Hmm it's definitely clever indeed.
I see in 2012 ... 1N2L .us domains sold for:
8se.us 285 USD 2012-10-03
GoDaddy
0mg.us 215 USD 2012-08-24
GoDaddy
I think this could probably be able to fetch high $xxx to low $xxxx to an end user. Thats if you are willing to actively try and find one. The good thing is that there are LOADS of potential end users (dentists) so it is very possible that some of them might like this domain and want to use it. Keep in mind that over and above everything else you are dealing with human beings, and as humans we all have varied tastes, likes and dislikes. So if YOU like the domain, isn't it possible that a few other human beings also might like it whom just happen to be Dentists.

- Again, the only obstacle I see here is that you would more than likely have to actively contact them... perhaps u can break it down by city and email like 20 dentists per day until u have mailed all from one city and then move onto the next city..and so on... all depends on how much time u want to invest into selling this domain I guess.
Good luck dude.. keep us posted.
***EDIT - Just thought about it now - but perhaps you should contact the dentist who have existing websites with crappy, ugly domain names...like if their have a long
@ss surname and their practice is called something like Dr BC Holtzhisen or whatever and lets his url is
www.DRholtzhisen.com -- those kinda ones would be easier sell. I mean how much better would
www.2th.us look on his business card compared to
www.drholtzhisen.com -