DD wasn't actually too bad a teether but the first one of the 2y molars was especially bad. Long long NWs, unsettled after BT, early waking etc etc. The really bad bit lasted a week - I gave pain meds (though in fairness they didn't seem to help that much with the 2y molars), reassurance, extra cuddles but then essentially used the same settling techniques as always, ie walk in, tuck back in, walk out and accepted it would take longer than usual. I didn't have a touchy sleeper so perhaps that made it easier but in general I've always tried to avoid introducing any new habit/technique that I wouldn't be happy with long term. So that for me would have made co sleeping a total no-no, but I'd for example be happy to sing an extra song or give an extra cuddle.