the dentist probably wants to use nitrous oxide for the procedure. it is not so much sedation as it is relaxation. he will actually be awake the whole time. 14 months is not too early for this procedure and she probably wants to get the cleaning in at the same time so that there isn't an additional office visit, with additional office charge and additional time to administer nitrous oxide. dentists, like doctors, work under similar codes of ethics when it comes to the right to do no harm and unnecessary treatments. if you have insurance, the cost is the same to you because most insurances cover preventive things such as cleanings and check-ups.
it's funny how many people visit the doctor for check-ups when nothing is particularly wrong (all the well baby check-ups we go to, for example) but when it comes to the dentist, they only go if there is a problem.
and btw, one of my children was nervous about the dentist and they used nitrous oxide. it wears off very quickly (within minutes) before she even got out of the chair. are you taking him to a pediatric dentist? while there are several family dentists that are good, pediatric dentists sometimes make a world of difference. and you want to use one who doesn't use any kind of restraints on children.