http://www.medscape.com/viewarticle/779091
Medscape Medical News
New Dental X-ray Guidelines Spell Out Radiation Reduction

Laird Harrison
Feb 11, 2013

Dentists who ignore the new American Dental Association (ADA) and US Food and Drug Administration (FDA) guidelines on radiography may be putting their patients at unnecessary risk, experts told Medscape Medical News this week.

Published in November 2012, the guidelines update the ADA-FDA's 2004 recommendations and, for the first time, offer detailed methods for limiting patients' exposure to radiation.

"As practitioners we need to follow the ADA-FDA guidelines because it is the right way to treat our patients," John Ludlow, DDS, a professor of oral radiology at the University of North Carolina, Chapel Hill, told Medscape Medical News in an email. "It's the way that I would want (and ask) to be treated as a patient."...
Also note this comment at the end of the article:

Some dentists also mistakenly believe that they have lowered their patients' radiation dose simply by shifting from film to digital radiography, said Allan G. Farman, BDS, PhD, MBA, DSc, a professor of oral and maxillofacial radiology and imaging at the University of Louisville, Kentucky, who was not involved in revising the guidelines.

"It's possible with [complementary metal-oxide-semiconductor] and storage phosphate to overexpose the patient," he told Medscape Medical News. "Digital does not always mean less radiation. If improperly used, it can mean higher doses."