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Radiographic Technique for Difficult Maxillary Third Molar Views
Radiographic technique for difficult maxillary third molar views Myron J. Kasle, DDS, Indianapolis
A satisfactory m axillary th ird molar radiograph is obtained by positioning the X-ray cone superior to the zygomatic arch and posterior to the m axil lary tuberosity in an oblique angle.
A satisfactory maxillary third molar periapical radiograph may be difficult to obtain in some pa tients. The palate may be too short anteroposteriorly to accommodate a type 2 intraoral film packet. Placement o f the film for this exposure according to the conventional technique may re sult in a radiograph such as Figure 1, left, which is adequate for the examination o f the first and second but not the third molars. In the technique we recommend, the open-end X-ray cone is positioned superior to the zygo matic arch and posterior to the maxillary tuber
osity with a vertical angulation o f + 3 0 ° . The central X-ray beam is directed perpendicular to the film surface and passes through the mandibu lar sigmoid notch. The exposure factors used are 70 kilovolt (peak), 15 ma at two seconds exposure with ultra-speed film. The resulting radiograph (Fig 1, right) clearly reveals the third molar which is only partially visible in Figure 1, left. The technique is described: An overview shows the cone position superior to the zygomatic arch (Fig 2, top). The central ray passes through the sigmoid notch projecting the third molar on the film. Figure 2, bottom, shows a closeup view o f the zygomatic arch and sigmoid notch with the film and film holder in position. A lateral-infe rior view shows the film and tooth relationship (Fig 3, top), and an inferior view shows the oblique angle formed by the film and the m axil lary third molar (Fig 3, bottom). This technique is used to obtain a satisfactory view o f the entire maxillary third molar. Impact-
Fig 1 ■ Left: View o f m axilla ry th ird m olar after placem ent o f film in conventional technique. Right: Radiograph taken w ith recommended technique clearly shows th ird molar. 1104 ■ JADA, Vol. 83, November 1971
Fig 3 ■ Top: Lateral-inferior view shows relatio n sh ip o f film and th ird molar. Bottom.- In fe rio r view shows o b liq u e angle. Fig 2 ■ Top: Overview of cone position. Bottom: Closeup view o f zygomatic arch with film in position.
ed or unerupted third molars are viewed in their entirety although the first and second molars are grossly overlapped and distorted. This is due to the fact that the radiograph is taken from the distobuccal and not the buccal surface aspect.
Appreciation is extended to Dr. R. A. DeCastro for th e art work. Doctor Kasle is an assistant professor, departm ent o f ra diology, Indiana U niversity-Purdue U niversity at In d ia n apolis School o f Dentistry, 1121 W Michigan St, In d ia n apolis, 46202. Kasle: RADIOGRAPHIC TECHNIQUE ■ 1105
A satisfactory m axillary th ird molar radiograph is obtained by positioning the X-ray cone superior to the zygomatic arch and posterior to the m axil lary tuberosity in an oblique angle.
A satisfactory maxillary third molar periapical radiograph may be difficult to obtain in some pa tients. The palate may be too short anteroposteriorly to accommodate a type 2 intraoral film packet. Placement o f the film for this exposure according to the conventional technique may re sult in a radiograph such as Figure 1, left, which is adequate for the examination o f the first and second but not the third molars. In the technique we recommend, the open-end X-ray cone is positioned superior to the zygo matic arch and posterior to the maxillary tuber
osity with a vertical angulation o f + 3 0 ° . The central X-ray beam is directed perpendicular to the film surface and passes through the mandibu lar sigmoid notch. The exposure factors used are 70 kilovolt (peak), 15 ma at two seconds exposure with ultra-speed film. The resulting radiograph (Fig 1, right) clearly reveals the third molar which is only partially visible in Figure 1, left. The technique is described: An overview shows the cone position superior to the zygomatic arch (Fig 2, top). The central ray passes through the sigmoid notch projecting the third molar on the film. Figure 2, bottom, shows a closeup view o f the zygomatic arch and sigmoid notch with the film and film holder in position. A lateral-infe rior view shows the film and tooth relationship (Fig 3, top), and an inferior view shows the oblique angle formed by the film and the m axil lary third molar (Fig 3, bottom). This technique is used to obtain a satisfactory view o f the entire maxillary third molar. Impact-
Fig 1 ■ Left: View o f m axilla ry th ird m olar after placem ent o f film in conventional technique. Right: Radiograph taken w ith recommended technique clearly shows th ird molar. 1104 ■ JADA, Vol. 83, November 1971
Fig 3 ■ Top: Lateral-inferior view shows relatio n sh ip o f film and th ird molar. Bottom.- In fe rio r view shows o b liq u e angle. Fig 2 ■ Top: Overview of cone position. Bottom: Closeup view o f zygomatic arch with film in position.
ed or unerupted third molars are viewed in their entirety although the first and second molars are grossly overlapped and distorted. This is due to the fact that the radiograph is taken from the distobuccal and not the buccal surface aspect.
Appreciation is extended to Dr. R. A. DeCastro for th e art work. Doctor Kasle is an assistant professor, departm ent o f ra diology, Indiana U niversity-Purdue U niversity at In d ia n apolis School o f Dentistry, 1121 W Michigan St, In d ia n apolis, 46202. Kasle: RADIOGRAPHIC TECHNIQUE ■ 1105