Dental health is often hard to maintain, and in some places, this difficulty starts at a young age.

Here are the percentage of third graders who have suffered at some point from tooth decay, based on state-level oral health survey data from the CDC’s website:

state child cavity map

Business Insider/Andy Kiersz, data from CDC

The southwest has the highest proportion of third graders who have had some form of tooth decay, with 75% of Arizona third graders, 73% of Texas third graders, and 71% of California third graders having tooth decay experience.

Meanwhile, both Connecticut and Massachusetts just had around 41% of their third graders suffering from cavities and tooth decay.

One possible factor in the variation in cavity and tooth decay rates between states is fluoridation of water. Here’s a scatterplot connecting the percentage of the population whose water supply is fluoridated (based on data from the CDC’s Water Fluoridation Reporting System) with the rate of third graders with tooth decay experience:

fluoridation vs cavities scatter plot

Business Insider/Andy Kiersz, data from CDC

There is a weak (r2 = 0.23), but statistically significant (p < 0.01), relationship between fluoride and cavity rates.