A radiographic infrabony defect described as '2-wall infrabony' involves how many osseous walls?

• A. One wall
• B. Two walls
• C. Three walls
• D. Four walls

Answer: (B)

Infrabony defects are described by how many osseous walls still surround the defect. A 2-wall infrabony defect means that two walls remain intact around the defect while the other two walls have been lost to bone resorption. The base of the defect sits apical to the crest, and the defect is specifically bounded by those two remaining walls. Therefore, the radiographic description of a 2-wall infrabony defect corresponds to two osseous walls.

If only one wall remained, it would be a 1-wall defect; if three walls remained, it would be a 3-wall defect. A four-wall description isn’t typically used for infrabony defects, as the standard patterns involve up to three walls around the defect.