USAFActs is a private-funded site who collects official information from several gubernamental offices from USA and converts those numbers and data in information that can be visualized. It's an impressive demonstration of the power of data analysis with data visualization. It's worth to see and explore in detail. I searched for some data about oral health, here the results, click on any image if you want:
Fortunately, there is some dental information under "dental"
Here is the expenditure in dental health from 1980 to in USA
The fact that USAFacts don't show to much information about oral health in USA doesn't means that there is no data. Actually the CDC has a rich site full of information, worth to visit in https://www.cdc.gov/oralhealthdata/. Also in https://www.cdc.gov/nchs/fastats/dental.htm are more reports.
The trends are not accesible via the website, but there are some reports, for example here. Would be nice to have the possibility to cross such information vs, the outcome, e.g., caries free children, edentulism in adults, prevalence of periodontal disease. The lack of easily accessible information about trends is an opportunity to fill this gap and to allow to start to cross the information in order to establish the effect of the the funding in oral health and how to improve to oral health of the people more effectively.