TABLE 3.

The effects of curcumin in periodontal inflammation, in vivo and in vitro.

Researcher (year)	Type of study	Experimental method/type of induction	Dose/Delivery of polyphenol treatment	Study outcomes
Shahzad et al. (2015)	In vitro	Inoculum suspension of S. mitis in artificial saliva	Planktonic minimum inhibitory concentration	• Inhibit adhesion of S. mitis, and biofilm formation and maturation
Izui et al. (2021)	In vitro	P. gingivalis outer membrane vesicles (OMV) induced cytotoxicity in HGE cells	0, 5, 10, 20 μg/ml	• Suppression of IL-6, IL-1β, and TNF-α gene expressions
				• Inhibit the cytotoxic effects of OMVs on cellular migration, adherence to and entry of cells, and cellular apoptotic death
Kumbar et al. (2021)	In vitro	P. gingivalis culture	MIC and MBC concentration (62.5 and 125 µg ml−1)	• Prevent bacterial adhesion and biofilm formation in a dose-dependent manner
				• Reduce the expression of genes coding for major virulence factors (Adhesions—fmA, hagA, and hagB. Proteinases - rgpA, rgpB, and kgp)
Xiao et al. (2018)	In vitro	LPS-induced gingival fibroblasts	10 and 20 μM	• Decrease IL-1β and TNF-α production, OPG/sRANKL ratio and NF-κB activation
	In vivo	Experimental periodontitis—silk ligation	30 and 100 μg/g	• Reduce alveolar bone loss, gingival inflammation and collagen fiber destruction
Zhou et al. (2013)	In vivo	Experimental periodontitis—nylon thread ligation	Oral gavage, 100 mg/kg, 30 days	• Lower bone resorption, RANKL, RANK, OPG, TNF-a and IL-6 expression
Guimarães et al. (2011)	In vivo	Experimental periodontitis—cotton ligation	Oral gavage, 30 and 100 mg/kg, 15 days	• No effect on bone resorption
				• Inhibit NF-κB activation but not p38 MAPK
				• Inhibit IL-6 and TNF-a gene expression
Guimarães et al. (2012)	In vivo	LPS injection in the gingival tissues	Oral gavage, 30 and 100 mg/kg, 15 days	• Inhibit NF-kB (lower dose), no effect on p38 MAPK
				• Reduce inflammatory infiltrate, increased collagen content and fibroblastic cell numbers