In the early stage, cryptocracks are mainly found in the enamel and are not easily detected by patients without subjective symptoms. Only when the cryptocracks get worse and enter the superficial or middle layer of the dentin, patients will have symptoms such as hot and cold discomfort or biting discomfort. Therefore, it is very difficult to detect the presence of cryptocracks by patients themselves, and clinical examination is the main way to detect cryptocracks. Cryptocracies are often found in the first molars, which are called sixth-aged teeth, followed by the second molars and premolars. The presence of cryptocracks can be detected during the clinical oral examination by visual inspection, by crossing the marginal ridge on the jaw surface to the adjacent surface or by reaching the buccolingual sulcus and overlapping with the buccolingual sulcus, or by multi-angle exposure to light or multi-angle reflection of the mouth mirror. It can also be detected by dipping in a dark colored liquid and then rinsing out the liquid to find a darker stain in the area where the fissure is located. You can also determine the presence of a fissure by asking the patient to bite on a cotton roll and the affected tooth will feel a little more painful than a normal tooth, or you can determine the presence of a fissure by the patient percussing, biting on a cotton swab, and using a probe to forcefully probe the fissure to cause pain.