2. LOCAL ANESTHESIA presented by deepti awasthi

3. CONTENTS Introduction Definitions History Ideal Properties of LA
Mechanism Of Action
Classification
Constituents
Pharmacokinetics- Uptake , distribution,
Metabolism , excretion
Vasoconstrictors
Local anesthetic agents
Topical anesthetics
Complication
Recent advances.
In pediatric dentistry
References

4. INTRODUCTION

5. DEFINITIONS Acc to Malamed 1980 :
Loss of sensation in a circumscribed area of the body caused by depression of excitation in nerve endings and inhibition of the conduction process in peripheral nerves

6. Reversible loss of sensation in a body part without the loss of consciousness or the impairment of central control of vital functions.
Damle

7. HISTORY
1860 – Albert Nieman was first to isolate cocaine & discovered its anesthetic properties
1884 – Karl Koller used cocaine as a topical anesthetic for opthalmological surgical procedures.
1905 – Alfred Einhorm developed procaine,
1943 – Lidocaine by Lofgren
Damle

8. IDEAL PROPERTIES OF LA
Nonirritating to the tissues.
Not cause any permanent alteration of nerve .
Low systemic toxicity.
It must be effective.
Time of onset should be short.
The duration of action must be enough.
It must be effective regardless of whether it is injected into the tissue or applied locally to mucous membranes
The duration of action must be enough to permit completion of procedure yet not so long as to require an extended recovery

9. Desirable properties by Bennett
Sufficient potency to give complete anesthesia without the use of harmful conc. solutions.
No allergic reactions.
Stable in solution & undergo biotransformation in the body.
Sterile or capable of being sterilized by heat without deterioration.

10. MECHANISM OF ACTION Acetyl choline theory Calcium displacement theory
Surface repulsion theory
Membrane expansion theory
Specific receptor theory

13. CLASSIFICATION ESTERS
Of benzoic acid
Cocaine
Butacaine
Piperocaine
Tetracaine
Ethyl amino benzoate (benzocaine)
hexylcaine
Of p-aminobenzoic acid
Procaine
Chlorprocaine
propoxycaine

14. AMIDES
Articaine
Bupivacaine
Dibucaine
Etidocaine
Lidocaine
Mepivacaine
Prilocaine
Ropivacaine
QUINOLINE
Centbucridine

15. Based on duration of action : Long acting ( 90 + mins )
Bupivacaine + epinephrine
Etidocaine
Intermediate acting ( 60 mins )
Articaine + epinephrine
Lidocaine + epinephrine
Mepivacaine + epinephrine
Short acting (30 mins)
Lidocaine
Mepivacaine
Prilocaine
Malamed

16. CONSTITUENTS Local anesthetic agents Vasoconstrictors purpose served :
Decreased blood flow to the site
Absorption of LA into the CVS is slowed.
Decreases the risk of LA toxicity.
Increased duration of action

17. 3. Reducing agents : To minimize oxidation of vasoconstrictor - sodium metabisulphite 4. Preservative : methyl paraben if allergic- caprylhydrocuprinotoxin. 5. Fungicide : thymol 6. Vehicle : modified ringer’s soln isotonic vehicle minimizes discomfort during injection. S.Tandon

18. PHARMACOKINETICS
Uptake
Distribution
Biotransformation
Excretion

19. UPTAKE :
All LA produces vasodilation, cocaine – only LA producing vasoconstriction.
Oral : absorbed poorly from GIT(except cocaine)
Topical : absorbed at diff rates
I.V. : primary management of ventricular dysrythmia.

20. DISTRIBUTION –
Highly perfused organs have higher level.
skeletal muscle – greatest % of LA
The blood level is influenced by factors :
Rate of absorption into CVS.
Rate of distribution to the tissues.
Elimination of the drug.
Crosses BBB

21. METABOLISM
Overall toxicity depends upon balance b/w rate of absorption & removal from blood.
ESTER : hydrolysed in the plasma by pseudocholinesterase ( Kalow W : hydrolysis of LA by human serum cholinesterase, J Pharmacol exp ther 104: , 1952)

22. Chlorprocaine , most rapidly hydrolysed
Tetracaine , 16 times slowly hydrolysed
Procaine undergoes hydrolysis to PABA ,

23. AMIDE : primary site of biotransformation is Liver.
Prilocaine – some also in the lung.
70% of a dose of injected lidocaine undergoes biotransformation in patient with normal liver function.

