Pharmacology of Local Anaesthesia for Dental Practice

Study Notes

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage
Effective control of orofacial pain facilitates the delivery of care and reduces anxiety about dentistry

Local anaesthetics are drugs that reversibly prevent the transmission of nerve impulses in the region to which they are applied, without affecting consciousness
They prevent or relieve pain and interrupt nerve conduction by inhibiting the influx of sodium (Na+) ions through voltage-gated Na+ channels within nerve membranes
Their effectiveness depends on lipid solubility and local pH

The first local anaesthetic to be used was cocaine, but it was addictive and had psychogenic effects
Procaine (novocaine) is no longer used, as more effective alternatives are available

Local anaesthetics can be classified as amide-linked or ester-linked
Examples of amide-linked local anaesthetics include lidocaine, prilocaine, articaine, and bupivacaine

Local anaesthetics work by preventing the transmission of nerve impulses by inhibiting the influx of sodium (Na+) ions through voltage-gated Na+ channels within nerve membranes
The lipid-soluble base form of the anaesthetic penetrates the nerve membrane, where it is converted to the ionized form, which binds to the inactivation site of the Na+ channel, keeping the channel closed
The pKa value of the anaesthetic determines the proportion of the ionized and non-ionized forms, which affects its potency and duration of action

Nociceptors are sensory receptors responsible for the detection of noxious stimuli, transforming them into electrical signals that are conducted to the CNS
They are distributed throughout the body, including the skin, muscles, and joints, and can be stimulated by mechanical, thermal, or chemical stimuli