Dr. Özkan ADIGÜZEL

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

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

6.  What about experienced operators?

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

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

15. Nerve to
mylohyoid

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

24. Adjunctive Strategies
 Additional Anaesthetic
 Higher injection
 Gow Gates
 Akinosi
 Nerve to mylohyoid
 PDL Injection
 Intraosseous Injection
 Intrapulpal Injection
 Different anaesthetic

26. Maximum Doses LA
 % means g/dL
 Example:
 1% = 1 g/dL
 1% = 10g/L
 1% = 10 mg/mL
 Therefore:
 2% = 20 mg/mL

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)

31. Maximum Doses Epi
 Cardiovascular patient 0.04 mg
 Healthy patient 0.2 mg

32. 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
 10-11 cartridges (epi)

34. Pregnant Patients
 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

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

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

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

47. Adjunctive Strategies
 Additional Anaesthetic
 PDL Injection
 Intraosseous Injection
 Intrapulpal Injection
 Different anaesthetic

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

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

55. Adjunctive Strategies
 Additional Anaesthetic
 PDL Injection
 Intraosseous Injection
 Intrapulpal Injection
 Different anaesthetic

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)

57. Stabident

58. Stabident

59. Stabident

60. Stabident

61. X-Tip

62. Success of Conventional IANB +
IO as Measured by EPT
Dunbar et al. 2% lido 1:100K 90%
Gallatin et al. 3% mepivacaine 100%
plain
Guglielmo et 2% lido 1:100K 100%
al.
Reitz et al. 2% lido 1:100K 94%

63. IANB + IO in Cases of
Irreversible Pulpitis
Nusstein et Lido 2% 91%
al. 1998 1:100K
Parente et al. Lido 2% 79%/ 91%
1998 1:100K
Reisman et Mepivacaine 80%/ 98%
al. 1997 3% plain
Nusstein et Lido 2% 82% (X-Tip)
al. 2003 1:100K
Bigby et al. Articaine 4% 86%
2006 1:100K

64. Adjunctive Strategies
 Additional Block (higher injection)
 PDL Injection
 Intraosseous Injection
 Intrapulpal Injection
 Different anaesthetic

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

66. Adjunctive Strategies
 Additional Anaesthetic
 PDL Injection
 Intraosseous Injection
 Intrapulpal Injection
 Different anaesthetic

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

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.”

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

84. Topical Anaesthetic
 Benzocaine Spray
 RCDSO Dispatch 21, 1, Feb/Mar 2007
pp.28-29
 Advice to Dentists
 Benzocaine Sprays and Methemoglobinemia
(MHb)
 Health Canada—9 suspected cases, none fatal

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