Oral Galvanic Effect Ever heard of the galvanic effect ? It’s an electrochemical process where one metal reacts preferentially when in contact with another — especially in the presence of an electrolyte. When this happens in your mouth, it’s called the oral galvanic effect  (or the battery effect). This occurs when different metals from fillings, crowns, or bridges interact with saliva , which often has a slightly acidic pH. This interaction isn’t just a simple chemical react