Is there a great amount of radiation to one's body when having a cone beam ct done for dental work? can a cbct be taken again during a 2nd opinion?

CBCT scans: The radiation for a cbct is greater than some imaging techniques and less than others. 'great' is a subjective term. When needed, the cbct scan is extremely helpful in making a diagnosis. There is no reason to take a second one as long as the first one is satisfactory which is almost a given. You can get a copy on a disk and take it with you when you go for the second opinion.

Usually not : Most modern dental cone beam ct's deliver between one and ten times the amount of natural background radiation we receive daily. Often cbct will reveal pathology not obvious on conventional 2d x-rays.

Variable: The radiation exposure during cbct varies on the machine used and the area being evaluated. Small field of view is preferred over larger fields, front teeth require less exposure than back teeth, upper teeth less than lower, in general. Many machines are very low risk to over exposure, and a second scan may very well be worth it. Cbct imaging is a valuable way to address your situation.

Relatively little: Cbct produce a fraction of the radiation produced by medical cat scanners. While one should recurve the least amount of radiation possible, if a second cbct is necessary i see no harm in taking it. As for affecting the whole body, the radiation is strictly confined to the head.