1. Local Anesthesia
Gary J. Wayne DMD
Diplomate American Board Of Oral/Maxillofacial Surgery
Boynton Oral & Maxillofacial Surgery and Dental Implant Center
Boynton Beach, Florida

2. Review of Neurophysiology
How do local anesthetics work?
What are the implications in my choice of anesthetics?

3. Summary
Local anesthetics dissociate into the ionic form in order to penetrate the nerve membrane. Anesthetics are available as salts clinical use.
Pka-the ability to dissociate into the ionic form in a given ph
The ph of a nerve is quite stable. The ph of the extracellular fluid is variable
The ph of a local anesthetic (and the surrounding tissue into which it is injected) greatly influences its nerve blocking action.
Ph of normal tissue is 7.4, ph of an inflamed area is 5 to 6

4. Summary
Local anesthetics containing epinephrine or other vasoconstrictors are acidified by manufacturers to inhibit oxidation of the vasopressor
The acidification causes more “burning” on injection
Ph of solutions without epinephrine are around 5.5, with epinephrine 3.3
Clinically this lower ph is more likely to produce a burning sensation, as well as a slightly slower onset of action

5. Summary
Increasing the ph (alkalinization) of a local anesthetic solution speeds the onset of its action, increases its clinical effectiveness, and makes its injection more comfortable
However, the local anesthetic base, because it is unstable, precipitates out of alkanized solutions, and this makes these solutions ill suited for clinical use
Adding sodium bicarb to the anesthetic solution immediately prior to injection provides greater comfort and a more rapid onset of anesthesia

6. Local Anesthetics Articaine Bupivacaine Dibucaine Etidocaine Lidocaine
Amides
Esters
Articaine
Bupivacaine
Dibucaine
Etidocaine
Lidocaine
Mepivacaine
Prilocaine
Butacaine
Cocaine
Benzocaine
Hexylcaine
Piperocaine
Tetracaine

7. Local Anesthetics PABA Type Chloroprocaine Procaine Propoxycaine
Esters
Others
PABA Type
Chloroprocaine
Procaine
Propoxycaine
Quinoline
Centbucridine
Diphenhydramine
Saline

8. Amide Local Anesthetics
Lidocaine “Xylocaine”
Mepivacaine “Carbocaine”
Prilocaine “Citanest”
Articaine “Septocaine”
Bupivacaine “Marcaine”

9. Lidocaine Available since 1943, most common
Available with/without vasoconstrictor
With 1:100,000 Epi
Max dose 7mg/kg not to exceed 500mg
Pulpal Anesthesia 60min
Soft Tissue Anesthesia 3-5hr
Pka 7.9
Onset of action 2-3 minutes

10. Mepivacaine 3 % Common for non-surgical procedures
Used in pediatrics and geriatrics
Onset of action minutes
Slight Vasodilation < Lidocaine
Pulpal Anesthesia minutes
Soft Tissue Anesthesia 2-3 hours
Pka 7.6
Maximum dose 6.6mg/kg not to exceed 400mg

11. Mepivacaine 2% with vasoconstrictor
1:20,000 Neo-Cobefrin/Levonordefrin
1/5 Vasoconstrictor Activity
Rapid onset minutes
Soft Tissue/Pulpal Anesthesia Similar to Lidocaine with vasoconstrictor
Maximum Dose 6.6mg/kg not to exceed 400mg
Is available with 1:100,000 epi (documented lidocaine allergy)

12. 4% Prilocaine Vasodilation >Mepivacaine,<Lidocaine Pka 7.9
Onset 2-4 minutes
Duration Pulpal 10min infiltration, 60 min block
Maximum Dose 6mg/kg not to exceed 400mg

13. 4% Prilocaine with 1:200,000 epi Rapid Biotransformation
Safest of all amides
Good for “epi sensitive” patients requiring prolonged pulpal anesthesia >60min
Duration of action pulpal 60-90min, soft tissue 3-8hrs
Maximum Dose 6mg/kg not to exceed 400mg

14. 4% Articaine with 1:100,000 epi Newest “wonder anesthetic” in U.S.
Pka 7.8
Onset of action minutes block,1-2 minutes infiltration
Claim is that can diffuse more readily, controlled comparisons failed to corroborate
Duration of action pulp min, soft tissue 3-6hrs
Maximum dose 7mg/kg not to exceed 500mg
Available 1:200,000 epi

15. .5% Bupivacaine
1:200,000 epi
Good for lengthy procedures as an adjunct/post operative analgesia
“Weak” anesthetic
Pka 8.1
Onset of action 6-10 minutes
Maximum dose 1.3mg/kg not to exceed 90mg
Duration pulpal min, soft tissue 4-9hrs (12hr reported)

16. Esters Can Use with documented allergy to Amides Procaine+Propoxycaine
Provides min of pulpal
2-3 hours of soft tissue
each cartridge 7.2 mg of Propoxycaine
36mg of Procaine
Maximum dose 6.6mg/kg

17. Vasoconstrictors
Epinephrine
Neo Cobefrin
Levonordefrin
Levophed

18. When to use/not use Discussion: Cardiovascular disease “allergy”
Pediatrics
Elderly
Post operative analgesia
Hemostasis

19. Vasoconstrictors
“Vasoconstrictors should be included in local anesthetic solutions unless specifically contraindicated by the medical status of the patient or by the duration of the planned treatment” S.Malamed

