In a hyperplasia scenario with probing depth 4 mm and tissue coronal to CEJ 1 mm, CAL is

• A. 3 mm
• B. 4 mm
• C. 1 mm
• D. 5 mm

Answer: (A)

Clinical attachment level is the distance from the CEJ to the base of the pocket. Here the gingival margin sits 1 mm coronal to the CEJ, so the distance from CEJ to the gingival margin is -1 mm. The base of the pocket is 4 mm apical to the gingival margin, so CAL = (-1) + 4 = 3 mm. Put another way, you subtract the coronal offset from the probing depth. So the CAL is 3 mm.