300-600 uses, then must be replaced|
|Time until sensor/plate can be used again||Sensor is automatically ready in 1-10 seconds||Screen must be “erased” using bright light, then placed into new sleeve|
|Sensor sizes available||Correspond to #0 and #2 dental film. No #4 sensor at this time. Some teeth require >1 view||Correspond to #0, #2, and #4 dental film. #4 screen allows larger teeth to be imaged in one view|
|Time until images can be viewed||A few seconds||60-90 seconds to remove plate from packet, feed film through scanner and replace screen into packet|
|Quality of image||Excellent but can vary depending on the particular system||Excellent|
|Total system cost||$6,000 - $15,000 Plus computer||Aprrox. $13,000 Plus computer|