Occult fissures are also known as “incomplete fissures” or “microfissures”. It refers to small, non-physiological cracks on the surface of the tooth crown that are often not easily detected. The cracks often penetrate deep into the dentin structure and are a cause of tooth sensitivity and toothache. Etiology of Occult Cracking Although teeth are very hard, the tooth structure also has its weak links, which are not only low in crack strength themselves, but are also the areas where stresses are concentrated when the tooth is subjected to normal forces. When pathological wear is too high, a traumatic force is formed that deepens and widens the enamel plate at the bottom of the sulcus towards the dentin, which is the beginning of the occult crack pattern. Effects of cryptocracks In general, superficial cryptocracks often have no obvious symptoms, while deeper ones have symptoms of irritation and sensitivity when exposed to heat or cold, or bite discomfort. Deeper fissures have chronic pulpitis symptoms because they have reached the dentin layer, and sometimes they can also have acute attacks and severe chewing pain. After a cryptoclastic tooth occurs, the patient is afraid to chew food in a certain part of the tooth, and it is usually painful when it is hot or cold, especially in the morning when brushing teeth with the first mouthful of cold water. Some patients may even experience involvement pain and radiating pain, i.e. half headache. This disease not only affects people’s quality of life, but is also an important cause of tooth loss in young and middle-aged people. Prevention and treatment First of all, do not eat too fine a diet and eat more fibrous food; secondly, chew food carefully and slowly to avoid teeth being choked by foreign objects. Hidden tooth crack should be treated as soon as possible: in the early stage, the doctor will observe and review regularly by sharpening the steep cusps and lowering the bite “dentition”. If the fissure is shallow, the tooth can be repaired by grinding away the fissure and using a filling material. In case of pulpitis, a complete endodontic treatment (i.e. root canal treatment) is required before crown restoration.