This document provides information on local anesthesia. It begins with definitions and history, describing how local anesthesia was developed by Koller in 1884 using procaine. It then discusses the various methods of inducing local anesthesia and the neuroanatomy and electrophysiology of nerve conduction. The remainder of the document focuses on the pharmacology of local anesthetics, including theories of action, properties, classification, pharmacokinetics, composition, and maximum permissible doses. Specific local anesthetic techniques for the maxilla and mandible are also outlined.

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Local
anesthesia
Dr Abhishek Shah
M.D.S – part 1M.D.S – part 1

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DEFINITION
It is defined as a loss of sensation in a
circumscribed area of the body caused by a
depression of excitation in nerve endings or an
inhibition of the conduction process in peripheral
nerves.
- Covino BG, Vasallo HG (1976)

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HISTORY
• Local anesthesia(LA) was developed by Carl Koller in
1884.
• Procaine - Alfred Einhorn and Richard Willstadter in
1905.
• In 1901, epinephrine was first used as a
vasoconstrictor in conjugation with LA solution.

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METHODS OF INDUCING LOCAL
ANESTHESIA:
Mechanical trauma
Low temperature
Anoxia
Chemical irritants
Neurolytic agents such as alcohol and phenol
Chemical agents such as local anesthetics

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NEUROANATOMYNEUROANATOMY

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Neuron

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ELECTROPHYSIOLOGY OF
NERVE CONDUCTION

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In its resting state the nerve membrane is :
• slightly permeable to Na+
• freely permeable to K+
• freely permeable to Cl-
ions

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Depolarization: Excitation of a nerve segment leads to
an increase in permeability of the cell membrane to Na+
.
This whole process takes 0.3msec.

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Repolarization: The action potential is terminated
when the membrane repolarizes.
• Inactivation of increased permeability to Na+
• Na+
and K+
move along concentration gradients.
• After reaching original level of -70mV slight excess of
Na+
so now sodium pump works to pump Na+
out and
K+
in. whole process takes about 0.7 msec.

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Impulse propagation: After initiation of action potential by a
stimulus, the new electrical equilibrium in this segment of nerve
produces local currents that begin flowing between the depolarized
and the adjacent resting area.

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Theories of local anaesthetic agents
1. Acetylcholine theory
2. Calcium displacement theory
3. Surface charge repulsion theory.
4. Membrane expansion theory
5. Specific receptor theory

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MEMBRANE EXPANSION THEORY

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SPECIFIC RECEPTOR THEORY

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Mechanism of action of local
anesthetics
1. Displacement of calcium ions from the sodium
channel receptor site
2. Binding of the L.A. Molecule to this receptor
3. Blockade of the sodium channel
4. Decrease in sodium conductance
5. Depression of the rate of electrical depolarization
6. Failure to achieve firing potential
7. Lack of development of action potential.
8. Conduction blockade

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Local anesthetic enters from the axoplasmic
side

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Possible Methods Of Interference Of Excitation
Process – Local Anesthetics
1. Altering the basic resting potential of the nerve
membrane
2. Altering the threshold potential
3. Decreasing the rate of depolarization
4. Prolonging the rate of repolarization

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PROPERTIES OF LOCAL ANESTHETICS
1. Non irritating to tissue to which it is applied
2. Not cause any permanent alteration of nerve
structure
3. Its systemic toxicity should be low
4. It must be effective regardless of whether it is
injected into the tissue or applied locally to
mucous membranes
5. Time of onset of anesthesia should be short
6. The duration of action should be long enough to
permit the completion of procedure

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7.It should have the potency sufficient to give
complete anesthesia with out the use of harmful
concentrated solutions
8.It should be free from producing allergic reactions
9.It should be free in solution and relatively undergo
biotransformation in the body
10.It should be either sterile or be capable of being
sterilized by heat with out deterioration

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PHARMACOLOGY
Acc to Chemical Structure
Ester group
• Cocaine
• Benzocaine
• Tetracaine
• Piperocaine
• Procaine
• Chloroprocaine
• Propoxycaine
Amide group
• Lidocaine
• Bupivacaine
• Mepivacaine
• Etidocaine
• Prilocaine
• Articaine
Quinoline
• centbucridine

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CLASSIFICATION

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BASED ON DURATION OF ACTION:
• Short duration : –
– eg: Lidocaine HCl 2%, Mepivacaine HCl 2%
• Intermediate duration :
– eg: Lidocaine HCl 2% + epinephrine 1:1,00,000
• Long duration :
– eg: Bupivacaine HCl 0.5% + epinephrine
1:2,00,000, 2% Etidocaine

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PHARMACOKINETICS
UPTAKE
All local anesthetics produce vasodilation except cocaine.
Vasodilation
Increase rate of absorption
Decrease duration & quality of pain control
Increase in anesthetic blood level
Toxicity

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Route of
administration
Rate of absorption
Oral Poor.
Topical Intact skin -- no anesthetic
action.
Skin damaged--they bring
rapid pain relief.
5 min
Injection Rapid.
1 min- i.v, 5-10min- i.m
Subcutaneous Depends on vascularity of
site.
30-90min