24. EXCRETION :
Kidneys – primary excretory organ
Esters : appear in very small conc as parent compound in urine
Amides : higher %
Malamed

25. VASOCONSTRICTORS DIRECT ACTING : Epinephrine Norepinephrine
Levonordefrin
Isoproteronol
Dopamine
Methoxamine
phenylephrine

26. INDIRECT ACTING :
Tyramine
Amphetamine
Methamphetamine
Hydroxyamphetamine
MIXED :
Metaraminol
ephedrine

27. Pyrocatechin derivative –
epinephrine & norepinephrine
Benzol derivative –
levonordefrine
Phenol derivative –
phenylephrine

28. Conc. of clinically used VC
CONCENTRATION
mg/ml
Therapeutic use
1:1000
1.0
Emergency- anaphylaxis (IM/SC)
1:10,000
0.1
Emergency – cardiac arrest (IV)
1:100,000
0.01 LA
1:200,000
0.005
Malamed

29. LOCAL ANESTHETIC AGENTS

30. PROCAINE First synthetic injectable LA. Ester type Onset : 6 - 10 mins
Produces the most vasodilation, used to aid in breaking arteriospasm.

31. LIDOCAINE Most commonly used. 1st amide LA in dentistry
By Lofgren, 1943
Onset –rapid (2-3 mins)
Effective dental conc. -2%
Half life – 90 mins
Topical action – 5%

33. MRD – 4 mg/kg or
7mg/kg with epinephrine
In dental procedures –
2% lidocaine with1:100,000 epinephrine
For hemostasis –
2% lidocaine with1:50,000 epinephrine

34. BUPIVACAINE Amide-type local anesthetic
Onset of action is slower than lidocaine and anesthesia is long acting.
Normally provides 2-4 hours of anesthesia
Can be extended in some cases by using solution with epinephrine to 7 hours
The duration of bupivicaine is significantly longer than with any other commonly used local anesthetic

35. 2 primary indication-
Lengthy procedures -90 mins (eg : full mouth reconstruction, implant surgery)
Management of surgery pain.
Rarely indicated in children.

36. MEPIVACAINE
AMIDE
Introduced into dentistry as 2% soln. containing levonordefrin & 3%without vc
Slight vasodilation
Onset –rapid
Mepivacaine plain – most used LA in pediatric patients & in geriatric patients.

37. PRILOCAINE Amide 40% less toxic
Orthotoluidine, induces the formation of methemoglobin –
Cyanosis
T/t – reversed within 15 mins with administration of 1-2 mg/kg body wt. of 1% methylene blue i.v. over a 5 min period
Effective conc. – 4%

38. ARTICAINE Amide type containing a thiophene group.
Synthesized in 1969 in Germany,
Effective conc percent with 1:100,000
epinephrine.
Able to diffuse through hard & soft tissues more
reliably than other LA.
The effect of numbness of soft tissues was longer
lasting.
IJPD

39. TOPICAL ANESTHETICS

40. TOPICAL ANESTHETICS
Topical anesthetic is effective on surface tissues (2-3 mm in depth) to reduce painful needle penetration of the oral mucosa.
A variety of agents are available in
Gel
Liquid
Ointment
Patch
Aerosol forms

41. Higher conc. Facilitates diffusion of the drug through the mucous membrane.
BENZOCAINE :widely used since1903
Odourless , white crystalline powder soluble in alcohol, fatty oils & dilute acids.
Absorbed very slowly from oral tssues & wounds.
140 mg/ml

42. COCAINE HYDROCHLORIDE
Highly soluble in water.
Onset – rapid ( 1 min )
2 to 10 %
Extreme abuse potential _ topical use in dentistry is not recommended.
DYCLONINE HYDROCHLORIDE
0.5%
Onset – 10 mins
Duration – 1 hr.
EMLA
LIDOCAINE forms : base- 5%
HCl- 2%

43. CONTRAINDICATIONS PROBLEM DRUGS TO AVOID ALTERNATIVE LA allergy
All LA in same class (eg. ester)
Amide
Bisulfite allergy
VC containing LA
Without VC
Atypical plasma cholinesterase
esters
amides
methemoglobinemia
prilocaine
Other amide
Significant liver prblm
Amides
Amides or ester
Significant renal prblm
Amides or esters
Significant CVS disease
High conc. of VC
1:200,000
Clinical hyperthyroidism
High conc. of VC
1;200,000

44. COMPLICATIONS LOCAL Needle breakage Paraesthesia
Facial nerve paralysis
Trismus
Soft tissue injury
Hematoma
infection
Pain on injection
Burning on injection
Edema
Sloughing of tissues
Post anesthetic intra oral lesions

