Department of periodontics

1. LOCAL ANESTHESIA
T.HUDSON JONATHAN,
Ist yr MDS

2. CONTENTS
• INTRODUCTION
• MODE AND SITE OF ACTION OF LOCAL ANESTHETICS
• EVOLUTION OF THEORIES
• MECHANISM OF ACTION
• COMPOSITION OF LA
• CLASSIFICATION
• VASOCONSTRICTORS
• MAXIMUM RECOMMENDED DOSES
• DOSING CONSIDERATIONS
• ARMAMENTARIUM

3. CONTENTS
• MAXILLARY INJECTION TECHNIQUES
• MANDIBULAR INJECTION TECHNIQUES
• SUPPLEMENTAL INJECTION TECHNIQUES
• COMPLICATIONS OF LA
• CONTRA INDICATIONS OF LA
• RECENT ADVANCES OF LA
• CONCLUSION
• REFERENCE

4. INTRODUCTION
• Local anesthesia has been defined as the loss
of sensation in a circumscribed area of the
body caused by depression of excitation in
nerve endings or inhibition of conduction
process in peripheral nerves.
• An important feature of local anesthesia is
that it produces this loss of sensation without
the loss of consciousness.

5. Mode and site of action of LA
• Local anesthetic agents alter the process of impulse
generation and transmission 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.
• Decreasing the rate of depolarization.
• Increasing the rate of repolarization.

6. Evolution of theories
Acetylcholine theory:
• Acetylcholine is involved in nerve conduction
together with its role as a neurotransmitter at
nerve synapses.
• But there is no evidence of involvement of
acetylcholine in neural transmission along the
body of the neuron

7. Calcium displacement theory:
• Displacement of calcium from certain
membrane sites that controls the permeability
to sodium.
• Altering the concentration of calcium ions has
no effect on local anesthetic policy.

8. Surface charge theory:
• Local anesthetics bind to the nerve membrane and
change the electrical potential at the membrane
surface.
• LA molecules carring net positive charge make the
electrical potential at the membrane surface more
positive,thereby increasing the threshold potential.
• Recent evidence shows that there is no alteration in
the resting potential by local anesthetics,and they act
within the nerve membrane channels rather than at
the surface.

9. Membrane expansion theory:
• Local anesthetic diffuses to hydrophobic
regions and expands the membrane
preventing the sodium permeability increase.
• Lipid soluble molecules alter the lipoprotein
matrix of nerve membrane and decrease the
diameter of sodium channels.
• There is no direct evidence to support this
theory.

10. Specific receptor hypothesis:
• It is the most favoured theory,Local anesthetics
act by attaching themselves to specific receptors
in the nerve membrane.
• The local anesthetic receptor is located at or near
the sodium channel in the nerve membrane
either on its external surface or on the internal
axoplasmic surface.
• Once the receptor access is gained,sodium ion
permeability is decreased or eliminated and
nerve conduction interrupted.

11. Mechanism of action
• Local anesthesia primarily acts by decreasing the
permeability of the nerve membrane to sodium
ions. They have an insignificant effect on
potassium conductance.
• Calcium ions present within the cell membrane
control the conductance of the sodium ion across
membranes.
• The release of calcium ion from this cell
membrane results in an increased sodium
permeability of the nerve membrane.

12. Displacement of calcium ions from nerve receptor site.
↓
Binding of local anesthetic molecule to this receptor site.
↓
Blockade of sodium channel.
↓
Decrease in sodium conductance.
↓
Depression of rate of electrical depolarization.
↓
Failure to achieve threshold potential level.
↓
Lack of development of propagated action potential.
↓
Conduction blockade.

