1. LA REVISION - I
Dr.V.RAMKUMAR
CONSULTANTDENTAL&FACIOMAXILLARYSURGEON
REGNO:4118 TAMILNADU-INDIA(ASIA)

2.  Local anesthesia has been 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.

3. Properties deemed most desirable for a LA solution –
 It should not be irritating to the tissue.
 It should not cause any permanent alteration of
nerve structure.
 Its systemic toxicity should be low.
 It must be effective regardless of whether it is
injected into the tissue or applied locally to
mucous membranes.

4.  The time of onset of anesthesia should be as
short as possible.
 The duration of action must be long enough to
permit completion of the procedure.
 It should be relatively free from producing
allergic reactions.
 It should be stable in solution and readily
undergo biotransformation in the body.

5. Electrophysiology of nerve
conduction

6. Exitation of nerve segment leads to an increase in permeability of the cell
membrane to Na ions
At firing threshold permeability increases dramatically

7. Reversed polarity
Repolarization (the action potential is terminated)

8. Mode and site of action of LA
LA interfere with the excitation process in a nerve
membrane in one or more of the following ways
 Altering the basic resting potential of the nerve
membrane
 Altering the threshold potential (firing level)
 Decreasing the rate of depolarization
 Prolonging the rate of repolarization

9. Where do local anesthetics work?
Various theories –
 Acetylcholine theory
 Calcium displacement theory (most popular)
 Surface charge (repulsion) theory
 Membrane expansion theory
 Specific receptor theory

10. How LA work?

11. Ca++ which exist in bound form within the cell membrane are
thought to exert a regulatory role on the movement of Na+ ions
Displacement of Ca++ ions from the Na+ channel receptor site
Ca++ Ca++
Ca++
Ca++

12. Binding of LA molecule to this receptor site produces –
Blockade of the Na+ channel –
and results in
conduction
blockade

13. Pharmacology of LA

14. Classification of LA
1…Esters
Benzoic acid Paraaminobenzoic
acid
Butacaine
Cocaine
Ethyl aminobenzoate
(benzocaine)
Hexylcaine
Piperocaine
Tetracaine
Chlouopeocaine
Procaine
Propoxycaine

15. 2…Amides
 Articaine
 Bupivacaine
 Dibucaine
 Etidocaine
 Lidocaine
 Mepivacaine
 Prilocaine
 Ropivacaine
3…Quinoline
 Centbucridine

16. Half life of LA
 Lidocaine – 1.6 hours
 Bupivacaine – 3.5 hours

17. Pharmacology of
vasoconstrictors

18. Vasoconstrictors are drugs that constrict blood
vassals.
Advantages –
 Decreases blood flow to the site of
administration.
 Absorption of LA into the CVS is slowed.
 Minimizing the risk of LA toxicity.
 Increasing the duration of action of LA.

19. Classification
Catecholamines Noncatecholamines
Epinephrine
Amphetamine
Norepinephrine
Methamphetamine
Levonordefrin
Phenylephrine
Felypressin (vasoconstrictor), a synthetic analogue
of the polypeptide vasopressin.

20. Maximum doses of LA
 Lidocaine with epinephrine
 7 mg/kg of body weight for the adult (not to exceed a
dose of 500 mg).
 Lidocaine without epinephrine
 4.4 mg of body weight for the adult (not to exceed a
dose of 300 mg).
 Same dose for children.

21. Calculation of number of
cartridges (for70 kg)
Lidocaine with epinephrine
 According to manufacturer –
20 mg/ml i.e. in 1 ml - 20 mg
 Considering cartridge as 1.8 ml
i.e. in 1.8 ml - 36mg(1.8×20)
or in 1 Cartridge - 36 mg
 Not to exceed a dose of 500 mg
So total no of cartridges 500/36 = 13.88 cartridges

22. Lidocaine without epinephrine
 According to manufacturer –
20 mg/ml i.e. in 1 ml - 20 mg
 Considering cartridge as 1.8 ml
i.e. in 1.8 ml - 36mg(1.8×20)
or in 1 Cartridge - 36 mg
 Not to exceed a dose of 300 mg
So total no of cartridges 300/36 = 8.33 cartridges

23. Armamentarium

24. Tow types of armamentarium
Major components
 Syringe
 Needle
 Cartridge
Other components
 Topical antiseptic
 Topical anesthetic
 Applicator sticks
 Cotton gauze (2×2
inches)
 Hemostat

25. Syringe –
It is the vehicle whereby the contents of the
anesthetic cartridge are delivered through the
needle to the patient.

26. Needle –
The needle permits the local anesthetic solution to
travel from the dental cartridge into the tissues
surrounding the needle tip.

27. Cartridge –
Is a glass cylinder containing the local anesthetic
drug.

28.  Topical anesthetic -

29.  Applicator sticks –

30.  Cotton gauze (2×2 inches) –

31.  Hemostat –

32. LA REVISION – II

33. Types of Local anesthetic
injection
 Local infiltration –
Small terminal nerve endings in the area of the dental
treatment are flooded with local anesthetic solution.
Example: administration of LA into an interproximal
papilla.