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DISTRIBUTION
• Distributed to all tissues esp. to highly perfused organs
(brain, liver, kidney).
• But skeletal muscle (not among highly perfused organ)
contains the greatest % of LA since it makes the largest
mass of tissue in body.
• Half life lidocaine – 1.6 hr

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BLOOD LEVEL OF LA DEPENDS ON
• Rate at which the drug is absorbed in systemic
circulation
• Rate at which the drug is distributed from blood
vessels to the tissues
• Rate at which the drug is metabolised and excreted

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Metabolism
•Agents with ester type linkage are metabolized by a
pseudocholinesterase found in liver as well as plasma.
•Agents with amide type linkage are metabolized in
liver by a hydrolytic process.

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EXCRETION
• Mainly excreted by kidney.
• Esters appear in small concentration.
• Amides are present in urine as parent compound .

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• Patient with renal impairment
Unable to eliminate
Parental / major metabolite from blood
Increased level in blood
Toxicity

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COMPOSITION OF LA
INGREDIENT FUNCTION
Local anesthetic agent Conduction blockade.
Vasoconstrictor Decrease absorption of local anesthetic
into blood, thus increasing duration of
anesthesia and decreases toxicity of
anesthetic.
Sodium metabisulphite Antioxidant for vasoconstrictor.
Methyl paraben Preservative to increase shelf life;
bacteristatic.
Thymol Antifungal.
Sodium chloride Isotonicity of solution.
Sterile water Dilutent.

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Maximum Permissible Dose of
Lignocaine
Without a vasoconstrictor – 4.4mg/kg body wt. not
exceeding 300 mg(15ml)
With vasoconstrictor – 6.6 mg/kg body weight not
exceeding 500 mg(25ml)

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ADDITION OF
VASOCONSTRICTOR
• Vasoconstrictors are added in LA to:
- Decrease blood flow to the site of administration.
- Decrease the rate of vascular absorption.
- To improve the depth and duration of
anesthesia.
- Decrease the chances of toxicity

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Vasoconstrictors used in addition with LA are as follows:-
-Epinephrine (most common)
- Nor epinephrine
- Phenylephrine
- Vasopressin
- Felypressin
Concentration of epinephrine in LA is 5µg/ml of
1: 200,000.
• Shelf life – 18months without VC
- 36 months with VC
• Recommended Dose of Vasoconstrictor is 0.2mg
Epinephrine or 0.34mg NorEpinephrine
• For Patient Having Cardiovascular Impairment-
0.04mg

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Local anesthetics in periodontal surgery
• Infiltration of 2% lidocaine with 1:50,000 epinephrine during
periodontal surgery reduces blood loss by about 50% compared to
2% lidocaine with 1:100,000 epinephrine
(Dionne RA, Wirdzek PR, J Am Dent Assoc 1984)
• A clinical trial of periodontal surgery comparing 1.5% etidocaine
1:200,000 epinephrine to 2% lidocaine 1:100,000 epinephrine
reported greater bleeding with the lower epinephrine formulation
(Crout RJ, Koraido G, Anesth Prog 1990)

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• A study found that articaine, administered as a 4% formulation,
may provide superior infiltration properties
(Kanaa MD, Whitworth JM, Corbett IP, J Endod 2006)
• Articaine, as well as prilocaine, have been reported to have slightly
higher incidence of mandibular and lingual paresthesia following
mandibular blocks
(Haas DA, Lennon D, J Can Dent Assoc 1995)
• When compared to the 1:200,000 epinephrine formulation, the
1:100,000 epinephrine formulation of 4% articaine has been found to
provide better visualization of the surgical field and less blood loss
(Moore PA, Delie RA, JOP 2007)

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Armamentarium
• 3 Essential Components:
• i) Syringe
• ii)Needle
• iii)Cartridge

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Types Of Syringes in Dentistry
• 1. NonDisposable Syringes
• 2. Disposable Syringes
• 3. Safety Syringes
• 4. Computer Controlled Local Anesthetic
Delivery Systems

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Syringe

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Needle

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Cartridge

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•Nerve block
•Field block
•Local infiltration
•Intra ligamentary injection
•Intra osseous injection

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TECHNIQUES OF ANAESTHSIA
LOCAL
INFILTRATIO
N
FIELD
BLOCK
NERVE
BLOCK

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Maxillary anesthesia
•Infraorbital nerve block
•Posterior superior nerve block
•Nasopalatine nerve block
•Greater palatine nerve block
•Maxillary nerve block

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INFRA ORBITAL NERVE BLOCK
 Nerves anesthetizedNerves anesthetized
• InfraorbitalInfraorbital
• Anterior & middle superior alveolar nervesAnterior & middle superior alveolar nerves
• Inferior palpebralInferior palpebral
• Lateral nasalLateral nasal
• Superior labial nerves.Superior labial nerves.
 Areas anaesthetizedAreas anaesthetized
• Incisors, cuspids, bicuspids & mesiobuccal root of 1Incisors, cuspids, bicuspids & mesiobuccal root of 1stst
molarmolar
• Upper lipUpper lip
• Lower eyelidLower eyelid
• Portion of nose on same sidePortion of nose on same side

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 Indications
• Surgical or operative procedure to be performed on 5 anterior
maxillary teeth.
 Needle pathway during insertion
Needle pathway
central incisor approach
 Anatomical landmark
• Infraorbital ridge
• Supraorbital notch
• Infraorbital notch
• Anterior teeth
• Pupil of eye
• Mental foramen
Bicuspid approach

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• Technique
Symptoms:
Tingling & numbness of upper lip, lower eyelid, & side of nose.

