1. Management of Local
Anaesthesia in Endodontics
Halton-Peel Dental Association
Andrew Moncarz
BSc, DDS, Dip. An, MSc, FRCD(C)
March 22, 2007
2. Objectives
Review of:
Reported rates of profound anaesthesia
Anatomical variations
Maximum doses of local anaesthetics
Pulpal inflammation as a complicating factor
Adjunctive strategies for profound mandibular
LA
3.
4. Reported Reasons for
Mandibular Anaesthesia Failure
1. Operator Inexperience
2. Armamentarium: Deflection of the needle tip
3. Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
5. Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
7. 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. mepiv 2%
80%
1999 1:20K
Reitz et al. 1998 lido 2% 1:100K 71%
8. Reported Reasons for
Mandibular Anaesthesia Failure
Operator Inexperience
Armamentarium: Deflection of the needle tip
Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
9. Always use a long 25 gauge needle (the
red one)
2 reasons:
1. Less deflection
2. Less false negative aspiration
10. Reported Reasons for
Mandibular Anaesthesia Failure
1. Operator Inexperience
2. Armamentarium: Deflection of the needle tip
3. Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
11.
12.
13. Ultrasound Guidance
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
14. Reported Reasons for
Mandibular Anaesthesia Failure
1. Operator Inexperience
2. Armamentarium: Deflection of the needle tip
3. Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
16. Reported Reasons for
Mandibular Anaesthesia Failure
1. Operator Inexperience
2. Armamentarium: Deflection of the needle tip
3. Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
17. Berns et al. 1962: injected radiopaque
material into pterygomandibular space
Spread is unpredictable
Suggestion: inject more LA
18. Reported Reasons for
Mandibular Anaesthesia Failure
1. Operator Inexperience
2. Armamentarium: Deflection of the needle tip
3. Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
19. 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
20. Reported Reasons for
Mandibular Anaesthesia Failure
1. Operator Inexperience
2. Armamentarium: Deflection of the needle tip
3. Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
21. Pulpal Inflammation
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
22. Effectiveness of Conventional
IANB: Irreversible Pulpitis
100% lip anaesthesia
Reisman et al. 1.8 mL lido 2%
25%
1997 1:100K epi
Nusstein et al. 1.8 mL lido 2%
19%
1998 1:100K epi
Cohen et al. 1.8 mL lido 2%
50%
2000 1:100K epi
1.8 mL lido 2%
Claffey et al. 1:100K epi 23%
2004
23. Adjunctive Strategies
Additional Anaesthetic
PDL Injection
Intraosseous Injection
Intrapulpal Injection
Different anaesthetic
Retest using the CC
27. Maximum Doses LA
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
28. Maximum Doses LA
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
29. Maximum Doses LA
Lidocaine 2% Articaine 4%
Max dose = 7 mg/kg Max dose 7 mg/kg
7mg/kg X 88=616 mg 7 X 88 = 616 mg
36 mg/1.8 mL 72 mg/1.8mL
616mg/36mg/cart.= 616 mg/72 mg/cart. =
17 cartridges ** 9 cartridges
30. Maximum Doses Epi
% = 1/100 = g/dL
Therefore:
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)
35. FDA categories (based on risk of
fetal injury)
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
36. Pregnant Patients
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
37. Advantages of Injecting
“Higher”
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
38. Gow-Gates Technique
Landmarks:
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
39.
40.
41. 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
42. Akinosi Technique
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
43.
44.
45. Akinosi Technique
Martinez Gonzalez et al. 2003
Pain to puncture less with Akinosi
Onset slower
17.8% failure vs. 10.7% IAB/LB
BUT-incomplete LB considered failure
Cruz et al. 1994
Gow Gates more effective, but Akinosi most
acceptable to patients
46. Nerve to Mylohyoid
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
48. PDL Injection
Technique:
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
49.
50. PDL Injection
Conventional vs. specific PDL syringes:
Malamed (1982):
similar rates of success
D’Souza et al (1987):
no sig. difference in anaesthesia achieved.
using the pressure syringe resulted in more spread
of anaesthetic to adjacent teeth
51. PDL Injection: Primary
Technique
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.”
