Depending on their material, if ceiling tiles should get wet, they could potentially get damaged beyond repair. Others are made from a waterproof material such as PVC. Keep in mind, too, that if your ceiling tiles are wet, that may be the least of your concerns. It could mean a leaking toilet, sink or tub from a bathroom above or, worse yet, a leaking roof.
Wet Ceiling Tiles
A small water patch on a non-waterproof ceiling tile might dry out. Remove it and allow it to air out for a day or two. You might even try blow drying it. Saturated tiles probably have to be replaced. Thanks to the modular nature of a drop ceiling, tile replacement is neither complicated nor expensive.