Mouth breathing  

In Japan, a survey of 3,534 children aged 3 to 12 across the country found that 31% showed symptoms of oral incompetence. Possible causes of mouth breathing (oral incompetence syndrome) include the following: 

1.Weakness of the muscles around the mouth

 2.Crooked teeth (malocclusion) 

3.Incorrect tongue position or posture 

4.Nasal conditions such as rhinitis 

5.Obesity 

The habit of mouth breathing can cause dryness in the mouth and throat, making the tonsils more likely to become enlarged. This may have the following negative effects on children: