Local anesthetic agents can be grouped based on their chemical structure. Following are the chemical groups of local anesthetics commonly used in dentistry which are classified accordingly based on their chemical structure. Local Anesthesia is used to attain local analgesia in a certain part of the body using chemical agents. Attaining local anesthesia helps in performing minor surgical procedures without leading to any discomfort to the patient. To attain perfect local anesthesia various factors need to be addressed such as, mode of delivery, spread of the solution into the tissue, maintaining the anesthetic effect for a certain period of time etc.
There are many local anesthetic agents based on the duration of anesthesia required for the surgical procedure and the various type of Nerve Blocks which are required to attain Local Anesthesia to certain regions of the Oral cavity. Inferior Alveolar nerve block helps in anesthetizing one side of the mandible (Teeth and soft Tissue) while local infiltration can be used for minor single tooth procedures which are not surgical.
Classification Of Local Anesthetic Agents
a) Esters of benzoic acid
- Cocaine (topical only)
- Ethyl aminobenzoate
- Benzocaine (topical only)
b) Esters of paba
- 2-Chloroprocaine (Nesacaine)
- Procaine (Novocain)
- Propoxycaine (Ravocaine)
- Tetracaine (Pontocaine)
c) Esters Of Meta Amino Benzoic Acid
- Lidocaine (Xylocaine)
a) Low potency, short duration
b) Intermediate potency & duration
c) High potency, long duration
4) Surface anesthetic
- Butyl amino benzoate(butamben)
Common Properties of Various Local Anesthetic Agents:
- They are all synthetic.
- they all contain amino groups.
- They all form salts with strong acids.
- The salts are water soluble.
- Alkali increases the concentration of the unionized free base.
- The unionized free base is soluble in lipids.
- They are all either hydrolyzed by plasma cholinesterase or undergo biotransformation in the liver.
- The actions of all drugs are reversible.
- They are all compatible with metal salts of mercury, silver etc.
- They all affect nerve conduction in a similar manner.
- They are all capable of producing toxic systemic effects when a sufficiently high plasma concentration is reached.
- They all have little or no irritating effect on tissues in anesthetic concentrations.