What was the furcation measurement observed in the 68-year-old patient?

• A. 3 mm
• B. 1 mm
• C. 5 mm
• D. 0 mm

Answer: (A)

The key idea here is what furcation measurement tells us about bone loss between roots. When a periodontal probe is placed into the furcation area of a multi-rooted tooth, a reading of 3 millimeters means there is about three millimeters of horizontal bone loss entering the furcation from the crest. That level of involvement is considered moderate: more than a mild, 0–1 mm reading, but not yet a severe, 5 mm or greater loss.

In a 68-year-old patient with periodontal concerns, this 3 mm furcation reading explains why cleaning the furcation is more challenging and why the tooth may require more advanced management (such as targeted debridement, possible surgical access, or regenerative considerations) to support long-term prognosis. If the reading were 0 mm, there would be no furcation involvement; 1 mm would be milder involvement; and 5 mm would indicate more extensive, likely advanced furcation loss.