Techniques of Local Anesthesia

TECHNIQUES OF LOCAL
ANAESTHESIA
Dr. Wael M. Talaat
Assistant Professor of Oral and
Maxillofacial Surgery

Objectives
Knowledge of the classification of local
anesthesia
2. Indications for each technique
3. Details on how to perform different
techniques of local anesthesia
1.

L.A can be produced by the action of
L.A agent on either the free nerve
endings , the terminal nerve endings or
the main trunk of the nerve

TOPICAL ANAESTHESIA
It is the application of ointments or solution
containing L.A agent to accessible
structures e.g skin or mucous membrane .
Topical anaesthesia has a limited effect on
the free nerve endings

INFILTRATION ANAESTHESIA
Infiltration anaesthesia is produced when
the terminal nerve endings is flooded by the
L.A solution

INFILTRATION ANAESTHESIA
I - Soft tissue infiltration anaesthesia
Submucosal
Para periosteal
Sub-periosteal infiltration
Field block (ring block)
II – Intra bony(intraosseous) infiltration
anaesthesia

I - Soft tissue infiltration
anaesthesia
1.

Submucous infiltration : accomplished by
inserting the needle beneath the
mucosal layer and depositing the
solution so that it diffuses in this
particular plane.

2.

3.
4.

Supra-periosteal (Para-periosteal)
infiltration : accomplished by depositing
the solution beside the periosteum and
not above it.
Sub-periosteal infiltration : difficult and
painful
Field block infiltration

Intra-bony infiltration
Intra-osseous infiltration : the cortical
plate is penetrated and the solution is
injected into the spongy bone, thus
terminal nerve endings are anesthetized.
2. Inter-septal infiltration : needle is inserted
into the thin porous inter-septal bone on
either side of the tooth to be
anesthetized. The solution is then forced
under pressure into the cancellous bone.
1.

NERVE BLOCK
ANAESTHESIA
The L.A solution is deposited in close
proximity to the main nerve trunk supplying
the operative field

Topical

Free nerve endings

Terminal nerve
endings

Main trunk

Infiltration

Nerve block

Factors that influence the choice
of local anaesthetic technique
1) The area to be anaesthetized
2) Extent of the surgical procedures
3) Duration of the required anaesthesia

Factors that influence the choice
of local anaesthetic technique
4) Haemostasis
5) Presence of infection
6) Age of the patient

Contraindications of local
anaesthesia
1.
2.
3.
4.
5.
6.
7.

Patient refusal due to fear and apprehension
Presence of infection
Allergy
Uncooperative patient as epileptic or mental
Major surgery
Patients with hyperthyrodism in whom local
anaesthia may precipitate a thyroid crysis
Patients with severe renal or liver disease

Advantages of local over general
anaesthesia
1.
2.
3.
4.
5.
6.
7.

Safety (intraoperatively and
postoperatively)
Ease of administration
Less cost
Co-operation of the patient
Unlimited operating time
Reduce bleeding during surgery
Patient is unfit for general anesthesia

Factors affecting the maximum
effect of local anesthesia
Distance of the nerve in contact with the
drug : at least 8-10 mm of the nerve
should be in contact with the drug ( 2-3
nodes of Ranvier
2. Size of the nerve fiber : the larger the
fiber, the more difficult it is to be
anesthetized
3. Drug concentration
1.

Injection procedure
1.
2.
3.
4.
5.
6.
7.
8.
9.

Sterile the cartridge by 70 % alcohol then thaw to body
temperature by water
The bevel of the needle towards bone
The syringe should contain no air
In critical areas with neighboring blood vessels, use
aspiration syringe
Slow injection
The site of injection should be disinfected
Stretch the tissues on injection.
Follow shortest way inside tissue.
Never bend to change direction

Maxillary infiltration
anaesthesia

Buccal and labial injections
 The needle is inserted into a point

opposite to the tooth to be extracted, with
the bevel facing the cortical bone.
 The needle is inserted 2 mm away from
the muco-buccal fold and at 45 degree to
the outer cortical plate till it touchs bone.
 About 1.5 ml of solution is injected.

Position of the patient:
The patient is placed with the maxillary
occlusal plane 45 degree with the floor
Position of the operator:
The operator stands on right side and front
of the patient

Palatal Injection
 The point of insertion of the needle is

located on the palatal side of the tooth,
midway between the gingival margin and
the middle line of the palate.
 The needle should be at right angle to the
vault of the palate. To achieve this, the
needle is derived from the opposite side.
 Only 0.3 ml of solution is slowly injected to
avoid pain and ulceration.

Mandibular infiltration
anaesthesia

Labial Injection:




The chair is adjusted such that the mandibular
occlusal plane is almost horizontal when the
mouth is open.

