Bitewing actually refers to the paper or plastic piece that is attached at right angles to a dental x-ray film packet in the form of a wing, while taking an x-ray. The patient bites at the paper structure between his /her teeth so that the film is held vertical inside the teeth. However, in informally, bitewings may refer to x-ray images so obtained.
Bitewings provide a convenient and safe means of holding the film inside the mouth of a patient without the operator or patient having to hold it in place. Further, the chance of a shake in the hands spoiling the x-ray image is also eliminated because the film is held static with respect to the teeth. Thus a very sharp image can be obtained. Bitewings radiography can get sharp images of crowns of top and bottom teeth together in one slide. Bitewings x-ray images are used for detection of caries, monitoring their progression, evaluation of existing restoration, and evaluation periodontal status.
Detection of caries requires overexposure, while assessment of progression demands under exposure. Also, safety demands the exposure be kept to a minimum acceptable level. Hence, exposure settings may be a compromise. Similarly, the frequency of x-ray exposure has to be weighed between patient need and radio exposure safety. A complete examination of the molars and premolars will require use of four slides (two on each side) for adult patients, while for children a two slides may be enough.
Films for bitewing x-rays are available in sizes of 22 x 35 mm, 31 x 41 mm, and 53 x 26 mm. Use of tabs as wings has advantages of simplicity, economy, and disposability. But there are some disadvantages. The tongue can displace the film. Conventional radiographs are not accurately reproducible, as positioning can vary. Use of film holders overcomes this disadvantage.