45. SYSTEMIC
Overdose
Allergy :
fever anaphylaxis
angioedema urticaria
photosensitivity dermatitis
idiosyncrasy

46. RECENT ADVANCES EMLA Lidocaine 2.5 % & prilocaine 2.5 %
Intact skin anesthesia, & is used primarily before painful procedures as venipuncture.
Routine use –circumcision ,leg ulcer debridement & in gynaecological procedures
1 hr before

47. Contraindicated <6mths
possibility of prilocaine inducing methemoglobinemia.

48. ROPIVACAINE – Long acting amide, has greater safety margin , less toxicity than bupivicaine.
pH ALTERATION- sodium bicarbonate is being added immediate to injection , which makes solution alkaline and thus increases its absorption into nerve.
Provides more rapid onset

49. CENTBUCRIDINE-
Quinoline derivative
5-8 times more potent
Significantly it does not affect the CNS, CVS adversely
Subarachnoid & extradural anesthesia(Suri Yv et al : double blind study on centbucridine, indian J mer res 76: , 1982)
Intravenous regional anesthesia & intaocular surgery.

50. HYALURONIDASE-
Breaks down intercellular cement.
Permits injected soln. to spread & penetrate tissues

51. CO2 – Enhances diffusion of LA, so more rapid onset of action
INTRAORAL LIGNOCAINE PATCH-
10-20% Lignocaine can be used on buccal mucosa for 15 mins.
ELECTRONIC DENTAL ANESTHESIA –
Use principle of transcutaneous electric nerve stimulation which relives pain. Pain control in case of needle phobia.

53. JET INJECTIONS
Solution is propelled out into mucosa as a jet without any needle.
Effective for palatal anesthesia.
The majority of local anesthesia procedures in pediatric dentistry involve traditional methods of infiltration or nerve block techniques with a dental syringe, disposable cartridges, and needles as described so far

54. CCLAD
1997 – introduced ( the WAND )
Least anxiety producing injection instrument based on visual appearance.
Disruptive behaviour in pediatric patients was significantly reduced.
Marked reduction in pain perception

55. ADVANTAGES :
Precise control of flow rate & pressure – comfortable injection.
Increased tactile feel & ergonomics
Non- threatening
Rotational insertion technique minimizes needle deflection.
Automatic aspiration.

56. DISADVANTAGES :
Requires additional armamentarium
cost

57. COMFORT CONTROL SYRINGE
Attempts to improve on the CCLAD concept.
2 stage delivery system :
Begins at extremely slow rate
After 10 sec - speed increases

59. Advantages :
Familiar syringe type delivery system
Less costly than CCLAD
All controls at the finger tips.
IONTOPHORESIS
Painless modality of administering anesthesia.

60. LIGNOCAINE PATCH :
Before placing mucosal site is dried
10% or 20% lidocaine is placed for15 mins on the buccal mucosa 2mm apical to the MGJ.

61. IN PEDIATRIC DENTISTRY
Diff. in the child & adult
Bone is heavier & more compact in adults.
Depth of penetration should be less.
Overdose : high no. of death have occurred in children, leading to the assumption that LA is more toxic
Arathi rao

62. Strict adherence to the MRD & anesthetize the quadrant being treated.
Use of LA containing vasopressor is considered unnecessary & unwarranted
Complications:
Accidental biting or chewing of lip,tongue & cheek.

64. Preventive measures :
Select LA with appropriate duration of action for the procedure
Advice both patient & accompanying adult about the possibility of injury.
Warning stickers are also available.

66. Techniques :
MAXILLARY
All primary teeth & permanent molar –
supraperiosteal infiltration.
Palatal – nasopalatine & greater palatine

67. MANDIBULAR
Supraperiosteal –primary teeth.
Buccal infiltration was as effective as IANB in all situations except when pulpotomy is to be performed.
IANB in children has greater success rate because of location of mandibular foramen.( distal & inferior to occlusal plane)

68. PDL infiltration is not recommended in primary teeth – possibility of development of enamel hypoplasia in the developing tooth
malamed

69. REFERENCES
Malamed SF. Handbook of local anesthesia. 5th ed. St. Louis: Mosby; 2004
Textbook of Pedodontics- Shobha Tondon 2nd ed
Text book of pediatric dentistry – S.G. Damle
Principles & practice of pedodontics – Arathi rao

70. D Ram & E Amir.Comparison of articaine 4% & lidocaine 2% in pediatric dental patient .int J ped dent;16(4):
Effectiveness of 20% Benzocaine as a Topical anesthetic for Intraoral Injections. John M. Nusstein, and Mike Beck, Anesth Prog 50: