Two cases of paresthesia were reported following treatment of 13,000 patients with articaine. While the Canadian data were for voluntary reporting of paresthesia, recent data reported all occurrences. A number of recent publications suggest that articaine is associated with a higher rate of paresthesia for mandibular block injections than was calculated in this paper. The relationship of chemical structure to the occurence of paresthesia should be investigated. 1 It is also the only local anesthetic having both an ester and amide bond. Although they may not be causative factors, articaine is the only local anesthetic with sulfur or a thiophene ring and an ester bond. The highest concentrations of local anesthetics were associated with endoneurial edema.Īnalysis of the data indicates that articaine has a 4% higher occurrence of paresthesia than prilocaine, though they are both 4% solutions. It has been determined that local anesthetic-induced nerve injury is concentration-dependent, with injuries increasing as concentration increases. The assumption is that half of all injections are for the maxillary arch,6 and the total number of cartridges was divided in half.
Analysis of the data allows the paresthesia rates for each local anesthetic to be calculated (Table 4).īecause all reported paresthesias were of the lingual nerve, inferior alveolar nerve, or both, maxillary injections are not considered in this analysis. However, it is clear from the number of cases listed and the number of cartridges used that articaine and prilocaine have precipitously higher rates of paresthesia. 11 The authors estimated that the incidence of nonsurgical paresthesia was one in 785,000 injections (Table 3). The data from the 1993 study were subsequently confirmed by a study of data collected in 1994 10 and data from 1994 to 1998. The authors were able to quantify local anesthetic usage by surveying Ontario dentists. The information for 1993 alone gives a detailed accounting of the association of anesthetic usage and paresthesia (see Table 3). 1-4,6-8 This article is a review of published data about the incidence of paresthesia induced by the administration of local anesthetic, which is not related to surgical trauma. 4,9 Paresthesia may occur if, during injection, the patient complains of a sensation described as electric shock along the path of the nerve that is contacted by the needle. 4,6-8 The primary factor in neurotoxicity of local anesthetics appears to be the concentration of the solution. 5-7 During the administration of local anesthesia prior to treatment of mandibular teeth or their associated structures, the lingual or inferior alveolar neurovascular bundle can be traumatized by the sharp needle-tip, the movement of the needle, extraneural or intraneural hemorrhage from trauma to the blood vessels, or from neurotoxic effects of the local anesthetic. Symptoms are most commonly associated with mechanical trauma during surgical procedures. Estimates of the use of these local anesthetic agents in the US were 62% lidocaine, 23% mepivacaine, and 13% prilocaine. The total number is above 100% because twelve of the eighty-three patients studied received more than one local anesthetic agent. 5,6 The occurrence of paresthesia in the United States has been studied, and it was found that 51% of paresthesias were related to lidocaine, 51% to prilocaine, and 8% to mepivacaine (these data were obtained prior to the introduction of articaine in the US). 4 Local anesthetic-induced lingual nerve and/or inferior alveolar nerve paresthesia is generally considered a rare occurrence. 2 Paresthesia can also be associated with a burning sensation, and patients can experience drooling, speech impediment, loss of taste, and tongue biting. Dysesthesia is defined as, painful sensation to nonnoxious stimuli and hyperesthesia as, increased sensitivity to noxious stimuli. The definition of paresthesia also includes hyperesthesia and dysesthesia 1-3 in which the patient experiences both pain and numbness. In general, most dentists and patients would define paresthesia as a prolonged numbness.
1-4 Tingling and itching are included as part of the definition as these sensations are considered partial anesthesia to the dentist and patient. Paresthesia can be defined as persistent anesthesia (anesthesia well beyond the expected duration), 1 or altered sensation (tingling or itching) well beyond the expected duration of anesthesia. This article examines the occurrences of paresthesia to the lingual and inferior alveolar nerve resulting from the injection of local anesthetic agents. The occurrence of paresthesia following the use of local anesthesia in dentistry, however, represents an important side effect.
Serious complications associated with the use of these drugs are rare. Local anesthetics allow dentistry to be practiced without patient discomfort.
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