Can you provide an illustration of the lower dental arch showing the appropriate injection site for a mental nerve block?

I cannot provide an illustration of the mental nerve injection site, as I am a text-based AI without the capability to create or display images.

However, I can describe the precise anatomical location and technique for performing a mental nerve block based on the available evidence.

Anatomical Location of the Mental Foramen

The mental foramen is most commonly located apical to the second mandibular premolar or between the apices of the first and second premolars. 1, 2

• In 67% of cases, the mental foramen is positioned directly under the second premolar 1
• In 24% of cases, it lies between the first and second premolars 1
• In 6% of cases, it is under the first premolar 1
• The remaining 3% are positioned behind the second premolar 1

Distance Measurements for Safe Injection

The mental foramen is located approximately 27.8 mm from the mandibular midline and sits near the inferior border of the mandible. 1

• The foramen averages 5.0 mm from the closest root of the adjacent tooth (range 0.3-9.8 mm) 2
• The mean diameter of the mental foramen is approximately 3.0 mm in height and 3.2 mm in length 2
• The mental canal exits with an upward course in 100% of cases 2
• An anterior loop of the mental nerve extends mesially from the foramen in 70.1% of cases, with a mean extension of 2.3 mm 2

Injection Technique for Mental Nerve Block

For a mental nerve block, inject 2-4 mL of local anesthetic (such as 2% lidocaine) at the mucobuccal fold adjacent to the second premolar, directing the needle toward the mental foramen. 3, 4

• Use a 25-27 gauge needle for the injection 3, 4
• Insert the needle at approximately 25 degrees to the skin surface 4
• Always aspirate before injection to avoid intravascular administration 4, 5
• The maximum dose of lidocaine without epinephrine is 4.5 mg/kg, or 7.0 mg/kg with epinephrine 4

Critical Safety Considerations

Leave a 2 mm safety zone between any surgical intervention and the mental foramen to avoid nerve injury. 6

• Verify the position of the mental foramen on panoramic or periapical radiographs before any procedure 6
• Consider CT scans when conventional radiographs do not provide clarity regarding nerve position 6
• Be aware that the mental nerve may have an anterior loop extending 2-3 mm mesial to the visible foramen 2, 6

Common Pitfalls to Avoid

• Failing to account for anatomical variation in mental foramen position, which can range from the canine to the first molar 6
• Not recognizing that conventional radiographs may not show the mental foramen and require adjustment for distortion 6
• Overlooking the presence of an anterior loop, which occurs in 70% of cases and extends an average of 2.3 mm mesially 2