Trigeminal nerve damage can occur during oral surgery procedures like inferior alveolar nerve blocks, dental implant placement, periodontal surgery, and third molar extractions. The lingual nerve is most commonly injured, followed by the inferior alveolar nerve. Nerve damage may be transient or permanent, with about 10% of cases resulting in long-term numbness or dysesthesia. Careful preoperative evaluation with imaging and attention to nerve anatomy during surgery can help reduce risks, but aberrant nerve positions also contribute to injuries. Treatment focuses on symptom management as most cases improve over several months, though microneurosurgery may sometimes restore function if performed shortly after damage occurs.

1. Nerve Involvement in
Oral Surgery
Dr. Hadi Munib
Oral and Maxillofacial Surgery Resident

2. Trigeminal Nerve
 Inferior alveolar nerve block
 Temporary, and occasionally permanent, nerve damage can occur
 The nerve predominantly affected appears to be the lingual nerve [twice as often
as the inferior alveolar nerve].
 Transient damage from inferior alveolar nerve block (those recovering even if
they take up to 9 months to do it) probably occurs five or six times as frequently.
 Lingual Nerve; possibly be related to the relative fascicular pattern of the nerve
in the area of the lingula, since in this area the lingual nerve may be uni-
fascicular in up to one third of cases, which may make it more liable to be
damaged.
 Direct Trauma, Neurotoxins, Hematoma to the nerve

3. Trigeminal Nerve
 These patients appear to have a high proportion of dysesthesia (over 30% of
such patients suffer from dysesthesia compared with only 8–10% of patients
having nerve involvement as a result of third molar
 extraction).
 Treatment is symptomatic; most cases recover within an 8–10 week-period,
and a smaller number recover over a 9-month period.
 About 10% of cases prove to be permanent, with occasional disabling
dysesthesia.

5. Nerve damage from dental implants
 Overextension
 The injury may be related to drilling prior to implant insertion, particularly
since most drills are 0.5–1.5 mm longer than the implant that will be fitted
 3-D Radiograph
 Proper Measurements

9. Periodontal Surgery
 Particularly when the nerve lies in an aberrantly superior position as is known
to occur in between 15 and 20% of cases.
 Studies have shown that in the majority of cases the lingual nerve lies around
8 mm below the crest of the alveolar ridge and some 2–3 mm lingual to the
lingual plate.
 If the nerve is damaged with a sharp instrument such as a scalpel, early
surgical nerve repair may give satisfactory results.

10. Dento-alveolar Surgery
 Lingual nerve, the inferior alveolar nerve, the long buccal nerve, and even
the mylohyoid nerve.
 Third molar removal
 The incidence of inferior alveolar nerve damage from the removal of third
molars varies in the literature from 0.5–5%.
 The cause is directly related to the anatomical relationship between the
inferior alveolar nerve and the roots of the third molar.
 Panoramic X-Ray
 CBCT

11. Signs of ID involvement to Third Molars
 Darkening of root
 Deflection of root
 Narrowing of root
 Bifid root apex
 Diversion of canal
 Narrowing of canal
 Interruption in white line of canal.

16. Lingual Nerve
 Lingual nerve injuries are less frequent than inferior alveolar nerve, in 0.2–2% of all lower
third molar removals.
 They do appear to be more troubling to patients.
 In most cases the lingual nerve is protected beneath the lingual plate of bone, as it lies
approximately 6–8 mm inferior to the lingual crest and some 2 mm medial
 Studies have shown, however, that in between 15 and 20% of cases the lingual nerve may
lie at or above the level of the lingual plate.
 During the initial incision if it is made too far lingually and the patient has an aberrant
lingual nerve;
 During flap retraction if a lingual flap is raised with a misdirected or sharp instrument and
the lingual nerve is in an aberrant position;
 The lingual split technique, if used to remove lingual bone prior to removal of third
molars
 Removal or fracture of lingual or distal bone during removal of the tooth can damage the
lingual nerve;
 Tooth sectioning, if the drill is placed too deeply and penetrates the lingual plate of
bone;

17. Lingual Nerve Damage
 Overaggressive removal of retained dental follicle on the lingual side may
damage an aberrantly placed nerve;
 Deep suturing may damage an aberrantly placed lingual nerve on the lingual
side of the incision;
 In some cases the lingual plate of bone may be absent congenitally or due to
infection or other pathologies.

22. Long Buccal Nerve
 It might be anticipated that this nerve would be involved in many cases
during third molar removal.
 Nevertheless, damage has been documented on a number of occasions and
can occasionally be troublesome
 In practice, it is virtually impossible to find the long buccal nerve surgically,
and equally impossible to repair it

23. Mylohyoid Nerve
 Involvement of the mylohyoid nerve has been reported in up to 1.2% of third
molar removals but is normally associated with lingual retraction, where the
retractor has been placed too deeply.
 Localized area of paresthesia beneath the point of the chin on the affected
side.
 Involvement of the mylohyoid nerve is usually temporary and of little clinical
significance.

24. Evaluation of Trigeminal Nerve Damage
 Most evaluation techniques for nerve involvement are semi-objective at best
and do rely on the presence of a cooperative patient.
 In all cases the normal side is tested first and the abnormal side is compared
to it.
 Semmes-Weinstein plastic filaments (often called Von Frey’s hairs) or its
equivalent are used to test sensation quantitatively.

25. Facial Nerve
 Extra-Oral Approach
 Posteriorly given ID Block
 In 53% of cases, the mandibular branch travels below the lower border of the
mandible but never more than 1.2 cm
 Incision placed one finger’s breadth (2 cm), below the angle of the mandible

28. Microneurosurgery
 Repair ID, Lingual, it is normally felt to be impractical for the long buccal,
mylohyoid, and chorda tympani nerves.
 Most authorities feel that it is not possible to restore taste surgically,
 There is normally end-organ degeneration after some 3 weeks and the taste
buds will not recover.
 Reports of microneurosurgery, carried out up to 6 months after injury, which
has restored some taste
 Many authorities would feel that surgery was not indicated if the patient has
protective reflexes, which occur at about 30% of normal feeling.
 3-7 days after injury

31. B12 OR B-COMPLEX

32. References
 Chapter 16: Nerve Involvement in Oral Surgery

33. THANK YOU!