How does a dentist tell whether you need a root canal?

Teeth Whitening in Dallas

it depends on a whole lot of things.
for example, when a cavity is very very close to the pulp, your dentist might suggest a root canal instead of a filling. on an xray, the cavities are shown as a slightly darker part on the tooth, and the pulp is the dark shade inside the tooth
(i found a picture on the internet, the arrows indicate the cavity:)

Teeth Whitening in Dallas

if the cavity is too deep or the bacteria reached the pulp..

Teeth Whitening in Dallas

if the decay when to the pulp its darker on x-ray

Teeth Whitening in Dallas

x ray

Teeth Whitening in Dallas

There are mulitple ways that a dentist can determine whether a tooth needs root canal.
From symptoms, a patient may have any of the following symptoms: constant pain, pain the linger, pain when biting on the tooth, gum swelling around the tooth.
From an X-ray: it may show a cavity reaching the nerve of the tooth, or infection at the end of the root of the tooth (appears as a dark area around the root)

Richmond Hill Dentist

Teeth Whitening in Dallas

They have lots of expensive equipment silly! I don't know, but my dentist does, and that's good!