Neurosensory Disturbances as a Result Of Chemical Injury to the Inferior Alveolar Nerve

Abstract

Summary This article has suggested a simple classification of chemically induced nerve injury based on the known and accepted subjective terminology of sensory deficits within the distribution of the involved nerve. The basis of this suggestion is that it is difficult to classify nerve injuries based on current schemes unless there is associated mechanical injury or axonal destruction. Table 1 lists chemical medicaments used in dentistry that are known to affect subjective sensory function when placed in contact with intact or injured trigeminal nerves. The more neurotoxic substances such as Carnoy's solution, aldehydes, and phenols are tissue fixatives that cause neural degeneration distal to the site of injury. The severity of sensory impairment and the prognosis for recovery is greatly affected by concomitant epineural injury and time length of chemical exposure. Relatively inert substances also may have long-term effects when extruded into the inferior dental canal. These effects are often mediated by chronic inflammation and disruption of intraneural microcirculation. The prognosis for these types of injuries depends more on the volume of substance in contact with the neurovascular bundle than with the toxicity of the chemical. Avoidance of known neurotoxic substances and attention to procedural detail is of utmost importance in limiting chemical insult to the branches of the trigeminal nerve. The judicious use of steroids to decrease inflammatory responses also may be helpful in limiting sensory disruption from endodontic and oral surgical procedures. Perhaps the most critical element in providing the best chance for sensory recovery is early detection and early decompression of the neurovascular bundle.