Mandibular anaesthesia

1. Mandibular anaesthesia 19 October 2017 I.Kassem,BDS,MSc,MFDS RCS Ed,MOMS RCPS Glasg, FDSRCS Consultant Oral & Maxillofacial surgeon

2. Mandibular Anesthesia Lower success rate than Maxillary anesthesia - approx. 80-85 % Related to bone density Less access to nerve trunks

3. Mandibular Nerve Blocks Inferior alveolar Mental - Incisive Buccal Lingual Gow-Gates Akinosi

4. Mandibular Anesthesia Most commonly performed technique Has highest failure rate (15-20%) Success depends on depositing solution within 1 mm of nerve trunk

5. Inferior Alveolar Nerve Block Not a complete mandibular nerve block. Requires supplemental buccal nerve block May require infiltration of incisors or mesial root of first molar

6. Inferior Alveolar Nerve Block Nerves anesthetized Inferior Alveolar Mental Incisive Lingual

7. Inferior Alveolar Nerve Block Areas Anesthetized Mandibular teeth to midline Body of mandible, inferior ramus Buccal mucosa anterior to mental foramen Anterior 2/3 tongue & floor of mouth Lingual soft tissue and periosteum

8. Inferior Alveolar Nerve Block Indications Multiple mandibular teeth Buccal anterior soft tissue Lingual anesthesia

9. Inferior Alveolar Nerve Block Contraindications Infection/inflammation at injection site Patients at risk for self injury (eg. children)

10. Inferior Alveolar Nerve Block 10%-15% positive aspiration

11. Inferior Alveolar Nerve Block Alternatives Mental nerve block Incisive nerve block Anterior infiltration

12. Inferior Alveolar Nerve Block Alternatives (cont.) Periodontal ligament injection (PDL) Gow-Gates Akinosi Intraseptal

13. Inferior Alveolar Nerve Block Technique Apply topical Area of insertion: medial ramus, mid-coronoid notch, level with occlusal plane (1 cm above), 3/4 posterior from coronoid notch to pterygomandibular raphe advance to bone (20-25 mm)

14. Inferior Alveolar Nerve Block Target Area Inferior alveolar nerve, near mandibular foramen Landmarks Coronoid notch Pterygomandibular raphe Occlusal plane of mandibular posteriors

15. Inferior Alveolar Nerve Block Precautions Do not inject if bone not contacted Avoid forceful bone contact

16. Inferior Alveolar Nerve Block Complications Hematoma Trismus Facial paralysis

17. a) Halstead method b) Gow-Gates method c) Akinosi method 1. Inferior Alveolar Nerve Block a) Individual variations in the locations of the mandibular foramen b) Be aware of the proximal extremity of the maxillary artery. Aspiration !

18. a) The finger in the retromolar fossa with the fingernail poiting backward a) A line is sighted from occlusal surfaces of the premolars of the opposite side to the midpoint of the fingernail b) Inject 0,5 - 1ml solution c) Continue to inject 0,5ml on removal from injection site to anesthetize the lingual branch a) Halstead Open-Mouth method

19. a) Inject remaining anesthetic into coronoid notch region in the mucous membrane distal and buccal to most distal molar to perform a long buccal nerve block

20. a) Field block anesthesia b) The injection site is higher than Halstead c) Below the insertion of the lateral pterygoid muscle at the anterior side of the condyle at maximal opening in relatively avascular area d) The injection line is parralel with the external line from the intertragal notch to the angle of the mouth b) Gow-Gates method

21. a) The diffusion of the anesthetic solution reach all three oral sensory portion of mandibular branch V.n. and other sensory nerves in this region b) High success rate, fewer complication x slower rate of onset

22. a) Field block anesthesia b) For patient with limited opening due trismus, ankylosis, fracture The gingival margin above the maxillary 2nd and 3rd molars and the pterygomandibular raphae serve as landmarks for this technique c) Vazirani-Akinosi closed mouth method

23. a) The needle is advanced through the mucous membrane and buccinator muscle to enter the pterygomandibular space b) Penetrate to a depht 25mm a) Remaining anesthetic in long buccal nerve area

24. 2. Mental Nerve Block a) Terminal branch of the inferior alveolar nerve, exits the mandible via the mental foramen b) The position of this foramen is most frequently near the apex of the mandibular 2nd premolar c) The foramen open upward and slightly posteriorly!

