Which of the following circumstances would cause a significant decrease in pH and therefore reduce the effectiveness of a local anesthetic?

Infection in an area can prevent effective anesthesia primarily because of which of the following?

Local anesthetics are considered vasodialators, some have weak vasodilation properties and some have strong vasodilation properties. This fact is one reason that vasoconstrictors are added to local anesthetics.

Which anesthetic contains 1:200,000 epinephrine and has these desirable properties: a short elimination half-life, a moderate duration, and rapid biotransformation?

During an aspiration a large amount of blood enters the cartridge, what should you do?

When a stimulus is sufficient enough to create an impulse and the permeability of the cell membrane is altered causing depolarization, which of the following does NOT happen DURING depolarization?

Which of the following refers tot he physioanatomical process that transmits pain from the free nerve endings to the CNS?

Even thought 50-72% of the population may be missing the MSA nerve, we still administer the MSA injection because we have no way of knowing if it is missing or not.

What injection(s) would be necessary to administer in order to totally anesthetize tooth #21 for an extraction?

A dental hygienist administers an inferior alveolar nerve block (IANB) injection on the left side using 1 carpule of lidocaine 2% 1:100,000. All teeth are numb except the left central incisor. What is the most likely explanation for this?