13. Mechanism of action

14. Composition of LA
Component Function
Local anesthetic drug Blockade of nerve conduction
Sodium chloride Isotonicity of the solution
Sterile water volume
Vasopressor ↑depth and duration of
anesthesia;↓absorption of local
anesthetic and vasopressor
Sodium(meta)bisulfite antioxidant
Methylparaban
Bacteriostatic agent

15. Classification
1. INJECTABLE: (Stanley .F.Malamed)
a.Low potency,short duration
-Procaine
-Chloroprocaine
b.Intermediate potency and duration
-Lidocaine
-Prilocaine
c.High potency,long duration
-Tetracaine
-Bupivacaine
-Ropivacaine
-Dibucaine

16. 2. SURFACE ANESTHETIC:
a.Soluble
-Cocaine
-Lidocaine
-Tetracaine
b.Insoluble
-Benzocaine
-Butylaminobenzoate
-Oxethazine

17. 1.ESTERS
 Esters of benzoic acid
-butacaine
-cocaine
-ethyl amino benzoate
-hexylcaine
-piperocaine
-tetracaine
 Esters of para aminobenzoic acid
-chloroprocaine
-procaine
-propoxycaine

18.  AMIDES
-articane
-bupivacaine
-etidocaine
-lidocaine
-mepivacaine
-prilocaine
- ropivacaine
 QUINOLINE
-centbucridine

19. Vasoconstrictors
• Vasoconstrictors are drugs that constrict blood
vessel and therby control tissue perfusion.
• They are added to the LA solution to oppose the
inherent vasodilatory action of LA.
• They are an important addition to the local
anesthetics for the following reasons.
By constricting blood vessels,vasoconstrictors
decrease blood flow to the site of drug
administration.

20. Absorption of local anesthetic into the
cardiovascular system is slowed,resulting in
lower anesthetic blood vessels.
Local anesthetic blood levels are
lowered,therby decreasing the risk of local
anesthetic toxicity.
More local anesthetics enter into the
nerve,where it remains for longer
periods,therby increasing the duration of
action of more local anesthetics.

21. Maximum recommended doses
Drug Formulation MRD mg/lb (mg/kg)
Articaine With epinephrine None listed 3.2 7.0
Lidocaine Plain
With epinephrine
300
500
2.0
3.3
4.4
7.0
Mepivacaine Plain
With levonordefrin
400
400
2.6
2.6
5.7
5.7
Prilocaine Plain
With epinephrine
600
600
4.0
4.0
8.8
8.8

22. Dosing considerations
Patient with cardiac history:
• Should limit dose of epinephrine to 0.04mg
• Most local anesthesia uses 1:100,000
epinephrine concentration (0.01mg/ml)
Pediatric dosing:
• Clark’s rule:
Maximum dose=(child weight in
lbs(pounds)/150) X max adult dose(mg)
• Simple method= 1.8cc of 2% lidocaine/20lbs

23. Armamentarium
• Anesthetic carpules
• Syringe
• Needle
• Mouth props
• Retractors
Carpules:
• 1.7 or 1.8cc
• Pre-made in blister packs or canisters
• Contains preservatives for epinephrine andlocal
anesthetics

24. Syringe:
• Aspirating type
• Non-aspirating type
Needle:
• Multiple gauges used 25g,27g, 30g
• Length:Short- 26mm,Long- 36mm
• Monobeveled

25. Topical anesthetic:
• Used prior to local anesthetic injection to
decrease discomfort in non-sedated patients
• Generally benzocaine(20%)

26. Maxillary injection techniques
• Supraperiosteal injection
• Posterior superior alveolar nerve block
• Middle superior alveolar nerve block
• Anterior superior alveolar nerve block
• Infra orbital nerve block
• Greater palatine nerve block
• Nasoplalatine nerve block
• Anterior middle superior alveolar nerve block
• Maxillary nerve block

27. Local infiltration:
• It is defined as a technique in
which the local anesthetic
solution is deposited at or above
the apex of the tooth to be
treated.
• Small terminal nerve ending in the
area of the dental treatment are
flooded with local anesthetic
solution.
• Incision is then made into the
same area in which the local
anesthesia has been deposited.

28. • An example of local infiltration is the administration
of a local anesthetic into a interproximal papilla
before root planning.
Field block:
• Local anesthesia is deposited near the larger
terminal nerve branches.
• So the anesthetized area will be circumscribed
preventing, the passage of impulses from the tooth
to the CNS.
• Incision is then made into the area away from the
site of the anesthetic.

