this is a recognised medical condition called Barodontalgia, which basically means pain caused by the change in atmospheric pressure.
Thanks Laz, I've now been able to find some medical journals on the net concerning this. Interestingly it can trigger sinus infections, which I also get. Looks like I need to stock up on more strong pain killers.
Get a bottle of whole cloves, suck on one until it goes soggy then replace it until you land. This does two things keeps the airways to the ears open and floods the teeth with a mild anesthetic. trust me
Thanks Duke, I'll try anything.