How much radiation exposure is in a 3-d digital dental ct scan?

CBCT Scan: See the following website for some basic information. It depends upon particular brand of unit, software, and extent of area scanned. The office actually doing the scan can give you more accurate information. Call and ask. http://www.dent.umich.edu/patients/cbct-imaging-service-frequently-asked-questions#radiation

Relatively low: Much less than the normal background exposure you would be exposed to spending 2 days in the mountains.