Local Anesthesia

In relation to the dose
The dose of local anesthesia is often reduced when a patient has any systemic health implications or habits which may cause an interference. From time to time the local anaesthetic itself should be reduced (therefore reducing the maximum dose). This is particularly done when alcoholism, anaemia (if using Prilocaine), anorexia, bradycardia or GORD is concerned. On other occasions the vasoconstrictor used (often adrenaline) must be reduced when an individual suffers from angina, bradycardia, chronic bronchitis, cardia disarrhythmia, COPD or glaucoma. These include drug abuse, calcium channel blocker containing medications, beta blocker medications or liver disease as this impairs the metabolism.
In relation to the technique
The variety of techniques associated when giving a local anaesthetic can affect the success and if done incorrectly lead to a possible fracture of the needle tip. It is extremely rare for the needle to fracture whilst giving an injection intra-orally unless an inadequate technique is adopted. To prevent such an occurrence, especially when performing an inferior alveolar nerve block, it is recommended to not bend the needle, to use the correct needle length and to not insert the needle up to the hub.Most common local anesthetic procedur The Inferior alveolar nerve anaesthesia or block or IANB (sometimes termed "inferior dental block", or wrongly referred to as the "mandibular block") probably is anesthetized more often than any other nerve in the body. An injection blocks sensation in the inferior alveolar nerve, which runs from the angle of the mandible down the medial aspect of the mandible, innervating the mandibular teeth, lower lip, chin, and parts of the tongue, which is effective for dental work in the mandibular arch. To anesthetize this nerve, the needle is inserted somewhat posterior to the most distal mandibular molar on one side of the mouth. The lingual nerve is also anesthetized through diffusion of the agent to produce a numb tongue as well as anesthetizing the floor of the mouth tissue, including that around the tongue side or lingual of the teeth.^[24]
Several nondental nerves are usually anesthetized during an inferior alveolar block. The mental nerve, which supplies cutaneous innervation to the anterior lip and chin, is a distal branch of the inferior alveolar nerve. When the inferior alveolar nerve is blocked, the mental nerve is blocked also, resulting in a numb lip and chin. Nerves lying near the point where the inferior alveolar nerve enters the mandible often are also anesthetized during inferior alveolar anesthesia, such as affecting hearing (auriculotemporal nerve). The facial nerve lies some distance from the inferior alveolar nerve within the parotid salivary gland, but in rare cases anesthetic can be injected far enough posteriorly to anesthetize that nerve. The result is a transient facial paralysis, with the injected side of the face having temporary loss of the use of the muscles of facial expression that include the inability to close the eyelid and the drooping of the labial commissure on the affected side for a few hours, which disappears when the anesthesia wears off. In contrast, the superior alveolar nerves are not usually anesthetized directly because they are difficult to approach with a needle. For this reason, the maxillary arch is usually anesthetized locally for dental work by inserting the needle beneath the oral mucosa surrounding the teeth so as to anesthetize the smaller branches.