TempDB is used for temp tbles, table variables, sort and hash spills, spools, version store and a few other things. If your queries aren't using temp tables theyn thyey may well not use TempDB, and that's not a problem.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability