Radiographic Interpretation of Dental Caries (Lecture 4)

What percentage of the total effective radiation dose in the US population in 2006 came from dental radiographs?

Only 0.26%, which is a very small dose.

How much radiation dose do dental radiographs contribute?

Just 0.007 mSv, a minimal amount compared to total exposure.

What are the effective radiation doses for common dental and medical exams?

Full-mouth survey with round collimation, D-speed film: 388 μSv;

Full-mouth survey with round collimation, PSP: 171 μSv

Full-mouth survey with rectangular collimation, PSP: 35 μSv

- just by changing from round --> rectangular, this ensures that there is no wasted radiation as the film is rectangular

Bitewings with rectangular collimation, PSP: 5 μSv

Panoramic: 9-24 μSv

Skull plain film: 70 μSv;Chest plain film: 20 μSv.

What is the position and distance rule?

Stand at a 90-degree or 135-degree angle from the x-ray beam and maintain a distance of at least 6 feet.

What is the fastest image receptor to reduce radiation exposure?

F-speed film or digital.

How does collimation reduce radiation exposure?

Collimating the beam to the size of the receptor, especially rectangular collimation, reduces exposure by fivefold.

What protective gear helps reduce radiation exposure?

Protective aprons and thyroid collars.

How can radiation exposure be minimized during imaging?

By limiting the number of images to the minimum necessary for essential diagnostic information.

When should radiographs be taken?

Only when needed.

What radiation dose should be used?

The lowest dose for needed information.

Why do radiographs need to be done right the first time?

To avoid retakes and extra exposure.

What is important after taking radiographs?

Proper processing, mounting, and complete interpretation (you need to document what you see in every radiograph)

What determines radiographic shades of grey?

Different mineralization levels absorb different amounts of x-ray photons.

What does more mineralization indicate on a radiograph?

More absorption, appearing RADIOPAQUE, representing sound tooth structure.

What does less mineralization indicate on a radiograph?

Less absorption, appearing RADIOLUCENT, representing unsound tooth structure.

What does ALARA stand for? What is ALARA a guidance for?

As Low As Reasonably Achievable.

Guide for radiation safety.

What are the three basic protective measures in ALARA?

Time, distance, and shielding.

What should you do in a radiation emergency?

Use time, distance, and shielding to protect yourself and your family.

What is the radiographic appearance of proximal caries?

Radiolucency just cervical to the proximal contact.

What is the radiographic appearance of occlusal or incisal caries?

A radiolucent zone beneath a pit or fissure.

What is the radiographic appearance of buccal or lingual caries?

A well-defined circular radiolucency that appears "through" the tooth.

What is cervical burnout and how can it be distinguished from caries?

Cervical burnout is an optical illusion that appears as a smooth, diffuse radiolucent band at the neck of the tooth due to decreased x-ray absorption.

It can be distinguished from caries by its symmetrical appearance and location, whereas caries appears more defined, irregular, and typically just below the contact point.

What is E0 or R0 in radiographic presentation of the approximal surface?

No radiolucency

What is E! or RA1/ E2 or RA2/ D1 or RA3 in radiographic presentation of the approximal surface?

Radiolucency may extend to the dentinoenamel junction or outer one third of dentin

Radiographs are not reliable for mild occlusal lesions

What is D2 or RB4 in radiographic presentation of the approximal surface?

Radiolucency extends into the middle one third of the dentin

What is D3 or RC5 in radiographic presentation of the approximal surface?

Radiolucency extends into the inner one third of the dentin