Local anesthesia for a complex lower lip laceration (Mental nerve block)

A 20-year-old male kick boxer sustains a lower lip laceration during a practice match. The wound is complex and crosses the vermilion border. Which is the best way to achieve anesthesia?

• (A) Local infiltration with 1 percent lidocaine
• (B) Local infiltration with 1 percent lidocaine with epinephrine
• (C) Inferior alveolar nerve block
• (D) Lingular nerve block
• (E) Mental nerve block

answer is E. 

A regional block is preferred for a complex lower lip laceration because it preserves tissue planes and landmarks, facilitating anatomically correct repair. 
The mental nerve supplies the skin and mucus membranes of the lower lip. The mental foramen is located inside the lower lip at its junction with the lower gum, just posterior to the first premolar tooth.

To avoid nerve injury, 1 percent lidocaine with epinephrine is injected close to, but not into, the mental foramen. The inferior alveolar and lingular nerves do not supply the lower lip and thus would not be effective in this patient.