alpha (Aα), beta (Aβ), gamma (Aγ)
motor, proprioception
B: Preganglionic autonomic (otherwise like
a delta
delta (Aδ)
sensory
C: Small, unmyelinated
sensory, postganglionic autonomic
Rapid depolarization closes
inactivation gate
Channel must “reset” before reopening
called refractory period
determined by the time needed for the axon to repolarize
charged agents not effective unless nerve is stimulated =
phasic block, with specific receptor theory
Organic:Aqueous Distribution Constant, Q
reflects ability to penetrate hydrophobic tissue
correlates with duration
Dissociation Constant, pKa
Proportion of ionized to un-ionized molecules
correlates with —-
onset
Susceptibility to Blockade
From most to least affected:
dull pain warmth cold sharp pain touch pressure proprioception
More lipophilic =
higher % bound
bupivacaine > mepivacaine > lidocaine
Conditions decreasing binding:
Pregnancy, oral contraceptive use, estrogen supplementation, acidosis, increasing dose
(—– has significant extrahepatic metabolism)
Prilocaine
The more —— an anesthetic is, the greater the proportion of cardiovascular to CNS effects, i.e.
cardiac toxicity becomes a proportionally greater risk.
lipophilic
Beta 1
Found in heart and small intestines
-Produces cardiac stimulation
3 classes of sympathomimetic agents
Direct Acting directly on adrenergic receptors
(e.g. Epi)
2) Indirect Acting use norepinephrine release
3) Mixed both direct and indirect actions
Refractory angina treat in
monitored setting
Coagulopathy
=
Congenital or acquired
alter technique to avoid deep blocks
Methemoglobinemia
avoid prilocaine
Dialysis patients
treat day after dialysis
Cocaine abuse
avoid epinephrine, stress defer treatment 24 hours
MAO inhibitors
limited concern (because COMT still
works)
monitor blood pressure
Nonselective beta blockers - nonselective
• monitor
pressure with epinephrine use
Amphetamines/Cocaine
Synthetize the adrenergic receptors to sympathomimetics
epinephrine may produce an exaggerated response
Supraperiosteal injection site
Intersection of LA of tooth and the height of MB fold
Sup. injection - The needle tip could be below the
apex of the tooth resulting in inadequate anesthesia
PSA Point of needle insertion :
Height of the MB fold over the second molar
PSA -Long needle :
½ of its length
MSA Point of needle insertion :
Height of the Mucobuccal fold above the maxillary second premolar
Infraorbital nerve block
Nerves to be anesthetized:
1- ASA
2-MSA
3- Infraorbital nerve
Infraorbital nerve Point of needle insertion :
Over maxillary 1st premolar
GP nerve block depth
Depth ~ 5mm
High tuberosity technique
same spot as PSA, 30mm deep however.
V2 Nerve Block
scary one
Long buccal (LB)
Buccal mucoperiosteum (soft tissues) of mandibular molars.
Lingual nerve
Anterior 2/3rds of the tongue and floor of the mouth
2- Lingual mucoperiosteum
IANB
Place the index finger in the coronoid notch
6-10 mm above the occlusal plane
Finger on the coronoid
Point of entry must be lateral to the pterygomandibular raphe
Lingual Nerve Block remove
5mm
IANB - Inadequate anesthesia ? Why ?
1) Mylohyoid (Accessory) Innervation
2) Overlapping fibers of the contralateral IAN
3) Bifid inferior alveolar nerve which would require IANB more inferior to the normal location
4) Poor injection technique
Mylohyoid Nerve
Solution :
Infiltration on the lingual surface of the tooth posterior to the tooth in question
LB nerve block Technique Point of needle insertion:
Mucous membrane distal and buccal to the most distal molar tooth in the arch
Parallel but lateral to the occlusal plane
Bone contact
Depth of penetration is approximately 2-4 mm
Mental nerve block
Anesthetizes buccal mucous membranes anterior to the mental foramen and skin of the lower lip and chin
Mental nerve Point of needle insertion :
MB between the apices of the 1st and 2nd premolars
Gow-Gates Technique
Insertion point/Landmark: a line from the intertragic notch to the corner of the mouth, just distal to the maxillary 2nd molar
Target area: lateral side of the condylar neck, just below the insertion of the lateral pterygoid muscle
Height of injection: place needle tip just below the mesiopalatal cusp of the maxillary 2nd molar
Ask patient to open wide to allow the condyle to assume a frontal position
Direct syringe from the corner of the mouth from theoppositesideofmouth
Epinephrine sensitive patients:
Limit lidocaine with epinephrine quantity Mepivacaine 3% without vasoconstrictor
Difficulty achieving local anesthesia:
Very short procedures:
Mepivacaine 3% without vasoconstrictor
Presence of primary teeth is a contraindication for
PDL injection
II- Intra-septal injection
Similar to PDL
May be useful when PDL is contraindicated infection/inflammation)
Anesthesia diffuse through the medullary bone
Nerves: Terminal nerve endings
Anesthesia : Bone, soft tissues
Intraosseous injection - Inability to perforate the cortical bone drilling——…….change the site
> 2 sec.
