Are Dental X-Rays Safe? and Other Questions about Dental X-Rays

Some of the most common questions we get at Menlo Park Dental Excellence have to do with dental x-rays: Are they safe? Why do I or my kids need them? And how often should I get them? These are great questions and we love how much you prioritize your health. The answers can get complex quickly, so we’ll do our best to cover the basics here.

Are Dental X-Rays Safe?

Let’s start with the most important question—safety. Both the Food & Drug Administration (FDA) and the American Dental Association (ADA) test dental x-rays to make sure they’re safe for patients of all ages. These governing bodies revise their guidelines when any advances in science and technology provide new methods to reduce exposure. Thanks to faster film speeds, digital X-rays, and protective aprons and thyroid collars, the X-ray of today is far superior to those of even just a decade ago. This applies to children, too. Today’s X-rays are so safe, in fact, that the amount of radiation a child is exposed to in an X-ray of the back molars is roughly equivalent to the amount of radiation they are exposed to in the environment on a daily basis.

Why Do You Need Dental X-Rays?

X-rays, also called radiographs, help your dentist spot conditions like decay, cavities, tooth position, infection and abscesses, bone cancer, salivary stones that they can’t see through a visual examination. X-rays are especially important for children because they are generally more susceptible to tooth decay than adults. The benefits of X-rays, which include diagnosing decay, pathology, or any abnormalities, far outweigh the risks of exposure to this minimal dose of radiation.

Table of Radiation Doses

Dental Radiation in Context

Radiation exposure associated with dentistry represents a minor contribution to the total exposure from all sources. The National Council on Radiation Protection and Measurements (NCRP) has estimated that the mean effective radiation dose from all sources in the U.S. is 6.2 millisieverts (mSv) per year, with about half of this dose (i.e., 3.1 mSv) from natural sources (e.g., soil, radon) and about 3.1 mSv from man-made sources.³ About half of the man-made radiation exposure is related to computed tomographic (CT) scanning. Dental radiographs account for approximately 2.5 percent of the effective dose received from medical radiographs and fluoroscopies (Table 1).⁴

Table 1. Effective Dose Exposures from Medical Examinations and Procedures^{5, 6}

Type	Average Effective Dose (Adults) in Millisieverts (mSv)	Equivalent Effective Dose (Adults) in Microsieverts (µSv)
Intraoral X-Ray	0.005 mSv	5.0 µSv
Dental panoramic radiography	0.01 mSv	10 µSv
Chest radiography	0.1 mSv	100 µSv
Dental computed tomography	0.2 mSv	200 µSv
Mammography	0.4 mSv	400 µSv
Upper G.I. tract radiography (including fluoroscopy)	6.0 mSv	6,000 µSv
Coronary computed tomography angiography	12 mSv	12,000 µSv

Radiation Exposure in Dentistry

Radiation dosage is expressed as effective dose, a term applied to the weighted sum of doses to tissues that are sensitive to radiation. This number is derived by calculation. Effective dose as a unit of measurement was devised by the International Commission on Radiological Protection in 1990, and the method of calculation was updated in 2007.⁷ Effective radiation doses for dental radiographic examinations are listed in Table 2.

Table 2. Effective Radiation Doses for Dental Radiographic Examinations^{7, 8}

Type of Exposure	Effective Dose (Adults) in Millisieverts (mSv)	Effective Dose (Adults) in Microsieverts (µSv)
Full mouth series – 18 images
With PSP storage or F-speed film and rectangular collimation	0.035 mSv	34.9 µSv
With PSP storage or F-speed film and round collimation	0.171 mSv	170.7 µSv
Bite wing (4 images) with PSP storage or F-speed film and rectangular collimation	0.005 mSv	5.0 µSv
Cone-Beam Computed Tomography
Dentoalveolar CBCT small and medium field view	0.011-0.674 mSv	11-674 µSv
Maxillofacial CBCT with large field of view	0.030-1.073 mSv	30-1073 µSv

Abbreviations: CBCT: cone-beam computed tomography; PSP: photo-stimulable phosphor

How Often Should I Get Them?

Your X-ray schedule depends on a number of factors, including your medical and dental history. Generally, patients without a history of cavities, dental disease, or gum diseases are recommended to undergo one set of X-rays every two years.
Adults and children with frequent cavities need to have X-rays in 6 months or a year in specific area for monitor progress of decay process. People with root canal therapy, crowns, and implants need to have annual X-rays to make sure recurrent disease are detected and treated early.

The best way to reduce the number of X-rays you need is to follow good oral hygiene like flossing and brushing right after you have a meal or sugary drinks at home and at school or work.