How far into soft tissue can a topical anesthetic generally reach?

How far into soft tissue can a topical anesthetic generally reach?

• A. 1-2mm
• B. 2-3mm
• C. 3-4mm
• D. 4-5mm

Answer: (B)

Topical anesthetics work by diffusing from the surface into the mucosa to reach the nerve endings that lie close to the surface. In oral soft tissues, this diffusion is limited by the epithelial barrier and by blood flow that quickly removes drug, so the anesthesia produced is confined to the superficial layers just beneath the mucosal surface. This shallow penetration is enough to numb the surface for minor procedures, but it doesn’t reach deeper tissues, which is why deeper anesthesia requires injections or nerve blocks. So the expected effect is a superficial, near-surface numbness rather than a deep one.

Topical anesthetics work by diffusing from the surface into the mucosa to reach the nerve endings that lie close to the surface. In oral soft tissues, this diffusion is limited by the epithelial barrier and by blood flow that quickly removes drug, so the anesthesia produced is confined to the superficial layers just beneath the mucosal surface. This shallow penetration is enough to numb the surface for minor procedures, but it doesn’t reach deeper tissues, which is why deeper anesthesia requires injections or nerve blocks. So the expected effect is a superficial, near-surface numbness rather than a deep one.