Properly placed dental sealants are _________% effective in protecting against the development of caries in sealed surfaces.

Properly placed dental sealants are considered to offer a high level of protection against caries, with studies indicating that they can be nearly 100% effective in preventing cavities on sealed surfaces. When sealants are correctly applied to the occlusal surfaces of molars, they create a smooth, protected layer that prevents food particles and bacteria from accumulating in pits and fissures, which are common sites for decay.

The effectiveness of sealants significantly reduces the incidence of caries in those areas, making them a valuable preventive measure, particularly in children and adolescents who are at higher risk for dental caries. It's important to note that while sealants can provide substantial protection, they are not infallible and must be monitored and maintained adequately through regular dental check-ups to ensure their continued effectiveness. Thus, the accuracy of stating that properly placed sealants are 100% effective aligns with the ideal scenario of their usage and effectiveness in dental health practices.