29. Nerve block:
• Local anesthetic is deposited close to main nerve
trunk,usually at a distance from the site of
operative intervention.
• Posterior superior alveolar,nasopalatine and
inferior alveolar are some examples of nerve
blocks.

30. Posterior superior alveolar nerve block:
• Used to anesthetize the pulpal
tissue,corresponding alveolar bone, and
buccal gingival tissue to the maxillary 1st, 2nd,
and 3rd molars.

31. Technique:
• Area of insertion- height of mucobuccal fold
between 1st and 2nd molar
• Angle at 45° superiorly and medially
• Insert about 15-20mm
• Aspirate then inject if negative

32. Middle superior alveolar
nerve block:
• Used to anesthetize the
maxillary premolars,
corresponding alveolus,
and buccal gingival tissue
• Used if the infraorbital
block fails to anesthetize
premolars

33. Technique:
• Area of insertion is height of mucobuccal fold
in area of 1st/2nd premolars
• Insert around 10-15mm
• Inject around 0.9-1.2cc

34. Anterior superior alveolar nerve
block:
• Used to anesthetize the
maxillary canine,lateral incisor,
central incisor, alveolus, and
buccal gingiva
Technique:
• Area of insertion is height of
mucobuccal fold in area of
lateral incisor and canine
• Insert around 10-15mm
• Inject around 0.9-1.2cc

35. Infraorbital nerve block:
• Used to anesthetize the maxillary 1st and 2nd
premolars, canine, lateral incisor, central
incisor, corresponding alveolar bone, and
buccal gingiva
• Combines MSA and ASA blocks
• Will also cause anesthesia to the lower eyelid,
lateral aspect of nasal skin tissue, and skin of
infraorbital region

36. Technique:
• Palpate infraorbital
foramen extra-orally and
place thumb or index
finger on region
• Retract the upper lip and
buccal mucosa
• Area of insertion is the
mucobuccal fold of the 1st
premolar/canine area
• Contact bone in
infraorbital region
• Inject 0.9-1.2cc of local
anesthetic

37. Greater palatine nerve block:
• Can be used to anesthetize the palatal soft tissue
of the teeth posterior to the maxillary canine
and corresponding alveolus/hard palate
Technique:
• Area of insertion is ~1cm medial from 1st/2nd
maxillary molar on the hard palate
• Palpate with needle to find greater palatine
foramen
• Depth is usually less than 10mm

38. • Utilize pressure with elevator/mirror handle to
desensitize region at time of injection
• Inject 0.3-0.5cc of local anesthetic

39. Nasopalatine nerve block:
• Can be used to anesthetize the soft and hard
tissue of the maxillary anterior palate from
canine to canine.
Technique:
• Area of insertion is incisive papilla into incisive
foramen
• Depth of penetration is less than 10mm

40. • Inject 0.3-0.5cc of local anesthetic
• Can use pressure over area at time of injection
to decrease pain

41. Mandibular injection techniques
• Inferior alveolar nerve block
• Gow gates mandibular technique
• Vazirani akinosi (closed mouth technique)
• Buccal nerve block
• Mental nerve block
25 gauge

42. Inferior alveolar nerve block
• IANB commonly referred to as the mandibular nerve block
is the second most frequently used and possibly the most
important injection technique in dentistry.
Nerves anesthetized:
• inferior alveolar,incisive,mental and lingual
Areas anesthetized:
I. mandibular teeth to midline
II. body of mandible,inferior portion of ramus
III. buccal mucoperiosteum
IV. mucous membrane anterior to mental foramen

43. V. anterior two-third of tongue and floor of oral cavity
VI. lingual soft tissue and periosteum
Landmark:
I. Coronoid notch
II. Pterygomandibular raphe
III. Occlusal plane of mandibular posterior teeth.
• Three parameters must be considered during
administration of IANB.
I. Height of the injection
II. The anteroposterior placement of the needle
III. The depth of penetration

44. Techniques:
• use a 25 gauge long needle,retract the tongue toward the
midline with the mirror handle or tongue depressor to
provide access and visibility to the lingual border of the
body of the mandible.
• Approach area of injection from contra-lateral premolar
region
• Use the non-dominant hand to retract the buccal soft
tissue (thumb in coronoid notch of mandible; index finger
on posterior border of extraoral mandible)
• Penetrate the soft tissue and advance the needle until
bone is contacted.The depth of penetration to bone is 3-
5mm.

