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DA is not a ranking factor but it is a nice metric made by Moz to help us get an idea how we're doing compared to our competitors in terms of quantity and quality of links. So having a higher DA doesn't automatically mean you should rank higher than your competitors. Also, since the EMD (exact match domain) update back in 2012, sites can't rank better just because of the keyword in the domain name if their site authority and optimization isn't great. My main suggestion for you would be to acquire more backlinks with "dental emergency" as the anchor text (making sure they are linking to the correct page on your site, of course). Obviously, don't over do this and build hundreds of links with exact match keywords in the anchor text but don't be shy about it either. As an example, one of the owner's of my company has a personal site and I asked him to change the anchor text of the link in his footer to our company's homepage from "Nozzle" to "Keyword phrase - Nozzle".  After Google recrawled that page, our rankings jumped up 10 spots. To be fair, I'm aware that jumping 10 spots while on page 3 is different than trying to go from #4 to #1 though. My point is to not be afraid to use exact match anchor text sometimes. Also make sure that your page that is ranking #4 also has internal links from other pages of your website pointing to it with the keyword in the anchor text. Test out things like moving that phrase to the front of your title tag and even trying to get it in there twice if at all possible. These will be tests and can be changed back if your rankings drop, so don't be scared to test. Pay attention to your CTR as well inside of Google Search Console to make sure you don't drop in CTR because of the changes too. Also, test out adding that phrase more times in the content of the page. Good luck!