Delayed-type hypersensitivity (type IV) reactions in dental anesthesia.

Area of Science:

• Allergy and Immunology
• Dermatology
• Anesthesiology

Background:

• Standard evaluation for local anesthetic reactions includes skin testing and challenge.
• The role of delayed hypersensitivity (Type IV) reactions is not well-documented.
• Investigating Type IV reactions is crucial for accurate diagnosis.

Observation:

• Three patients with localized edema after dental anesthesia were evaluated.
• Initial testing with lidocaine and mepivacaine was negative in all patients.
• One patient reacted to lidocaine and mepivacaine patch testing and challenge with delayed swelling.

Findings:

• Delayed swelling indicated a Type IV reaction in one patient previously exposed to EMLA.
• Two patients with contact dermatitis history showed strong reactions to benzocaine.
• Patients reacting to benzocaine tolerated lidocaine, and vice versa.

Implications:

• Screening for Type IV reaction risk factors is recommended for local anesthetic testing.
• Consider delayed swelling and contact dermatitis history in patient evaluation.
• Accurate diagnosis impacts anesthetic choice and patient safety.