Occlusal fissures in equine cheek teeth: µCT and histological findings

This study suggests that fissures can provide a pathway for microorganisms to enter the dentinal tubules, potentially resulting in local pulpal inflammation. It appears that in healthy teeth, vital odontoblasts react by producing reactionary (tertiary) dentin, which lacks patent tubules and thus provides a proper seal.
Source: The Veterinary Journal - Category: Veterinary Research Source Type: research