Friends of mine who have had to face this issue have dealt with it differently. One went back for check ups every three months to keep on top of it. The child was older, still baby teeth and they were waiting for them to fall out, which they did before they caused trouble.
I've a friend with an almost three year old who recently found cavities, and they drilled with a very fine drill, without anaesthesia, and then had it sealed with a fluoride releasing sealant. The only paediatric dentists I know of will avoid sedation if possible.