Chapter 6 - The treatments for the accidental symptoms
Ministry of Foreign Affairs, Division of Health and Welfare, a technical official of Medical Clinic
Shigenari Mashu
I.

The treatment for the inferior alveolar nerve injury

A.

Damages to the nerve fibers

The damages to the inferior alveolar nerves at the implantation to the mandibular molars have been
noted to be created by the tools (burs), compressions from hematoma, by the implant body, and thecompression with the bone.
The damaged nerve fibers can be divided into three groups depending on the extent of their conditions,neuraparaxia, axonotmesis and neurotmesis1). Under the clinical settings, different combinations of thenerves in these three different classes exist with the functional nerves giving rise to a variety of sensory
dysfunction. Generally, the neurapraxia has been noted take three to ten weeks, and neurotmesis six
months for their recovery, respectively2). For a case of complete neurotmesis, a neurorrhaphy or grafting
would be required, but there is a risk of damages to result from the surgical procedures itself, therefore
considerations must be taken.
The main symptoms for the inferior alveolar nerve injury are: sensory paralysis of the lower lip on theaffected side, the mental region and the gingivae; stiffness, persistent pain; neuropathic pain such as
allodynia; and pain and discomfort with occlusion.
B. Examination of the inferior alveolar nerve injury
The confirmation of the patient’s complaint of the shooting pain during the procedure, confirmation of theperforation of the mandibular canal by palpation or inspection, and for whether the soft tissues become
attached during aspiration of the plating cavity are necessary. Diagnosis of the condition after the surgery
should be done with consideration of the complaint by the patient (Dysaethesia such as the numbness in
the lips and chin, hypesthesia, or pain), the presence of sensory perceptions for touch of brush (incomparison with the unaffected side), extent of sensory perception for pain stimuli conducted with the tipof the forceps (Scored such that the unaffected side to have 10 and painless to be 0), X-ray radiography
analysis with CT scan (The positional relationship of the mandibular canal with either the planting
cavity or the implant body). In some cases, additional examination may be required for furtherassessment such as: tapping check of the teeth, electric pulp test, sense of warmth with application ofwarm cotton ball, and for sense of cold with alcohol cotton ball.
It is important to record the primary symptoms in order to note the progress of the sensory recovery. In
order to accurately obtain the level of sensing ability of the mucosal membranes, conduct von Frey test.
This is a method whereby the tip of the nylon filament of standardized thicknesses are lightly applied tothe region till bending, and recording which one of these were felt with touch sensation or with pain (Fig.
3-6-1), thus generally enabling measurements of the sense of touch as well as sense of pain. The markingsof the area where there is a distinction with the unaffected side in a figure should enable a clear
monitoring of the progress.

Fig. 3-6-1 Von Frey filament
C. Treatment of the inferior alveolar nerve injury
In confirming that the inferior alveolar nerve has been injured during implant treatment, stop thebleeding, and discontinue the implant treatment if necessary. The location of the implant body should be
confirmed using X-ray radiography. Inform the patient of the problem, the symptoms likely to manifest
and the treatment for it being careful not to alarm the patient from the error explained.
In confirming with postoperative analysis with CT scan the compression of the nerves, either affected by
the implant body itself, or indirectly via the bone, the procedure to alleviate the pressure should be done
as soon as possible (within two weeks). Either replace the implant body to a shorter type, or lift it out of
the jaw bone slightly. To avoid secondary nerve injury from its development, preventative measuresagainst inflammation and infections are necessary with anti-inflammatory and antibiotics.
In case of significant nerve damage, the transport of nerve growth factor (NGF) would be inhibited fromreaching the tips of the nerves from this point onwards therefore the nerve termini start to degenerate via
wallerian degeneration. This is the main reason why the treatment needs to be conducted as early as
possible. The patient should be referred to the specialist (anesthesiology or pain clinic) for an accurateanalysis of the conditions and treatment. As a preparative measure, pharmacotherapy should beconducted before referring to the specialist departments. The concomitant administration of vitamin B12
preparations that are effective for the repair and regeneration of the nerves, and adenosine triphosphate
disodium preparations are typical. This should be discontinued where the pharmacological effects havenot been evident after several months of administrative course. As an additional measure, where theinflammation in the affected area has subsided, instruct the patient to apply a towel that has been wettedwith hot water to the affected area for 5 - 10 minutes.
Treatments conducted by the specialists include the pharmacotherapy as mentioned above,
electro-acupuncture, stellate ganglion block and infrared radiation in addition to the application of warm,
moist towel. The efficacy of each of these therapeutic approaches cannot be determined separately since
the level of recovery and the periods required are largely dependent on the extent of the nerve damage.
1.

