Transcript Document

Management of Local
Anaesthesia in Endodontics
Halton-Peel Dental Association
Andrew Moncarz
BSc, DDS, Dip. An, MSc, FRCD(C)
March 22, 2007
Objectives
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Review of:
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Reported rates of profound anaesthesia
Anatomical variations
Maximum doses of local anaesthetics
Pulpal inflammation as a complicating factor
Adjunctive strategies for profound mandibular
LA
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues

What about experienced operators?
Effectiveness of Conventional
IANB as measured by EPT
Childers et al. 1997
lido 2% 1:100K
63%
Clark et al. 1999
lido 2% 1:100K
73%
Dunbar et al. 1996
lido 2% 1:100K
43%
Guglielmo et al.
1999
mepiv 2%
1:20K
80%
Reitz et al. 1998
lido 2% 1:100K
71%
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
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Always use a long 25 gauge needle (the
red one)
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2 reasons:
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1. Less deflection
2. Less false negative aspiration
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
Ultrasound Guidance
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Hannan et al. 1999:
Repeated-measures design
40 subjects injected twice at separate
appointments—once with landmarks, once with
ultrasound guidance
EPT after profound lip numbness reported
Anaesthetic success 38%-92%, no difference
between the techniques
Conclusion: accuracy of needle placement is not
the primary reason for failure of IANB
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
Nerve to
mylohyoid
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
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Berns et al. 1962: injected radiopaque
material into pterygomandibular space
Spread is unpredictable
Suggestion: inject more LA
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
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Decrease in the pH locally
Can influence the amount of LA available
in the lipophilic form to diffuse across the
nerve membrane
Result is less drug interference of sodium
channels
Less likely to influence mandibular block
anaesthesia
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
Pulpal Inflammation
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Causes activation and sensitization of
peripheral nociceptors
Causes sprouting of nerve terminals in the
pulp
Causes expression of different sodium
channels: TTX-resistant class of sodium
channels are 4 times as resistant to
blockade by lidocaine and their expression
is doubled in the presence of PGE2
Effectiveness of Conventional
IANB: Irreversible Pulpitis
100% lip anaesthesia
Reisman et al. 1.8 mL lido 2%
25%
1:100K epi
1997
Nusstein et al. 1.8 mL lido 2%
19%
1998
1:100K epi
Cohen et al.
2000
Claffey et al.
2004
1.8 mL lido 2%
50%
1:100K epi
1.8 mL lido 2%
1:100K epi
23%
Adjunctive Strategies
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Additional Anaesthetic
PDL Injection
Intraosseous Injection
Intrapulpal Injection
Different anaesthetic
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Retest using the CC
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Adjunctive Strategies
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Additional Anaesthetic
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Higher injection
Gow Gates
Akinosi
Nerve to mylohyoid
PDL Injection
Intraosseous Injection
Intrapulpal Injection
Different anaesthetic
Maximum Doses LA
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% means g/dL
Example:
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1% = 1 g/dL
1% = 10g/L
1% = 10 mg/mL
Therefore:
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2% = 20 mg/mL
Maximum Doses LA
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A cartridge contains 1.8 mL
Therefore a cartridge of 2% local
anaesthetic contains 20 mg/mL X 1.8 mL =
36 mg of local anaesthetic
Maximum Doses LA
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How much LA can you give?
193 lb 33 yo male
Lidocaine 2% 1:100K
Articaine 4% 1:200K
2.2 lbs = 1 kg
193 lbs = 88 kg
Maximum Doses LA
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Lidocaine 2%
Max dose = 7 mg/kg
7mg/kg X 88=616 mg
36 mg/1.8 mL
616mg/36mg/cart.=
17 cartridges **
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Articaine 4%
Max dose 7 mg/kg
7 X 88 = 616 mg
72 mg/1.8mL
616 mg/72 mg/cart. =
9 cartridges
Maximum Doses Epi
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% = 1/100 = g/dL
Therefore:
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1/100 = 1% = 1g/dL = 10 mg/mL
1/1000 = 0.1% = 0.1 g/dL = 1 mg/mL
1/10000 = 0.01% = 0.01 g/dL = 0.1 mg/mL
1/100000 = 0.001% = 0.001 g/dL = 0.01mg/mL
A cartridge contains 1.8 mL
 Therefore a cartridge of 1:100 000 epi contains
0.01 mg/mL X 1.8 mL = 0.018 mg
(or about 0.02 mg)
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Maximum Doses Epi
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Cardiovascular patient 0.04 mg
Healthy patient 0.2 mg
Maximum Doses LA
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Lidocaine 2%
Max dose = 7 mg/kg
7mg/kg X 88=616 mg
36 mg/1.8 mL
616mg/36mg/cart.=
17 cartridges **
10-11 cartridges (epi)
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Articaine 4%
Max dose 7 mg/kg
7 X 88 = 616 mg
72 mg/1.8mL
616 mg/72 mg/cart. =
9 cartridges
Pregnant Patients
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Which Local Anaesthetic to use?
