Locate the Object: September 2014 ANSWERS


Here is the answer for the September 2014 Locate the Object We will be going over both image shift and SLOB (Same-Lingual, Opposite-Buccal). .

Image shift

Before starting to use the image shift principle it is important to know/remember two key points

  1. Images move in the opposite direction from the movement of the source.
  2. Images of objects farther from the image receptor will move more (aka objects (images) more facial/buccal will appear to move more).

 

locate the object mesiodens september 2014 drgstoothpix

The first thing to do is pick a stationary object that is seen on both radiographs and appears to move in comparison to the supernumerary tooth. On these radiographs, we will use the left central incisor (#9). The most obvious angle change is the horizontal angle. Starting with the right lateral incisor/central incisor periapical radiograph and moving to the left central incisor/lateral incisor periapical radiograph, the source of radiation (tubehead) moves posteriorly increasing the horizontal angle.  According to point 1 above, this means the images move anterior.

Looking at the second radiograph (left central incisor/lateral incisor periapical radiograph), we need to compare the image movement of the supernumerary radiograph versus the left central incisor (#9) to see which object moved more anterior following point 2 listed above.

The left central incisor (#9) appears to be more anterior on the left central incisor/lateral incisor periapical radiograph meaning it is farther from the image receptor compared to the supernumerary tooth. This gives us an answer of the supernumerary tooth being to the lingual/palatal of the left central incisor (#9).

SLOB (Same-Lingual, Opposite-Buccal)

The first thing to do is again pick an object with a known fixed location – the left central incisor (#9).

The second thing to do is determine which direction we are moving from the right lateral incisor/central incisor periapical radiograph to the left central incisor/lateral incisor periapical radiograph and the answer would be – distal.

Lastly, on the left central incisor/lateral incisor periapical radiograph determine what direction the supernumerary tooth appears to have moved in relation to the left central incisor (#9) – distal. Here is where the acronym comes into play. Did the unknown object move in the SAME direction as the radiographs or in the OPPOSITE direction? Our answer is – same and the acronym states that same is lingual, so the supernumerary tooth is to the lingual of the left central incisor (#9).

Another case will be coming next month. If you have any questions or comments, please let me know below. Thanks and enjoy!

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