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
Management of Local Anaesthesia in Endodontics Halton-Peel Dental Association Andrew Moncarz BSc, DDS, Dip. An, MSc, FRCD(C) March 22, 2007
“ 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…”