Articaine 4% 1:200 000 epi
Lidocaine 2% 1:100 000 epi
Mepivacaine 2% 1:20 000 levo
Mepivacaine 3% plain
FDA categories (based on risk of
fetal injury)
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A: controlled studies in humans—no risk to
fetus demonstrated
B: animal studies show no risk, no human
studies; or animal studies have shown a
risk but human studies have shown no risk
C: animal studies show risk, no human
studies; or no animal or human studies
Pregnant Patients
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Which Local Anaesthetic to use?
Articaine 4% 1:200 000 FDA category C
Lidocaine 2% 1:100 000 FDA category B
Mepivacaine 2% 1:20 000 FDA category C
Mepivacaine 3% plain FDA category C
Advantages of Injecting
“Higher”
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Failure to achieve profound local
anaesthesia attributed to being “too low”
and “too far forward”
Injecting superiorly and more distally may
block accessory innervation
3 nodes of Ranvier may not be true
Gow-Gates Technique
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Landmarks:
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Corner of the mouth (contralateral side)
Tragus of the ear
Disto palatal cusp of the maxillary second
molar
AIMING FOR THE NECK OF THE CONDYLE
Efficacy of the Gow-Gates
Technique
Author
Year
GG (%)
IANB (%)
Watson and Gow-Gates
1976
98.4
85.4
Gow-Gates and Watson
1977
96.2
85.5
Levy
1981
96
65
Malamed
1981
97.5
Montagnese et al.
1984
35
38
Akinosi Technique
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Closed-mouth technique
Does not rely on a hard-tissue landmark
Parallel to occlusal plane, height of the
mucogingival junction
Advanced until hub is level with distal
surface of maxillary second molar
Delayed onset of anaesthesia
Akinosi Technique
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Martinez Gonzalez et al. 2003
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Pain to puncture less with Akinosi
Onset slower
17.8% failure vs. 10.7% IAB/LB
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BUT-incomplete LB considered failure
Cruz et al. 1994
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Gow Gates more effective, but Akinosi most
acceptable to patients
Nerve to Mylohyoid
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Deposit ¼ cartridge of LA on lingual
surface of tooth in alveolar mucosa
Goal is to bathe the nerve as branches of it
enter the lingual surface of the mandible
Adjunctive Strategies
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Additional Anaesthetic
PDL Injection
Intraosseous Injection
Intrapulpal Injection
Different anaesthetic
PDL Injection
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Technique:
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needle inserted into the gingival sulcus at a 30
degree angle towards the tooth
bevel placed towards bone
advanced until resistance felt
anaesthetic injected with continuous force for
about 15 seconds.
approx. 0.2 mL of solution
25 vs. 30 gauge needle
PDL Injection
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Conventional vs. specific PDL syringes:
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Malamed (1982):
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similar rates of success
D’Souza et al (1987):
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no sig. difference in anaesthesia achieved.
using the pressure syringe resulted in more spread
of anaesthetic to adjacent teeth
PDL Injection: Primary
Technique
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Melamed 1982: 86% overall
Faulkner 1983: 81% overall
White 1988: variable, short duration esp.
md. molars
Walton 1990: “In reviewing the clinical and
experimental literature…the periodontal
ligament injection does not meet all of the
necessary requirements for a primary
technique.”
PDL Injection: Supplemental
Technique
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Walton and Abbott 1981:
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Inadequate pulpal anaesthesia following IAB
92% overall
included situations where multiple PDL
injections required
most critical factor was to inject under strong
resistance
Smith, Walton, Abbott 1983:
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83% overall with high pressure syringe
PDL Injection: Anaesthetic
Distribution
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Garfunkel et al 1983, Smith and Walton
1983, Tagger et al 1994, Tagger et al
1994*
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spread along path of least resistance
influenced by anatomical structures and fascial
planes
through marrow spaces
avoided PDL route
appears to be a form of intraosseous injection
PDL Injection: Effects on the
Periodontium
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Animal histological studies
Most studies: no long term evidence of
tissue disruption or inflammation
Roahen and Marshall 1990: evidence of
localized external resorption
Adjunctive Strategies
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Additional Anaesthetic
PDL Injection
Intraosseous Injection
Intrapulpal Injection
Different anaesthetic
Intraosseous Injection
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Technique for mandibular infiltration
Perforate the cortical plate to introduce LA
in medullary bone
Bathes the periradicular region in LA
2 commercial systems available:
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Stabident (Patterson)
X-Tip (Tulsa Dentsply)
Stabident
Stabident
Stabident
Stabident
X-Tip
Success of Conventional IANB +
IO as Measured by EPT
Dunbar et al.
2% lido 1:100K
90%
Gallatin et al.
3% mepivacaine
plain
100%
Guglielmo et
al.
2% lido 1:100K
100%
Reitz et al.
2% lido 1:100K
94%
IANB + IO in Cases of
Irreversible Pulpitis
Nusstein et
al. 1998
Lido 2%
1:100K
91%
Parente et al. Lido 2%
1998
1:100K
79%/ 91%
Reisman et
al. 1997
Mepivacaine
3% plain
80%/ 98%
Nusstein et
al. 2003
Lido 2%
1:100K
82% (X-Tip)
Bigby et al.
