ADVANCED LOCAL ANAESTHESIA

CROWN & BRIDGE STUDY CLUB

APRIL 16, 2021

PETER NKANSAH

PHARMACOLOGYANATOMYTECHNIQUESTIPS, TRICKS & GADGETS

OUTLINE

HISTORY OF LOCAL ANAESTHETICS

• LOCAL ANAESTHETICS (LA) HAVE BEEN ISOLATED SINCE THE 1860S

(COCAINE)

• SENSORY NERVE BLOCKADE WAS FIRST DESCRIBED BY HALSTED IN 1884

• “NOVOCAINE” (PROCAINE) WAS THE FIRST COMMONLY USED LOCAL

ANAESTHETIC IN DENTISTRY

• LIDOCAINE IS THE ORIGINAL AMIDE LA

• COMMERCIALLY AVAILABLE IN 1948

• ARTICAINE IS THE NEWEST POPULAR LA

• RELEASED IN CANADA IN 1982 (US IN 2000)

PURPOSE OF LA

• TO STOP THE GENERATION AND CONDUCTION OF NERVE IMPULSES

• TO ABORT IMPULSES FROM STIMULI

• TO DECREASE POSTOPERATIVE PAIN

MECHANISM OF ACTION

• LOCAL ANAESTHETICS BIND TO

SITE ON NA+ CHANNEL

• INHIBITS THE PERMEABILITY

TO NA+

• BLOCK PROPAGATION OF

ACTION POTENTIALS

STRUCTURE

3 COMMON FEATURES:

• LIPOPHILIC (AROMATIC)

GROUP

• INTERMEDIATE CHAIN

WITH AMIDE OR ESTER

LINKAGE

• HYDROPHILIC (TERTIARY

AMINE) GROUP

LA SOLUTIONS

• BY THEMSELVES, LA SOLUTIONS ARE WEAKLY BASIC, POORLY

SOLUBLE IN WATER AND UNSTABLE

• USED AS SALT SOLUTIONS (USUALLY HCL) WHICH ARE WATER-

SOLUBLE AND STABLE

• WITH THE ADDITION OF VASOPRESSORS, THE SOLUTIONS BECOME

ACIDIC

• TRUE ALLERGY IS POSSIBLE BUT RARE

• < 1% OF REPORTED REACTIONS

BIOTRANSFORMATION & ELIMINATION

• AMIDE LAS ARE PRIMARILY BIOTRANSFORMED IN THE LIVER

• CYTOCHROME P450 CYP3A4

• ARTICAINE HAS THE SHORTEST HALF-LIFE

• MEDICAL HISTORY CONCERNS:

• SEVERE LIVER DYSFUNCTION

• PSEUDOCHOLINESTERASE DEFICIENCY (FOR ESTERS)

LA PROPERTIES

Characteristic Factor(s)

Onset time Concentration

pKa

Lipid solubility

Duration Concentration

Protein binding

Potency Lipid solubility

pKa

COMMON LA PREPARATIONS

• ARTICAINE

• BUPIVACAINE

• LIDOCAINE

• MEPIVACAINE

• PRILOCAINE

PKA OF LOCAL ANAESTHETICS

pKa % base at pH

7.4

Time to onset

(min)

Mepivacaine 7.6 40 2-4

Articaine 7.8 29 2-4

Lidocaine 7.9 25 2-4

Prilocaine 7.9 25 2-4

Bupivacaine 8.1 18 5-8

Procaine 9.1 2 14-18

DURATION OF ACTION

Maxillary Paraperiosteal (min) IAN Block (min)

Preparation Pulp Soft Tissue Pulp Soft Tissue

Lidocaine w epi 60 150 75 180-300

Articaine w epi 60 120-360 75 120-360

Prilocaine w epi 40 120 75 180

Prilocaine plain 15 60-90 60 150

Mepivacaine w levo 50 180-300 75 180-300

Mepivacaine plain 20 120-180 40 120-180

Bupivacaine w epi 60 240-540 180 240-540

COMFORTABLY NUMB

GRADE “A” ANAESTHESIA

GRADE “B” ANAESTHESIA

GRADE “C” ANAESTHESIA

REASONS FOR FAILURE

• PRACTITIONER IMPATIENCE

• PRESSURE SENSATION = PAIN

• PRESENCE OF INFECTION

• IMPROPER EQUIPMENT/TECHNIQUE

• ANXIETY/FEAR

• ANATOMIC VARIABILITY

PRACTITIONER IMPATIENCE

• DEPENDING ON THE TOOTH, MANDIBULAR TOOTH PULPAL NUMBNESS

CAN TAKE FROM 5.2 (2ND MOLAR) TO 13.6 (CANINE) MINUTES TO SET

IN

• POSSIBLE EXCEPTION FOR BUFFERED LOCAL ANAESTHETIC SOLUTIONS

PRESSURE SENSATION AS PAIN?

• IS RESIDUAL PAIN THE RESULT OF PRESSURE AND ITS INTERPRETATION?

• VOLTAGE-GATED SODIUM CHANNELS CAN BE SUBDIVIDED

• USE-DEPENDENT CHANNELS

• TETRODOTOXIN-SENSITIVE AND TETRODOTOXIN-RESISTANT SODIUM

CHANNELS

• TETRODOTOXIN-RESISTANT CHANNELS ARE ABOUT 4X MORE RESISTANT TO THE

EFFECTS OF LIDOCAINE THAN TETRODOTOXIN-SENSITIVE CHANNELS

Ref.: Wells et al., JOE, 33(10): 1172, 2007

TESTING, TESTING…

• SOFT TISSUE NUMBNESS IS A GOOD (NOT EXCELLENT) INDICATOR OF

PULPAL ANAESTHESIA

• 23% FAILURE FOR THE LOWER FIRST MOLAR

• COLD TESTING OR ELECTRIC PULP TESTING ARE MORE RELIABLE

Ref.: Reader et al., Successful Local Anesthesia, 2017

HENDERSON-HASSELBALCH EQUATION

pKa – pH = log 10Ionized (BH+)Unionized (B)

DRUG IONIZATION

EXAMPLE: LIDOCAINE

• PKA – PH = LOG [IONIZED/UN-IONIZED]

• 7.9 – 7.4 = LOG [IONIZED/UN-IONIZED]

• 100.5 = IONIZED/UN-IONIZED

• ~3/1 = IONIZED/UN-IONIZED

DRUG IONIZATION

EXAMPLE: LIDOCAINE AT THE SITE OF INFECTION

• PKA – PH = LOG [IONIZED/UN-IONIZED]

• 7.9 – 4.9 = LOG [IONIZED/UN-IONIZED]

• 103 = IONIZED/UN-IONIZED

• 1,000/1 = IONIZED/UN-IONIZED

MANDIBULAR INFILTRATION ANAESTHESIA

• INFILTRATION/PARAPERIOSTEAL TECHNIQUES ARE SIMPLER, SAFER

AND MORE COMFORTABLE THAN BLOCK TECHNIQUES

• THICK CORTICAL PLATES ARE (SOMETIMES) BARRIERS TO LA DIFFUSION

• AMSA TECHNIQUE?

