Nerve Repositioning

Nerve Repositioning : General Information

Placement of intraoral implants requires adequate bone. However, there are several instances when the adequacy of the lenticular bone is not the norm in surgical implantology, as there are many cases of loss of the lenticular bone due to periodontal disease, destruction of the parietal bone usually due to extraction, or even resorption due to chronic numbness.  Furthermore, the posterior mandible presents a difficulty because the mandibular angiovascular ligament passes through the mandibular medulla before passing through the genial foramen to nerve half of the lower lip. This difficulty occurs from the third molar region up to the second premolar region.

Nerve Repositioning : What is the Treatment and What are the Parameters for Selecting the Method

The methods that have been proposed to treat this problem are Ring Bone technique, Sandwich type technique, autogenous block from intra-oral or extra-oral donors, allogeneic block, transposition of the inferior fossa nerve, titanium membrane for retention of autogenous in combination with allogeneic chip, and implant placement.

In terms of the parameters that determine the choice of treatment and treatment method, the patient’s history is the first to be considered. The existence of atypical facial pain or pain suggestive of trigeminal neuralgia, a history of trauma and/or fracture of the mandible, as well as the existence of not only a typical mental illness, such as depression and schizophrenia, for example, but also a type A personality and the fact that the patient is hyper-anxious or neurotic, play a very important role in the process of deciding on treatment.

Subsequently, a clinical examination is carried out, which emphasizes the person’s ability to perceive pain and wrestling (lip vibration) in the third branch of the trigeminal nerve in general and specifically, as well as the full course of the nerve and its exit from the geniculate segment. Furthermore, in the examination the doctor also pays attention to the free space, the parietal position of the nerve, as well as the presence of keratinized gums.

Nerve Repositioning : What Are the Techniques, Advantages and Disadvantages

There are two techniques for transposition of the inferior fossa nerve:

• Displacing the nerve to a more posterior position by touching the geniculate foramen.
• Displacing the nerve outwards while maintaining the geniculate foramen.

In both cases, the operation may be performed under local or general anesthesia.

The posterior technique has certain advantages and disadvantages. The advantages are:

• It is a quick technique.
• It avoids grafts that are vulnerable to resorption over time.
• There are high success rates.
• It allows for immediate loading.
• We can utilize almost the entire height of the mandible and place large implants.
• No additional materials are used beyond those of the implants, and so additional disadvantages are avoided and costs are reduced.

However, the disadvantages are as follows:

• Neuropathic pain, with a probability of about 1%.
• The possible hypesthesia of the lower facet nerve (2-12 months).
• In some cases, the final prosthetic restoration is carried out with teeth with large cusps.

Complications of this method are likely to be neurotomy of the mandibular nerve, mandibular fracture, bleeding, axonotomy of the mandibular nerve, and fracture of the parietal cortex during implant placement.