45. • Aspirate in two planes,if negative,slowly deposite approxi
1.5ml of anesthetic.
• Inject remaining anesthetic into coronoid notch region of the
mandible in the mucous membrane distal and buccal to most
distal molar to perform a long buccal nerve block.
Indications:
I. Procedures on multiple mandibular teeth in one quadrant
II. When buccal and lingual soft tissue anesthesia is necessary

46. Gow-gates technique
• Gowgates technique is a true mandibular nerve block
because it provides sensory anesthesia to virtually the
entire distribution of mandibular nerve.
Landmarks:
• Extra-oral- lower border of tragus,corner of the
mouth
• Intra-oral:
 Height of injection established by placement of the
needle tip just below the mesiolingual cusp of
maxillary second molar.
 Penetration of soft tissue just distal to the maxillary
second molar at the height established.

47. Nerves anesthetized:
• Inferior alveolar, mental, incisive, lingual, mylohyoid,
auriculotemporal, buccal.
Areas anesthetized:
• Mandibular teeth to midline
• buccal mucoperiosteum and mucous membrane on the
side of injection
• anterior two third of the tongue and floor of the oral
cavity
• lingual soft tissue and periosteum
• body of the mandible
• inferior portion of the ramus

48. • skin over zygoma
• posterior portion of the cheek and temporal
regions.

49. Vazirani- Akinosi technique
• In 1997,Dr.Joseph Akinosi reported a closed
mouth approach for mandibular anesthesia.
• Although this technique can be used whenever
mandibular anesthesia is desired,its primary
indication remains those situations in restricted
mouth opening.
Landmarks:
• Mucogingival junction of the maxillary third
molar or second molar.
• Maxillary tuberosity.

50. Nerves anesthetized:
• Inferior alveolar
• Incisive
• Mental
• Lingual
• Mylohyoid
Areas anesthetized:
• Mandibular teeth to midline
• Body of mandible and inferior portion of ramus
• Buccal mucoperiosteum and mucous membrane
anterior to the mental foramen
• Anterior two-third of tongue and floor of oral cavity
• Lingual soft tissue and periosteum

51. Precaution:
• Do not overinsert the needle (>25mm)
• Decrease the depth of penetration in smaller
patients;the depth of penetration will vary
with the anteroposterior size of patient’s
ramus.

52. Mental nerve block
• Mental and incisive nerves are the terminal
branches for the inferior alveolar nerve
• Provides sensory input for the lower lip
skin,mucous membrane, pulpal/alveolar tissue
for the premolars, canine, and incisors on side
blocked.
Technique:
• Area of injection: mucobuccal fold at or anterior
to the mental foramen. This lies between the
mandibular premolars

53. • Depth of injection ~5-6mm
• Inject 0.5-1.0cc of local anesthesia

54. Intraligamentary injection:
• Because of the thickness of the cortical plate of
bone in most patients and in most areas of the
mandible,it is not possible to achieve profound
pulpal anesthesia on a solitary tooth in the adult
mandible.
• The intraligamentary injection is also known as
the periodontal injection,which was originally
described as so.
• In clinical studies in which an inferior alveolar
nerve block failed to provide adequate pulpal
anesthesia to the first molar.
Supplemental injection techniques

55. • So the doctor inserted a needle along long axis of
the mesial root as far apically as possible and
deposited a small volume of local anesthetic
solution under pressure.
• This technique invariably provided effective pain
control.

56. Intraseptal injection:
• The intraseptal injection is similar in technique
and design to the PDL injection.
• It is useful in providing osseous and soft tissue
anesthesia and hemostasis for periodontal
curretage and surgical flap procedures.
• In addition it may be effective when the
condition of the PDL in the gingival sulcus rule
out the possibility of using PDL injection.

57. • Saadeun and Malamed have shown that the path of
diffusion of the anesthetic solution is through
medullary bone as in the PDL injection.

