local anesthesia

2. LOCAL ANESTHESIA
BY: HASSAN KHAN
FINALYEAR BDS
CLASS NO:35

3. CONTENTS
▪ INTRODUCTION
▪ HISTORY
▪ DEFINITION
▪ CLASSIFICATION
▪ THEORIESOF MECHANISMSOFACTION

4. INTRODUCTION
▪ PAIN CONTROL AS GREATEST CHALLENGE IN MEDICINE
▪ PAIN FREE OPERATIONS
▪ LOCAL ANESTHESIA AS MAINSTAY OF PAIN CONTROL
▪ EFFECTIVENESS AND USAGE DEPENDING ON:
▪ PATIENT CONSIDERATION
▪ CHOICE OF DRUG ANDTECHNIQUE
▪ SKILL AND EXPERIENCE OFTHE PRACTITIONER

5. HISTORY
▪ Alcohol is the oldest known sedative. It was used in the ancient
Mesopotamia thousands of years ago.
▪ The ‘Euphoric’ effect ofOpium was discovered by Summerians
in 3400 B.C.
▪ InWestern Europe between 1750 to 1850 chemists and
physicians collected samples of coca leaves for experiments.
▪ In 1860, German chemist Albert Niemann successfully isolated the
active ingredient of coca leave; he named it cocaine.

6. DEFINITION
THETEMPORARYLOSSOF
SENSATION INA CIRCUMSCRIBED
AREAOFTHE BODYCAUSED BY
DEPRESSIONOF EXCITATION IN
NERVE ENDINGS OR INHIBITIONOF
THE CONDUCTIONPROCESS IN
PERIPHERAL NERVES.

7. CLASSIFICATION
▪ ONTHE BASIS OF PHARMACOLOGICAL NATURE
▪ ONTHE BASIS OF ROUTE OF ADMINISTRATION
▪ ONTHE BASIS OFTECHNIQUES

8. ONTHE BASIS OF PHARMACOLOGICAL NATURE
ESTERS
• PROCAINE
• TETRACAINE
• BENZOCAINE
• COCAINE
AMIDES
• LIDOCAINE
• MEPIVACAINE
• BUPIVACAINE
• PRILOCAINE
• ARTICAINE

9. ON THE BASIS OF ROUTE APPLICATION
TOPICAL INJECTABLE

10. ON THE BASIS OF TECHNIQUE
▪ LOCAL INFILTRATION:
▪ SMALLTERMINALNERVE ENDINGSINTHEAREAOF DENTALTREATMENTAREFLOODEDWITHTHE
LOCALANESTHETICSOLUTION.
▪ FORINSTANCE;ADMINISTRATIONOFLA INTOAN INTERPROXIMAL PAPILLA.
▪ FIELD BLOCK:
▪ LOCALANESTHETICIS DEPOSITEDNEARTHE LARGERTERMINALNERVE BRANCHES.
▪ MAXILLARYINJECTIONADMINISTEREDABOVETHEAPEXOFTHETOOTHTO BETREATEDARE
PROPERLYTERMED FIELDBLOCKS.
▪ NERVE BLOCK:
▪ LOCALANESTHETICIS DEPOSITEDCLOSETOA MAIN NERVETRUNK.
▪ FOREXAMPLE;POSTERIORSUPERIORALVEOLARANDINFERIORALVEOLARetc.

11. THEORIES OF MECHANISMS OF ACTION
▪ ACETYCHOLINE THEORY:
▪ STATEDTHATACETYCHOLINE WAS INVOLVED IN NERVE CONDUCTION AT NERVE SYNAPSES.
▪ THERE IS NO EVIDENCE THATACETYCHOLINE IS INVOLVED IN NERVE TRANSMISSION.
▪ CALCIUM DISPLACEMENT THEORY:
▪ IT STATESTHAT LOCAL ANESTHETIC NERVE BLOCK WAS PRODUCED BY DISPLACEMENT OF CALCIUM FROM
SOME MEMBRANE SITE THATCONTROLS PERMEABILITY OF SODIUM.
▪ SURFACE CHARGE (REPULSION) THEORY:
▪ LOCAL ANESTHETIC ACTS BY BINDING TO NERVE MEMBRANE AND CHANGING THE ELECTRICAL POTENTIAL
AT MEMBRANE SURFACE,THUSDECREASING THE EXCITABILITYOF NERVE BY INCREASING THRESHOLD
POTENTIAL.
▪ CURRENT EVIDENCE INDICATES THAT RESTING POTENTIAL OF NERVE MEMBRANE IS UNALTERED BY
LOCAL ANESTHETIC.

12. ▪ MEMBRANE EXPANSION THEORY:
▪ IT STATESTHAT LOCAL ANESTHETIC MOLECULES DIFFUSETO HYDROPHOBIC REGIONS OF EXCITABLE
MEMBRANE,PRDUCING EXPANSION INTHE MEMBRANE,THUS DECREASING THE FLOW OF SODIUM IONS.
▪ THIS RESULTS IN DECREASE DIAMETER OF SODIUM CHANNEL WHICH LEADSTO INHIBITION OF SODIUM
CONDUCTION AND NEURAL EXCITATION.
▪ SPECIFIC RECEPTOR THEORY:
▪ THE MOST FAVOREDTHEORY, PROPOSED THAT LOCAL ANESTHETIC ACT BY BINDING TO SPECIFIC
RECEPTORS ON SODIUM CHANNELS.
▪ INHIBITING THE SODIUM INFLUX THROUGH SODIUM-SPECIFIC ION CHANNELS INTHE NEURONAL CELL.
▪ WHEN INFLUX OF SODIUM IS INTERUPTED,ACTION POTENTIAL CAN'T RISE AND SIGNAL CONDUCTION IS
INHIBITED.
▪ REVERSIBLY DECREASE THE RATEOF DEPOLARIZATION AND REPOLARIZATION OF
EXCITABLE MEMBRANE.