52. PDL Injection: Supplemental
Technique
Walton and Abbott 1981:
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:
83% overall with high pressure syringe
53. PDL Injection: Anaesthetic
Distribution
Garfunkel et al 1983, Smith and Walton
1983, Tagger et al 1994, Tagger et al
1994*
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
54. PDL Injection: Effects on the
Periodontium
Animal histological studies
Most studies: no long term evidence of
tissue disruption or inflammation
Roahen and Marshall 1990: evidence of
localized external resorption
56. Intraosseous Injection
Technique for mandibular infiltration
Perforate the cortical plate to introduce LA
in medullary bone
Bathes the periradicular region in LA
2 commercial systems available:
Stabident (Patterson)
X-Tip (Tulsa Dentsply)
65. Intrapulpal Anaesthesia
VanGheluwe and Walton 1997:
under back-pressure, efficacy of LA=saline
injection
Conclusion: back-pressure is the key to
intrapulpal anaesthetic success
68. Articaine
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)
69. Articaine
More effective than other local
anaesthetics?
No difference found:
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)
70. Articaine
Claffey et al. 2004:
Articaine vs. lidocaine IANB for irreversible
pulpitis of mandibular teeth
Articaine 9/37 (24%)
Lidocaine 8/35 (23%)
(all subjects had subjective lip anaesthesia)
71. Articaine
Paraesthesia?
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”
72. Articaine
Paraesthesia?
Dower 2003 (Dentistry Today)
Review article
Paraesthesia rates up to 2-4% when using
articaine for lingual blocks or IANBs
73.
74. 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.”
75.
76.
77. 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…”
78. Articaine
Hillerup and Jensen 2006:
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.
79. Articaine
What about a mandibular infiltration?
Recommended by Steve Buchanan
Kanaa et al. 2006
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
80. Reported Reasons for
Mandibular Anaesthesia Failure
1. Operator Inexperience
2. Armamentarium: Deflection of the needle tip
3. Patient factors:
Variations in anatomy
Accessory innervation
Unpredictable spread of LA
Local infection
Pulpal inflammation
Psychological issues
81. Kleinknect and Bernstein 1978: positive
correlation between anxiety and reported
pain during dental treatment
82. Topical Anaesthetic
Benzocaine or Lidocaine
Effectiveness?
Gill and Orr 1979: 15
second application no
more effective than
placebo
Stern and Giddon 1975:
2-3 minutes=profound
soft tissue anaesthesia
83. Topical Anaesthetic
Recommendations:
Dry mucous membranes first
2-3 minutes, but concern with tissue sloughing
Tip of the tongue
85. Topical Anaesthetic
Benzocaine spray/Methemoglobinemia
Recommendations:
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
86. Methemoglobinemia
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.
87. Conclusions:
1. Consider topical anaesthetic
2. Re-test using patient’s chief complaint
2. Inject again
Higher
More Local Anaesthetic
Nerve to Mylohyoid
3. Consider PDL/Intraosseous Anaesthesia
4. Consider Intrapulpal Anaesthesia
5. If they say it hurts, it hurts
88. Thank you
Questions?
Please feel free to contact me:
416-223-1771
andrew_moncarz@yahoo.com
www.endoasleep.ca
Hinweis der Redaktion
Vital asymptomatic md. 6s: no response to max. EPT, 2 tests within 1 hour Subjective report of lip numbness at baseline Wong 2001: 69% weighted success rate
Arises within the middle cranial fossa from the trigeminal ganglion—large relay station. Mostly sensory, some motor. Nerve drops down through foramen ovale and enters the infratemporal region and divides into multiple branches: Branches from the stem: 3 motor: medial pterygoid, tensor tympani (middle ear), tensor palati (soft palate) 1 sensory: nervus spinosus (sensory): dura of the middle cranial fossa Branches from the anterior division: 3 motor: masseter, temporalis, lateral pterygoid 1 sensory: buccal branch (long buccal nerve) Branches from the posterior division: 1. auriculotemporal nerve—mostly sensory but carries autonomic info from the otic ganglion. Auricular, articular, temporal all sensory. Secretory fibres with ANS info. Otic ganglion: sensory, sympathetic and parasympathetic innervation. Only parasympathetic synapses in the ganglion. Post synaptic sympathetic and parasympathetic fibres hitchhike with the auriculotemporal nerve to the parotid gland. 2. lingual nerve—sensory 3. Inferior alveolar nerve—sensory and motor: Passes downward along the medial side of the mandibular ramus to the mandibular foramen. The mandibular foramen lies at the centre point of the internal face of the ramus. Just about the same height as the occlusal plane. At that point, the nerve to mylohyoid branches off. Nerve to mylohyoid: motor: passes to the submandibular region. Supplies the mylohyoid muscle and the anterior belly of the digastric. Intramandibular portion: passes downward and anteriorly through the mandibular canal. Sends small branches to supply the pulps of the teeth. Mental nerve is a branch that emerges from the mental foramen. Sensory for skin and mucous membrane of the lower lip, skin of the chin, and vestibular gingiva of the mandibular incisors.
