My son was the exact same way. He was over 1 yrs old before he actually broke a tooth through his gums. I thought we were going to have to take him to a dentist and have his gums cut because they were just to hard for his teeth to break through. Luckily, that was something both me and his father were strongly against and at last his teeth started shooting through after his first tooth broke free. I say, give it a little longer, if there are much concerns, ask her doctor what her thoughts are and go from there. I was told by my sons doctor that this is something that is very common, you just don't hear about it that often.
I know a set of Twins who just turned One and only one of them has One tooth...i thought it was a little odd myself but every baby develops at their own rate! I also know a Newborn who popped 2 teeth at 2 weeks old....how's that for crazy??
Well my daughter almost made it to her 1st birthday without a tooth. I remember 3 weeks before her bday I took her to the drs and the someone at the office told me to give my daughter a bone lol I thought it was the craziest thing I had ever heard. She was talking about a rib bone or chicken bone. Well the baby sitter gave her a chicken bone and a week later her tooth came right on in. lol So like the lady said at my daughters dr ofc, give that baby a bone. LOL