Bad oral habits are abnormal behavioral habits that occur in the oral cavity and are harmful to the child’s dental, jaw, and facial growth and development. They are common in children in their early years, but also occur in a few patients at an older age. Most of them are unconscious behaviors, and only a few are conscious behaviors. Because bad oral habits can disrupt the balance of the oral environment, they can cause dental, jaw and facial deformities. For example, finger-sucking habits can cause partial open dentition, and lower lip biting habits can cause jaw recession, etc. Long-term bad oral habits may not only cause malocclusion but also affect the normal function of the oral system. The following are several common bad oral habits: a mouth breathing habits mouth breathing upper and lower lips open, airflow through the mouth. Long-term abnormal power to form the upper front teeth protrusion, facial narrowing, open lips and teeth, narrowing of the upper dental arch, palatal cover high arch and mandibular recession deformity. The causes are commonly found in nasal airway blockage or partial obstruction caused by nasal tract abnormalities such as nasal tract narrowing, nasal septum deviation, nasal tract polyps, rhinitis, tonsillar enlargement, etc. There are also people with normal nasal tract but habitual mouth breathing. Therefore, for mouth breathing, first of all, we should check whether there is nasal obstruction, if there is rhinitis and other diseases should be actively treated to prevent the occurrence of obstructive mouth breathing. In the absence of nasal obstruction, corrective treatment can be done to correct bad habits. Second, tongue habits Tongue habits include tongue spitting, licking and tongue extension habits. Tongue is placed between the upper and lower front teeth when tongue is exhaled. The pressure of the tongue muscle inhibits the growth of the upper front teeth, resulting in an open dentition with a pike shaped opening in the front teeth. The licking habit is formed because the tongue is often used to lick the gaps, stump crowns, and stump roots in the dental arch. When licking the upper front teeth, it causes the upper front teeth to tilt towards the lip, resulting in deep overlap and overlay of the front teeth; when licking the lower front teeth, it causes the lower front teeth to protrude forward, resulting in anterior anterior teeth; if licking the upper and lower front teeth at the same time, it causes the upper front teeth and lower front teeth to protrude forward, or causes the double arch to protrude forward (commonly known as “whistling teeth”). Tongue extension habit is often due to enlarged tonsils and poor breathing, narrowing of the dental arch and limited lateral movement of the tongue, often resulting in open malocclusion. If the tongue is stretched forward, the lower jaw is also forward, which can cause the lower jaw to protrude forward and the anterior teeth to fit together. If you have the above tongue habit, you should find a specialist orthodontist for consultation and treatment as soon as possible. Finger sucking habit Almost all children have the habit of sucking fingers in infancy (thumb sucking is more common), but it does not last long. As children grow older, they are gradually attracted to other things outside and give up the finger-sucking habit, which will not cause the occurrence of malocclusion. If the finger-sucking habit continues until after the age of 3 and has an adverse effect on the development of the teeth and jaws, leading to the occurrence of malocclusion, it is considered a bad oral habit and needs to be treated. Fourth, lip habits Bad lip habits include biting the lower lip, sucking the lower lip, sucking the upper lip, etc. The more common one is the lower lip sucking habit. Bad lip habits disrupt the balance of the muscles inside and outside the dental arch. The lower lip biting and lower lip sucking habits add to the force outside of the mandibular arch, make the mandible grow forward and increase the force outward of the maxillary arch, and the long-term effect can make the upper jaw protrude forward and the upper front teeth lip tilt, causing abnormal relationship between the upper and lower jaw. At the same time, the occurrence of malocclusion can destroy the normal lip-tooth relationship, causing the upper lip to be too short, open lips and teeth, upper incisors covering the lower lip, etc., which seriously affects the appearance of children, so they should seek medical attention and eliminate the bad habits as soon as possible.