Why You Have Difficulty Flossing Your Rear Teeth      Flossing is one of those things that people should do, but most somehow find an excuse not to. Actually, there is good reason not to floss. It's a real pain. If you think about it, flossing the front part of your mouth is easy and does not pose any difficulty. It is the rear area of the mouth that poses the challenge and is the toughest part to reach.      The rear teeth are difficult to reach because the fingers have to extend further into the mouth. It's easy to put your index finger on the cheek side and touch your rear tooth. Putting your index finger in the middle of your mouth (tongue part), to touch the rear tooth, is more difficult because your front teeth are almost touching your knuckles. To put the fingers of both hands in your mouth at the same time, as required in flossing, is very difficult; your jaw can only expand so far and your mouth can only stretch so far.