Try these techniques for limiting your results:
There are many articles in PubMed that relate to dental statistics. Here are some tips for searching for them:
Congratulations on selecting a research topic! Now it's time to search! There's heaps of information available and using these tips can help you find what you're looking for. Using these three phrases will help you be able widen or narrow your search. Databases are smart- capitalize your searching different terms!
Now that you've done you initial advanced search it's time to get even more serious. Taking your search a step further will allow you to get more extensive results. This can be done by combining Boolean search terms and adding alternatives or synonyms to your keyword terms.
How are terms combined? By using parenthesis! Using parenthesis allows you to take two keyword searches and turn them into one.
Bike AND (Car OR Cars)
(Bus OR Busses) AND Transportation AND (Car OR Cars)
What if your keyword is actually a phrase? Use quotation marks around the phrase to yield the result you want. Not using quotations will bring up both words in the phrase in any part of the result- separate and together. This will lead to many irrelevant results which which is frustrating!
"Motion Sickness"
Sometimes there are cases where multiple words can mean the same thing. It's also important to note that not everyone uses the same phrasing. That's when creating a synonym or descriptors table comes in handy. Using a table makes it easy to see alternatives that can be used to describe your keywords. You can then combine these into your searching to yield more results useful to your topic.
Put it all together: "Motion sickness" AND (Medication OR Medicine) AND Transportation AND (CAR NOT Bus)