When taking radiographs using film the white side of the film is always placed?

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Graduate Assistant at Texas A&M University

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1. 1. 0 Bitewing Technique The following slides describe techniques used in taking bitewing films. In navigating through the slides, you should click on the left mouse button when you see the mouse holding an x-ray tubehead or you are done reading a slide. Hitting “Enter” or “Page Down” will also work. To go back to the previous slide, hit “backspace” or “page up”.
2. 2. Patient Preparation Prior to starting to take films, the patient must be positioned properly. Seat the patient and ask them to remove their glasses and any removable partial dentures or orthodontic appliances. Adjust the headrest to support the head while taking films. Raise or lower the chair to a comfortable height for the operator. Place the lead apron and thyroid collar on the patient. You are now ready to begin taking films. It is a good idea to inform the patient about the number of films you will be taking so they know what to expect, especially when doing a full-mouth series.
3. 3. Bitewing Technique
4. 4. Bitewing Film This film gets its name from the tab (“wing”) that the patient bites on to hold the film in place. The bitewing film is used for the detection of interproximal caries and the condition of the alveolar bone. This film shows the crowns of both the maxillary and mandibular teeth and a portion of the roots. A premolar film and molar film are normally taken on each side for a total of four posterior bitewing films.
5. 5. Head Position The head is normally positioned so that the maxillary arch is parallel to the floor and the midsagittal plane (MSP) is perpendicular to the floor. This is a definite requirement when using bitewing tabs to hold the film in position; it is not as important when using the Rinn Bitewing Instrument. MSP head supported by headrest
6. 6. Bitewing Film Placement Tabs The traditional method of bitewing placement uses tabs. The tab in the photo below left is attached to a sleeve through which the film is inserted. The disadvantage to this type of tab is that the film can move forward or backward as the patient closes. The preferred type of tab, below right, sticks to the white side of the film and does not allow the film to move during closure.
7. 7. Bitewing Film Placement Bitewing Instrument The Rinn Bitewing Instrument pictured below is frequently used instead of tabs. The instrument facilitates placement and the ring insures correct alignment of the PID.
8. 8. Rinn Bitewing Instrument Instrument set-up The prongs on the bar are aligned with the holes in the biteblock and the two are attached. The ring is placed on the bar so that it is centered on the biteblock.
9. 9. Rinn Bitewing Instrument Before placing the film in the biteblock, the film should be bent gently around a finger (white side down, long axis in line with finger).
10. 10. Rinn Bitewing Instrument Place the film, white side facing ring, under one tab, centered front to back, and then gently place the opposite edge of the film under the other tab. The film may curve slightly away from the ring. The location of the identifying dot on the film is not important.
11. 11. Rinn Bitewing Instrument Make sure the all-white side of the film is visible through the ring (White-in-sight). You are now ready to place the film in the mouth. This set-up works for both sides of the mouth (Instrument does not need to be changed).
12. 12. Bitewing Technique Film Position (Same for tabs or Rinn BW instrument) The premolar bitewing film is approximately centered on the 2nd premolar; the front edge of the film should be at least in the middle of the canine. The molar film is centered on the 2nd molar if the third molars are present. The long axis of the film is horizontal. The position of the film dot doesn’t matter; it will be beyond the crowns of the teeth on the film. long axis premolar molar (3rds)
13. 13. Bitewing Technique Film Position If the third molars are not erupted into the mouth, it is not necessary to position the film to cover the third molar region. It is better to move the film slightly forward, centered on the contact between the first and second molars. This gives you duplicate information in the second premolar/first molar areas, which may aide in making a diagnosis in these areas. molar (no 3rds)
14. 14. Bitewing Technique Film Placement It is important to always start with the premolar bitewing. This allows apprehensive patients or those with active gag reflexes to somewhat get used to the film before proceeding to the more posterior molar film. Both films on one side should normally be completed before moving to the other side. However, if a patient has problems with gagging on the premolar film, I recommend immediately going to the other side and taking the premolar film. Once the two premolar films are taken, you can attempt to take the molar films.
15. 15. Vertical Angulation (with tabs) When the film is positioned in the mouth, the upper portion of the film is angled approximately +20° as it contacts the palate. In the mandible, the film is upright (0° angle). The average between these two angles is +10°. This +10° is the vertical angulation selected when using bitewing tabs. +20º 0º