The operator stands on right side and front of the
patient

Lingual Injection
 The insertion of the needle should be just

above the muco-lingual fold to avoid
dissemination of the solution into the floor
of the mouth, 0.2 – 0.3 ml of the solution is
injected slowly.

Techniques of Nerve Block
anaesthesia
Maxillary nerve
block
 Posterior superior
alveolar N.B
 Infra Orbital N.B
 Nasopalatine N.B
 Greater palatine N.B
 Maxillary N.B

Mandibular nerve
block
 Mental N.B
 Inferior alveolar N.B
 Lingual N.B


Mandibular N.B

Maxillary nerve block
1)Posterior superior alveolar N.B
2)Infra Orbital N.B
3)Nasopalatine N.B
4)Greater palatine N.B
5)Maxillary N.B

Posterior Superior
Alveolar N.B
(Tuberosity Injection)

Posterior Superior Alveolar N.B
of the patient

Posterior Superior Alveolar N.B
Area anaesthetized :
Pulp of the maxillary molars except mesiobuccal root
And
The buccal mucoperiosteum of the molar
area

Anaesthetized area
1.
2.
3.
4.
5.

Upper third, second and first molar
except the mesio-buccal root of the latter
Associated periodontal membranes
Investing alveolar bone
Neighboring buccal mucosa
Maxillary antrum

 Injection site :

distal aspect of the maxillary tuberosity
above and behind the third molar.

Technique
1.
2.

3.
4.

Mouth should be partly closed
Needle is inserted opposite the mesial root of
the first molar at the deepest part of the
mucobuccal fold
Needle passes around the curvature of the
posterior part of the maxillary tuberosity
The needle should be kept close to the bone to
avoid entering the pterygoid venous plexus

Infra Orbital N.B
of the patient for right side injection and
facing the patient in left side injection

Infra orbital Nerve Block
Solution is deposited at the orifice of the
infra-orbital foramen, and will diffuse along
the canal to involve both the anterior and
middle superior alveolar nerve.

Pulps of the maxillary premolars and
anteriors (and the mesiobuccal root of
maxillary first molar)
And
the buccal mucoperiosteum from midline to
the area of maxillary second premolar

Technique
Infra-orbital ridge is palpated and the
infra-orbital notch located with the tip of
the index finger, which then moves
downward to lie over the infra-orbital
foramen.
2. The tip of the needle is directed towards
the foramen using any of 2 approaches :
1.



Approach A:
1- Direct the syringe in the line passing oblique from the mesioincisal
angle of the central incisor, to the distocervical angle, and to the
apical region of the root of the canine.
2- The needle is inserted at about 5 mm out in the mucobuccal fold
above the tip of the root of the canine.

3- The needle is pushed till it contacts the boundary of the foramen

Approach B:
1. By holding the syringe in the same line
with the long axis of the upper second
premolar
2. Insert the needle at the reflection of the
mucobuccal fold, 5 mm out from the fold


Area Anesthetized:
The main trunk of the maxillary nerve and
all its branches.
1. Maxillary teeth
2. Investing bone
3. Buccal mucoperiosteum
4. Palatal mucoperiosteum


of the patient for right side injection and
facing the patient in left side injection

Technique
Needle is inserted over the apices of the
second molar, little distance away from
the bone to clear the zygomatic process
2. The needle passes upwards and inwards
till reaching the spheno-palatine fossa,
with an angle 30 degrees
3. Four ml of anesthetic solution is
deposited
1.

Incisive (Nasopalatine) Injection
(
Area Anesthetized:
1. Palatal alveolar plate opposite six
anterior teeth
2. Overlying mucoperiosteum


Technique
 Point of needle insertion:

Marked by the incisive papilla in the
midline, one cm posterior to the central
incisor.
 Direction of the needle is parallel to the
long axis of maxillary central incisor.
 0.5 ml of solution is injected very slowly

Greater palatine Nerve Block
Detection of greater palatine
foramen
The index finger is moved (with slight
pressure) from the palatal area opposite to
Maxillary first molar Backwards until a
Bleaching of the mucosa occurs .

Detection of greater palatine
foramen
The needle is inserted in the bleached area
, a drop is felt (greater palatine foramen)

Incisive foramen

Greater
palatine
foramen

Palatal mucoperiosteum from maxillary first
premolar to the maxillary third molar

Techniques of
mandibular nerve
block

Mandibular nerve block
1)Mental N.B
2)Inferior alveolar N.B
3)Lingual N.B
4)Mandibular N.B

Mental N.B
The patient is placed in a position that when
he opens his mouth widely the mandibullar
occlusal plane is parallel to the floor
The operator stands on right side and
behind the patient

Mental Nerve Block
Labial m.m and skin from the mental
foramen to the midline

Aim
 To block the inferior dental and lingual

nerve by deposition of the anesthetic
solution around them when they are in the
pterygomandibular space, and before the
entrance of the inferior alveolar nerve to
the mandibular foramen.

