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What is an unpleasant sensory and emotional experience and can be thought of as one of the oldest of all dental problems?
What creates a numbing feeling that eliminates the feeling of sensation in a specific area without loss of consciousness?
What is achieved via the vasoconstrictor in the anesthetic?
The points at which sensation starts to be painful and discomfort results.
Neurologic experience of pain
The personal interpretation and response to the pain message and is hihgly variable among individuals
Local anesthetic provides a chemical roadblock between the source of the impulse and the brain. The impulse therefore is unable to reach the brain.
All incoming information traveling along sensory or afferent pathways
consist of all outgoing information along motor or efferent pathways
Nerve cells (neurons)
The basic functioning units of the nervous system
What are the functional unit for communication between the CNS and all parts of the body?
A nerve contains many cable like bunches of peripheral axons, they are encapsulated together. The nerve provides a pathway for the electrochemical nerve impulses to be transmitted along each of the axons
Fasciculi located in the mantle region are called?
Fasciculi located in the core regions are called?
Mantle bundles are located near
The outside of the nerves
Core bundles are located closer
To the center of the nerves
Local anesthetic diffuse through the nerve to the mantle bundle initially at a higher concentration and then to the core bundles at a more diluted concentration because some anesthetic is absorbed by capillaries and lymphatics.
Because the mantle bundle are affected by the local anesthetic first, these bundles also begin to lose anesthesia before the core bundles.
What is responsible for sharp pain?
A fibers, primarily delta fibers
What is responsible for dull, aching pain?
Both A and C fibers are found in the oral cavity, with __________ in greater distribution.
Larger A fibers require more anesthetic volume than smaller C nerve fibers to provide complete nerve block.
Local anesthesia drugs act mainly by inhibiting Na+ influx through Na+ specific ion channels in the neuronal cell membrane; in particular the so- called _______________
voltage-gated sodium channels
All nerve fibers are sensitive to local anesthetic, generally, those with a _______ diameter tend to be more sensitive.
The ________ the diameter of the nerve fiber, the greater the amount of local anesthetic needed to prevent depolarization IA and PSA block require more anesthetic for successful nerve blockage than supraperiosteal injections
What are agents that block the sensation of pain by reversibly blocking nerve conduction when applied to a circumscribed area of the body?
Local anesthetics bind to specific receptors in the nerve membrane to prevent influx of ______ _____ through the cell membrane
The use of ______ local anesthetic chemical agents is the most common method to secure pain control in dental practice
What are the two major groups of local anesthetics?
The ester and amides
Most significant difference between esters and amides?
Esters have a high probability of producing an allergic reaction compared with amide local anesthetics.
Slower onset of action
Rapid onset of action
There are two major routes of delivery of local anesthetic drugs
Topical and submucosal injection
Which agents are prepared in higher concentration than injectable anestheticsto faciliate diffusion of the drugs through the mucous membranes?
What is the study of the action of drugs within the body?
The PKa is the primary factor determining the onset of action. The PKa of a local anesthetic determines the amount of drug that exists in an ionized (acidic) form at any given pH
Which is described as an increased tolerance to a drug that is administered repeatedly
Vascularity of injection site
vascularity increases absorption of the anesthetic, allowing the drug to leave the injected area faster, decreasing potency as well as duration
presence or absence of a vasoconstrictor drug
added vasoconstrictors to a local anesthetic decrease the vasodilatory properties of local anesthetics by constricting the surrounding blood vessels at the site of administration, increasing the duration of the anesthetic
The importance of the vasodilating properties is the increase in the rate of absorption of local anesthetics and the decrease in the rate of action. Higher blood levels of the drug increase the chance of the patient developing an overdose
period of time it takes for 50% of the drug to be metabolized/ removed.
What is primary metabolized in the liver?
What is primary excretory organ for the metabolites of all local anesthetic agents?
What is the most commonly used vasoconstrictor in dental local anesthetics and is referred to as the benchmark?
How is concentration of vasoconstrictors in local anesthetics referred to?
Ratio rather than a percentage
What is effective in decreasing blood flow during surgical procedures and nonsurgical periodontal therapy?
What is the recommended maximum dose per visit of epinephrine for a healthy patient?
What is the maximum does per visit of epinephrine for a cardiovascularly compromised patient or patient needing treatment modifications?
The time interval between the initial deposition of the anesthetic solution at the nerve site until complete conduction blockade.
Older patients generaly have higher pain reaction thresholds compared with younger patients, as they have accepted pain as part of life.
dissociation constant (pKa)
represents the pH at which 50% of the molecules exist in the lipid-soluble tertiary form and 50% in the quaternary, water soluble form.
3 tasks carried out by neurons
receiving, processing, and sending information.
Properties of ideal local anesthetics
3. no local reactions
4. no systemic reactions
5. no allergic reactions
6. rapid onset
7. satisfactory duration
8. adequate tissue penetration
9. low cost
10. stability in solution
11. ease of metabolism and excretion
What is combined with local anesthetics to counteract the vasodilating properties of local anesthetics?
Why are vasoconstrictors important?
Their ability to constrict blood vessels, providing a decrease in blood flow, an increased duration, slower absorption
· What's the preservative that's used with epi?
Mepivacaine 2% has?
persistent anesthesia beyond the expected duration or altered sensation, such as tingling or itching beyond the usual level with slight trauma
Why is it difficult to numb tissue that is already infected?
The acidic environment associated with an active infection causes a much lower tissue pH in the vicinity of 5 to 6, which favors the quaternary water soluble configuration, and the amount of free base is reduced even further, leaving fewer bas molecules to penetrate the nerve
How do local anesthetics work?
They prevent sodium channels from opening, thus blocking action potentials and blocking the travel of the pain signal to the brain
Contraindications for vasoconstrictors
Recent myocardial infarction, coronary bypass surgery, cerebrovascular accident within the past 6 months and uncontrolled hypertension, agina, arrhythmias, or hyperthyroidism
Adverse effects of vasoconstrictors
Tension, anxiety, apprehension, nervousness, tremors, increased heart rate and blood pressure, throbbing headache, hyperventolation
Concentrations (highest and lowest) for vasocontrictors
Highest- 1:50, 000
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