58. Intrapulpal injection:
• Obtaining profound anesthesia in the pulpally
involved tooth was a significant problem
before the rediscovery of IO anesthesia.
• It is seen especially in mandibular molars
where the nerve block anesthesia, proved to
be ineffective in the presence of infection and
inflammation.
• Deposition of local anesthetic(0.2-0.3ml)
directly into the coronal portion of the pulp
chamber of a pulpally involved tooth provides
effective anestheia

59. • The intrapulpal injection provides pain control
through both the pharmacologic action of the
local anesthetic and applied pressure.
• This technique is used once the pulp chamber
is exposed surgically or pathologically.

60. Intraosseous injection:
• Deposition of LA into interproximal bone
between two teeth has been practiced in
dentistry since 20th century.
• Originally IO anesthesia necessitated the use of
half –round bur to provide entry into interseptal
bone that had been surgically exposed,by which
LA is deposited.
• In recent years IO technique has been modified
with introduction of Stabident system,intra
flow,X-tip.

61. • Some persons had difficulty in placing the needle
for LA deposition in previously drilled hole.
• The X-tip eliminated this problem,where it is
composed of a drill and guide sleeve.
• The drill leads the guide sleeve through cortical
plate and the guide sleeve remains in the bone
and easily accepts a 27 gauge needle.

62. Complications of LA
• Needle breakage
• Prolonged anesthesia
• Facial nerve paralysis
• Trismus
• Soft tissue injury
• Hematoma
• Pain on injection
• Burning on injection
• Edema
• Infection
• Slouging of tissues

63. Contraindications of LA
Absolute contraindication
Relative contraindication
Absolute contraindications
• History of allergy to local anesthetic agents
• Local anesthetic agents belonging to same
chemical group should not be used.
• LA of different chemical group can be used.
Relative contraindications
• Fear and apprehension
• Presence of acute inflammation or suppurative
infection.

64. • Infants or small children
• Mentally retarded patients
• Restricted mouth openings
• Patients with cardiovascular diseases, hepatic
dysfunction, renal dysfunction, clinical
hyperthyroidism.
• Presence of developmental defects
• Presence of congenital methemoglobinemia

65. Recent advances of LA
Eutectic mixture of local anesthesia(EMLA)
• It is developed to diffuse through intact skin and
to reduce the pain during needle injection
through skin.
• Composition- 5% cream contains
25microgram/gram lidocaine and prilocaine.
• It is applied to skin atleast 1 hr before injection.
• It is contraindicated in children below 6 years of
age

66. DENTIPATCH
• These are controlled releasing devices.
• Topical agent is incorporated into a matrix, which will
adhere to mucosa and allow slow release of
anesthetic drug.
• Eg: lidocaine transoral delivery system in 10% and
20% concentrations.
JET INJECTIONS
• Also called as needle less anesthesia.
• It can penetrate mucous membrane/ skin under
pressure with out causing exceesive tissue trauma.
Eg: syrijet, madjet

67. WAND:
• It is computer controlled injection system.
• Dosage is controlled by computer.
Trans electronic nerve stimulation(TENS)
• Electronic stimulation of nerve endings is used
for anesthetic effect.
• Indicated in needle phobic patients and where
local anesthesia is ineffective.

68. Conclusion
• Ideal properties as listed by Bennett says:
It should have potency sufficient to give complete
anesthesia without the use of harmful
concentraed solutions.
It should be relatively free from producing
Allergic reactions.
It should be stable in solution and should readily
undergo biotransformation in the body.

69. It should be sterile or capable of being
sterilized by heat without deterioration.
• No local anesthesia in use today satisfies all of
these criteria.However ,all anesthetics do meet
a majority of them.
• Research is continuing in a effort to produce a
newer drugs that possess a maximum of
desirable factors and a minimum of negative
ones.

70. References
1. Textbook of oral and maxillofacial surgery-
S.M.Balaji.
2. Handbook of local anesthesia-Stanley .F.
Malamed.
3. Textbook of oral and maxillofacial surgery-
Neelima Anil Malik.