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Posterior superior alveolar block
 Nerve anesthetized
• Posterior superior alveolar nerve
 Area anesthetized
• Maxillary molars except mesio-buccal root of 1st
molar
• Buccal alveolar bone- periosteum, connective tissue, mucous
membrane
• Floor of Maxillary sinus
 Anatomical landmark
• Mucobuccal fold & its concavity
• zygomatic process of maxilla

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• Infratemporal surface of maxilla
• Anterior border & coronoid process of ramus of mandible.
• Tuberosity of maxilla.
 Indication
• Operative procedure in maxillary molars.
 Needle pathway during insertion
• Mucosa
• Areolar tissue
• Buccal pad fat
• Posterior fibers of buccinators muscle

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• Technique

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Nasopalatine nerve block
 Nerves anesthetized
• Nasopalatine nerve
 Area anesthetized
• Anterior portion of hard palate
• Back of bicuspids
 Anatomic landmark
• Central incisor teeth
• Incisive papilla

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 Indication
• Block anterior & middle superior alveolar bone
• Complete anesthesia of nasal septum

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Anterior palatine nerve block
Nerve anesthetized
• Anterior palatine nerve
Anatomical landmark
• 2nd
& 3rd
molar
• Palatal gingival margin of 2nd
& 3rd
molar
• Midline of palate
• A line approx. 1 cm from palatal gingival margin
toward midline.

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• Indication
• Palatal anesthesia + PSA
• Surgery of posterior position of hard palate

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Maxillary nerve block
 Nerve anesthetized
• Entire maxillary nerve
 Area anesthetized
• Maxillary teeth on affected side
• Alveolar bone
• Hard palate& portion of soft palate
• Upper lip
• Cheek
• Side of nose
• Lower eyelids

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Indications
• Extensive surgery
• Diagnostic purpose - neuralgia

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Mandibular nerve block
• Inferior alveolar nerve block
• Mental nerve block
• Long buccal nerve block
• Gow gate
• Vazirani akinosi nerve block

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Classical inferior alveolar nerve block
Nerve anesthetized
• Inferior alveolar nerve
• Lingual nerve
• Buccinator nerves
Areas anesthetized
• Body of mandible & an inferior portion of ramus
• Mandibular teeth
• Mucoperiosteum anterior to the 1st
mandibular molar

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Anatomical landmark
•Mucobuccal fold
•Anterior border of ramus
•External oblique ridge
•Retromolar triangle
•Internal oblique ridge
•Pterygomandibular ligament
•Buccal sucking pad
•Pterygomandibular space

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Vazirani Akinosi nerve block
 Nerve anesthetized
• Inferior alveolar nerve & its subdivision
• Lingual nerve, Buccal nerve
• Mental nerve
• Incisive nerve
 Area anesthetized
• All mandibular hard & soft tissue to midline- floor of mouth,
anterior 2/3rd
of tongue
 Anatomical landmark
• Occlusal plane of occluding teeth
• Mucogingival junction of maxillary molars
• Anterior border of ramus

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Gow gate nerve block
 Anatomical landmark
• Anterior border of ramus
• Tendon of temporal muscle
• Corner of mouth
• Inter-tragic notch of ear
• External ear
 Indications
• When buccal to lingual anaesthesia from 3rd
molar to midline

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Mental nerve Block
Nerves anesthetized
• Mental nerve
Area anesthetized
• Lower lip
• Buccomucoperiosteum
Anatomical landmark
• Mandibular bicuspids
• Mental foramen

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 Indication
• Surgery of lower lip or mucous membrane

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Long buccal nerve
Nerve anesthetized
• Buccinator nerve
Areas anesthetized
• Buccal mucous membrane & mucoperiosteum of
mandibular molar
Anatomical landmark
• External oblique ridge
• Retromolar pad area

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PERIODONTAL LIGAMENT
INJECTION
• Area of
insertion : long
axis of the tooth
to be treated on
mesial and
distal of the root

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Local complications
• Needle breakage
• Paresthesia
• Facial nerve paralysis
• Muscle trismus
• Soft tissue injury
• Hematoma
• Pain on injection
• Burning on injection
• Infection
• Edema
• Sloughing / tissue necrosis
• Post anesthetic intraoral lesion

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Systemic complications
• Syncope
• Toxicity
• Hypersensitivity / allergy
• Idiosyncrasy
• Malignant hyperthermia
• Drug interaction
• Other systemic conditions.

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Thanks….!!