Module 6: Pharmacology of Local Anesthetic
profound anesthesia
onset and duration
agent
technique
general factors
concentration
diffusion to site
lipid solubility
protein binding
block: longer duration
infiltration: faster onset
PROS: faster onset, simple, safe, good hemostasis w vasoconstrictor
CONS: multiple injections for multiple teeth, shorter duration of anesthesia
anesthetics
general characteristics
types
lidocaine
mepivacaine
prilocaine
articaine
bupivacaine
vasoconstrictor presence
physiology of anesthetics
size :overall diameter of the nerve bundle
lipid : amount of myelin sheath
Central Core Theory : peripheral fibers anesthetized first; proximal first = molars; central fibers to most distal = incisors
anesthetic volume, tissue space and density critical length = 3 nodes minimum/ 5 mm
infiltrations : 1/2 to 3/4 cartridge
IA nerve block: 3/4-1 is ideal
delayed or failed onset
disassociation rate: BH+ must disasociate to unionized base form to pass through nerve membrane
transport/perfusion rate : rate of passage through membrane
reassociation rate : needs to reassociate to bind
binding rate: rate of actual binding to membrane/sodium gated ion channels
reasons for anesthetic failures
anatomical/physiological variations
technical errors of administration
patient anxiety
inflammation and infection
defective/expired solutions
decreased tissue pH --> decreased disassociation of BH+ to B
hybrid anesthetic; good for pt with liver problems
troubleshooting
- block injection
- PDL/intraosseous injection OR Buccal/Lingual infiltration w articaine/prilocaine
amides
2% plain : plural anesthesia 5-10min; soft tissue 1-2 hours
2% w/ 1:100k or 1:50k : pupal anesthesia 1-2 hours, soft tissue 3-5 hours
xylocaine, octocaine, lignospan
3% plain : plural anesthesia 20-40 min, soft tissue 2-3 hours
2% w/ 20k levonordefrin : plural 1-1.5 hours, soft tissue 3-5 hours
4% plain = citanest; plural 40-60 min, soft tissue 2-3
4% 1:200k epi = citanest forte: pulpal 1-1.5 hours; soft tissue anesthesia 3-8 hours
4% 1:100k -1:200k epi: pulpal anesthesia 1-1.5 hours, soft tissue 2-4 hours
0.5% with 1:200k long-acting by block injection, plural anesthesia 1.5-4 hours, up to 7 hours; soft tissue anesthesia 5-12 hours
good for short procedures <1 hour as infiltrate or block
short procedures <1 hour as a block
as a block, > 2 hour or post-op analgesia
for difficult patients (w/ vasoconstrictor)
contraindications
relative
absolute
patients on tricyclic antidepressants
unstable angina
myocardial infarction < 6 mo
coronary artery bypass surgery <3 mo
refractory arrhythmia
untreated/uncontrolled HTN
untreated or uncontrolled congestive heart disease
uncontrolled diabetes or other endocrine diseases
phenothiazine antipsychotics
nonselective beta blockers
recreational drugs or ADD/ADHD meds