34.  Field block –
LA solution is deposited near the larger terminal
nerve branches so the anesthetic area will be
circumscribed.

35.  Nerve block –
LA is deposited close to a main nerve trunk.

36. Common Techniques of
Anesthesia (Maxillary / Mandible)
1…Supraperiosteal (infiltration)
2…Periodontal ligament injection (intraligamentary
injection)

37. 3…Intraseptal

38. 4…Intracrestal
5…Intraosseous

39. Techniques of maxillary
anesthesia
 Posterior superior alveolar nerve block

40.  Infraorbital nerve block

41. Middle superior alveolar nerve block
 Is present in only about 28% of the population

42. Palatal anesthesia
 Greater palatine nerve block

43.  Nesopalatine nerve block

44. Techniques of mandibular
anesthesia
 Inferior alveolar nerve block

45.  Lingual nerve block –
After depositing LA solution for inferior alveolar
nerve pull the needle half way out, aspirate and
deposit the LA solution for lingual nerve
Advantage – nicking of soft tissue will be avoided.

46.  Buccal nerve block –
a. Parallel with occlusal plane on the side of
injection but buccal to it.
b. Distal and buccal to the last molar.

47.  Mental nerve block

48.  Mandibular nerve block: the GOW-GATES
technique

49.  VAZIRANI-AKINOSI closed-mouth mandibular
block

50. Complications of local anesthesia
Local complications
 Needle breakage
 Persistent anesthesia or
paresthesia
 Facial nerve paralysis
 Trismus
 Soft-tissue injury
 Hematoma
 Pain on injection
 Burning on injection
 Infection
 Edema
 Sloughing of tissues
 Post-anesthetic intraoral
lesions
Systemic complications
 Vasodepressor syncope
 Over dosage (toxic reaction)
 Allergy
 Psychogenic reactions

51. Local complications

52. Needle breakage
Causes –
 Weakening of the dental needle by bending it
before it’s insertion.
 Sudden unexpected movement by the patients.
Prevention –
 Use a 25-gauge needle.
 Use long needle requiring penetration (> 18 mm).

53. Persistent anesthesia or
paresthesia
Causes –
 Trauma to any nerve.
 Injection of contaminated LA solution.
 Hemorrhage into or around the neural sheath
(Bleeding increases pressure on the nerve)
Prevention –
 Strict adherence to injection protocol.
 Proper care and handling of dental cartridges.

54. Causes –
 Transient facial nerve paralysis is commonly caused by the
introduction of LA into the capsule of the parotid gland.
Prevention –
 Adhering to protocol with the IANB .
 A needle tip should be in contact with the bone.
Management –
 Reassure the patient
 Contact lance should be removed
 An eye patch should be applied to the affected eye.
 “tincture of time” is the recommended medicine.

55. Trismus
Causes –
 Trauma to muscles or blood vessels.
 Contaminated LA solution.
 Hemorrhage.
 A low grade infection.
 Excessive volumes of LA solution.
Prevention –
 Practice atraumatic insertion and injection technique.
Management –
 Heat therapy, physiotherapy.
 Warm saline rinses.
 Anti-inflammatory, Analgesics, Muscle relaxants, Antibiotics.

56. Soft-tissue injury
Causes –
 Common in younger children and mentally or physically
disabled children or adults.
Prevention –
 Proper instruction and education of guardian

57. Hematoma
Causes –
 The effusion blood into extravascular spaces due to
nicking of blood vessel (artery or vein) during injection.
Prevention –
 Use a short needle for PSA nerve block.
 Minimize number of needle penetration.
Management –
 Direct pressure should be applied to the site of bleeding.
 Do not apply heat to the area for at least 4 to 6 hours.

58. Pain on injection
Causes –
 Careless injection technique.
Prevention -
 Proper technique.
 Use of sharp needle.
 Use of topical anesthetic.
 Inject LA slowly.

59. Burning on injection
Causes –
 pH of the solution (pH = 5 acidic)
 Rapid injection of LA.
 Contamination of LA cartridges
Prevention –
 Slowing the injection ( ideal rate 1 mm per sec.)

60. Infection
Causes –
 Contamination of needle.
 Injecting LA solution into an area of infection.
Management –
 Rx treatment consist of those procedures to manage
Trismus.

61. Edema
Swelling of tissue is a clinical sign of the presence of
some disorder.
Causes –
 Trauma, Infection, Allergy, Hemorrhage.
Prevention –
 Complete medical evaluation of the patient before drug
administration.

62. Sloughing of tissues
 Prolonged irritation or ischemia of gingival soft
tissue may led to –
 Epithelial desquamation
 Sterile abscess

63. Post-anesthetic intraoral
lesions
These are recurrent aphthous stomatitis and
Herpes simplex.
Management –
 Primary management is symptomatic.

64. Systemic complications
 Vasodepressor syncope
 Over dosage (toxic reaction)
 Allergy
 Psychogenic reactions

65. Thank You