Which of the following is often used to protect against substantial losses in medical expenses?

Health insurance is the correct choice because it is specifically designed to cover a significant portion of medical expenses that an individual may incur due to various health-related issues. This type of insurance helps individuals manage costs associated with doctor visits, hospital stays, surgeries, and other medical treatments, thereby protecting them from financial strain caused by substantial medical bills.

Dental insurance primarily focuses on oral health and thus does not provide coverage for other medical expenses outside of dental care. Life insurance offers financial protection to beneficiaries in the event of the policyholder's death, but does not cover medical expenses incurred during the policyholder's life. Accidental insurance typically provides limited coverage for injuries resulting from accidents but does not encompass the broader range of health-related expenses that health insurance addresses. Therefore, while the other options have specific benefits, none extend the comprehensive coverage for medical expenses offered by health insurance.