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ePaper created 2015-03-06, 09:14:48 | version 1.33.01
technology _ dental radiography I ducedintothedentalmarketplace.Ingeneral,they can be used with existing X-ray units. As a major benefit to dental patients, a significant decrease in radiation emission is required. Practitioners look- ing to update and upgrade their traditional (silver halide) radiographic systems have excellent clini- cal options. One of the most important selection criteria is the sensor-to-computer data transfer mode. Some digital chip sensors, such as the CCD (Charge Coupled Device) and CMOS (Complemen- tary Metal Oxide Sensor), are hardwired to the computer through a USB or utilise a Bluetooth connection.ThedigitalPSP(PhosphorStoragePlate) sensors (ScanX, Air Techniques, Melville, NY, USA) are wireless, and are most similar in appearance, function and convenience to traditional radio- graphic film. Wireless digital sensor technology (Fig. 1) is the most popular digital radiography process worldwide, with more than 50,000 den- tists having incorporated PSP into their practices. Thethreetypesofsensors,CMOS,CCD,andPSPare equivalent in terms of the data that they accumu- late per square millimetre during their very brief exposure to ionizing radiation, and then transfer to a digital image format. Sensordiagnosticsurfacearea Sensor dimensions are crucial to diagnostic utility.Thelargertheactivesurface(orimage)area, the greater the amount of information the sensor provides to the practitioner. A traditional size 2 film provides about 1,100 mm2 of diagnostic area. Similarly, a size 2 ScanX wireless digital sensor offers 1,080 mm2 of diagnostic area. Digital chip sensors typically have a smaller active area, pro- viding correspondingly less diagnostic informa- tion. There is a further complication for the wired chipsensorswithbitewingimages(Fig.2).Thesen- sor wire must be placed between the posterior teeth, preventing their complete intercuspation. Unlike a thin cardboard or plastic bitewing tab, the wire is 4–6 mm in diameter, leaving the teeth that distance apart. The resulting empty interocclusal space is non-diagnostic for dental structures, and in fact, prevents the effective imaging of the gingival areas and the crestal bone. This often necessitates a vertical reorientation of the sensor and/or more radiographs, requiring a greater radi- ation exposure for the patient (Fig. 3). Sensorthickness The thickness of the sensor can be a major bar- rier to patient comfort and proper positioning of the sensor. A traditional size 2 film, at approxi- mately 1.0 mm of thickness, can be rather uncom- fortable for some patients, particularly individuals with small mouths or conditions such as lingual tori. Wired digital sensors range from 5.5–8.3 mm in thickness. Their thickness makes them more dif- ficult position in the mouth and more difficult for the patient to retain comfortably. The ScanX wireless digital sensor is less than half as thick as a conventional X-ray film at 0.4 mm. Furthermore, unlike the rigid, wired sensors, the PSP sensor Figs. 4a & b_In some cases, effective imaging requires a greater radiation exposure for the patient. Fig. 5_ScanX wireless digital sensors are available in different sizes. I 41cosmeticdentistry 1_2015 Fig. 4a Fig. 4b Fig. 5 CDE0115_40-43_Freedman 26.02.15 10:39 Seite 2 CDE0115_40-43_Freedman 26.02.1510:39 Seite 2