What does tooth eruption and replacement look like?

Human teeth are composed of two sets of dentition, the primary dentition and the permanent dentition, the primary dentition develops in the embryonic stage, and the first baby teeth of a child erupt about 6 months after birth, and all the baby teeth erupt about 20 months after birth. The permanent dentition begins to develop at the age of 3 to 4 months, and the first permanent tooth erupts at the age of about 6 years old, and the permanent tooth is commonly known as the "sixth instar tooth", and the replacement of the permanent dentition and the deciduous dentition is completed at about the age of 12. The rules of tooth replacement are:

first the lower jaw and then the upper jaw, first the middle and then the side; There are only 3 exceptions, i.e., the first molars erupt first, the canines and the first pair of canines that follow them are reversed, and the maxillary lateral incisors may emerge first than the mandibular lateral incisors. In addition, the left and right teeth of the same name erupt at the same time, and girls change their teeth half a year earlier than boys, and this permanent teeth and baby teeth are the same, whether it is a long baby tooth or a permanent tooth replacement, it is collectively referred to as tooth eruption in medicine. Teeth erupt over a certain period of time and in a certain order.

The left and right eponymous teeth are grown in pairs. People often think of the time when a tooth erupts as a sign of a child's development and growth. If the teeth are not aligned in a certain order.

Generally, teething begins at about 6 months old, and all the baby teeth come out around 2 and a half years old, with a total of 20 baby teeth. The lower teeth generally erupt earlier than the upper teeth of the same name, and the first deciduous molars erupt earlier than the deciduous canines in front of it. In this regard, parents should not mistake it for abnormality.

Some babies teething a little later, which can be three or four months apart, and if they are more than 1 year old and have not teethed, they should be checked by a doctor. There are also babies who teething prematurely, and baby teeth erupt soon after birth, because the baby tooth germ is closer to the oral mucosa. As long as the tooth that erupts too early does not cause difficulty in breastfeeding, does not damage the jaw teeth, does not loosen, and does not pose a danger of inhalation into the trachea, it can be left alone.

Otherwise, it should be removed as soon as possible. When a child reaches the age of 6, the baby teeth are about to fall out and their mission will be fulfilled by the permanent teeth. The time for permanent teeth to replace baby teeth is 6 to 12 years old, this period is called the children's tooth replacement period, this period is also called the mixed dentition period because the child has both baby teeth and permanent teeth in the mouth.

Babies generally start teething at 6 months after birth. The lower front teeth usually grow first, then the upper front teeth, followed by the back teeth. All 20 teeth grow around 2 years old.

These first erupted teeth are baby teeth. Later, around the age of 6, the baby teeth begin to fall out, and new larger teeth erupt below, and then other baby teeth will also fall out. By the age of 12, all the baby teeth are lost and 28 new teeth erupt.

These second erupted teeth are permanent teeth. Permanent teeth are generally similar in shape to the original baby teeth, but they are larger than the baby teeth. By the age of 28, some people may still have a tooth erupting at the back of their mouth.

These teeth are also permanent teeth. The period of eruption and replacement of each tooth is different, but it is basically symmetrical, you can refer to the table below to understand the normal eruption time of each tooth. If baby teeth are not replaced by permanent teeth at the normal time, there is a chance that the teeth of the permanent teeth will not align in the future.

Refers to the phenomenon of the tooth breaking through the oral mucosa, which begins when the root of the tooth develops. It is divided into pre-germination, germination and post-germination. Pre-eruption Prophase refers to the movement of the tooth germ in the bony crypt during the development of the tooth germ, and its movement is threefold

1.During root formation, the tooth germ moves towards the occlusal surface. 2.

As the jaw develops, the tooth germ moves in the direction of the vestibule. 3.The anterior teeth move to the mesial media, and the hind teeth move distal to the media.

Eruption Period: The eruption phase begins with root formation and lasts until the tooth enters the oral cavity and reaches its functional position. When the tooth is fully erupted, the retracted glazed epithelium forms a combined epithelium at the neck of the tooth. In the late stage of eruption, when the tooth erupts to the occlusion is established, the alveolar bone density increasesThe main fibers of the periodontal ligament are arranged in a certain direction and form various groups of fiber bundles.

When the tooth first erupts, the root is not yet fully formed, and after eruption, the root continues to develop. The loss of alternating primary teeth is the result of resorption of the root of the tooth and the loss of contact with the periodontal tissue. The order and time of tooth eruption There is a certain time and sequence of tooth eruption, which is basically consistent with the sequence of tooth germ development; However, the maxillary canines erupt later and develop earlier.

Tooth eruption has a constant temporality, but the physiological range is wider. The left and right eponymous teeth erupted at about the same time. The mandibular teeth are slightly earlier than the maxillary teeth of the same name.