Ref.: J Meechan, JADA, 2011

MANDIBULAR INFILTRATION ANAESTHESIA

• SUPPLEMENTARY INFILTRATION CONSISTENTLY INCREASES

ANAESTHETIC EFFICACY

• PRIMARY INFILTRATION

• METHOD OF CHOICE FOR THE INCISORS

• ESPECIALLY WITH DOSE-SPLITTING

• WORKS BEST FOR THE MOLARS WHEN YOU THE MORE CONCENTRATED

SOLUTIONS

• SUCCESS RATES ALWAYS LOWER THAN WITH BLOCKS

Ref.: J Meechan, JADA, 2011

IMPROPER EQUIPMENT/TECHNIQUE

• REASONABLY COMMON PRACTICE TO USE 30-GAUGE AND/OR

SHORT NEEDLES FOR MANDIBULAR BLOCKS

• THIS IS A BAD IDEA

• NEEDLE DEFLECTION

• NEEDLE TIP DOESN’T REACH THE INTENDED END POINT

• UNRELIABLE ASPIRATION RESULTS

• NEEDLE BREAKAGE

SOLUTION DIFFERENCES

• MOST COMPARISONS IN THE LITERATURE ARE BETWEEN LIDOCAINE

AND ARTICAINE

• THE RESULTS ARE DIVIDED

• ARTICAINE IS MORE EFFECTIVE THAN LIDOCAINE IN THE MAXILLARY ARCH

• BOTH ARE VERY GOOD LOCAL ANESTHETICS

ANATOMY &ANATOMIC VARIABILITY

ANATOMY & ANATOMIC VARIABILITY

• MANDIBULAR FORAMEN LOCATION IS QUITE VARIABLE

• THE INFERIOR ALVEOLAR NERVE CAN BE BIFID OR TRIFID

• AND HAS A VARIETY OF WAYS TO ENTER THE MANDIBLE

• THE GREATER PALATINE FORAMEN IS OFTEN AT OR DISTAL TO THE

MAXILLARY SECOND MOLAR

• THE MENTAL FORAMEN IS USUALLY AT THE APEX OF THE SECOND

PREMOLAR

• AND ALMOST NEVER AT THE FIRST PREMOLAR

• THE MAXILLARY ARTERY IS (ALMOST) IN YOUR WAY

TROUBLESHOOTING

POSTERIOR SUPERIOR ALVEOLAR (PSA) NERVE BLOCK

• BRANCHES OF THE PSA CAN ENTER THE PALATAL ROOT OF THE

MOLARS OR THE LINGUAL ASPECT OF THE PREMOLARS OR BOTH

• CONSIDER SUPPLEMENTATION WITH A GREATER PALATINE BLOCK

Ref.: P Blanton and A Jeske, JADA, 134:753-760. (2003)

INFRAORBITAL BLOCK

• A.K.A. ASA NERVE BLOCK

• MUST INJECT CLOSE TO THE BONE IN ORDER TO AVOID CN VII (THE

FACIAL NERVE)

• THIS PROXIMITY IS REDUCED IN CHILDREN

Ref.: P Blanton and A Jeske, JADA, 134:753-760. (2003)

MAXILLARY (V2) NERVE BLOCK

MAXILLARY NERVE BLOCK

MAXILLARY NERVE BLOCK:HIGH TUBEROSITY APPROACH

MAXILLARY NERVE BLOCK:HIGH TUBEROSITY APPROACH

MAXILLARY NERVE BLOCK:HIGH TUBEROSITY APPROACH

MAXILLARY NERVE BLOCK:GREATER PALATINE CANAL APPROACH

MAXILLARY NERVE BLOCK:GREATER PALATINE CANAL APPROACH

MAXILLARY NERVE BLOCK:GREATER PALATINE CANAL APPROACH

MAXILLARY NERVE BLOCK:GREATER PALATINE CANAL APPROACH

MAXILLARY NERVE BLOCK:GREATER PALATINE CANAL APPROACH

MANDIBULAR BLOCKS

MANDIBULAR FORAMEN

WHERE IS THE MF?

• NICHOLSON (1985) DISSECTED 80 CADAVERS AND MEASURED THE

POSITION OF THE MANDIBULAR FORAMEN

• USUALLY ANTERIOR TO THE MIDPOINT OF THE RAMUS

• BELOW THE OCCLUSAL SURFACES OF THE MOLARS 75% OF THE TIME

Ref.: ML Nicholson, The Anatomical Record, 212:110-112 (1985)

WHERE IS THE MF?

• LASEMI ET AL. (2019) STUDIED THE MF LOCATION VIA 194

PANORAMIC RADIOGRAPHS

• MF = 5 MM ABOVE THE OCCLUSAL PLANE

• MF = 16.5 MM BEYOND THE ANTERIOR BORDER OF THE RAMUS

Ref.: E. Lasemi et al., Anesthesia Progress, 66:20-23. (2019)

HOW MANY NERVES ARE THERE?

• ONE OR TWO OR THREE

• BRANCHES CAN ARISE HIGH IN THE INFRATEMPORAL FOSSA

• AND CAN ENTER THE MANDIBLE ANYWHERE FROM THE BASE OF THE

CORONOID PROCESS TO THE RETROMOLAR FOSSA

• PLUS THE MYLOHYOID NERVE

• PROVIDES INNERVATION TO THE MOLARS 60% OF THE TIME

Ref.: P Blanton and A Jeske, JADA, 134: 753-760. (2003)

WHICH BLOCK IS BEST?

