What causes galvanic shock in dental procedures?

Galvanic shock occurs when two different metals are placed in direct contact within the oral environment, with saliva serving as a conductive medium. This interaction generates a small electric current, which can lead to a sensation of shock or discomfort for the patient. In a dental setting, this commonly occurs when different types of metallic restorations are used, such as amalgam and gold or any mixture of metals. The presence of saliva enhances this effect by allowing ionic movement, which intensifies the galvanic response. Understanding this phenomenon is essential for dental practitioners, as they must be aware of material compatibility to minimize patient discomfort and potential complications during treatment.

The other choices, while related to dental procedures, do not accurately describe the cause of galvanic shock. Overlapping sutures and thermal expansion deal with different aspects of dental material behavior and patient management, while mechanical forces pertain to how instruments and procedures are applied in dentistry, not to the electrical phenomena that produce galvanic effects.