In the sagittal plane, which sign corresponds to an anterior crossbite?

In the sagittal plane, which sign corresponds to an anterior crossbite?

• A. Deviation of midline
• B. 1/3 coverage of the lower incisors
• C. Vertical inocclusion
• D. Anterior crossbite

Answer: (D)

In the sagittal plane, an anterior crossbite is defined by the upper front teeth biting behind the lower front teeth, producing a negative overjet. Clinically you’d see the lower incisors ahead of the uppers when the jaws are closed. This reversal of the normal front-to-back relationship is the hallmark of an anterior crossbite. The other signs point to different aspects of occlusion: deviation of the midline describes sideways misalignment of the dental arches, not the front-to-back relationship; the degree of vertical overlap (for example, one-third coverage of the lower incisors) describes overbite rather than sagittal crossbite; and vertical occlusion relates to the vertical dimension between teeth, not the anterior crossbite itself.

In the sagittal plane, an anterior crossbite is defined by the upper front teeth biting behind the lower front teeth, producing a negative overjet. Clinically you’d see the lower incisors ahead of the uppers when the jaws are closed. This reversal of the normal front-to-back relationship is the hallmark of an anterior crossbite.

The other signs point to different aspects of occlusion: deviation of the midline describes sideways misalignment of the dental arches, not the front-to-back relationship; the degree of vertical overlap (for example, one-third coverage of the lower incisors) describes overbite rather than sagittal crossbite; and vertical occlusion relates to the vertical dimension between teeth, not the anterior crossbite itself.