Why children can't use electric tooth brush for adults?what will happen if they use adult machine with small head. does it irritate developing follicle

Why not?? : Depends upon the age of the child. Until age 8 or 9, they lack the dexterity to safely and effectively clean their own teeth--so we must rely on the parents. Unfortunately, oftentimes, they aren't all that helpful either! I have used floss followed by a sonicare to clean my son's teeth every night since he was 3 years old--before that we did it manually. He has no dental issues related to disease.

Not sure: If your child has the appropriate manual dexterity he/she should be able to use an electric toothbrush. Before about 8-9 dexterity is a problem, and parents should be brushing their children's teeth. Remember that brushing only removes about 65% of bacteria, and therefore daily flossing is required. Best to review your child's oral hygiene program with his/her dentist.