Q: Why does an oral habit like thumb sucking effect the oral structures in some children but not others? I have seen kids who suck their thumbs who have no dental problems, and I have seen kids who suck their thumbs who have terrible open bites.

As I understand things, any oral habit can affect oral structures depending upon the following three factors––

Frequency –– How often the client engages in the habit.

Once per day? Ten times per day?

Duration –– How long the client engages in the habit each time he does.

5 minutes? 5 hours? All night long?

Pressure –– How much pressure is exerted against the teeth and bones.

Is the object/finger just sitting there, or does the client push it hard, or suck it hard?

These are the reasons an oral habit can have a severe detrimental consequence on oral structures in one child but not another. I learned this from an orofacial myofunctional therapist 20 years ago. I do not know if there is research to support this basic notion.

For more information about oral habits, oral rest posture, swallowing, and speech, please visit the website of the International Association of Orofacial Myology.