Which size of image receptor is rarely used in dental practice?

The size of image receptor that is rarely used in dental practice is size 3. This size is larger than other common receptor sizes and is generally considered less practical for typical dental imaging needs.

Typically, sizes 0 and 1 are frequently used for pediatric and adult bitewing radiographs, respectively, as they fit comfortably in the mouth and provide adequate diagnostic information. Size 2 is the most commonly used receptor in dentistry, as it is versatile for various types of radiographs including periapical and bitewing images.

In contrast, size 3 is primarily designed for specific applications and is often regarded as impractical for routine use due to its larger dimensions, which can make positioning more difficult and uncomfortable for patients. Size 4 is primarily used for extraoral imaging, such as panoramic radiographs, and is not typically used for intraoral imaging. Consequently, size 3 is not commonly found in the dental practice repertoire, which is why it is considered the rarest in regular application.