Sealants are not inherently bad for teeth; they are often beneficial in preventing tooth decay, especially in children and adolescents. Sealants create a protective barrier on the chewing surfaces of teeth, shielding them from bacteria and food particles that can lead to cavities. However, improper placement or maintenance of sealants can potentially trap bacteria and cause decay if not monitored carefully. Additionally, sealants may need to be replaced periodically to maintain their effectiveness. When applied correctly and maintained properly, sealants can be a valuable tool in maintaining good dental health.