Does Thumb Sucking Shift Your Teeth?


My mother showed me a sonogram of me sucking my thumb! So, before I was born, I had caught the habit of thumb sucking. When I was a child, I always sucked my thumb, even when others told me not to because it was ‘gross.’ Once my baby teeth fell out and my new teeth started to grow in, my thumb sucking habits got worse and my teeth shifted. Is there a correlation between sucking your thumb and shifting teeth?

According to HowStuffWorks, if thumb sucking becomes habitual for a child, the position of the mouth can be heavily affected. This shift of the teeth is labeled as malocclusion, which affects the growth of the top teeth. In addition, thumb sucking can also develop speech impairments in a child. The habit will therefore affect the speech and structure of the teeth. J.H. Sillman conducted a study, involving sixty children ranging from infants to adolescents. In this study, Sillman found that thumb-sucking is a physiological and psychological habit that children has the control to stop. He also found that thumb-sucking impacted children with poor biting.

When I continued to suck my thumb, the top of my teeth were crowded together and my two front teeth were crooked. I also developed an overbite and years after, I had to get braces to improve the placement of my teeth. Based on this anecdote and Stillman’s study, it can be greatly confirmed that thumb-sucking in children is more likely to shift teeth.

Null hypothesis: Thumb-sucking has no effect on the teeth

Alternative hypothesis: Sucking your thumb shifts teeth

x-variable: thumb sucking; y-variable: shifting of teeth

Reverse causation: Ruled out

Third Confounding Variables: Poor teeth care (eating candy, other sweets; hygiene)

Chance? Possibly


My before and after! Credit to me!

So, what’s the deal with thumb-sucking? We can accept the alternative hypothesis because thumb-sucking does indeed shift your teeth. We can rule out reverse causation because thumb-sucking is not the result of teeth impairments, but we can also consider that poor teeth care is another confounding variable correlated with teeth impairments. Children are more likely to eat sweets or use other objects to soothe mouths during teeth growth.

Thumb-sucking was a habit for me, and I can honestly say I’ve learned my lesson!





3 thoughts on “Does Thumb Sucking Shift Your Teeth?

  1. Raegan S Pechar

    Contrary to your situation, I was never really a thumb sucker! I really wasn’t even into using my pacifier honestly, which always seemed weird to me because so many of my friends couldn’t shake their dependence on sucking their thumb until they were drastically older. I like how you broke it down between null hypothesis and confounding variables, etc. – it really demonstrates your knowledge of what we’ve been focused on in class!

  2. Patrick Ryan

    Great post! I can relate to this because when I was little I would do the same thing, but I never knew how bad it could be. I like how you added the different causation for this experiment because you know what the study is trying to say. Its nice to see that you can incorporate things we’ve learned in class to an outside topic. Check out this website about other types of habits kids do that are similar to thumb sucking…

  3. Madelyn Erin Peikin

    This post was extremely relatable for me because I also sucked my thumb at a young age. I had a blanket that I would use and I would constantly be sucking my thumb. I was sucking my thumb for years, until finally I broke the habit. My teeth were also affected my my thumb sucking because I had a HUGE overbite. The orthodontist said it was most likely from sucking my thumb because my overbite was so big and she saw how much my teeth were affected. I also wondered while reading your post how much bacteria and germs there are! As a child, we are definitely not as sanitary and I don’t think sucking my thumb helped! Thanks for sharing.

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