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  • 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

Transcript

  • 1. Management of LocalAnaesthesia 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. Reported Reasons forMandibular Anaesthesia Failure1. Operator Inexperience2. Armamentarium: Deflection of the needle tip3. Patient factors:  Variations in anatomy  Accessory innervation  Unpredictable spread of LA  Local infection  Pulpal inflammation  Psychological issues
  • 4. Reported Reasons forMandibular 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
  • 5.  What about experienced operators?
  • 6. 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%
  • 7. Reported Reasons forMandibular 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
  • 8.  Always use a long 25 gauge needle (the red one)  2 reasons:  1. Less deflection  2. Less false negative aspiration
  • 9. Reported Reasons forMandibular Anaesthesia Failure1. Operator Inexperience2. Armamentarium: Deflection of the needle tip3. Patient factors:  Variations in anatomy  Accessory innervation  Unpredictable spread of LA  Local infection  Pulpal inflammation  Psychological issues
  • 10. 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
  • 11. Reported Reasons forMandibular Anaesthesia Failure1. Operator Inexperience2. Armamentarium: Deflection of the needle tip3. Patient factors:  Variations in anatomy  Accessory innervation  Unpredictable spread of LA  Local infection  Pulpal inflammation  Psychological issues
  • 12. Nerve tomylohyoid
  • 13. Reported Reasons forMandibular Anaesthesia Failure1. Operator Inexperience2. Armamentarium: Deflection of the needle tip3. Patient factors:  Variations in anatomy  Accessory innervation  Unpredictable spread of LA  Local infection  Pulpal inflammation  Psychological issues
  • 14.  Berns et al. 1962: injected radiopaque material into pterygomandibular space Spread is unpredictable Suggestion: inject more LA
  • 15. Reported Reasons forMandibular Anaesthesia Failure1. Operator Inexperience2. Armamentarium: Deflection of the needle tip3. Patient factors:  Variations in anatomy  Accessory innervation  Unpredictable spread of LA  Local infection  Pulpal inflammation  Psychological issues
  • 16.  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
  • 17. Reported Reasons forMandibular Anaesthesia Failure1. Operator Inexperience2. Armamentarium: Deflection of the needle tip3. Patient factors:  Variations in anatomy  Accessory innervation  Unpredictable spread of LA  Local infection  Pulpal inflammation  Psychological issues
  • 18. 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
  • 19. 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
  • 20. Adjunctive Strategies Additional Anaesthetic PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic Retest using the CC
  • 21. Adjunctive Strategies Additional Anaesthetic  Higher injection  Gow Gates  Akinosi  Nerve to mylohyoid PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic
  • 22. Maximum Doses LA % means g/dL Example:  1% = 1 g/dL  1% = 10g/L  1% = 10 mg/mL Therefore:  2% = 20 mg/mL
  • 23. 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
  • 24. 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
  • 25. 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
  • 26. 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)
  • 27. Maximum Doses Epi Cardiovascular patient 0.04 mg Healthy patient 0.2 mg
  • 28. 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)
  • 29. 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
  • 30. 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
  • 31. 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
  • 32. 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
  • 33. 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
  • 34. Efficacy of the Gow-Gates TechniqueAuthor Year GG (%) IANB (%)Watson and Gow-Gates 1976 98.4 85.4Gow-Gates and Watson 1977 96.2 85.5Levy 1981 96 65Malamed 1981 97.5Montagnese et al. 1984 35 38
  • 35. 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
  • 36. 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
  • 37. 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
  • 38. Adjunctive Strategies Additional Anaesthetic PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic
  • 39. 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
  • 40. 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
  • 41. 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.”
  • 42. 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
  • 43. 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
  • 44. 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
  • 45. Adjunctive Strategies Additional Anaesthetic PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic
  • 46. 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)
  • 47. Stabident
  • 48. Stabident
  • 49. Stabident
  • 50. Stabident
  • 51. X-Tip
  • 52. Success of Conventional IANB + IO as Measured by EPTDunbar et al. 2% lido 1:100K 90%Gallatin et al. 3% mepivacaine 100% plainGuglielmo et 2% lido 1:100K 100%al.Reitz et al. 2% lido 1:100K 94%
  • 53. IANB + IO in Cases of Irreversible PulpitisNusstein et Lido 2% 91%al. 1998 1:100KParente et al. Lido 2% 79%/ 91%1998 1:100KReisman et Mepivacaine 80%/ 98%al. 1997 3% plainNusstein et Lido 2% 82% (X-Tip)al. 2003 1:100KBigby et al. Articaine 4% 86%2006 1:100K
  • 54. Adjunctive Strategies Additional Block (higher injection) PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic
  • 55. Intrapulpal Anaesthesia VanGheluwe and Walton 1997: under back-pressure, efficacy of LA=saline injection Conclusion: back-pressure is the key to intrapulpal anaesthetic success
  • 56. Adjunctive Strategies Additional Anaesthetic PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic
  • 57. 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)
  • 58. 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)
  • 59. 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)
  • 60. 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”
  • 61. Articaine Paraesthesia?  Dower 2003 (Dentistry Today)  Review article  Paraesthesia rates up to 2-4% when using articaine for lingual blocks or IANBs
  • 62. 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.”
  • 63. 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…”
  • 64. 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.
  • 65. 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
  • 66. Reported Reasons forMandibular Anaesthesia Failure1. Operator Inexperience2. Armamentarium: Deflection of the needle tip3. Patient factors:  Variations in anatomy  Accessory innervation  Unpredictable spread of LA  Local infection  Pulpal inflammation  Psychological issues
  • 67. Kleinknect and Bernstein 1978: positive correlation between anxiety and reported pain during dental treatment
  • 68. 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
  • 69. Topical Anaesthetic Recommendations:  Dry mucous membranes first  2-3 minutes, but concern with tissue sloughing  Tip of the tongue
  • 70. 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
  • 71. 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
  • 72. 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.
  • 73. 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
  • 74. Thank you Questions? Please feel free to contact me:  416-223-1771  andrew_moncarz@yahoo.com  www.endoasleep.ca