Emerging wisdom tooth
You might feel toothache when you bite down if you have an emerging wisdom tooth. Wisdom tooth often grows in an awkward position which causes intense molar tooth pain, especially when you apply pressure on it. One may decide to remove the wisdom tooth if the pain is too much to bear.
If your wisdom tooth is making it difficult to eat contact your dentist.
Congestion or sinus pressure
Your teeth roots are close to your nasal sinuses, so you may also feel pain if you have inflamed sinuses. This pain is more common in the upper teeth because the most sensitive teeth are your molars and premolars. More commonly, back tooth pain is usually traced to inflamed sinuses.