20. Local Complications Needle Breakage Pain on Injection
Burning on Injection
Persistent Anesthesia or Paresthesia
Trismus
Hematoma
Infection
Edema
Sloughing of Tissues
Soft Tissue Injury
Facial Nerve Paralysis
Post Anesthetic Intraoral Lesions

21. Systemic Complications
Overdose

22. Overdose Patient Factors Age Weight Other Drugs Sex (pregnancy)
Presence of Disease
Genetics
Mental Attitude and enviroment

23. Overdose Drug Factors Vasoactivity Concentration Dose
Route of Administration
Rate of Injection
Vascularity of the Injection Site
Presence of Vasoconstrictors

24. Overdose
“Many local anesthetic overdose reactions occur as a result of the combination of inadvertant intravascular injection and too rapid rate of injection, both of which are virtually 100% preventable” S. Malamed

25. Minima/Moderate Overdose Levels
Signs
Talkativeness Apprehension
Excitability Slurred Speech
Generalized Stutter Euphoria
Dysarthria Nystagmus
Sweating Vomiting
Failure to follow commands Disorientation
Loss of response to pain ^Blood Pressure
^Heart Rate ^Respiratory Rate

26. Minimal/Moderate Overdose Levels
Symptoms (progressive with increasing blood levels)
Light-Headedness and dizziness Restlessness
Nervousness Numbness
Sensation of twitching, before observed Metallic Taste
Visual Disturbances Auditory Disturbances
Drowsiness and disorientation Loss of consciousness

27. Moderate/High Overdose Levels
Tonic-Clonic seizure activity followed by
Generalized CNS Depression
Depressed blood pressure, heart rate, and respiratory rate

28. Management of Mild Overdosage>5min
Reassure patient
O2 via nasal cannula or hood
Monitor and record vital signs
IV if able
Self Limiting, discharge when recovered

29. Mild Overdose-Slower Onset>15min
Biotransformation trouble
All of the previous methods plus
Anticonvulsant
Summon medical assistance
Patient to be examined by physician or hospital

30. Severe Overdose
BLS
Anticonvulsant
Terminate treatment
Summon Help

31. Epinephrine Overdose More common in gingival retraction cord Symptoms
Fear,Anxiety Respiratory difficulty
Tenseness Palpitations
Restessness Pallor
Throbbing Headache Dizziness
Tremor Weakness
Perspiration

32. Epinephrine Overdose Signs of epinephrine overdose
Sharp elevation in blood pressure, systolic
Elevated heart rate
Possible cardiac dysrhythmias (PVC,Vtach,Vfib)

33. Management of Epinephrine Overdose
Terminate procedure
Position patient –Semisitting or erect
Minimized CNS Effect
Monitor Blood Pressure
Administer O2 (except hyperventilation)
Recover-Most are self limiting

34. Allergic Reactions Rare with amides
Seen with topical anesthetics-esters
Sodium metabisulfites-only with vasoconstrictors
Treatment
BLS
Oral Histamine Blocker
Sub Q epi
IM Histamine Blocker
Bronchial Treatment
Laryngeal Treatment

35. Maxillary Anesthesia Field Block Infiltration Nerve Block Intraseptal
Intraosseous
Periodontal Ligament

36. Infiltration
Area of treatment is flooded with local anesthesia Periodontal treatment Selective restorative procedures

37. Field Block
Anterior Superior
Middle Superior
Posterior Superior

38. Nerve Blocks Maxillary (Second Division)
Junction of Vertical/Horizontal Shelves
Second Molar
Long Needle
2cc of solution
Greater Palatine
Nasopalatine
Infra-orbital

39. Infraorbital

40. Problems with Maxillary Anesthesia
Few
Related to inflammation/infection
Posterior teeth
Use Nerve Blocks
Infraorbital-Extra/Intra Oral
Nasopalatine
Secondary Division

41. Mandibular Anesthesia

42. Mandibular Anesthesia

43. Inferior Alveolar Block
80-85% Successful
Related to Greater Density of Bone
Limited Accessibility
Wide Variation of Anatomy
Solution Depot within 1mm
Most Important Block
Variations
Accessory Innervation

44. Inferior Alveolar Block
Deepest Part of Ascending Ramus
Parallel to Occlusal Plane
Lateral To Raphe
Hit bone
Pull Back?
Bevel aimed away, assist in needle deflection and direction of liquid

45. Accessory Innervation
Determine Objective Anesthesia of IAN
Mylohyoid
Accessory Foramina
Cervical Branches

46. Mental Nerve Block Does not anesthetize incisive branch
Angle needle anterior
Second Premolar
High risk of nerve injury

47. Buccal Nerve Block Bevel Toward Bone
Distal and buccal to most distal molar

48. Gow-Gates Anesthetizes all branches
IAN,lingual,mylohyoid,mental, incisive auriculotemporal and buccal
High Success >95%
Low Aspiration
Parallel tragus to anterior border of ramus
Mesiolingual cusp of maxillary second molar
Hit neck of condyle and back off 1mm
Stay open 1-2 minutes-bite block

49. Gow-Gates Target

50. Vazirani-Akinosi Closed Mouth Block
IAN, Incisive, Mental, Lingual and Mylohyoid
Mucogingival of Maxillary Third or Second Molar
Parallel Maxillary Occlusal Plane
Medial of Anterior Ramus
Approximate 25mm (midway)

51. Supplemental Aids Ligamentary Injections Intraosseous Injections
Intrapulpal
Electronic
Hypnosis
Nitrous Oxide
IV/General Anesthesia
Always reduces local anesthesia
“Gizmos”