my puppy is four months old and is teething. The adult teeth on the top are perfect but he has three adult teeth on the bottom and a baby tooth either side. These adult teeth have come through crooked. Will they gradually straighten out? or will they remain crooked? ie they are crossing over each slightly, like mine!

It's quite possible they will straighten as his lower jaw grows & makes room for the bigger adult teeth. Teeth can do all sorts of funny things before they settle down. He should actually end up with 6 teeth at the bottom (I assume you're referring to the incisors -small teeth between the bottom canines?) Keep an eye on the baby teeth as they sometimes don't come out when they should & need removing by the vet.