• GOLDBERG ET AL. (2008) COMPARED THE THREE MANDIBULAR BLOCK

TECHNIQUES TO COMPARE THE DEGREES OF PULPAL ANAESTHESIA,

THE PAIN ON INJECTION, AND THE EXTENT OF SOFT TISSUE

ANAESTHESIA

• 40 ADULT SUBJECTS IN GOOD HEALTH, EACH RECEIVED ALL THREE

BLOCKS (3.6 ML OF 2% LIDOCAINE W/ 1:100,000 EPINEPHRINE) FROM

A SINGLE PRACTITIONER

• MISSED BLOCKS WERE ELIMINATED (10 V-A, 8 G-G)

Ref.: Goldberg et al., JOE, 34(11): 1307, 2008

WHICH BLOCK IS BEST?

• STATISTICALLY SIGNIFICANT DIFFERENCES WERE SEEN IN:

• MEAN ONSET TIME BETWEEN IANB AND GOW-GATES

• MEAN ONSET TIME BETWEEN IANB AND VAZIRANI-AKINOSI

• CLINICAL STRATEGIES SHOULD ACKNOWLEDGE SUCCESS

PROBABILITIES

GOW-GATES MANDIBULAR BLOCK

• INDICATED FOR PATIENTS WITH:

• FAILURE HISTORIES

• SUSPECTED ACCESSORY INNERVATION

• A DESIRE TO BE PROFOUNDLY NUMB

GOW-GATES

GOW-GATES

Extraoral landmarking

Follow the extraoral landmark

line inside the mouth

Injection point

THE VAZIRANI-AKINOSI MANDIBULAR BLOCK

• INDICATED FOR PATIENTS WITH:

• TRISMUS

• MACROGLOSSIA

• HYPERACTIVE GAG REFLEX

• UNPOPULAR BECAUSE OF VISUAL CHALLENGES AND NO BONY

ENDPOINT FOR THE NEEDLE TO CONTACT

VAZIRANI-AKINOSI

ADVERSE REACTIONS

ADVERSE REACTIONS TO LA

• PSYCHOGENIC REACTIONS

• TOXICITY FROM LOCAL ANAESTHETIC OR THE VASOCONSTRICTOR

• ALLERGIC REACTIONS TO THE LOCAL ANAESTHETIC AGENT (OR TO

METABISULFITE)

• METHEMOGLOBINEMIA

• HEMATOMA

• PARAESTHESIAS

P Blanton & A Jeske. The Journal of the American Dental Association 2003 134, 888-893.

Copyright © 2003 American Dental Association

LA MAXIMUM DOSES (FOR ADULTS)

Drug Max

(mg/kg)

Max (mg) Max

(mg w/o

epi)

# cart. (for

70 kg adult)

Lidocaine 7 500 300 13

Articaine 7 500 300 7

Prilocaine 8 600 400 8

Bupivacaine 2 200 75 10

Mepivacaine 7 450 300 8

DOSAGE

• HOW MANY CARTRIDGES OF ARTICAINE CAN A 23-KG, 7-YEAR-OLD

HAVE?

DOSAGE

EXAMPLE: 2% LIDOCAINE

2% = 20 MG/ML

1 CARTRIDGE HAS 1.8 ML OF FLUID

= 36 MG OF DRUG/CARTRIDGE

PARAESTHESIAS

• THERE ARE NUMEROUS REPORTS REGARDING THE ASSOCIATION

BETWEEN 4% SOLUTIONS AND A HIGHER-THAN-EXPECTED INCIDENCE

OF PARAESTHESIAS

• NOTE THE RISK:BENEFIT EQUATION

• OVERALL PARAESTHESIA INCIDENCE IS 1:785,000 INJECTIONS (RARE)

• THERE HAS BEEN AN RCDSO ADVISORY REGARDING 4% SOLUTIONS

USED FOR BLOCKS

• UNIVERSITY OF TORONTO DENTAL STUDENTS

Ref.: Haas and Lennon, JCDA, 1995

PARASTHESIAS

• MOST ARE TRANSIENT, USUALLY RESOLVING WITHIN 8 WEEKS

• IF NOT, PROGNOSIS IS VERY POOR

• PRECISE CAUSE NOT KNOWN WITH CERTAINTY

• DIRECT NEEDLE TRAUMA

• HEMORRHAGE INTO NERVE SHEATH

• SCAR FORMATION

• NEUROTOXICITY (CONTROVERSIAL)

