Complications of third molar removal (trigeminal nerve damage)

Question 1

Minor complications of third molar removal (9)

Answer 1

– Pain, swelling, trismus
– Infection
– Fracture
– Bleeding and bruising
– TMJ problems
– Temporary nerve damage
– Periodontal problems
– Damage to other teeth
– Oral-antral communication

Question 2

Pain after third molar removal (3)

Answer 2

Guaranteed after surgical removal of lower 3rd molars 
-can be severe
Pre-op
-warn patient
-advise on analgesics

Question 3

Swelling and trismus after third molar removal (3)

Answer 3

Guaranteed after surgical removal of lower 3rd molars
-variable but can be marked
Pre-op
-warn patient
-provide advice on how to minimise (NSAIDs)

Question 4

Infection after third molar removal (5)

Answer 4

Difficult to assess incidence as diagnosis not always
straightforward
– higher incidence of postop infection in lower third molar sockets
– good oral hygiene post-operatively
– no good evidence for routine use of antibiotics
– consider all the variables – antibiotics have a role (co-morbidity, local and systemic)

Question 5

Damage to adjacent teeth after third molar removal (3)

Answer 5

• Mobilisation of second molars
• Damage to restorations
• Fracture of adjacent teeth

Question 6

Damage to adjacent teeth after third molar removal - pre-op (3)

Answer 6

– Assess clinically and radiographically
– Warn patient
– Have plan in place to minimise risk and deal with complication

Question 7

Fractured mandible (4)

Answer 7

• Elderly, edentulous patients with
atrophic mandible
• Pre-existing bone pathology
• Large bone defects
• Excessive use of force (cryers, large elevators)

Question 8

Displacement of third molars (2)

Answer 8

Upper 8’s
– Oral-antral communication
– Fractured tuberosity
see maxillary antrum lecture

Question 9

Trigeminal nerve injuries after third molar removal (3)

Answer 9

Trigeminal nerve injuries occur commonly in Oral Surgery
Usually during removal of wisdom teeth
Also implantology, trauma, soft tissue surgery

Question 10

Prevalence of nerve damage after third molar removal (4)

Answer 10

IAN
• Temporary 5-7%
• Permanent 0.5% - 1%
Lingual
• Temporary 3-7%
• Permanent 0.3-0.5% 
-minimum 300 lingual nerve injuries a year, more IAN

Question 11

Aetiology of trigeminal nerve damage (6)

Answer 11

• Third Molar (majority)
• Implantology
• Other surgery, e.g orthognathic
• Trauma
• Needle Stick (neuropraxia)
• Endodontics

Question 12

Why so many nerve injuries? (3)

Answer 12

• Mainly drill injuries
• Still lingual flaps being raised
• Increase lingual nerve injuries – coronectomy?

Question 13

The effect of trigeminal nerve injury (5)

Answer 13

Complete loss of sensation to half the anterior tongue and/ or chin/ lip
Paraesthesia - reduced sensation
Dysaesthesia - pain, tingling, burning
Allodynia (painful response to non-painful stimuli
Loss of taste

Question 14

What do the patients with nerve injuries complain of? (9)

Answer 14

Pain, unpleasant burning and tingling
They feel as if they are dribbling
They bite their lip
Avoid eating in public
Don’t enjoy kissing
Bite their tongue
‘Tongue feels like a large lump of jelly’
‘Lose food’ under their tongue
Don’t enjoy food

Question 15

Surgical technique for lingual nerve injuries (7)

Answer 15

Lingual flap raised and lingual periosteum divided
The central and distal nerves stumps identified and mobilised
The damaged segment of nerve (4-14mm mean 9.5mm) was excised
Direct reapposition with 5-10 (mean 7) 8/0 ethilon epineurial sutures
All patients given dexamethasone and antibiotics
Initial study prospective, quantitative assessment of 53 patients pre-op and >12 months post-op
Now have >200 patients, with larger growing database of outcomes following treatment