Articaine is classified as an amide but contains a —— instead of a benzene ring like other amide local anesthetics.
A second difference is that it contains an —–
thiophene ring
extra ester linkage
Articaine - Maximum Recommended Dose:
7mg/kg
EPT Readings Less Than —-
(Maximum Output) Resulted in Pain During Restorative Procedures.
80
Mepivacaine has a
Higher Concentration and Higher pH than Lidocaine.
Should be Less Painful
Increasing the Volume of 2% Lidocaine with 1:100,000 Epinephrine to 3.6 mL
Does Not Increase the Incidence of Pulpal Anesthesia with the Inferior Alveolar Nerve Block.
If Patient Has Profound Lip Numbness do not repeat
IANB
Key to Success of the Intraosseous Injection
Flow of the Anesthetic Solution Into the Cancellous Space.
INtrapulpual injection used as a
last resort following intraosseous
Needle breakage - Causes:
1- “Hubbing the needle”
2- 30-guage short needles
3- Intentional bending before injection
4- Unexpected movements
5- Forceful bone contact
Do not use —– for IANB
Do not use ——- for IANB
Do not bend the needle when inserting them in the soft tissues
Extra caution when inserting needles in ———
short needles
30-guage needle
children
One of the main causes of dental practice litigations
prolonged anesthesia/parathesia
Causes of prolonged para/anesthesia
1- Needle injury to the ———
2- ——- LA solution (e.g. alcohol)
3- ——-
nerve (e.g. inserting the needle to a foramen, bending the sharp edge of the needle )
Electric shock feeling!
Contaminated
LA solution itself
(e.g. 4% Articaine)
3- Facial nerve paralysis from
injecting LA into parotid gland (IANB, AKINOSI)
IAN: to prevent nerve paralysis
bone contact at the medial side of the ramus before injecting the LA
Trismus causes
Causes:
1- Trauma to the muscles (especially in multiple needle punctures)
2- Contaminated solutions irritates the muscles
3- Hemorrhage
4- Infection
Trismus Prevention:
1- Use sharp needles
2-Proper handling of LA cartilages
3- Adherence to principles to avoid multiple injections
Trismus is not always avoidable
Trismus management
Management:
1- Heat therapy
2- Warm saline rinses
3- Analgesics
4- Muscle relaxants if necessary
5- Physiotherapy
Consider infection as the cause if >48 hrs. (Abx will be needed in that case)
Trismus can last for average of 6 weeks
Burning during injection:
1- PH of the LA
2- Rapid injection on dense tissues
3- Alcohol contamination
4- Anesthetic temperature
Idiosyncrasy:
Abnormal, unexpected response to a drug. Neither overdose or allergic reaction
e.g.: Stimulation that develops after administering a CNS depressant
Hard to predict
Might have genetic predisposition
Treatment : symptomatic ABCs as necessary
—— topical anesthesia increase the risk of adverse reaction due to high rate of mucosal absorption
Amide
Benzocaine
(ester) topical anesthesia is poorly absorbed
Aspirate in 2 planes
rotate and aspirate again
MOderate to High reaction to anesthetic -
Generalized tonic-clonic seizure activity
Epinephrine Overdose
Sharply elevated BP (systolic)
Increased heart rate/palpitations
Cardiac tachyarrhythmia
Management - v/c overdose
Stop dental treatment
Reassure patient, administer O2
Monitor BP and pulse until fully recovered
Get help!!
Delayed skin reaction - use
Benadryl - 50 mg stat & Q6H X 3-4 days
Immediate skin reaction - use
Epinephrine 0.3 mg IM or SC
Benadryl - 50 mg IM
Observation, medical consultation
Benadryl - 50 mg Q6H X 3-4 days
Bronchial constriction - use
O2 - 6 L/min Inhaler or Epinephrine 0.3 mg IM or SC Benadryl - 50 mg IM Observation, medical consultation Benadryl - 50 mg Q6H X 3-4 days