Why are sealants contraindicated with proximal caries?

Sealants are designed primarily to prevent decay in healthy pits and fissures of teeth, where they serve as a barrier against plaque and bacteria. When proximal caries are present, it indicates that there is already decay in the tooth structure. The key consideration is that treating a tooth with sealants in the presence of proximal caries not only fails to address the existing decay but can also lead to further complications.

The choice highlighting that posterior proximal tooth preparations typically involve the occlusal pits and fissures is significant. When proximal caries are present, dental professionals usually need to prepare the affected tooth to remove the decay, which often includes accessing both the occlusal and proximal surfaces. Therefore, placing a sealant would be inappropriate as it would not effectively protect the tooth and could inadvertently cover an area needing treatment, allowing the decay to advance unnoticed.

This understanding directly addresses the risk associated with sealing over decayed surfaces. Other options may point to related concerns about sealant efficacy or adhesion but do not encapsulate the necessity to actively treat decay before preventive measures like sealants can be appropriately applied.