Inhibition of Initiation and Progression of Periodontal Disease by Curcumin

Objective: We hypothesize that curcumin, a major constituent of turmeric, reduces periodontal disease by intervening in key inflammatory pathways leading to resistance to periodontitis and reduced alveolar bone destruction.

Method: An established animal model of aggravated periodontal disease was induced in diabetic rats by injection with 100μg LPS from the human periodontal pathogen, Porphyromonas gingivalis, into the gingival tissue between the maxillary first and second molars, bilaterally, 3X a week over three-five weeks. To evaluate the effect of curcumin, rats received 50mg/kg curcumin beginning on day 5 of diabetes and daily until sacrifice. 

Result: Periodontal inflammation was evaluated from gingival tissue at the first and second maxillary molars. Gingiva from control rats demonstrated normal histology including an outermost layer of parakeratin overlying the major component of keratinocytes in the stratum spinosum. Gingiva from diabetes + LPS rats demonstrated a breakdown in normal histology with significant edematous epithelium, separated from the underlying connective tissue. In the curcumin treated, diabetes + LPS rats a significant improvement in gingival histology was observed. Palatal alveolar bone loss was analyzed at the furcation of the 2^nd molar and at the mesial surface of the 2^nd molar. Jaw microphotographs, radiographs and microCT demonstrated a significant increase in the CEJ-AC distance in diabetes + LPS rats compared to normal rats, which was reversed to control levels in the presence of curcumin.  IL-6, a pro-inflammatory mediator implicated in periodontal disease, was analyzed from the maxillary palatal gingiva. Compared to control rats, a significant increase in IL-6 mRNA was observed in diabetes + LPS rats, which was reduced to control levels in the presence of curcumin. 

Conclusion: Curcumin treatment in vivo (i) reduced gingival inflammation; (ii) reduced key inflammatory cytokines; and (iii) inhibited alveolar bone loss, which may lead to new therapeutic molecules for the treatment of chronic diseases like periodontitis.