The Effect of Periodontitis on Expression of Interleukin-21: A Systematic Review

Table 2

Excluded studies.

S. number	Citation	Reason for exclusion
	Ebersole et al. [4]	Animal study
	Araujo-Pires et al. [25]	IL-21 was estimated in periapical granuloma in subjects without periodontitis
	Li et al. [26]	Animal study
	Wang et al. [27]	No abstract/full text available