Your projector doesn't need a dentist, but some do need regular cleaning. Those classrooms with Epson projectors will need to remember to get the filter cleaned. (The 3M projectors are DLP which means they do not have filters.)
What does the filter do? It keeps some dust particles out of the inside as the machine draws in air to cool the mechanics. Unfortunately, as the filter gets more clogged, less cooling air comes in and the machine will more quickly overheat or burn out the bulb prematurely.
Remember, dead bulbs are the consumable cost of the campus. Help them live longer by keeping the filters clean! The official Epson directions for cleaning a filter can be found here.
Otherwise, one can carefully locate the filter, remove it, clean it, and replace it with minimal techno-skill.
This filter is very clogged. When you see it, think "running a marathon breathing through a straw!" It really needs to be cleaned.
Keeping your filter clean means checking it every 2-3 months. Don't let it get bad enough to kill the projector.