Hi.. Can understand your concern.. As per your query Dexilant and Nexium both are proton pump inhibitors and are given to patient of acid reflux to relieve the symptoms like heartburn.. Both these medicines can cause some level of dryness of mouth and when there is insufficient saliva it causes decreased flushing of debris from teeth and thus can lead to poor hygiene and bacterial growth leading to cavitation of teeth.. Other thing is that in patient with acid reflux the acid can reflux back to mouth causing erosion of teeth and loose of the hard enamel layer and exposure of soft inner dentin layer of teeth which can be attacked easily by bacteria and can cause tooth decay.. BUT as you told there were just 3 small cavities it is not necessarily due to the above explained conditions and can be just due to improper brushing habits due to which some areas are remained uncleaned causing food deposition and cavitation. I would suggest you to maintain a good oral care( proper brushing, floss and mouth wash) and if you have any symptoms like dryness of mouth you can consult your doctor so that he can provide you with some mouth lubricating agents called Artificial Saliva(if at all it is needed).... Hope your query is solved.. Thanks and regards. Dr.Honey Nandwani Arora..