Direct Mandibular Injection
 Position

of the patient:
The patient is placed in a position that
when he opens his mouth widely the
mandibullar occlusal plane is parallel to
the floor
The operator stands in front of the patient
for the right mandibular injection. And on
right side and behind the patient for the left
mandibular injection

Point of needle insertion
The index of the left hand is placed in the
mucobuccal fold opposite the premolar
area
2. The external oblique ridge and the
anterior border of the ramus are located
3. The greatest depth of the anterior border
of the ramus which is the coronoid notch
is located
1.

The index finger is rotated lingually to
occupy the retromolar triangle, and the
fingernail faces the lingual side
5. With the fingernail in this position, the
finger tip will rest on the internal oblique
ridge
6. The point of needle insertion is at 5 mm
in front of the middle of the tip of the
index finger
4.

7.

8.
9.
10.

A syringe with a long needle is held over
the premolar region of the opposite side
and parallel with the mandibular occlusal
plane.
The needle is inserted to a depth 20 – 30
mm till it touches bone.
1.2 ml of solution is deposited slowly
The needle is withdrawn about 10 mm
and 0.3 ml of solution is deposited

Long buccal nerve :
Anesthetized by either :
1. Soft tissue infiltration
2. Long buccal nerve block:
0.3 – 0.5 ml of anesthesia is deposited in
the midpoint of the retromolar triangle
between the external and internal
oblique ridges.


Symptoms of anaesthesia
1) Subjective
Tingling and numbness of the lower lip
in the injected site
2) Objective
instrumentation shows no pain of the
related teeth and associated
structures

Errors during Inferior
Alveolar Nerve Block

High injection
Numbness of the ear

Injection near the auriculotemporal
nerve

High injection
Trismus

Injection into the lateral pterygoid
muscle

High injection
Toxicity

Injection into the pterygoid plexus of
veins

Low injection
Trismus

Injection into the medial pterygoid
muscle

Low injection
Toxicity

Injection into the posterior facial vein

Low & Deep injection
Facial paralysis

Injection into substance of the
parotid gland (Facial nerve)

Mandibular Nerve Block
1) Gow Gates technique
2) Akinosi technique

Mandibular Nerve
Block
1) Gow Gates
technique

Aim
 To anesthetize the inferior alveolar, mental

nerve, incisive, lingual, mylohyoid,
auriculotemporal and buccal nerves.

Target area:
The lateral aspect of the neck of the
condyle
1. The patient is asked to extend the neck
and open the mouth as wide as possible
2. Extraoral landmarks:
•
Intertragic notch
•
Corner of the mouth


The index finger is used to retract the
tissues
4. Tissues at the side of injection are
prepared
5. The barrel of the syringe is placed on the
side opposite to that of injection
6. Needle penetration occurs at a site just
distal to the maxillary second molar and
at a height equal to the palatal cusp of
the second molar
3.

The needle is aligned to a plane
extending from the corner of the mouth
to the tragus
8. Needle is slowly advanced till bone is
contacted
9. 1.8 ml of solution is deposited
7.

Advantages
1.
2.
3.
4.
5.

Increased success rate
Constancy of landmarks
Decreased positive aspiration rate
Decreased incidence of trismus
Only one injection is required

Mandibular Nerve
Block
2) Akinosi technique

Aim
 To anesthetize the inferior alveolar,

mental, incisive and buccal nerve.

Target area:
Area between the vertical ramus and
maxillary tuberosity
1. The patient is asked to close the teeth
2. Cheek is distended using the fingers of
the left hand
3. The mucosa buccal and distal to upper
third molar is wiped


The needle is positioned at the level of
the maxillary marginal gingiva with the
barrel parallel to the maxillary occlusal
plane.
5. The needle penetrates the tissues in the
embrasure between the vertical ramus
and maxillary tuberosity
6. 2.5 – 3 cm of the needle is buried in the
tissues
4.

Advantages
Painless
2. One prick of the needle
3. Rapid onset
4. Can be used in patients suffering from
trismus
1.

1.
2.

3.

4.
5.

Discuss Factors that influence the choice of
local anaesthetic technique ?
A surgeon is about to remove a lesion
extending from upper left central incisor to
upper left second premolar. Describe two local
anesthetic techniques which can be used.
Enumerate the 6 amide local anesthetics.
State which is long, intermediate or short
acting.
Discuss the pain pathway.
Enumerate complications of inferior alveolar
nerve block.

Techniques of Local Anesthesia

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