Welcome, Leslye!
We're so glad you found us. This is a great forum, with lots of knowledgeable people, and lots of support and understanding.
No, it doesn't sound silly that your tinnitus could have been caused by a visit to the dentist. With all the high-speed equipment that is used today, it's possible that the cleaning could have set off your tinnitus. We may never really know what caused the tinnitus to begin, but that is definitely possible. It could be that your ear was already sensitive, or that you had some undetectable hearing loss, and that might have set the stage for the tinnitus to begin.
We're glad to welcome you as a member of Tinnitus Talk!
Best wishes,
Karen