As a dental hygienist & founder of this group, I wanted to clarify some confusion.

Dr. Oz's recommendation was thyroid shield for dental x-rays & not recommended for mammography.
Mammograms are a very important screening tool against breast cancer.
The information that was left with our group after Dr. Oz's show was that the amount of radiation received to the thyroid without a shield was more beneficial than having the thyroid shield obstruct any possible breast cancer lesion.
Here is the link: http://www.snopes.com/medical/toxins/thyroidguard.asp
“If the thyroid guard blocks the tail end of breast tissue near the axilla (arm pit) or deep tissue abutting the chest wall, your mammogram could not show a small cancer (or make it easy to miss.)
If you are worried, discuss the pros and cons with your physician.