Many kinds of bad oral habits can cause malocclusion, the common ones are: 1, finger sucking habit Finger sucking habit in infancy is not a bad habit, generally after 2 years old gradually reduce and disappear on their own, if this habit continues until after 3 years old, can cause obvious malocclusion. 2.Tongue licking habit Children during the teething period often lick the tip of the tongue to lick the loose milk teeth and permanent teeth that have just erupted, some will form the tongue habit. 3, lip biting habit biting upper and lower lips, forming a habit over time, resulting in malocclusion. 4, the habit of biting objects to bite a pencil is most common. 5, jaw forward habit This habit can lead to anterior teeth. 6, side-chewing habits often chew food with one side, can cause misalignment and facial asymmetry deformity. There are many bad habits often not easy to be discovered by parents, until the performance of the misshapen jaw to attract attention, when the best period of orthodontic treatment may have been missed. Therefore, parents are reminded to observe whether their children have bad habits so that early prevention can be achieved.