A literature review on various complications associated with administration of local anesthesia in dentistry

Psychogenic reaction

These psychogenic reactions some times happen to the patient, due to the anxiety related to the dental treatment or from the fear of injection. Or might be due to the secretion of the adrenaline from the vasoconstrictor agent. This might result in changes in the heart rate, respiration rate of the patient, changes in the mood, and also the altered blood pressure. Patient might shows symptoms of hyperventilation, nausea, vomiting, erythmatic blush over the skin. In this situation the patient is asked to be relaxed, dental procedure need to be stopped, and to avoid these psychogenic reactions oral administration of drug is an efficacious method to manage the dental fears prior to the administration of the local anesthetic solution, for patient with short clinical oral surgical procedure antihistamines can be used. 13, 14

Systemic toxicity

Systemic toxicity develops in the patient after the administration of sufficient amount of local anesthetic agent reaches the central nervous system as well the cardiovascular system. Symptoms such as hypertension, tachycardia, initially convulsions and latterly loss of consciousness, flicker, tremors in the extremities. To prevent systemic toxicity, patient should be evaluated prior to the administration of the local anesthetic solution, proper history of the patient should be taken, is the patient is allergic to any pharmacological agent or not? should be asked. Proper dosage of drug should be given after calculating the drug dosage with patient age and weight. For the healthy adults accepted maximum safe dose of 2 percent lignocaine is 1:80000 ( 180 to 198 mg ), for 3 percent prilocaine, maximum safe dose is 400 mg. If any symptoms appear of toxicity, initially ongoing dental procedure should be stopped immediately, if convulsion seen, administration of 100 % oxygen should be given, supine position with both the legs bended and elevated should be given if patient becomes unconscious.15

Allergy or allergic reaction or hypersensitivity reaction

These hypersensitivity reactions are initiated by specific allergen to which the patient is allergic. It is stated that ester type local anesthetic solution are found to be more allergenic when compared to the amide type of local anesthetic solution. Symptoms like urticarial, itching, sweating, erythema, respiratory distress are seen. Skin prick test should be done in order to check the allergy from anesthetic agent, if allergic reaction occur in the dental office, the first step is to remove the causative agent, pharmacologically it is treated initially with the administration of antihistamines diphenhydramine 25 mg to 50 mg orally or intramuscularly should be given. Ointment containing hydrocortisone should be applied over the skin to relieve the itching from the skin. If the condition still persists, admistration of epinephrine 0.3 – 0.5 mg intramuscularly or subcutanaeiusly should be given and the patient should be transfer to the hospital immediately. 16, 17

Methemoglobinemia

It is a condition in which the iron which is present in the hemoglobin is totally stabilized in the form of the ferric and is unable to attach oxygen which finally results in hypoxia of the tissue. Methemoglobinemia can be both i.e. it can be inherited or it can be acquired also. When the local anesthetic administration is in excessive doses (most commonly administered local anesthetic solution that leads to methemoglobinemia is prilocaine and benzocaine ) may lead to the condition of methaemoglobinemia. Patient gives symptoms of headache, dyspnea, dizziness, restlessness, and tachycardia. Management started with immediately restricting the procedure and administration of 100 percent oxygen to the patient is the first line treatment. In severe cases methylene blue should be administered in the dosage of 0.1 ml per kg of 1 percent solution from the intra venous route over five to ten minutes every hour up to 7mg / kg to the maximum.17, 18, 19

Pain on injection

Pain during injection is from different causes like the velocity of injecting the solution, the temperature of the solution to be administered, barb of the needle, aggressive insertion of the needle, damaged to the soft tissue. In order to prevent these complications, topical anesthetic solution should be applied over the soft tissue to avoid the pain of pricking, injecting the local anesthetic solution with slow speed, use smaller gauge needle, always use fresh needle for pricking multiple times in the same spot of the lesion. It is stated that injecting the solution at the rate of 30 ml per second is recommended.20, 21

Needle fracture

fracture of the needle is one of the rarest complication that can happen, but it can happen some time. most commonly the fracture of the needle happened with 30 gauge needle and most commonly in the inferior alveolar nerve block due to in accurate positioning of the needle or making a bend in the needle. If the needle is broken and is placed superficially it should be removed immediately with the help of hemostat and if it is placed deeply computed tomography of the needle to be done to ensure the proper site of the needle. A superficial mucosal incision perpendicular to the trajectory of the needle should be made which is followed by supra periosteal dissection.22

Prolonged paresthesia

In case of prolonged paresthesia, that happens due to a nerve injury, in this case if the nerve is damaged the first line of treatment is to treat the pain with the help of pain killers and usage of multivitamin and vitamin B is prescribed to enhance the healing of the nerve as well as the function of the nerve.23

Other complications like trismus, infection, hematoma, soft tissue injury and ompthmalic complications

Trismus is a condition in which patient is unable to open and close the mouth and there is pain while opening and closing the mouth with limited mandibular movement. Trismus might occurs due to breakage of the needle, multiple insertion of needle in the muscle, wrong insertion of the needle, hematoma formation during multiple pricks of the needle. In the management of the trismus, some patient problem resolved easily and some patient problem take time, in the management patient is advised to take soft diet, occlusal hard splint can be given to the patient to be worn at the night time, heat packs should be advised to the patient, ask the patient to open and close beyond the limits of pain to increase the opening of the jaw, and injection of normal saline mixed with local anesthetic solution can be given to the patient.

Local infection due to trauma at the surgical site, trauma due to multiple pricks of the needle, infection, bad oral hygiene, infection due to breakage of the needle, these should be managed by appropriate injecting techniques, avoiding multiple traumas at the single site, removal of needle if it is broken inside the soft tissue, patient is given antibiotics to reduce the infection. Hematomas and soft tissue injuries might occurs due to multiple pricks or breakage of needle, these are managed by giving ice packs in the initial step followed by antibiotics and painkiller. Opthalmic complications include diplopia, ptosis, mydriasis, they are avoided by numerous aspiration before injecting and the clinician has a good knowledge of anatomy of all the vessels.