If it is an obsolete pattern that you purchased when it was authorized you can still wear it subject to it being one of the following:
the CF midnight blue mess dress and pre-DEU combat arms mess dress may be worn by those serving on, and who purchased the uniform prior to 19 June 1986;
or
obsolete mess dress patterns of the Royal Canadian Navy, Canadian Army, and Royal Canadian Air Force may be worn by those serving on, and who purchased the uniform
prior to 1 February 1968. Information on the applicable regulations can be obtained from NDHQ/DHH.
I'm going to assume it is option 1, the pre-DEU combat arms mess dress. In that case, if you re-enroll into the infantry you should be able to. I think you had a kind and caring Squadron Chief or equivalent, because the dress regs also say:
CF members are allocated environmental identity and
uniformed according to the functional branch to which they belong.
So my interpretation is that you can continue to wear the infantry mess dress as long as you are infantry, but if you belong to the Air Force you wear the Air Force uniform. Of course the person to ask is the AF CWO or your wing Chief Warrant Officer. http://www.dnd.ca/dsa/app_bio/engraph/FChiefOfficerAddressBook_e.asp?SectChoice=2
They're the people that can give you the interpretation.
Edit- Spelling
