. : When to take dental X-rays

What are the benefits of taking dental radiographs (x-rays)?

Dental radiographs can help the dentist evaluate, monitor and definitively diagnose oral conditions and diseases as well as to follow the development and the progress or prognosis of dental tissue. However, the decision for the dentist to take dental x-rays must weigh the benefits of taking dental x-rays against the risk of exposing the patient to dental x-rays. Present technology allows the dentist to use digital imaging that can reduce the radiation dose by 40-60 percent.

In 1987, FDA announced the guidelines to minimize the x-ray exposure to the dental patient titled, “The Selection of Patients for X-Ray Examination.” A panel of dental experts convened by the Center for Devices and Radiological Health of the United States create these guidelines. Later, the American Dental Association, in collaboration with some dental specialty organizations and the FDA, published the updated guidelines in 2004 and revised them in 2012.

These guidelines are not a substitution for clinical examinations, patient’s signs, symptoms and oral and medical histories. This diagnostic information can help determine the type and frequency of dental conditions. Dentists should only prescribe dental X-ray when additional diagnostic information benefits the patients.

How often do you need to have dental radiographs (x-rays)

According to American Dental Association (ADA), the prescribing of dental radiographs is subject to the clinical judgment of a dentist to each patient. The dental x-rays are to be used only after reviewing the patient’s health history and completing a clinical examination by a dentist. Even though, radiation exposure from dental x-rays are small; it is the dentist's responsibility to follow the ALARA Principle (As Low As Reasonably Achievable) to minimize the patient's exposure.

American Dental Association does not recommend dental radiographic screening for the purpose of detecting disease before clinical examination. Instead, prior to an x-ray, ADA recommends:

A thorough clinical examination
Review the patient dental history
Examine past radiography
Determine caries risk assessment
Consideration of both the dental and the general health needs of the patient

See guidelines tables, a revised version in 2012 below (click the table to enlarge).

Recommendations for prescribing dental radiographs: source American Dental Association (click the table to enlarge)

Summarize and a brief explanation of recommendation for prescribing dental radiographs (x-rays)

Child with baby teeth (primary dentition)

When Decay develops between a contact point of posterior teeth, the closed proximal contact between the teeth prevents the dentist to examine dental decay visually. In this case, radiography assessment is necessary. However, there is evidence that dental decay will remain in the dental enamel for at least 12 months or longer depending on fluoride exposure of an individual. This extensive period of developing decay in the enamel allows sufficient time for the dentist to implement and evaluate the tooth.

The guideline suggests using;

A periapical/occlusal dental radiographs for anterior teeth
Bite-wing dental radiographs for posterior teeth if the proximal surface cannot be visualized. For patients with open contact and have no evidence of dental decay, the bitewing dental radiographs are not necessary.

In high-risk patients, if the dentist can not examine the proximal surface for dental decay, a posterior bite-wing x-ray recall is recommended at 6 to 12-month intervals. High-risk patients are those who have poor oral hygiene, frequent diets that contain sugar, and deficient fluoride intake are more likely to have proximal decay.

Note: a patient’s caries risks status may change over time and that an individual’s radiographic recall interval may also change accordingly.

For low-risk children without evidence of dental caries, and proximal surfaces of posterior teeth cannot be examined visually or with a probe, a posterior bitewing dental x-rays is recommended at 12 to 24 months interval.

A child with mixed dentition (baby teeth and permanent teeth )

The guideline suggests using;

Posterior bitewings to detect dental decay.
Panoramic x-rays to evaluate craniofacial trauma and dental development.
Selected periapical x-rays to evaluate the detailed structure of the tooth and surrounding tissues.
Occlusal radiographs used separately or in conjunction with panoramic radiographs to localize tooth position and confirm pathological occurrence

Recall x-rays intervals are the same as a child with baby teeth.

Adolescent with permanent dentition (16-19 years)

There is a need, at this period, to assess the dental and skeletal relationships to diagnose and treat malocclusion and the presence and development of third molars. Radiographic assessment can best be made by the use of selected periapical or panoramic x-rays.

The guideline suggests using;

Posterior bite-wings to detect dental decay
Panoramic x-rays to evaluate the status of dental development, dental diagnosis and treatment planning
Occlusal or periapical x-rays to detect supernumerary tooth or unerupted tooth
Full mouth periapical x-rays to determine the extensive of dental and periodontal disease

Recall x-rays for at-risk patients; the intervals are the same as a child with baby teeth.

Recall x-rays for patients who are free of clinical dental caries and not in a high-risk group should have bite-wing x-rays every 18 to 36-month. On average, the caries process takes more than three years to progress through the enamel. However, evidence suggests that the enamel of permanent teeth undergoes post-eruptive maturation are susceptible to faster progression of dental caries.

Adults with partially edentulous (loss some permanent teeth)

The guideline suggests using;

Posterior bitewings to detect dental decay.
Panoramic x-rays to evaluate the status of dental development, dental diagnosis and treatment planning
Occlusal or periapical x-rays to detect supernumerary tooth or unerupted tooth
Full mouth periapical x-rays when there is clinical evidence of extensive dental or periodontal disease

High-risk patients recall x-rays: posterior bitewing radiographs at 6 to 18 months intervals.

Low-risk patients who receive regularly dental care and are free of signs and symptoms of the oral disease, a recall bitewing dental radiographs will be 24-36 month intervals.

Adults with edentulous (loss all permanent teeth)

An initial assessment for prosthetic treatment;
Full mouth periapical x-rays or a combination of panoramic x-rays, occlusal and other extraoral x-rays is recommended The data suggest that patients who already received continuous dental care do not exhibit new findings that require treatment. Therefore, no recall radiographs are recommended.

For patients with clinical sign of periodontal disease

A recall dental x-rays, e.g., bitewings or periapical x-rays help to find the stage of periodontal disease. Use clinical judgment to determine the need and type of dental x-rays necessary for periodontal treatment evaluation.

Some of the clinical findings that dental radiographs are required include: