The results of a recent national oral health epidemiological sample survey show that the oral condition of Chinese residents has improved significantly in the past 10 years, but the task of oral health care is still difficult. The most common oral diseases among adults are periodontal disease and caries, of which periodontal disease is the most common, with a prevalence rate of up to 80%, and periodontal disease is the primary cause of tooth loss. Survey results show that 59% of children, 97.3% of middle-aged people and 88.7% of the elderly have dental calculus. More than half of our 12-year-old children have bleeding gums, and nearly 80% of middle-aged people have bleeding gums. Repeated swelling and bleeding of the gums with tooth loosening is the main symptom of severe periodontal disease, 10% of the elderly have severe periodontal disease, only 14% of middle-aged people periodontal tissue is basically healthy. The prevalence of caries in adults can reach 50%. The results of this survey show a significant decrease in the prevalence of caries in children, with the prevalence in the 5 year old group decreasing from 77% to 66%, a reduction of one carious tooth per child on average. In contrast, the prevalence of caries in the elderly was as high as 98.4%. For the first time, the survey also obtained nationwide information on the prevalence of oral mucosa, with 5% of middle-aged people having abnormal changes in the oral mucosa and 8% of elderly people having abnormal changes in the oral mucosa. Such a state of oral health is quite related to the lack of knowledge and awareness of oral health care among the population. We hope that the oral knowledge introduced here will be helpful to you. The oral cavity in medicine refers to the teeth, tongue, mouth, lips, face, temporomandibular joints and neck. Upper and lower lip, jaw is the external form of the oral cavity, teeth, tongue is the internal features of the oral cavity. There are two sets of teeth in a person’s life, the first set is milk teeth and the second set is permanent teeth. There are a total of 20 milk teeth, 10 in the upper and 10 in the lower jaw, which are called milk incisors, milk lateral incisors (anterior teeth), milk cuspids (canines), first molar and second molar (posterior teeth). There are 28-32 permanent teeth, 14-16 in each of the upper and lower jaws, called mesial incisors, lateral incisors (anterior), cuspids (canines), first premolar, second premolar, first molar, second molar, and third molar (posterior), with some people erupting one or two third molars, and some people erupting three or four. Since the third molar usually does not begin to erupt until about 18 years of age, when the body and intellect have reached a more mature stage of development, the third molar is also called the wisdom tooth. Human milk teeth begin to occur in the second month of the embryo, initially with only two layers of cells, which then rapidly proliferate to form a plate, which then divides into individual tooth buds, develops into a tooth germ, forms the outline of a milk tooth, and mineralizes into a tooth. The lower front teeth begin to erupt around 8 months after the baby is born. The upper front teeth, molar teeth, and cuspids erupt in that order. It takes until about 2 1/2 years of age for all 20 baby teeth to emerge. At around 6 years of age, the milk teeth begin to loosen and fall out, to be replaced by their corresponding permanent teeth, and by around 12 years of age, all milk teeth will have been replaced by permanent teeth. Human permanent teeth begin to occur in the fourth month of the embryo, around the age of 6 years began to erupt the first molar, which is commonly known as the “six-year-old teeth”, around the age of 12 years 28 teeth come out, around the age of 18 years began to erupt the third molar, that is to say, at the peak of our intellectual development, began to grow “wisdom teeth! “. The teeth that grow after the age of six are permanent teeth, and permanent teeth are the chewing organs that we enjoy for life, so they will not be replaced. “Food for the people, food for the teeth first”, three meals a day, we can not leave the teeth, talking and communication, but also can not leave the teeth, in the long journey of life, we should take good care of our teeth, so that the teeth for us to serve a lifetime, so, and do not treat their own teeth yo!