I suffer from painful Jaws, its because of my spine + i grind my teeth at night, meant to wear a gum shield and do exercises, but never bothered.
It is a condition and a very painful 1. ( my bottom jaw is mis-aligned.) I cant find the sheet i was given by the dental hospital, but found this, its almost exactly the same, more so with the tongue at the roof of the mouth, (and that does hurt.) If it dont settle Duffield see dentist and see if your jaws are out of true. (Teeth can be a problem for sore jaws.
Here is the Link.
http://www.ehow.com/how_2352238_cure-tmj-jaw-exercises.html

Chew chewing gum. Like that gal in Grandpa Jones' song.

According to my studies you need to obtain a few packs of Chewits and some bubble gum.

The Chewits are even chewier than a 15-storey block of flats and if spread through the course of a day or so will soon get those all important mastication muscles sleek, shiny and ready for anything.

For those times when the Chewits aren't appropriate - for example you don't want to ruin your appetite for that 450gm bar of Dairy Milk, that's when the gum comes in to its own. You will find that this exercises not only that all important up and down motion, but can also be used for the daring side to side manouv..manoov...maneouv..movement, formerly attempted only by Olympians.
In fact, start now and 2012 could beckon.