25. a) Anesthetized lower lip, chin, labial gingiva, alveolar mucosa, pulpal/periodontal tissue for the canine, incisors and premolars on side blocked Technique The tip of needle be directed or anterior to approximate the position of the foramen, but not enter the foramen ! Penetrate to a depth 5 mm, inject 0,5 - 1,0 ml To provide incisive nerve anesthesia via the application of finger pressure over the foramen after local anesthetic solution is deposited there

26. Mental nerve

27. 3. Lingual Nerve Block a) Nerve passes from the infratemporal fossa into the floor of the mouth, in the vicinity of the 2nd and 3rd molars, is quite vulnerable b) Is anesthetizes during the inferior alveolar nerve block or with a bolus of anesthetic solution injected after an inferior alveolar nerve block a) Anesthetized anterior ⅔ of the tongue, lingual gingiva and adjacent mucosa

28. Lingual nerve

29. 4. Buccal Nerve Block a) Arises in the infratemporal fossa and crosses the anterior border of the ramus to give multiple branches b) Supplies buccal gingiva and mucosa of the mandible for a variable length, from the vicinity of the 3th molar to the canine

30. Technique - anterior ramus of the mandible at the level of the mandibular molar occlusal plane in the vicinity of the retromolar fossa

31. Buccal nerve Lingual nerve Inferior alveolar nerve Mental nerve

32. Reported Reasons for Mandibular Anaesthesia Failure 1. Operator Inexperience 2. Armamentarium: Deflection of the needle tip 3. Patient factors: 1. Variations in anatomy 2. Accessory innervation 3. Unpredictable spread of LA 4. Local infection 5. Pulpal inflammation 6. Psychological issues

34. ■ What about experienced operators?

36. ■ Always use a long 25 gauge needle (the red one) ■ 2 reasons: ■ 1. Less deflection ■ 2. Less false negative aspiration

39. Nerve to mylohyoid

42. ■ 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

44. 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

45. Adjunctive Strategies ■ Additional Anaesthetic ■ PDL Injection ■ Intraosseous Injection ■ Intrapulpal Injection ■ Different anaesthetic ■ Retest using the CC

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

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

48. 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

49. 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

50. Maximum Doses LA ■ Lidocaine 2% ■ Max dose = 7 mg/kg ■ 7mg/kg X 88=616 mg ■ 36 mg/1.8 mL ■ 616mg/36mg/cart.= ■ 17 cartridges ** ■ Articaine 4% ■ Max dose 7 mg/kg ■ 7 X 88 = 616 mg ■ 72 mg/1.8mL ■ 616 mg/72 mg/cart. = ■ 9 cartridges

51. 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)

52. Maximum Doses Epi ■ Cardiovascular patient 0.04 mg ■ Healthy patient 0.2 mg

53. Maximum Doses LA ■ 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) ■ Articaine 4% ■ Max dose 7 mg/kg ■ 7 X 88 = 616 mg ■ 72 mg/1.8mL ■ 616 mg/72 mg/cart. = ■ 9 cartridges

54. 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

55. 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

56. 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

57. 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

58. 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

59. 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

60. 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

61. Adjunctive Strategies ■ Additional Anaesthetic ■ PDL Injection ■ Intraosseous Injection ■ Intrapulpal Injection ■ Different anaesthetic

62. 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

64. 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. Stabident

66. Stabident

67. Stabident

68. Stabident

69. X-Tip

70. Adjunctive Strategies ■ Additional Block (higher injection) ■ PDL Injection ■ Intraosseous Injection ■ Intrapulpal Injection ■ Different anaesthetic

71. Intrapulpal Anaesthesia ■ VanGheluwe and Walton 1997: ■ under back-pressure, efficacy of LA=saline injection ■ Conclusion: back-pressure is the key to intrapulpal anaesthetic success

73. 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)

74. 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)

75. 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)

76. 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”

77. Articaine ■ Paraesthesia? ■ Dower 2003 (Dentistry Today) ■ Review article ■ Paraesthesia rates up to 2-4% when using articaine for lingual blocks or IANBs

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

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