2006
Articaine 4%
1:100K
86%
Adjunctive Strategies
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Additional Block (higher injection)
PDL Injection
Intraosseous Injection
Intrapulpal Injection
Different anaesthetic
Intrapulpal Anaesthesia
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VanGheluwe and Walton 1997:
under back-pressure, efficacy of LA=saline
injection
Conclusion: back-pressure is the key to
intrapulpal anaesthetic success
Adjunctive Strategies
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Additional Anaesthetic
PDL Injection
Intraosseous Injection
Intrapulpal Injection
Different anaesthetic
Articaine
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Reputation for improved local anaesthetic
effect—short linear molecule
Amide local, contains a thiophene ring
instead of a benzene ring
Partial hydrolysis by plasma esterases
4% solution—concern with toxicity
Potential for methemoglobinemia (like
prilocaine)
Articaine
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More effective than other local
anaesthetics?
No difference found:
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Haas et al. 1990 (vs. prilocaine)
Vahatalo et al. 1993 (vs. lidocaine)
Malamed et al. 2000 (vs. lidocaine)
Donaldson et al. 2000 (vs. prilocaine)
Claffey et al. 2004 (vs. lidocaine)
Mikesell et al. 2005 (vs. lidocaine)
Articaine
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Claffey et al. 2004:
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Articaine vs. lidocaine IANB for irreversible
pulpitis of mandibular teeth
Articaine 9/37 (24%)
Lidocaine 8/35 (23%)
(all subjects had subjective lip anaesthesia)
Articaine
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Paraesthesia?
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Haas and Lennon 1995: higher incidence of
paraesthesia associated with prilocaine and
articaine. Attributed to the higher
concentration of drug required for comparable
clinical effect
14/11 000 000 injections
Statistically higher
Clinical relevance? Claffey et al 2004 “clinically
rare event”
Articaine
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Paraesthesia?
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Dower 2003 (Dentistry Today)
Review article
Paraesthesia rates up to 2-4% when using
articaine for lingual blocks or IANBs
RCDSO Dispatch
Summer 2005 pg. 26

“Until more research is done, it is the
College’s view that prudent practitioners
may wish to consider the scientific
literature before determining whether to
use 4% local anaesthetic solutions for
mandibular block injections.”
College Registrar Replies
Dispatch Fall 2005 vol. 19, #4

“This college received legal advice from our
general counsel, and from outside counsel,
before publishing what we did…The advice
we received was that it was certainly within
our obligation to advise members to be
aware of the literature…”
Articaine
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Hillerup and Jensen 2006:
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Danish population—all cases in Denmark
referred to authors for evaluation
54 injection injuries in 52 patients
54% of all nerve injuries associated with
articaine
Substantial increase in number of injection
injuries following introduction of articaine to
Danish market in 2000.
Articaine
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What about a mandibular infiltration?
Recommended by Steve Buchanan
Kanaa et al. 2006
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Cross-over design comparing articaine and
lidocaine for mandibular infiltration for first
molars
Anaesthesia measured by maximal EPT X2
Lidocaine 38% effective
Articaine 65% effective
Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
1.
2.
3.
1.
2.
3.
4.
5.
6.
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
Kleinknect and Bernstein 1978: positive
correlation between anxiety and reported
pain during dental treatment
Topical Anaesthetic
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Benzocaine or Lidocaine
Effectiveness?
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Gill and Orr 1979: 15
second application no
more effective than
placebo
Stern and Giddon 1975:
2-3 minutes=profound
soft tissue anaesthesia
Topical Anaesthetic
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Recommendations:
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Dry mucous membranes first
2-3 minutes, but concern with tissue sloughing
Tip of the tongue
Topical Anaesthetic
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Benzocaine Spray
RCDSO Dispatch 21, 1, Feb/Mar 2007
pp.28-29
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Advice to Dentists
Benzocaine Sprays and Methemoglobinemia
(MHb)
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Health Canada—9 suspected cases, none fatal
Topical Anaesthetic
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Benzocaine spray/Methemoglobinemia
Recommendations:
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Avoid in patients with a history of MHb
Consider lidocaine as an alternative
Broken/inflamed tissue may promote uptake
Use only amount deemed necessary
If suspicious, send patient to hospital for
methylene blue tx
O2 won’t help, but give it anyways
Methemoglobinemia
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Fe2+ ion of the heme group of the
hemoglobin molecule is oxidized to Fe3+
Hemoglobin converted to methemoglobin,
a non-oxygen binding form of hemoglobin
that binds a water molecule instead of
oxygen.
Conclusions:
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1. Consider topical anaesthetic
2. Re-test using patient’s chief complaint
2. Inject again
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Higher
More Local Anaesthetic
Nerve to Mylohyoid
3. Consider PDL/Intraosseous Anaesthesia
4. Consider Intrapulpal Anaesthesia
5. If they say it hurts, it hurts
Thank you
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
Questions?
Please feel free to contact me:
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416-223-1771
[email protected]
www.endoasleep.ca