The effect of natural products in animal models of temporomandibular disorders

Treatment of temporomandibular disorders (TMD) is a challenge for health care professionals. Therefore, new approaches have been investigated, such as the use of natural products. OBJECTIVE: This systematic review aims to summarize the natural products used in treatment of experimental models of TMD. METHODOLOGY: A systematic search was performed in the databases Medline, Web of Science, Scopus, Embase, SciELO, LILACS, and Scholar Google databases in January 2020, dating from their inception. Pre-clinical studies with natural products for intervention in experimental TMD were included. Two reviewers independently selected the studies, extracted the data, and evaluated the risk of bias. RESULTS: 17 records were selected, and 17 different natural products were found, including three lectins, three plants or algae extracts, three sulfated polysaccharides, three cocoa preparations, and five isolated compounds. Concerning the risk of bias, most studies lacked on randomization and blinding. Nociception induced by phlogistic agents was evaluated in most articles, and in five studies it was associated with analysis of inflammatory parameters. In order to investigate the mechanism of action of the natural products used, eight studies evaluated expression of neural or glial molecular markers. CONCLUSIONS: 16 of 17 natural products found in this review presented positive results, showing their potential for treatment of TMD. However, the lack of methodological clarity can influence these results.