To determine if a dropped carabiner is still safe to use, you should inspect it for any dings or significant damage. Light scratches and good gate action indicate that it may still be safe for use. However, it's important to remember that only you know the history of your gear, so if you have any doubts about its safety, it's best to retire the gear and not take any risks. Keep in mind that the only way to truly know if a dropped carabiner is still safe is to test it to its breaking point, but this is not practical or recommended for everyday use.