1. Bitewing radiography

2. Main indications Detection of interproximal caries
Monitoring the progression of dental caries
Assessment of existing restorations
Assessment of the periodontal status

3. Ideal technical requirements
The bite-platform should be positioned on the middle of the film packet and parallel to the upper and lower edges of the film packet
The film packet should be positioned with its long axis horizontally for a horizontal bitewing or vertically for a vertical bitewing\

4. The posterior teeth and the film packet should be in contact or as close as possible
The posterior teeth and the film packet should be parallel- the shape of the dental arch may necessitate two separate film positions to achieve this requirement for the premolars and the molars
In the horizontal plane, the X-ray tubehead should be aimed so that the beam meets the teeth and the film packet at right angles, and passes directly through all the contact areas I

5. In the vertical plane, the X-ray tubehead
should be aimed downwards approximately
5 to 8 degrees to the horizontal to compensate for the upwardly rising curve of Spee
The positioning should be reproducible

6. Positioning techniques
Using a tab attached to the film packet and aligning the X-ray tubehead by eye
Using a holder with beam-aiming device to facilitate the positioning and alignment of the X-ray tubehead

7. Film holders

8. Basic components of film holders
A mechanism for holding the film packet parallel to the teeth
A bite platform that replaces the wing
An X-ray beam-aiming device

9. The appropriate size film is selected as follows:
Large film packets ( 31*41mm ) for adults
Small film packets ( 22*35 mm ) for children under 12 years. Once the second permanent molars have erupted the adult size film is required

10. The patient is positioned with the head supported and occlusal plane horizontal
The operator holds the tab between thumb and forefinger and inserts the film packet into the lingual sulcus opposite the posterior teeth
The anterior edge of the film packet should be positioned opposite the distal aspect of the lower canine- in this position, the posterior edge of the film packet extends usually just beyond the mesial aspect of the lower third molar

11. The tab is placed on to the occlusal surfaces of the lower teeth
The patient is asked to close the teeth firmly together on to the tab
As the patient closes the teeth, the operator pulls the tab firmly between the teeth to ensure that the film packet and the teeth are in contact

12. The operator releases the tab
The X-ray beam is aimed directly through the contact areas, at right angles to the teeth and the film packet, with an approximate 5-8 degrees downward vertical angulation
To ensure that the anterior part of the film is exposed the front edge of the cone should be positioned adjacent to the corner of the mouth

13. Advantages of using film packets with tabs
Simple
Inexpensive
The tabs are disposable, so no extra cross- infection control procedures required
Can be used easily in children

14. Disadvantages
Operator-dependent assessment of horizontal and vertical angulation of the X-ray tubehead
Radiographs are not reproducible
Cone cutting is common
The tongue can easily displace the film packet

15. Advantages of film packet holders
Simple
Film packet held firmly in position and cannot be displaced by the tongue
X-ray beam is always at right angles to the film packet
Avoid cone cutting
Holders are autoclavable

16. Disadvantages
Positioning of the film holder can be uncomfortable for the patient
Some holders are relatively expensive
Holders are not suitable for children

17. Ideal exposure factors
Assessment of caries and restoration-high kV which ensures good contrast to allow differentiation between enamel, dentin and allow EDJ to be seen
Assessment of periodontal status- low kV to avoid burn-out of the thin alveolar crestal bone
In the X-ray machines with fixed kV and mA these results are achieved through exposure time