I need to replace a couple of bulbs in my apartment which are controlled by an "old" dimmer switch, which predates the advent of LED bulbs. My understanding is that I cannot use a dimmable LED bulb here, so I'm going for an incandescent. If this is wrong, I will buy LEDs and the rest of this question is irrelevant. (previously it had CFLs, which seemed inappropriate and would flicker)
Bulbs: I got "Ecosmart" dimmable incandescent bulbs from Home Depot. 43W ("60W Replacement"). Natural light (I mention this because a similar model with a different light color has very different warnings on the back, including having an internal Halogen (!) which this does not mention, though it still may have for all I know).
Fixture: My fixture appears to say "660W 250V". (Does that sound right? I'm in the U.S.) so it sounds like I'm well within limits. It's on the ceiling, and it has a cover that I would describe as white and translucent and encloses the bulbs completely. The fixture also has a silver sort of surface above the bulbs, presumably to insulate the ceiling from them.
I can attach photos of either if desired.
My concern is this:
Among the warnings on the back of the packaging is "Suitable for use in open fixtures". However, it does not say "Unsuitable for use in closed fixtures". Should I infer this? Am I in danger of fire if I use this thing with the cover on? (Guy at Home Depot thought it over and ultimately concluded it should be fine, but I want to double-check) Right now I have been using it with the cover off.