This document discusses local anesthesia. It begins with an introduction that describes local anesthesia as the mainstay of pain control in medicine and how its effectiveness depends on patient factors, drug choice, and practitioner skill. It then covers the history of pain medications, provides a definition of local anesthesia, and classifies local anesthetics based on pharmacological nature and route of administration. The document concludes by describing several theories of how local anesthetics work, with the specific receptor theory seen as the most favored explanation involving binding to sodium channels.

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.