One of the things I am picky about int he office is that our light curing units are covered with the protective barrier sleeve. So you are probably thinking, "Of course since it goes in the patients mouth". Making sure we don't transfer germs from one patient to the other is super important. However, the reason I am super picky about this has to do with the lifespan of the light guide at the end of the curing unit, and proper light curing efficiency.