PARAESTHESIAS

• A 21-YEAR RETROSPECTIVE STUDY OF REPORTS OF PARESTHESIA

FOLLOWING LOCAL ANESTHETIC ADMINISTRATION

• HAAS AND LENNON, JCDA, 1995, 61:319-330

PARAESTHESIAS

• THE OVERALL INCIDENCE OF PARAESTHESIA FOLLOWING LOCAL

ANESTHETIC ADMINISTRATION FOR NON-SURGICAL PROCEDURES IN

DENTISTRY IS VERY LOW →1:785,000

• IF, HOWEVER, PARAESTHESIA DOES OCCUR, THE RESULTS SUGGEST

THAT IT IS MORE LIKELY IF EITHER ARTICAINE OR PRILOCAINE IS USED

• REASONS ARE SPECULATIVE ONLY

RESULTS (1973-1993)

0

10

20

30

40

50

60

Articaine Bupivacaine Lidocaine Mepivacaine Prilocaine

PARAESTHESIAS

• RETROSPECTIVE REVIEW OF VOLUNTARY REPORTS OF NON-SURGICAL

PARESTHESIA IN DENTISTRY

• GAFFEN AND HAAS, 2009, JOURNAL OF THE CANADIAN DENTAL

ASSOCIATION, 75(8): 579

• OBJECTIVES:

• TO ANALYZE CASES OF PARESTHESIA ASSOCIATED WITH LOCAL ANESTHETIC

INJECTION THAT WERE REPORTED TO THE PROVINCE OF ONTARIO’S

PROFESSIONAL LIABILITY PROGRAM (PLP) FROM 1999 TO 2008 INCLUSIVE

• TO UPDATE PREVIOUS STUDY (1995)

DISTRIBUTION OF PARESTHESIAS

0

10

20

30

40

50

60

70

articaine bupivacaine lidocaine mepivacaine prilocaine

Percentage

JADA (JULY 2010)

JADA (JULY 2010)

CONCLUSIONS

• INCIDENCE IS VERY LOW

• PRILOCAINE = 1:2,070,678 INJECTIONS

• ARTICAINE = 1:4,159,848 INJECTIONS

• LIDOCAINE = 1:181,076,673 INJECTIONS

• YET DATA ARE STRONGLY SUGGESTIVE OF AN ASSOCIATION

• NO PROOF OF CAUSE-EFFECT

• IT IS NOT THE DRUG PER SE

• HIGHER CONCENTRATIONS MAY SIMPLY PREDISPOSE TO GREATER EFFECT

STUDIES OF DOSE-DEPENDENT NEUROTOXICITY

• FINK AND KISH, ANESTHESIOLOGY, 1976

• BARSA ET AL, ANESTHESIA ANALGESIA, 1982

• RIGLER ET AL, ANESTHESIA ANALGESIA, 1991

• LAMBERT AND HURLEY, ANESTHESIA ANALGESIA, 1991

• KALICHMAN ET AL, JOURNAL OF NEUROPATHOLOGY, 1993

• SELANDER, REGIONAL ANESTHESIA, 1993

• LAMBERT ET AL, ANESTHESIOLOGY, 1994

• KANAI ET AL, ANESTHESIA AND ANALGESIA, 1998

• CORNELIUS ET AL, JOURNAL CRANIO-MAXILLOFACIAL SURGERY, 2000

• JOHNSON ET AL, ANESTHESIOLOGY, 2002

WHAT’S DIFFERENT?WHAT’S NEW?

THE WAND® COMPUTER GUIDED ANESTHESIA SYSTEM

CALAJECT

DENTAPEN

• MANUFACTURED AND

DISTRIBUTED BY

SEPTODONT

• USES REGULAR NEEDLES

• HAS A “STANDARD” FINGER

GRIP

• LIGHT (40 G IN WEIGHT)

DENTAPEN

• CORDLESS

• THREE INJECTION SPEEDS

• SLOW = 1 ML/90 SEC

• MEDIUM = 1 ML/60 SEC

• FAST = 1 ML/30 SEC

• AUTOMATIC ASPIRATION

DENTAPEN

DENTAPEN CONTROL PANEL

Aspiration button

Power button

Speed selection

Mode selection

Rewind

INTRAOSSEOUS ANESTHESIA

• DIRECT INJECTION IN THE SPONGY BONE,

CLOSE TO THE APEX.

