Final answer:
Dental sealants are used to cover and protect the grooves and depressions on the occlusal (biting) surfaces of teeth, preventing decay and cavity formation in those hard-to-clean areas.
Step-by-step explanation:
The protective measure used to shield difficult-to-clean occlusal surfaces of teeth from carries is dental sealants.
Dental sealants are a prophylactic treatment that provides a barrier against cavities by covering the hard-to-reach grooves and depressions in the occlusal surfaces of teeth. Toothpaste and mouthwash contribute to overall oral hygiene and the prevention of dental carries by delivering fluoride, which strengthens the enamel and has antimicrobial properties.
In contrast, floss is important for removing food particles and plaque from between the teeth, which are areas that toothbrushes may not reach effectively. However, among the listed options, dental sealants are specifically designed to adhere to the occlusal surfaces, thereby providing a protective layer against decay-causing bacteria and food particles.