Theoretically, local anaesthetic deposited at the mandibular foramen should provide anaesthesia to: all mandibular teeth of that side, the vestibular gingiva anterior to the mental foramen, the lower lip, and the chin.
Lingula and mandibular foramen
Inferior alveolar nerve, before entering md. foramen branches into mylohyoid nerve. Mylohyoid nerve runs along medial ramus in mylohyoid groove to provide motor function to mylohyoid muscle. Foramina found in pm region of md. associated with the mylohyoid. 1972—study—able to elicit pain response by stimulating nerve. Not anaesthetized by block because of branching—classically thought to be 5 mm above mandibular foramen. Wilson 1984—mean 14.7 mm, range 5 to 23 mm. LA may not bathe critical length of axon.
Complaint of pain in time with the heartbeat Potentially need 4 times as much LA to block nerve conduction
Felt pain at any time during the procedure Clinical diagnosis of irreversible pulpitis based on prolonged response to EndoIce. After injection, 15 minute wait. Asked pt. about subjective lip numbness. If not present, pt. Excluded. Therefore, 100% of patients used for data analysis had profound lip anaesthesia.
Hargraves: bathe more than the 3 nodes of ranvier. May be advantageous to give a gow gates or a high standard block.
Montagnese et al. 1984 Repeated measures design 40 subjects injected twice at separate appointments—once with GG, once with conventional IANB EPT after profound lip numbness reported Results: Higher reports of tongue numbness with GG EPT: GG: 35% no response to maximal stimulation Conventional IANB: 38% no response to maximal stimulation No significant difference
To overcome the high pressures necessary for the technique using a standard syringe, can use either a short 25 gauge needle (recommended by Melamed OOO 1982) or an ultrashort 30 gauge needle (recommended by Branstromm et al J Dent Child 1982). This will help minimize bending of the needle when it’s driven into the sulcus.
White 1988: White et al (JOE 1988) found that duration and depth of anaesthesia was widely variable (PDL injection, primary technique). Adequate anaesthesia time was sometimes was as little as 10 minutes. With mandibular molars for example, 80 % were adequately anaesthetized after 2 minutes, but only 20% were still adequately frozen at 10 minutes. With maxillary lateral incisors, only 39% had adequate anaesthesia after 2 minutes, and then rates dropped.
Tagger E, Tagger M, Sarnat H, Mass E. (Int J Paediatr Dent 1994) Dog study, primary dentition: Similar protocol to above. The solution usually reached the alveolar bone crest, seeped under the periosteum and alongside vascular channels into bone marrow, reaching natural cavities such as the crypts of tooth buds and the mandibular canal. The ink did not penetrate into the enamel organ or contact the permanent tooth buds. The solution appeared to spread along the path of least resistance, governed by the intricacies of anatomical structures and fascial planes. Therefore the risk of mechanical damage to permanent tooth germs appears to be minimal.
Solid 27 gauge wire with a beveled end. Used in a slow speed handpiece to perforate the cortical plate.
Most apical extent of attached gingival margins of adjacent teeth used as landmark for locating appropriate perforation point (cortical bone in mandibular molar region is thinnest within crestal third of alveolar process); after application of topical anesthetic and infiltration of local anesthetic into gingival mucosa, perforation is performed mesial or distal to tooth; after removal of perforator, injection needle is introduced to deliver local anesthetic into periradicular medullary bone
Abstract JDR 1994: Miller and Lennon. 5X greater incidence