16. 16. Vertical Angulation (with tabs) Adjust tubehead so that the 10° mark is opposite the position guide. The 10° setting may be above or below the zero mark, depending on which way the tubehead is rotated around the supporting yoke (see photos middle and right below). The PID must be angled downward for all positive angulations; if it is angled upward it is a negative angulation. 10° position guide
17. 17. Make sure the maxillary arch is parallel to the floor and the midsagittal plane is perpendicular to the floor before aligning the tubehead. In the photo below left the PID is angled downward at 10 degrees as recommended, but the patient’s head is tipped to the side. Rotating this same picture (below right) to position the maxillary arch parallel to the floor (dotted line) shows that the true angle of the PID is upward in relation to the film. This will give a distorted image. +10°
18. 18. Vertical Angulation (with instrument) When using the Rinn BW instrument, align the PID with the ring. This automatically aligns the x-ray beam with the correct vertical angulation, no matter how the head is positioned.
19. 19. Horizontal Angulation (with tabs) The horizontal angulation is adjusted so that a line connecting the front and back edge of the PID (yellow line below) is parallel with a line connecting the buccal surfaces of the premolars and molars (green line below). The x-rays will then pass straight through the contact areas between the teeth. The front edge of the PID should be ¼” anterior to the front edge of the film to keep the beam centered on the film. correct incorrect
20. 20. Horizontal Angulation (with instrument) When using the Rinn BW instrument, align the PID with the ring. This automatically aligns the x-ray beam with the correct horizontal angulation, assuming the film was positioned properly in the mouth. (See following slide).
21. 21. The film should be equidistant from the teeth in an anterior- posterior direction (the distance from the front edge of the film to the lingual surface of the teeth should be the same as the distance from the back edge of the film to the lingual surface of the teeth). The film should be positioned in this manner for both the premolar and molar radiographs. This helps to avoid overlap (see “Errors”). correct incorrect incorrect
22. 22. When aligning the PID, have the patient “smile big” with their teeth together; this allows you to see the buccal surface of the posterior teeth when using tabs. When using the Rinn instrument, this helps you make sure the patient is biting completely, not just tightening their lips around the instrument. The center of the x-ray beam (dotted line) should be directed at the occlusal plane; this centers the beam top to bottom.
23. 23. Where teeth are missing, it is often necessary to use a cotton roll to help support the tab or instrument. Position the film in the mouth and then slide the cotton roll into the edentulous area. Make sure the cotton roll does not rest on top of the occlusal surface of the teeth that are present. cotton roll
24. 24. In the film at left, a cotton roll was not used and the tab and film dropped down into the edentulous area, resulting in a tipped film. In the film at left, a cotton roll was used, keeping the tab and long axis of the film parallel with the occlusal plane.
25. 25. 0 Another thing to consider when there are edentulous areas is to position the bitewing tab forward or backward on the film so that the tab comes in maximum contact with the teeth that are present. In the premolar placement below, the tab was moved forward for maximum contact with the mandibular premolars. For the molar film, the tab would be moved toward the back end of the film to contact the 2nd molar.
26. 26. The film may be angled in the mouth to facilitate anterior placement when using the tabs. As long as the horizontal angulation is aligned properly, the teeth will not be overlapped. When using tabs, make sure the film clears the palatal gingiva as the patient closes to keep the film from being pushed down into the mandible.
27. 27. 0 If lingual tori are present, the film must be placed lingual to the torus (both with tabs and the instrument). When using tabs, it is often helpful to attach another tab to the one attached to the film; this lengthens the portion you hold on to, making it easier to position the film more toward the tongue and lingual to the torus. film torus extra tab extra length tab on film
28. 28. Bitewing Films 0 Premolar Bitewing: covers Molar Bitewing: covers both premolars, first molars molars. In this patient, and at least a portion of with no third molars, the second molars. film was positioned too far posteriorly.
29. 29. Bitewing Films If third molars are not erupted into the mouth, the molar film should be positioned more anteriorly, as seen above. Make sure ¼” of film extends posterior to second molar so that the distal aspect of both upper and lower second molars, including the bone, can be seen.
30. 30. Bitewing Films In some patients, one film may cover all posterior teeth if the third molars are not present. This can often be determined during film placement or by looking at previous films. If you’re not sure, take both premolar and molar films.
31. 31. Bitewing Films If the first premolars are missing (often seen with orthodontic patients) and the third molars are not present, one bitewing per side is enough.
32. 32. Bitewing Films If it is determined that bitewing films are needed on a patient that is completely edentulous in one arch, a complete denture may be left in the mouth to help support the bitewing tab or bitewing instrument. The maxillary complete denture is used in the film above.
