Mandibular Nerve Block

Mandibular Nerve Block

One of the struggles that many dentists face are Mandibular Nerve Blocks and the Inferior Alveolar Nerve Block.

Mandibular nerve block involves blockage of the auriculotemporal, inferior alveolar, buccal, mental, incisive, mylohyoid, and lingual nerves. It results in anesthesia of the following areas:

1. Ipsilateral mandibular teeth up to the midline
2. Buccal and lingual hard and soft tissue on the side of the block
3. Anterior two-thirds of the tongue
4. Floor of the mouth
5. Skin over the jaw, the posterior part of the cheek, and the temporal area

Indications

The mandibular nerve area is generally blocked by using more specific nerve blocks rather than by performing a complete nerve block. Indications for complete nerve block include the following:

1. Patients in whom the inferior alveolar nerve (IAN) block fails or is not feasible – Sometimes the teeth may be innervated by an accessory nerve that arises proximal to the IAN and thus may be spared by an IAN block
2. Patients undergoing surgical procedures of the mandible – Mandibular nerve block may be done either as an isolated nerve block or as a complement to general anesthesia; this is applicable to several dental procedures on the lower teeth and surrounding soft tissues

Contraindications

Contraindications for mandibular nerve block include the following:

1. Acute inflammation at the site of injection
2. Trismatic patients, uncooperative patients, and children (these are specific to the Gow-Gates block [see Technique])
3. Acute infection in the pterygomandibular space, fracture of the mandible, presence of a tumor, or distortion of the regional anatomy (these are specific to the Vazirani-Akinosi block [see Technique])
4. Patients with known allergies to local anesthetic

Technical Considerations

The mandibular nerve is the largest division of the trigeminal nerve, with sensory roots from the trigeminal ganglion and motor roots from the pons and the medulla. The 2 roots exit the cranium via the foramen ovale and unite just outside the cranium to form the mandibular nerve. After giving off 2 branches, the mandibular nerve bifurcates into anterior and posterior divisions.

Motor nerves from the anterior division include the following:

• Masseteric nerve, which supplies the masseters
• Temporal nerve, which serves the temporalis
• Lateral pterygoid nerve, which supplies the lateral pterygoid muscle

Sensory nerves from the anterior division include the buccal nerve, which is sensory to the mucosa of the mouth and gums and the skin on the cheek.

Sensory nerves from the posterior division include the following:

• Auriculotemporal nerve, which is sensory to the external auditory meatus and the external surface of the tympanic membrane
• Lingual nerve, which travels inferiorly into the pterygomandibular space between the mandibular ramus laterally and the medial pterygoid muscle medially; this nerve provides general sensation to the anterior two-thirds of the tongue, the floor of the mouth, and the lingual gingiva

The IAN descends into the pterygomandibular space along with the lingual nerve. Its sensory branch enters the mandibular canal and is sensory to the lower teeth and gums. It then exits via the mental foramen as the mental and incisive nerves, which are sensory to the chin and the lower teeth. The motor branch to the mylohyoid is given off before the nerve enters the mandibular canal and serves as motor supply to the mylohyoid muscle.

Mandibular Nerve Block Periprocedural Care

Equipment

Equipment used for mandibular nerve block includes the following:

• 25-gauge long needle (36 mm)
• Sterile syringe (either aspirating or nonaspirating)
• Cotton-tip applicators for controlling bleeding
• Mouth retractors
• Local anesthetic solutions – Lidocaine 1-2% with or without epinephrine (1:100,000 or 1:200,000 concentration), bupivacaine 0.5%, or mepivacaine 2-3%

Approach Considerations

The following 3 techniques are used to perform a mandibular nerve block ^{[1, 2]} :

1. Gow-Gates technique
2. Vazirani-Akinosi technique
3. Coronoid approach

The second maxillary molar tooth is placed between the first and third molar teeth and is the seventh tooth from the midline. The visible part of the tooth is called the crown, and the parts covered by the gum are the 3 roots of the tooth. The dividing line that separates the roots from the crown is called the cervical line.

The crown has the following 5 surfaces:

1. Occlusal
2. Buccal
3. Lingual (palatal)
4. Mesial
5. Distal

The occlusal, buccal, and lingual surfaces are self-explanatory, referring to those particular surfaces of the tooth. The mesial surface is the anterior surface of the tooth—in this case, the surface adjoining the first molar tooth. The distal surface is the posterior surface—in this case, the surface adjoining the third molar tooth.

The buccal surface of the tooth has the following 2 protuberances or cusps, which are separated by the buccal groove:

• An anterior protuberance, called the mesiobuccal cusp
• A posterior protuberance, called the distobuccal cusp

References

1.  Budenz AW, Osterman SR. A review of mandibular anesthesia nerve block techniques. J Calif Dent Assoc. 1995 Sep. 23(9):27-34. [Medline].

2.  Gaum LI, Moon AC. The "ART" mandibular nerve block: a new approach to accomplishing regional anesthesia. J Can Dent Assoc. 1997 Jun. 63(6):454-9. [Medline].

3.  Sisk AL. Evaluation of the Gow-Gates mandibular block for oral surgery. Anesth Prog. 1985 Jul-Aug. 32(4):143-6. [Medline]. [Full Text].

4.  Gow-Gates G, Watson JE. Gow-Gates mandibular block--applied anatomy and histology. Anesth Prog. 1989 Jul-Oct. 36(4-5):193-5. [Medline].

5.  Kafalias MC, Gow-Gates GA, Saliba GJ. The Gow-Gates technique for mandibular block anesthesia. A discussion and a mathematical analysis. Anesth Prog. 1987 Jul-Aug. 34(4):142-9. [Medline]. [Full Text].

6.  Sisk AL. Evaluation of the Akinosi mandibular block technique in oral surgery. J Oral Maxillofac Surg. 1986 Feb. 44(2):113-5. [Medline].

7.  Haas DA. Alternative mandibular nerve block techniques: a review of the Gow-Gates and Akinosi-Vazirani closed-mouth mandibular nerve block techniques. J Am Dent Assoc. 2011 Sep. 142 Suppl 3:8S-12S. [Medline].

8.  http://emedicine.medscape.com/article/2040639-medication

9.       Malamed SF. Is the mandibular nerve block passé?. J Am Dent Assoc. 2011 Sep. 142 Suppl 3:3S-7S. [Medline].