Question 16

Outcomes measured for lingual nerve injuries (6)

Answer 16

Light touch
Pin prick
Two point discrimination
Gustatory response
Altered sensation – dysaesthesia
Subjective assessment

Question 17

Is lingual nerve repair effective (5)

Answer 17

Majority of patients regain some sensation
Fewer patients tend to bite their tongue
Significant improvement was shown in tests using
-light touch stimuli
-pin prick stimuli
-gustatory stimuli
-two point discrimination
Patients consider it worthwhile
Remember – It will never return to normal

Question 18

Inferior alveolar nerve injury (3)

Answer 18

Mainly due to proximity to lower third molars
Increasing amount due to implant placement
Some from trauma

Question 19

Management of IAN following third molar removal (8)

Answer 19

The nerve is usually well supported in the mandibular canal
Even after transection the ends do not usually retract
Primary repair is not normally required
Control bleeding with temporary packing with gauze
AVOID
Diathermy
Whitehead’s varnish and other medicaments
Surgicel
Bone wax

Question 20

Injuries from implantology (6)

Answer 20

Can be from drill or implant
Many drills longer than implant length 
-'y' dimension (can be 1.5mm)
Overdrilling
-low resistance bone - slippage of drill
-missing at roof of canal
Miscalculation of position of IAN
Immediate placement (primary stability) - more likely to cause IAN
Safety zone - 2-4mm

Question 21

Mental foramen area - high risk (2)

Answer 21

Mental foramen – 4mm anterior to ensure avoidance of anterior loop.
Consider surgical exposure

Question 22

Intraoperative factors of implant injury (5)

Answer 22

‘Sudden give’
‘Electric shock’
Arterial bleed – large percentage of injuries – secondary to haematoma
May be sensible to wait 2 days and then place implant – avoid compression ischemia
No evidence though!

Question 23

Management post-injury from implant - evidence and short-term (7)

Answer 23

Good evidence that neural recovery with implant related injuries, inversely proportional to time
Ideally remove implant within 24 – 36 hours
Postoperative call – same day or following day
Short-term remove implant
Inform patient
Take radiograph for localisation of lesion
Evaluate – time elapsed, proximity of implant etc
Neurosensory evaluation

Question 24

Indications for surgical intervention (2)

Answer 24

Persistent anaesthesia

Dysaesthesia/Pain

Question 25

IAN decompression / neurolysis (5)

Answer 25

Cannot excise complete segment
Can remove bony obstruction
Can remove bony compression
Can remove remove soft tissue tethering/tension
Can remove ‘neuroma’	-  dysaesthesia

Question 26

Direct trauma from LA (3)

Answer 26

Face bevel laterally
?Hypothetical but consider with multiple injections
Most nerve injuries caused by LA injection - multiple injections

Question 27

How to minimise nerve damage (6)

Answer 27

IAN injuries usually ‘drill injuries’
Some are crush injuries – following forceps extraction
Low threshold for sectioning
Avoid forceps
Elevator removal preferable
Avoid lingual flaps

Question 28

Radiographic assessment of impaction (7)

Answer 28

Type of impaction
Depth of tooth within bone
Crown form
Root form and number
Coronal or root pathology
Other pathology (cyst, caries in 2nd molar)
Relationship with mandibular canal (IAN) or maxillary sinus

Question 29

Assessment of IAN on radiograph (5)

Answer 29

A:Radiolucency
B:Deviation/Constriction
C:Loss of cortication
D:Deviation of roots
E:Narrowing of roots

Question 30

CT for third molar removal (3)

Answer 30

Not routinely indicated
May be appropriate in high risk cases
CBCT

Question 31

Coronectomy - to do or not to do (4)

Answer 31

Controversial
Pros and cons
Lower risk.....
Second procedure....
Medico-legal issue
Should document discussed with pt if high risk of IAN damage
Pt choice