This smells like a ChatGPT output lol. But yes, a dentist LOR should outline what was said above. Honestly, you don't 'need' and dentist LOR unless the school specifically asks for it. If you are a non-trad or a career changer it may help to have one to help adcoms. I didn't have one and no one mentioned that I didn't have one or even asked if I planned on getting one. I had the shadowing hours, I explained my experience within the practice and how I liked that experience and knew it was a good fit.
It sounds like part of this experience is also a little bit of volunteer work. Though you could count all the hours as shadowing if you so choose, I don't think it would make a huge difference.
Is the dentist asking you to write the letter or what you'd like to be put into the letter?