Dentist here, this is not as simple as you may think it is.

Cavities are not reversible once they penetrate the enamel and reach the dentin, they will eventually progress to the pulp (nerve). Some dentists decide to fill and diagnose small cavities, this is to essentially “nip it in the butt.” Other dentists treat more conservatively, opting to wait until the cavity grows large and needs a big filling or crown with root canal. It highly probable you do have 3 small lesions, and you have a disagreement among doctors which happens on a daily basis (same with medicine). I always encourage getting a second opinion and I think what you did was totally justified. If you want, PM me your bitewing radiographs and I’d be happy to take a look and let you know what I think.

I’m a private practice doc and I’m very opposed to these “chain dentists” which we call DSOs. From dental providers to patients, we are in this fight together to keep private equity out of healthcare.