Which of the following situations are indications for placement of a dental sealant?

The placement of dental sealants serves as a preventative measure to protect teeth, particularly those prone to caries due to their anatomy. Both a deep occlusal fissure and an incipient Class 1 carious lesion are valid indications for sealant application.

In the case of a deep occlusal fissure, these structures can harbor plaque and bacteria, making them susceptible to caries. Sealants act as a barrier, effectively sealing off the fissures and preventing decay from taking hold, thus decreasing the risk of future cavities.

An incipient Class 1 carious lesion is a very early stage of decay that may not have progressed significantly. Applying a sealant in this scenario can help to re-mineralize the enamel and halt the progression of the carious process while still maintaining tooth structure. The use of sealants in this situation can prevent the lesion from advancing into a more significant cavity.

Therefore, both scenarios—deep occlusal fissures and incipient Class 1 carious lesions—are appropriate for sealant placement, which is why the correct response encompasses both indications. The other options do not adequately support the use of sealants in such a preventative context.