What is furcation involvement, and how is it clinically and radiographically assessed?

• A. Involvement of the area between tooth roots; probed with a periodontal probe; radiographs show radiolucent areas between roots.
• B. Involvement of the tooth crown due to enamel defects; observed only on radiographs.
• C. A fracture line through the tooth crown seen on bitewing radiographs.
• D. A lesion on the gingival margin unrelated to roots.

Answer: (A)

Furcation involvement is the loss of supporting bone in the area where the roots diverge on a multirooted tooth. It is assessed clinically by gently inserting a curved furcation probe (such as a Nabers probe) into the space between the roots to determine whether there is attachment loss and how deep the involvement is. Radiographically, you look for radiolucent areas between the roots on the film, which indicate bone loss in the furcation region. Keep in mind that early furcation changes may not be obvious on standard radiographs because of how the roots overlap, so angled or specialized views can help reveal the involvement.

The other descriptions don’t fit furcation involvement: a crown enamel defect describes a surface crown issue; a fracture line through the crown is a crack of the crown itself; a gingival-margin lesion not related to the roots wouldn’t reflect bone loss between roots.