ElectroacupunctureThis is performed with a 30 mm, No. 3 (0.2 mm diameter) disposable needle, which are applied to six toeight different areas in total including: facial acupuncture points (e.g. St-7, St-4 and St-5), acupuncture
points of upper limbs (e.g. LI-10 and LI-4), and symptomatic lower lip and the chin region. The injected
needled is connected to the low frequency therapeutic device in order to apply electric stimulation of 2 Hz
frequency for a period of 30 minutes3) (Fig. 3-6-2). If the treatment has been performed within a monthfrom the nerve damage, it should be conducted every day as a preventative measure for the developmentof wallerian degeneration. An immediate effect cannot be expected for if the symptoms have persisted forover a year, and the treatment should be conducted weekly for a few months before the re-evaluation of
the symptoms. If improvements with the treatment can be observed with the decrease in the area affectedor the extent of the damage, the treatment should be continued. The treatment of the inferior alveolar
nerve injury with electroacupuncture is generally conducted to the mandibular nerves occupying thesame area of as the affected area, to expect regulation of the input from the caudal part of spinal tract
nucleus of trigeminal nerve of the lower lip and the mental region, as well as the humoral mechanism ofanalgesia. Additionally, the promotion of nerve regeneration with the improved blood flow can be expected
locally.

Fig. 3-6-2 Electroacupuncture2.

Stellate ganglion block

Set a 25 G injection needle in the 10 ml cylinder, and use 1% lidocaine as the local anesthetic agent (Fig.
3-6-3). It should be administered everyday if it is within a month from the time of injury, as withelectroacupuncture. The treatment is usually conducted once to three times a week. This treatment aims
to increase the blood flow in the inferior alveolar nerve tissues and in the brain; promotion of theregeneration of the nerve fibers; and to alleviate the neuropathic pain 4).
3.

Infrared irradiation

Insert the irradiation probe of the infrared irradiation device to the affected site, and irradiate for thirty
minutes per session (Fig. 3-6-4). This treatment aims to promote regeneration of the nerves.
These treatments are also adopted with the same methods for the damages to the mental nerves.

Fig. 3-6-3 Stellate ganglion block

Fig. 3-6-4 Far infrared radiation irradiator

References
1) Suzuki N. Trigeminal paralysis. Furuya H, and others eds. Dental anesthesia, 5 th ed. Tokyo. Ishiyaku
Pub, Inc. 2000; 554-555. (in Japanese)
2) Zinno S. Useful for general clinicians –Measures for paralysis and pain. The Nippon Dental Review.
2004; 64(11): 135-144. (in Japanese)
3) Mashu S. et al: Acupuncture Therapy to Inferior Alveolar Nerve Injury Following Placement of aDental Implant. A Case Report. PAIN RESEARCH 1998; 13(2): 47-52.
4) Mizuma K, and others. Stellate Ganglion Block Therapy for Neuropathic Pain following Extraction of
Mandibular Third Molar-Three Case Reports-. Journal of Japanese Dental Society ofAnesthesiology. 2007; 35(3): 373-380. (in Japanese)