As a general dentist, I would unequivocally recommend dental sealants to be placed on permanent teeth for children and sometimes adults. They are effective, especially, on the posterior molars. Please see the picture above for a clearer visualization.
A sealant is simply a protective covering that is bonded onto the deep grooves of the teeth to help prevent the development of cavities. Long-term studies have shown that pit and fissure caries account for approximately 80% of all cavities on posterior permanent teeth. They also show that placement of sealants has consistently been shown to reduce caries incidence by as much as 86%.
As a result, I would highly encourage you to say yes to sealants! They are a sure way to help you and your child stay cavity-free.