PSR Code 0 criteria include which of the following?

• A. Bleeding present, no calculus, PD below black band <3.5mm
• B. Bleeding present, calculus present, PD above black band >3.5mm
• C. No bleeding, no calculus, PD below black band <3.5mm
• D. Bleeding present, calculus present, PD below black band <3.5mm

Answer: (C)

PSR uses a WHO probe with a black band marking 3.5–5.5 mm. Code 0 is given when there is no bleeding on probing, no calculus, and the deepest probing depth is 3.5 mm or less (i.e., below the black band). The description of no bleeding, no calculus, and a probing depth below the black band fits this exactly, indicating a healthy sextant. If any of those signs were present—bleeding, calculus, or a deeper pocket—the code would be different (bleeding without calculus and shallow depth would be a code 1; calculus present or depth in the 3.5–5.5 range would be code 2; depth over 5.5 mm would be code 3).