QUICKSLEEPER 5

QUICKSLEEPER 5

• PAINLESS NEEDLES

• CUTTING EDGE BEVEL

• SPECIFIC INDICATOR

S TA N DA R D

N E E D L E S

P a i n l e s s& e f f i c i e n t

T r a u m a t i c

P E R I O S T E U M

H OW TO B E PA I N L E S S ?

ONSET®

• BUFFERED LA SOLUTIONS

• BRANDED AS ONSET

• USES NA(HCO3) AND CO2

TO RAISE THE PH LEVEL OF

THE LA SOLUTION

• THEORETICALLY RESULTS IN

FASTER ONSET AND LESS

DISCOMFORT DURING AND

AFTER INJECTIONS

• PULPAL ANAESTHESIA

TWO MINUTES AFTER

IAN BLOCK

BUFFERED LOCAL ANAESTHETICS

ORAVERSE®

• PHENTOLAMINE MESYLATE

• A NON-SELECTIVE Α-

ADRENERGIC ANTAGONIST

• INCREASES THE

REDISTRIBUTION OF LA

AWAY FROM INJECTION

SITE

• REDUCES DURATION OF

ANAESTHESIA BY 50%

• NON-TOXIC AND WELL-

TOLERATED < AGE 6 YEARS

NEVERMIND THE OPIOIDS…

• BENZOCAINE AND LIDOCAINE AS ADULTERANTS FOR COCAINE

• BENZOCAINE ADULTERANTS HAVE LEAD TO METHEMOGLOBINEMIA IN

THE ED

• LIDOCAINE INCREASES THE NASAL NUMBNESS ASSOCIATED WITH

SNORTING COCAINE

• LEADS TO SEIZURES IN THE ED

• VERY COMMON COCAINE ADULTERANT

Ref.: Saraghi & Hersh, JADA, March 2014

DEXAMETHASONE INJECTIONS

• CHEN ET AL. (2017) EXAMINED THE ABILITY OF SUBMUCOSAL

INJECTIONS TO REDUCE POSTSURGICAL DISCOMFORT (COCHRANE

REVIEW)

• MODEL USED WAS FOR THIRD MOLAR EXTRACTIONS

• REVIEWED 11 ARTICLES

• 4 MG OF DEXAMETHASONE SM REDUCES EDEMA AND EARLY TRISMUS

• NO STRONG EVIDENCE TO SUPPORT THE MINIMIZATION OF PAIN OR

LATE TRISMUS

Chen et al., JADA, 148(2): 81, 2017

LIPOSOMAL BUPIVACAINE(EXPAREL®)

INJECTABLE BUPIVACAINE LIPOSOME SUSPENSION

• TRADE NAME: EXPAREL® (PACIRA PHARMACEUTICALS INC.)

• MARKETED AS AN OPIOID-FREE WAY TO MANAGE POST-SURGICAL PAIN

• CONSISTS OF MULTIVESICULAR LIPOSOMES (DEPOFOAM®) THAT RELEASE

DOSES OF BUPIVACAINE AS THE CHAMBERS BREAK DOWN

• INJECTED INTO AND/OR AROUND THE SURGICAL SITE

• NOT USED FOR NERVE BLOCKS

• CAN PROVIDE UP TO 96 HOURS OF PAIN RELIEF

• IT’S EXPENSIVE

• $300 FOR A 20-ML VIAL

Ref.: https://www.exparel.com

EXPAREL® IN ORAL SURGERY

DOWN THE ROAD…

• PAIN-ONLY LA

• THE TRPV1 CHANNEL IS PRESENT ONLY IN PAIN-SENSING NEURONS

• THESE CHANNELS RESPOND TO NOXIOUS HEAT, PROTONS,

ENDOCANNABINOIDS, AND CAPSAICIN

• WHEN OPENED BY AN AGONIST, QX-314, A CHARGED LIDOCAINE

DERIVATIVE, CAN BE DELIVERED