Estrogenic effects on temporomandibular disorder and pain

Purpose It has become more apparent that studies focusing on the effect of sex steroids on orofacial pain in humans and animals require careful attention to the methods of hormone replacement. As a result, the purpose of this review is to highlight differences in estrogen concentration and its effects on temporomandibular joint (TMJ) pain and behavior. Methods This literature review searched keywords TMJ, orofacial, pain, nociception sex steroids, estrous cycle, menstrual cycle estradiol, and progesterone. Results In the case of estrogen, the change in concentration was a consideration, as a rise in estrogen can lead to protective effects and a decrease in estrogen appears to exacerbate the pain response. The dosage and timing was important when administering sex steroids as many orofacial pain studies conducted on animals have used large pharmacologic dosages and/or have given the hormone in a nonphysiologic way that does not mimic natural secretion patterns. Conclusions The results demonstrate that when performing studies or experiments these factors can result in alteration of the pain or behavioral response, as well as, joint structure and inflammatory response. Therefore, these factors must be considered when designing experiments focused on determining the mechanisms of action for sex steroids.