National Dental Assisting Examining Board (NDAEB) Practice Exam

What phenomenon occurs when two metals touch in the mouth creating a small shock?

1. Electrolysis

2. Galvanic action

3. Conductive response

4. Metallic resonance

The correct answer is: Galvanic action

The phenomenon that occurs when two different metals come into contact in the mouth and generate a small electrical shock is known as galvanic action. This happens due to the electrochemical reactions between dissimilar metals, which can create a flow of electric current. In a dental context, dental materials such as amalgams, gold, or other metal restorations may inadvertently form a galvanic cell when they touch. The moisture in the mouth acts as an electrolyte, facilitating the transfer of ions and leading to the sensation of an electrical shock. This phenomenon can be uncomfortable for patients and is often referred to as "galvanic sensitivity." The other options pertain to different concepts that do not accurately describe this specific interaction. For example, electrolysis involves the chemical decomposition of a substance due to an electric current, which isn't directly applicable to the scenario of metal contact in the mouth. Conductive response and metallic resonance do not accurately capture the electrochemical interactions resulting from contacts between different metals. Therefore, galvanic action is the most appropriate term for the phenomenon described in the question.