33. 33. Vertical Bitewing For the routine bitewing film, the long axis of the film is horizontal (side-to-side). In patients with advanced periodontal involvement, the bone loss may be so extensive that it does not show up on the normal bitewing. For these patients, some dentists prefer to have the bitewing film positioned with the long axis placed vertically (up-and-down). This is called a vertical bitewing. long axis
34. 34. Vertical Bitewing Two bitewings (premolar and molar) are normally taken on each side posteriorly, just as with regular bitewings, for a total of four posterior films. If indicated, vertical bitewings can also be taken in the anterior region. A total of three anterior films would be used: one centered on the midline to show the incisors and one on each side to image the canine regions. right right right incisor left left left molar premolar canine canine premolar molar
35. 35. Vertical Bitewing Vertical bitewing films can be taken using tabs or a bitewing instrument, just as with regular bitewings. The vertical angulation is +10° with tabs; the PID is aligned with the ring when using the instrument. The horizontal angulation is determined in the same manner as it is with regular bitewings. The object is to open the contacts between the teeth on the film.
36. 36. Bitewing Technique Errors The following slides identify some of the most common errors seen when using the bitewing technique.
37. 37. Overlap If the horizontal angulation is not aligned correctly, so that the x-rays pass through the teeth contacts at an angle, the contact areas will be overlapped (see arrows on film below). Overlap is the superimposition of part of one tooth with part of the adjacent tooth (dotted circles below left). The red arrow represents the direction of the x-ray beam; the x-ray beam should be perpendicular to the dotted line below. (See discussion of horizontal angulation on earlier slide).
38. 38. Overlap Sometimes overlap is unavoidable due to the malposition of some teeth. One or more teeth may be more buccal or lingual than the adjacent teeth, resulting in crowding and changing the angle of contact between these teeth. The arrow in the film below points to an example of this type of overlap. If the majority of contacts are open on a film, with only a few areas overlapped, this would not be considered an error.
39. 39. Improper Film Placement Improper film placement is a common error seen in the bitewing technique. In the premolar film below left, the film was placed too far back, cutting off the mesial of the first premolar. In the molar bitewing, below right, the film was not back far enough, cutting off the distal aspect of the third molars.
40. 40. Improper Film Placement If the top edge of the film contacts the palatal gingival ledge, the film may be pushed down into the floor of the mouth as the patient closes. This results in a bitewing that looks more like a periapical film, as seen in the two films below. This is more likely to happen when using tabs.
41. 41. Cone Cutting If the x-ray tubehead is not positioned properly, the x-ray beam may not cover the entire film. This is known as conecutting, which results in a clear (white) area on the film where the silver halide crystals were not exposed to x-rays (see films below). In the diagram below right, the dotted circle represents where the x-ray beam should have been positioned; the solid circle shows the actual position of the x- ray beam (too posterior).
42. 42. Patient Movement If the patient moves or opens the mouth slightly during exposure, a blurred or distorted image may result. The film below was produced when the patient opened the mouth partway through the exposure. It looks similar to a double exposure.
43. 43. Reversed Film 0 If the tab is placed on the colored side of the film or the film is placed in the bitewing instrument with the colored portion facing the ring, the lead foil in the film packet will be between the teeth and the film. This results in the pattern stamped on the lead foil appearing on the film (see small dark squares on right side of film below). The film will also be lighter than the other films taken at the same time.
44. 44. Unnecessary Films The patient below has no second or third molars on the right side. The premolar film is all that is needed on this patient. The patient received uneccessary exposure by taking the molar film. M PM
45. 45. Unnecessary Films This patient had a complete upper denture and a lower partial denture which replace all the molars on the left side. This film showing only denture teeth should obviously not have been taken.
46. 46. Full Mouth Series The paralleling and bisecting angle techniques are used to take periapical films and have nothing to do with the bitewing technique. When taking a full mouth series on a patient with a full compliment of teeth, four bitewing films are normally taken. These are combined with 15 periapicals (# 1 films used anteriorly) when using the paralleling technique or 14 periapicals (# 2 films used anteriorly) when using the bisecting angle technique. Paralleling full mouth series of periapicals + 4 bitewings = 19 films Bisecting angle full mouth series of periapicals + 4 bitewings = 18 films

When exposing a dental film the white side of the film packet faces the tube?

Where should the anterior edge of the film be placed in the mouth when taking a premolar bitewing?

In which position is the film placed in relation to the tooth during the paralleling technique?

In which position is the film placed in relation to the tooth during the bisecting angle technique?