The summer heat is unbearable. Perhaps eating a piece of chilled watermelon is a good choice to beat the heat. However, recently Mr. Zhang was quite troubled, because he always felt that his teeth will be vaguely painful when he touches colder things, not to mention the cold food, even the cold water stimulation in the morning when brushing teeth is very obvious. So Mr. Zhang came to a professional dental hospital for consultation. After examination, the doctor found that Mr. Zhang had a deep groove at the junction of the root of several teeth and gums. The doctor introduced: this belongs to the common “cervical wedge defect”, mainly due to incorrect brushing method. It turns out that some people use too hard toothbrushes for a long time, coupled with the force of lateral sawing brushing method, so that the cervical tissue on the lip and buccal side of the teeth is worn, thus forming a deep groove, because the defect is often wedge-shaped, so the medical term “wedge-shaped defect”. There are many causes of wedge-shaped defects, and incorrect brushing is the main cause, so some people also call wedge-shaped defects brushing wear. In addition, the structure at the cervical enamel-bone boundary is weak and easily worn away, which facilitates the occurrence of defects. Secondly, acidic exudate in the gingival sulcus is associated with defects. The defect of hard tissue below the gingival margin sometimes seen clinically is a hint of this relationship. In addition, the cervical part of the buccal side of the tooth is the area of concentration of the dental force stress. Long-term masticatory dental forces fatigue the dental tissues and damage occurs in the stress concentration zone. Physician introduction, with the growth of age, the oral cavity in terms of physiological function and anatomical morphology will undergo degenerative changes, gingival recession leads to the exposure of the cervical part of the tooth, when the horizontal brushing is more likely to rub the cervical part of the tooth, so the middle-aged and elderly people have more opportunities to form wedge-shaped defects. In the early stage of wedge-shaped defect, most of the patients have no discomfort, so it is often not easy to be noticed. However, when the tooth defect reaches a certain level and the root (dentin) is exposed, the patient will experience pain when stimulated by cold, hot, sweet and sour food, and even dare not breathe in, which can cause nerve pain and periodontal disease in serious cases. What’s more, wedge-shaped defect can also cause the tooth to break laterally from the cervical part of the tooth. Wedge defect occurs in the premolar teeth, especially the first premolar teeth, which are located at the most protruding part of the arc of the dental arch and are subjected to more force and more times when brushing. In order to prevent the occurrence of wedge-shaped defect, first of all, we should correct the brushing method, avoid the lateral sawing brushing method, and use softer toothbrushes and toothpaste with finer abrasives. For those with wedge-shaped defects, if the defect is small and asymptomatic, no special treatment is needed; if the defect is large, filling treatment should be done at the hospital as soon as possible. This can not only relieve the discomfort caused by acid and cold stimulation, but also stop the further development of the defect. If not treated in time, when the defect invades the pulp, it can cause pulp infection or periapical disease, and may even cause lateral fracture of the tooth, at which time, not only the treatment cost is greatly increased, but also the treatment effect is greatly reduced. In some cases, the tooth may need to be extracted because of its low retention value. This shows that it is very important to prevent the problem.