Method: A crossover randomized control trial was perfomed in 27 healthy men (20-31 years old range). Algometry meassurements (Kg/F) were performed in masseters muscles and upper lip before and after appliying a cold thermal stimuli as a conditioning stimuli (CS). In the trigemino-trigeminal (TT) intervention the CS was applied in the forehead and in the trigemino-spinal (TS) intervention the CS was applied in the forearm. Pain intensity evoked by the CS was measured in a subjective pain scale.
Result: CPM was achieved in TT intervention (p=0,002) with coresponding 95% confidence interval, but was not achieved in TS intervention (p=0,188). No differences were found when correlating CPM intensity in interventions TT and TS with the pain intensity evoked by the CS (p=0,1631 and 0,190 respectively).
Conclusion: CPM in the orofacial region was achieved by applying cold thermal stimuli in the same region but not in a spinally innervated area, this result suggests that CPM in the orofacial region is site dependent. The pain intensity evoked by the CS was not related with the CPM intensity in both interventions.