Topical Anesthetics and Vasoconstrictors in Dentistry

Flashcards covering the properties, chemical classifications, specific agents (Benzocaine, Oraqix, EMLA), contraindications, and application techniques of topical anesthetics as well as an introduction to vasoconstrictors.

Topical Anesthetics

Agents that act only on surface tissues ($2\text{--}3\,mm$) by being applied in high concentrations to allow diffusion through mucous membranes.

Amphipathic

The property of local anesthetics having both a lipophilic part to enter nerve membranes and a hydrophilic part to dissolve in body fluids.

Lipophilic part

The fat-loving component of a local anesthetic that helps the drug penetrate the nerve membrane.

Hydrophilic part

The water-loving component of a local anesthetic that helps the drug dissolve in body fluids; agents without this are highly lipid-soluble and suitable for topical but not injectable use.

Benzocaine

An ester topical anesthetic with low systemic uptake and toxicity risk, but it may inhibit the antibacterial action of sulfonamides.

Cetacaine

A proprietary name for a formulation containing benzocaine ($140\,mg/mL$), butamben ($20\,mg/mL$), and tetracaine hydrochloride ($20\,mg/mL$).

Cocaine Hydrochloride

A Schedule II drug that is the only local anesthetic naturally producing vasoconstriction, but is not recommended in dentistry due to high abuse potential.

EMLA (Eutectic Mixture of Local Anesthetics)

A topical cream that provides anesthesia on intact skin, requiring application $1\,\text{hour}$ before a procedure with a peak effect at $2\text{--}3\,\text{hours}$..

Trypanophobia

The clinical term for needle phobia, often managed using topical agents like EMLA.

Oraqix

A topical gel with a rapid onset of $30\,\text{seconds}$ and a duration of approximately $20\,\text{minutes}$, specifically indicated for scaling and root planing (SRP) procedures.

Lidocaine Hydrochloride

A water-soluble form of lidocaine that penetrates tissue more efficiently than the base form but carries a higher risk of systemic toxicity.

Tetracaine Hydrochloride

A potent ester anesthetic five to eight times more powerful than cocaine when applied topically, with a slow onset and high potential for systemic toxicity.

Esters

A chemical group of topical agents (e.g., benzocaine) that are more likely to cause allergic reactions due to the production of the PABA metabolite.

Amides

A chemical group of topical agents (e.g., lidocaine) characterized by an exceptionally low incidence of allergic reactions.

PABA (Para-Aminobenzoic Acid)

A metabolite produced by ester-type anesthetics which is frequently responsible for localized allergic reactions.

Local Anesthetic Systemic Toxicity (LAST)

A systemic complication where high blood levels of anesthetic affect the central nervous system (e.g., seizures) and cardiovascular system.

Methemoglobinemia

A condition associated especially with benzocaine and prilocaine that reduces the oxygen-carrying capacity of blood, resulting in cyanosis.

Tissue Sloughing

A local complication involving the shedding of surface tissue caused by prolonged contact with high concentrations of topical anesthetics.

Cotton Applicator (Q-tip)

The tool used to apply a minimal quantity of topical anesthetic directly to the intended site of needle penetration.

Adrenergic agents (catecholamines)

Sympathomimetic drugs used as vasoconstrictors in dentistry, including Epinephrine, Norepinephrine, Levonordefrine, Isoproterenol, and Dopamine.