Table 2.

Characteristics of the included studies.

Author, year of publication, and country	Study design	Study size	IBD patients	Control	Rate, IBD/control	Periodontal manifestations	Definition of periodontitis	Reference
Zervou et al. (2004), Greece	Case-control	77	30	47	0.06/0	Periodontitis; gingivitis; gingival bleeding	Not described	[24]
Grössner et al. (2006), Germany	Case-control	121	62	59	0.81/0.64	%PI; %BOP; PPD; %CAL ≥ 4 mm; %CAL ≥ 5 mm	≥1 sites with CAL ≥ 4	[14]
Brito et al. (2008), Brazil	Case-control	253	179	74	0.85/0.67	Periodontitis (at least 4 × CAL ≥ 3 mm); %PI; %BOP; PPD; CAL; %CAL ≥ 3 mm	≥4 sites in different teeth with CAL ≥ 3 mm	[11]
Rikardsson et al. (2009), Sweden	Case-control	2346	1598	748	0.7/0.51	Periodontitis; gingival bleeding	Self-reported	[23]
Habashneh et al. (2012), Jordan	Case-control	260	160	100	0.58/0.4	Periodontitis; PI; GI; PPD; CAL; GR; %BOP; %PPD ≥ 3; %PPD ≥ 4; %CAL ≥ 3; %CAL ≥ 4; %CAL ≥ 5	≥4 teeth with one site or more having PD ≥ 4 mm and CAL ≥ 3 mm	[12]
Zhang et al. (2020), China	Case-control	654	389	265	0.38/0.19	PD; CAL; GR; GI; PI; %PD ≥ 4; %PD ≥ 5; %CAL ≥ 3; %CAL ≥ 4; %GR ≥ 1; %GR ≥ 2; %BOP; %CI	≥2 interproximal sites with CAL ≥ 3 mm, and ≥2 interproximal sites with PD ≥ 4 mm (not on the same tooth), or ≥1 site with PD ≥ 5 mm	[25]

PI: plaque index; BOP: bleeding on probing; PPD: probing pocket depth; CAL: clinical attachment loss; GI: gingival index; GR: gingival recession; CI: calculus index.