 In oral surgery, primary hyperalgesia is the awareness of the receivers of the mucosa and the periosteum by a range of mediators of inflammation such as prostaglandins. Secondary hyperalgesia is central sensitization of neurons in the nucleus trigeminal and spinal supra structures. Secondary hyperalgesia can be observed over the time, while the primary hyperalgesia is provable within a few hours after the injury; Prostaglandins are synthesized quickly after damage to the tissue and appear in significant concentrations 1 hour after trauma. 