Nerve Blocks in Dental Patients UK

Nerve Blocks
in Dental
Patients
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Dentistry Mini
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NERVE BLOCKS IN DENTAL PATIENTS 1

What Do You Need?
You’ll need:
• 24G-27G needle (for large dogs, a spinal needle can be helpful)
• Small syringe (1-2ml)
• Skin/mucosa prep (chlorhexidine swab)
• Gloves/sterilised hands
Drug choice:
The following local anaesthetic drugs are commonly used. There
is currently no strong evidence of a benefit to combining local
anaesthetic drugs, and some evidence that this reduces efficacy.
\Lidocaine
• Fast onset (2-5mins), short duration (up to 2 hours)
• Total dose should be no more than 2-4mg/kg in cats and 4-6mg/kg
in dogs, and don’t forget to take into account lidocaine spray used
for intubation
\Bupivacaine
• Slower onset (10-20mins), longer duration (6-10 hours)
• Total volume should be no more than 1mg/kg in cats, 2mg/kg in dogs
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Adjuncts to local
anaesthetics:
Some authors describe addition of adjuncts
designed to extend the duration of action
of local anaesthetic blocks. The evidence
for these is still weak.
\Adreneline
\Buprenorphine
\Dexmedetomidine
NERVE BLOCKS IN DENTAL PATIENTS 3

The Innervation of
the Teeth and Gums
Head Blocks — Trigeminal Branches
Maxillary branch
A
Mandibular branch
B
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Injecting Local
Anaesthetics – Top Tips
1
Calculate total allowable dose of the chosen drug,
then divide it by the number of blocks. This is
the maximum allowed at each site, but in most
cases the needed volume will be far smaller –
just 0.2ml in cats and 1ml in dogs is usually
sufficient for any site.
2
Don’t forget that each side of the jaw will
need blocking, so you may need up to four
nerve blocks
3
Always aspirate before injection, to avoid
accidental intravenous injection
(risk of cardiac problems)
4
5
You should not inject if you feel
resistance - intra-nerve injection is
possible and can cause nerve damage
It’s not uncommon for a block to fail, so
other analgesia should always be used
NERVE BLOCKS IN DENTAL PATIENTS 5

The Maxillary
Nerve Block (A)
Maxillary branch
A
\The nerve:
• The maxillary branch of the trigeminal nerve,
at the pterygopalatine fossa
\What this block desensitises:
• Upper lip, upper teeth, palate, maxilla, and most of the nose (may not
be complete buccal desensitisation)
\How to perform it:
• There are two ways to perform this nerve block – intraoral and
extraoral. The intraoral approach is only suitable in medium to large
dogs.
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Intraoral approach:
1. Open the patient’s jaw wide, move the upper lip caudally, and
visualise and palpate tooth 110/210 (in dogs).
2. With the needle perpendicular to the palate insert it just caudal to
110/210, inserting it 3-5mm beyond the mucosa.
3. Aspirate to avoid accidental intravenous injection, then inject
anaesthetic - note, larger volumes may be needed at this site as
there’s no foramen to control the movement of the drug.
NERVE BLOCKS IN DENTAL PATIENTS 7

Extraoral approach:
1. Surgically prepare the skin around the zygomatic arch.
2. Insert needle perpendicular to the long axis of the head, under the
zygomatic arch and in line with the lateral canthus of the eye.
3. Aspirate to avoid accidental intravenous injection, then inject
anaesthetic - note, larger volumes may be needed at this site as
there’s no foramen to control the movement of the drug.
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The Mandibular
Nerve Block (B)
Mandibular branch
B
\The nerve:
• The mandibular branch of the trigeminal nerve, as it leaves the
mandibular foramen
\What a block here desensitises:
• The lower teeth, mandible, skin, and mucosa of lower lip
\How to perform it:
• There are two routes to performing the mandibular nerve block
– intraoral and extraoral. The extraoral is usually easier in most
animals, and is the one described here.
NERVE BLOCKS IN DENTAL PATIENTS 9

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Extraoral approach:
1. Surgically prepare the skin under the ramus of the mandible
2. With your hand inside the mouth, palpate the inner angle of the jaw
(the lingual side of the mandible), feeling for the mandibular foramen
just caudal to the last molar. It can be hard to feel in cats and small
dogs.
3. Insert long needle from the skin side, directing it along the inner
aspect of the mandible, feeling with your fingers for when it reaches
the foramen.
4. Aspirate to avoid accidental intravenous injection, then inject
anaesthetic – you can palpate the tissue bleb as you do so.
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