Nerve Block, Mental

Author: Vito J Rocco, MD, FACEP; Chief Editor: Meda Raghavendra (Raghu), MD more...

Updated: Jun 28, 2010

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Overview
Indications
Contraindications
Anesthesia
Equipment
Positioning
Technique
Pearls
Complications
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Overview

Lacerations of the lower lip and of facial soft tissue in the lower chin require proper anesthesia to ensure adequate cosmetic closure. The mental nerve block is a simple technique to supply anesthesia to this area. The mental nerve is a branch of the inferior alveolar nerve that exits via the mental foramen and divides into 3 branches below the depressor anguli oris muscle. One branch supplies the skin of the chin and the other 2 innervate the skin and mucous membrane of the lower lip. Note that this nerve block does not provide anesthesia to the teeth or mandibular soft tissue. The pain associated with the mental nerve block is significantly less than with other intraoral nerve blocks.^[1]

Lacerations of the lower lip
Lacerations to the soft tissue of the chin that extend from the lip anteriorly to the alveolar process (see side view below) and caudally to the mid body of the mandible (see front view below) Region of anesthesia (side view). Region of anesthesia (front view).

Noncooperative patient
Overlying cellulitis

Some local anesthetic agents are typically used for dental procedures.
- Lidocaine 1% (Xylocaine); rapid onset with duration of action lasting 30-60 min (longer duration if epinephrine added)
- Mepivacaine 3% (Carbocaine); moderate onset with duration of action lasting 45-90 min
- Bupivacaine 0.5% (Marcaine, Sensorcaine); slow onset with duration of action 2-4 h^[2]
Topical anesthetic agents are often useful prior to local anesthetic administration but are not required.
- Viscous lidocaine (Xylocaine)
- Tetracaine (Pontocaine)

Local anesthetic agent of choice
25-27 gauge needle
5 mL syringe
Topical anesthetic (optional)
Gauze pads
Adequate light source

Positioning

Place the patient in a semi-recumbent position, or in a dental/ENT chair, if available.

Apply topical anesthesia if desired.
Draw 2-5 mL of local anesthetic into the syringe. Agents may be combined (eg, lidocaine and bupivacaine) to achieve a longer duration of anesthesia
The intraoral approach to the mental nerve block with adjunctive topical anesthesia has been reported as subjectively and objectively less painful than the percutaneous approach.^[3]
Locate the mental foramen.
- Retract the cheek laterally.
- The mental foramen is palpable between the 2 lower premolar teeth in adults and between the first and second primary molars in children.
- The position of the mental foramen may differ among ethnic groups.^[4]
Insert the needle along the lower gum line into the buccal fold between the premolar teeth (in adults) near the foramen (see image below). Do not place the needle directly into the foramen. Mental nerve block injection site.
Aspirate.
Inject 2-3 mL of anesthetic.
- Do not inject directly into the foramen.
- Slow injection is significantly more comfortable than rapid injection (P < 0.001)^[5]

The mental nerve block provides anesthesia only to the lower lip and soft tissue of the chin.
If the foramen is not directly palpable, the anesthetic can be injected into the buccal mucosa between the 2 lower premolar teeth. Never inject into the foramen, as this can permanently damage the neurovascular bundle.
A dental aspirating syringe with a dental carpule can be used in place of a regular syringe. Slide the carpule into the syringe and place the needle on the end.

Bleeding
Infection
Needle fracture
Intravascular injection
Neurapraxia (secondary to direct injection into the mental foramen)

Contributor Information and Disclosures

Author

Vito J Rocco, MD, FACEP Associate Residency Director, Emergency Medicine, William Beaumont Hospital

Vito J Rocco, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

Specialty Editor Board

Andrew K Chang, MD Associate Professor, Department of Emergency Medicine, Albert Einstein College of Medicine, Montefiore Medical Center

Andrew K Chang, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Neurology, American College of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Pharmacy Editor, eMedicine

Disclosure: Nothing to disclose.

Luis M Lovato, MD Associate Clinical Professor, David Geffen School of Medicine at UCLA; Director of Critical Care, Department of Emergency Medicine, Olive View/UCLA Medical Center

Luis M Lovato, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Gil Z Shlamovitz, MD Assistant Professor of Emergency Medicine, University of Connecticut School of Medicine; Attending Physician, Emergency Department, Windham Community Memorial Hospital, Willimantic, CT; Attending Physician, Emergency Department, Hartford Hospital, Hartford, CT

Gil Z Shlamovitz, MD is a member of the following medical societies: American Academy of Emergency Medicine and American College of Emergency Physicians

Disclosure: Nothing to disclose.

Chief Editor

Meda Raghavendra (Raghu), MD Associate Professor, Program Director, Pain Management Fellowship, Section of Pain Management, Department of Anesthesiology, Stritch School of Medicine, Loyola University Medical Center

Meda Raghavendra (Raghu), MD is a member of the following medical societies: American Association of Physicians of Indian Origin, American Society of Anesthesiologists, American Society of Interventional Pain Physicians, American Society of Regional Anesthesia and Pain Medicine, and Association of Anesthesiology Subspecialty Program Directors (AASPD)

Disclosure: Nothing to disclose.

References

Kaufman E, Epstein JB, Naveh E, Gorsky M, Gross A, Cohen G. A survey of pain, pressure, and discomfort induced by commonly used oral local anesthesia injections. Anesth Prog. Winter 2005;52(4):122-7. [Medline].
Thomson CJ, Lalonde DH. Randomized double-blind comparison of duration of anesthesia among three commonly used agents in digital nerve block. Plast Reconstr Surg. Aug 2006;118(2):429-32. [Medline].
Syverud SA, Jenkins JM, Schwab RA, Lynch MT, Knoop K, Trott A. A comparative study of the percutaneous versus intraoral technique for mental nerve block. Acad Emerg Med. Nov-Dec;1(6):509-13. [Medline].
Yesilyurt H, Aydinlioglu A, Kavakli A, et al. Local differences in the position of the mental foramen. Folia Morphol (Warsz). Feb 2008;67(1):32-5. [Medline].
Whitworth JM, Kanaa MD, Corbett IP, Meechan JG. Influence of injection speed on the effectiveness of incisive/mental nerve block: a randomized, controlled, double-blind study in adult volunteers. J Endod. Oct 2007;33(10):1149-54. [Medline].
Amsterdam JT. Mental nerve block. In: Rosen P, Chan T, Vilke G, Sternbach G. Atlas of Emergency Procedures. St. Louis, Mo: Mosby; 2001:166-7.
Amsterdam JT. Regional Anesthesia of the Head and Neck. In: Roberts JR, Hedges JR. Clinical Procedures in Emergency Medicine. 3^rd ed. Philadelphia: WB Saunders; 1998:33:507.
Salam, G MD, DO. Regional Anesthesia for Office Procedures Part I Head and Neck Surgeries. American Family Physician. 2/2004;69:585-590. [Full Text].