Tooth decay
Chapped lips and cracking of tooth enamel, most of the time, this happens due to biting on a hard object, which can cause the tooth to crack. In most cases, the crack is so small that it cannot be seen with the naked eye.

In such a situation, the tooth becomes sensitive to cold and hot liquids, but the appearance of the tooth is normal. In addition, the fracture line may be subgingival or difficult to see due to its small size.