How is the Plaque Control Record score calculated?

• A. Total Surfaces / Plaque Surfaces x 100
• B. Debris Surfaces / Total Surfaces x 100
• C. Plaque Surfaces / Total Surfaces
• D. Plaque Surfaces / Total Surfaces x 100

Answer: (D)

The score is a percentage of tooth surfaces that have plaque. To calculate it, count how many surfaces show plaque and divide that by the total number of surfaces examined, then multiply by 100 to turn it into a percent. In practice, you typically use 28 teeth with 4 surfaces each (112 surfaces total, excluding third molars). So if plaque is present on 28 surfaces, the PCR would be 28 ÷ 112 × 100 = 25%.

This matches the idea of plaque surfaces divided by total surfaces, with the result expressed as a percent. The other approaches either swap the numerator and denominator, omit the multiplication by 100, or use debris instead of plaque.