In 2012, I noticed increased sensitivity on one side of my mouth. I went to my "dentist" (I use that phrase very loosely. She didn't take insurance, and she didn't take credit cards. She had an office and used those tools you generally associate with the practice, but I'm not at all sure she was actually a dentist. She was always very sketchy and I stayed with her way too long) who prescribed a special toothpaste that did nothing.
About two years later, I dumped this "dentist" and went to another one, who decided to ignore my complaints about stabbing pain on the left side of my mouth and give me a referral to see an oral surgeon about a burn mark on the roof of my mouth. I threw the referral away along with that dentist's number. Then I went to another dentist who sprayed my teeth with a numbing agent which gave me relief for a few hours and fitted me for a mouth guard to prevent teeth grinding. I wore it. Nothing changed. I had pretty much given up on ever biting down on my left side ever again without feeling pain.
Then, last year, I found my new dentist. First, he filed down some of my teeth because he said they were not landing properly. That didn't work, and the pain intensified. Finally, he told me "you need a root canal. Right now." The next day, I had that procedure done (all the jokes are true. It's a horrible thing to go through.) I was in pain for two days, but since then I've had zero problems biting down on my left side. For the first time in a decade, I can chew normally.
And it only took four dentists.
The bottom line: If your dentist tries to brush you off (no pun intended) with "try a toothpaste for sensitivity," ask right then and there what happens if (when) it doesn't work, and make a follow-up appointment for the following month. Ask if it's a root canal issue. And don't think for one minute that a spray or paste is going to solve the problem if it's been a problem for any length of time. The dentist in this ad is taking money to recommend Sensodyne, and I'm sorry, but that's not the way to put the needs of the patient first. Do your job, dentists. Do. Your. Damn. Job.