A microdermabrasion is rarely used at my business now that I am a corneotherapist. Over exfoliation can cause premature aging as we need to preserve the integrity of the skin at all times and not make it thinner. If after an analysis of your skin I think one is required I will do it but I often prefer to use other treatment modalities such as an enzyme or terra sana clay mask.
I know a lot of businesses suggest regular microdermabrasions of the skin but I do not agree with this. It is a tool that should only be used if your skin requires it. You need to be very careful of what ingredients are applied to the skin after these treatments also.