Invisible cavities

[Hazel]

Question for those who have worked with dental x-rays. I know it is possible to have inner cavities that cannot be seen through the tooth enamel. Do those cavities become visible when the x-ray is put on the screen where the dentist looks at it? If not, how does he know there are cavities there?

Just curious.

 

[GodMark2]

The short answer is yes, they do.

The long answer is that enamel, dentin, nerves, and cavities all absorb different amounts of X-ray radiation, causing the film to be exposed to more or less depending on the composition of the tooth. However, different amounts of material also affect the absorption (more material absorbs more) so the picture on the film is a composite of material and thickness. This means that there is a bit of expertise/interpretation involved. So, some dentists may see cavities that others miss on the same film (and vice-versa).

 

[Giordano]

I am not a dentist, so I do not know in theory if one can have a "cavity" without an opening to the enamel surface. But I think that the surface of teeth can be irregular enough that an opening on the surface (as opposed to a closed groove) can be very hard to judge by eye, whereas a space on the inside is much easier to detect on X-rays. This is probably related to GodMark2's answer.

 

[Hazel]

I am not a dentist, so I do not know in theory if one can have a "cavity" without an opening to the enamel surface. But I think that the surface of teeth can be irregular enough that an opening on the surface (as opposed to a closed groove) can be very hard to judge by eye, whereas a space on the inside is much easier to detect on X-rays. This is probably related to GodMark2's answer.

Thank you both. I do know - well, I've read it with explanation of why - you can have a cavity inside the tooth that does not show on the enamel at all. That said, you've answered my question. A space on the inside but not on the outside can be seen on X-rays. That's what I wanted to know.