Are these ceiling tiles easy to fix?

[Mitchell Litam]

i Live in a Pre WW2 house. Built in 1902. I have these ceiling tiles. I dont know what they are called but I want to replace these ones cause they look droopy. I just replaced the roof cause it seemed there was water damage. I attached pictures below to get some advice. There also appears to be weird screws in the tiles that look like they have been damaged. 

Anyone know what these tiles are called? If they are easy to replace?

I would like to have a better understanding before I try and remove them and just have a huge hole in my ceiling.

[Peter B.]

Those are NOT drop ceiling tiles. They appear to be glue up. Or concealed grid tile (I doubt they are concealed grid, that is a commercial system)... Either way they they are grooved on all 4 sides. They have splines in the grooves that keep the edges consistant. You should be able to run an utility knife on the edges to cut splines then pull/scrape them off. They are easy to replace, the challange is finding an exact match.

I would google Armstrong ceiling systems or USG ceiling systems that would probably be your best bet.