How can they no?

how can doctor tell whats wrong beside your tooth befor he does a xray ?How can they no?
there are external signs.
because within amazing
training and experience.
They can tell because in attendance are signs and symptoms that the dentist can be pretty sure. Then when the x-ray is taken it's just conformation. Also it's time and experience
Did you close-fisted "know"? Jeez...
Apparently the Dr. could actually see what be wrong with the tooth, or he used dental instruments to check the tooth. X-rays are done to be capable of see between the teeth, under filling, and root & bone structure (to name a few).
There are usually just a few possibilities for certain symptoms. They do the xray to confirm their diagnosis and to form sure there are not a hint other problems (i.e. if they have to do a wadding they need to sort sure the decay have not gone to the nerve).