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            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
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                    "question": "WRITE THE QUESTION HERE",
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            Text:
            rve; however, the concentration of local anesthetic within the nerve continues 
to rise as diffusion progresses. 
• These processes continue until an equilibrium results between intraneural and extraneural 
concentrations of anesthetic solution. 
 
• Therefore, core fibers are exposed to a decreased concentration of local anesthetic, which 
explain the clinical situation of inadequate pulpal anesthesia in the presence of subjective 
symptoms of adequate soft tissue anesthesia. 
Complete conduction blockade of all nerve fibers in a peripheral nerve requires: 
1. Adequate volume of LA.  
2. Adequate concentration LA.  
● No clinical situation is 100% of the fibers within a peripheral nerve blocked, even in cases 
of clinically excellent pain control. 
Induction Time: 
● Defined as the period from deposition of the anesthetic solution to complete conduction 
blockade.  
factors controlling the induction time of LA: 
1) Those under the operator’s control:  
a) Concentration of the drug. 
b) pH of LA.  
 
2) Those not under the clinician’s control:  
a) Diffusion constant of the drug. 
b) Anatomic barriers to diffusion. 
Physical Properties and Clinical Action: 
1. Effect of the dissociation constant (pKa) on the rate of onset of anesthesia:  
Drugs with a lower pKa possess a more rapid onset of action than those with a higher pKa. 
2. Lipid solubility of a local anesthetic is related to its intrinsic potency:  
Greater lipid solubility permits the anesthetic to penetrate the nerve membrane (which itself 
is 90% lipid) more easily, therefore increased potency of the anesthetics.  
LA with greater lipid solubility produce more effective conduction blockade at lower 
concentrations (lower-percentage solutions or smaller volumes deposited) than is produced 
by less lipid-soluble LA.  
3. The degree of protein binding of the local anesthetic molecule is responsible for the 
duration of anesthetic activity:  
After penetration of the nerve sheath:  
● A re-equilibrium occurs between the base and cationic forms of the local anesthetics. 
● RNH+ ions bind at the receptor site at the sodium ion channel.    
● LA (e.g., etidocaine, ropivacaine, bupivacaine) possessing a greater degree of protein 
binding than others (e.g., procaine):  
1. Attach more to the protein receptor sites.  
2. Possess a longer duration of clinical activity. 
      4. Vasoactivity affects both the anesthetic potency and the duration of anesthesia provided 
by a drug:  
● Injection of local anesthetics, such as procaine, with greater vasodilating properties 
increases vascular perfusion at the injection site. 
● The injected LA is absorbed into the cardiovascular system more rapidly and taken away 
from the injection site and from the nerve, thus providing a shortened duration of anesthesia 
+ decreased potency of the drug. 
Table 1.8 summarizes the influence of various factors on local anesthetic action 
 
 
 
 
Recovery From Local Anesthetic Block  
● Recovery pattern of LA is the rev

            Quiz: