It may quite possibly have caused damage. Only time will tell. My mates 700 series turbo'd volvo screwed up after a connection down stream of the filter came loose, he didnt relaise it and ran it for a year plus with unfiltered air going in.
The analogy the mechanic made was that it was like chucking a handful of sand in every few weeks. OTT maybe but the principle is the same.
I would suggest this vehicle is checked out and serviced very very thoroughly very soon , check all details such compression etc. Then you'll have an idea what , if and when the next problem may be :thumb2