My wife just had a panoramic x-ray at the dentist and he forgot to use a shield. shes nervous now, whats the chances of that causing a problem later?

Very little risk: It occurred over and over there is room for concern but a one time occurrence with the low rads this type of xray uses she will be fine. I hope this helps her feel better.

Virtually Zero: Do not worry, your wife will be just fine.

X-ray without shield: Assuming she was not in the early stages of pregnancy likely minimal risks. Remember 99% of the x-ray beam follows in a straight line from the x-ray tube/source to the film target. There is minimal backscatter and thus potential for exposure. See http://www.xrayrisk.com/calculator/calculator-normal-studies.php She can type in her age and see what her risk might be

Minor error: The error was fortunately minor and thankfully no harm will come because of it. Dental X-rays are very safe with minimal radiation and maximum resolution.

Virtually none: Very low dosage. Less radiation than from airplane flight, or a day in the mountains, or two on the beach. Beam is collimated and directed, therefore not exposing radiation sensitive tissues. Filtration reduces back splatter. Discuss your concerns with the Dentist, but greater risk of injury from a fall in the bathroom.