Inferior Alveolar Nerve Lateralization Technique

Where Is Inferior Alveolar Nerve Lateralization Technique Indicated?

The inferior alveolar nerve is a mandibular nerve branch that supplies the nerve sensations to the lower teeth of our jaw. Though dental implants have been considered a highly predictable treatment for patients with an edentulous posterior mandible (no teeth remaining in the lower jaw bone), in cases of severe atrophy, the quantity of bone above the inferior alveolar nerve (IAN) may not be sufficient for adequate dental implant placement without damaging the inferior alveolar nerve.

In that way, reconstructive method strategies, such as osteodistraction, onlay or inlay autogenous bone grafts, guided bone regeneration with barrier membranes, short implants, and IAN lateralization, have been proposed to avoid any IAN injury.

What Is Inferior Alveolar Nerve Lateralization Technique?

Surgical Procedure and Antibiotic Prophylaxis:

1. In the IAN lateralization technique, the nerve is exposed and laterally retracted during implant placement.

2. After implant installation, the nerve is released onto the lateral surface of the implant.

3. For the surgical procedure, a single dose of antibiotics (Amoxicillin 2 g) associated with a steroidal anti-inflammatory agent (Dexamethasone 4 mg) is prophylactically administered one hour before surgery.

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4. The intraoral asepsis and extraoral asepsis are made with 0.12% and 2% Chlorhexidine Gluconate, respectively.

5. A full-thickness mucoperiosteal flap is raised, and a bone window is made with a piezoelectric device centralized on the IAN canal position.

6. After dissection, the IAN may be moved buccally with a sterile elastic strip to keep it retracted. At usually the fourth month follow up, the screw-retained prosthesis will be installed, guaranteeing the recovering masticatory function.

IAN lateralization performed thus with an adequate surgical technique can be successfully indicated for longer implant placement in the edentulous atrophic posterior mandible with no permanent neural damage as per current case reports of the technique performed.

What Are The Complications Associated With Lateralization Technique?

Despite the high implant survival rates at IAN lateralization sites (93.8% - 100%), the surgical procedure was associated with a risk of postsurgical neurosensory deficits because of extending the IAN or vascular damage.

Other complications or risks after the procedure include mandibular fracture at the surgical site. The potential risk of fracture in IAN lateralization is associated with a significant loss of structural integrity during the buccal cortex osteotomy in combination with the multiple implant placements.

Furthermore, implant loss, hemorrhage (result from neurovascular bundle damage), and osteomyelitis were also related to the IAN lateralization procedure. The risk of accidental injury to the IAN during osteotomy could be minimized using a piezoelectric device.

What Are the Advantages and Disadvantages of the IAN Lateralization Technique?

Disadvantages of IAN Lateralization:

1. Among the disadvantages of IAN lateralization is the occurrence of hypoesthesia, paresthesia, or hyperesthesia in a majority of cases, 1 to 6 months after the surgical procedure. 99.47% of IAN lateralization procedures were associated with transient neurosensory disturbances, while only 0.53% of procedures demonstrate permanent neural damage.

2. The IAN damage during the lateralization may occur during flap elevation when the mental nerve is placed under tension.

3. Also, when the osteotomy is being performed to expose the nerve, or during insertion of the implant, the nerve regeneration after compression or less severe crush injuries usually requires several weeks to 6 months; however, if no sensory recovery was observed during this time, permanent loss of continuity in the nerve trunk should be expected.

4. Patients show clinical signs of transient paresthesia with complete resolution after two months, with no longer IAN lateralization complications including mandibular fracture, implant loss, hemorrhage, or osteomyelitis. The neurosensory disturbance periods can be directly related to the quantity of compression and tension applied to the IAN during the nerve retraction procedure.

5. Nerve dysfunction could also result from the direct contact between the IAN and dental implants. The use of a resorbable membrane between the IAN and the dental implant surface has been proposed to reduce this contact.

Advantages of IAN Lateralization:

1. This method offers attractive advantages, including the minimal surgical time, lower cost, and the possibility of using longer implants, allowing for bicortical anchorage, better primary stability, and corono-radicular biomechanical relationship in comparison with the use of short implants. Moreover, the IAN lateralization also reduces the necessity for a second surgical procedure, as required for other treatments such as bone grafting or alveolar distraction.

2. In addition, osteotomies using the piezoelectric device are associated with inflammatory cell reduction and increased osteogenic activity in the surgical site. A piezoelectric device presents less power, and a longer time is required to execute an osteotomy in comparison with conventional burs.

3. The IAN lateralization technique offers a better quality bone in comparison with the region with grafts once the implants are placed using the higher cortical and basal body of the mandible. The IAN lateralization process does not require the donor areas, which decreases the patient morbidity, reduces the costs, provides the ready installation of long implants, and accelerates the treatment finalization, thereby avoiding the patient's graft integration wait time (6-8 months).

What Are the Advantages of Piezoelectric Devices?

1. It aids in the posterior rehabilitation of an atrophic mandible with dental implants by the IAN during the osteotomy and reduces the nerve damage risk.

2. The IAN lateralization and transposition techniques are surgical procedures that reposition the IAN to allow for the placement of longer implants without bone augmentation. Vercellotti showed that more favorable bone repair was observed when osteotomy and osteoplasty were performed with a piezoelectric device in comparison with carbide and diamond bur.

3. Moreover, in contrast to conventional burs, where the visibility is low, the operative field with the usage of the piezoelectric device remains almost blood-free during the cutting procedure. The piezoelectric device also produces less vibration and noise than conventional surgery because it uses micro-vibrations. These features could minimize a patient's anxiety and fear during the osteotomy under local anesthesia.

Conclusion:

The IAN lateralization performed with piezosurgery can be successfully used for longer implant placement in patients with edentulous atrophic posterior mandible with no permanent neural damage. However, the maxillofacial surgeon should inform the patient of the risks involved in this procedure and also minimize these risks of lateralization procedure using piezosurgery.