What is the diameter range for soft toothbrush bristles?

• A. 0.16 to 0.22 mm
• B. 0.23 to 0.29 mm
• C. 0.30 mm and greater
• D. 0.12 to 0.15 mm

Answer: (A)

The main idea is that bristle diameter largely determines how soft a toothbrush feels and how gently it cleans. Softer bristles come from thinner filaments, which bend more easily and distribute brushing pressure more evenly, reducing irritation to developing teeth and gingiva. The diameters commonly cited for soft nylon bristles fall around 0.16 to 0.22 millimeters, which provides effective cleaning while keeping tissue contact gentle—ideal for children.

If bristles are thicker, around 0.23–0.29 mm or more, they become firmer and can be harsher on enamel and gums, increasing the risk of trauma. Conversely, diameters much smaller than 0.16 mm tend to be extra-soft and may wear out more quickly or feel less effective. Thus, 0.16–0.22 mm best matches the balance of gentle tactile sensation with adequate cleaning in pediatric use.