Dentistry/mysterious boundary in x-ray of molar
The attached image shows my tooth #19 twice. The picture on the left is unaltered, and the one on the right highlights some places where the texture of the image changes abruptly. I think I understand some of those texture changes, and one I don't.
I believe I understand the places highlighted in light green and orange. The two roots shown in the image are each double roots with what one dentist called a figure 8 loop structure. I believe the area between the orange line and the light green line represents the back loops (i.e., the parts of the figure 8s farthest from the x-ray camera).
This would explain why they are darker than the rest of the tooth in the image: there is more bone between them and the camera. It makes perfect sense.
However, I don't think that explanation works very well for the yellow border. At least not to my satisfaction. It just doesn't look right. Notice how close the yellow border is to the root canal and how irregular the bottom half is. (The actual border is more irregular than my yellow highlight indicates.)
If it represented the same thing as the orange border (just on the other side), then the back loop (of the left root) appears behind the front loop on both sides of the front loop. Geometrically, that could only happen if the front loop was much smaller than the back loop.
That doesn't seem right. Maybe I'm vain, but I don't believe my tooth is so misshapen that it would have a figure 8 structure that would lead to that yellow border. I think that yellow border represents something else.
When I asked my dentist, he just vaguely talked about camera angles. What does that yellow border indicate to you? Is it something to worry about?
You are looking at a 2D image of a 3D object . Everything looks ok .
The shadows you see are superimposed since the x ray beam is penetrating the tooth from one direction and hitting the sensor plate as a flat capture. The different lines you see represent the shape of the root.