Table 3.

Description of cases and controls.

Parameters	Description
Author, year, reference	Helenius et al. (2005) (22)	Pischon et al. (2010) (24)	Sezer et al. (2012) (25)
Study type	Case-control	Case-control	Case-control
Country	Finland	Germany	Turkey
Source of funding	Helsinki University Central Hospital, Orion Research Foundation, Finnish Dental Association, Finnish Women’s Dental Association	German Research Foundation and Habilitation Fellowship from Charite Universitatsmedizin	NR
Diagnostic criteria used for AS	mNY	mNY	mNY
Disease duration of AS (years)	14.7 (8.9%)	11.7 (7.4)	5.04 (6.13)
Diagnostic criteria used for PD	CPI score ≥3 (PPD≥4 mm)	Mean CAL >3 mm	1999 consensus classification of periodontal disease; at least 4 teeth with PPD>5 mm+CAL ≥ 2 mm at the same time
Study duration	NR	36	6
Sample size	Cases: 18 Controls: 77	Cases: 48 Controls: 48	Cases: 48 Controls: 48
Sex, n (%)	Female Cases: 6 (33.3) Controls: 50 (64.9)	Female Cases: 14 (29.2) Controls: 14 (29.2)	Female Cases: 13 (27.1) Controls: 13 (27.1)
Age mean (±SD) (years)	Cases: 42.4 (11.6) Controls: 42.2 (12.7)	Cases: 40.4 (11.7) Controls: 39.8 (12.1)	Cases: 34.27 (9.73) Controls: 33.33 (9.67)
Recruitment	Cases: Rheumatology Outpatient Department, Meilahti Hospital, Helsinki University Central Hospital Controls: Institute of Dentistry, University of Helsinki	Cases: Department of Rheumatology and Clinical Immunology, Charite-Universitatsmedizin Controls: General Dental Office	Cases: Department of Rheumatology, Gaziantep University, Faculty of Medicine Controls: Gaziantep University, Faculty of Dentistry
Inclusion criteria	Cases: Meeting the current classification criteria related to AS Controls: Randomly selected volunteer dental patients, no AS	Cases: Individuals with prevalent AS who attended for routine examination Controls: Healthy individuals attending a general dental office	Cases: Individuals with AS diagnosed by 2 rheumatologists Controls: Systemically healthy individuals
Exclusion criteria	Cases: NR Controls: History of diabetes, rheumatic disease, or any other disease affect the masticatory system	Cases and controls: History of periodontal therapy or use of antibiotics during the last 3 months prior to examination, pregnancy, or lactation	Cases and controls: History of systemic diseases or conditions, periodontal treatment within the last 6 months, antibiotic or corticosteroid medication within the last 3 months, <18 teeth, current smoker
PI	NR	Cases: 0.55 (0.37) Controls: 0.32 (0.19) p<0.001, S	Cases: 1.60 (0.61) Controls: 1.53 (0.52) p=0.547, NS
PPD	NR	Cases: 3.06 (0.71) Controls: 2.67 (0.49) p=0.002, S	Cases: 3.17 (0.82) Controls: 3.15 (0.90) p=0.91, NS
CAL	NR	Cases: 3.20 (0.74) Controls: 2.73 (0.50) p<0.001, S	Cases: 2.35 (1.93) Controls: 2.04 (1.81) p=0.419, NS
BOP	NR	Cases: 56.5 (23.0) Controls: 25.0 (37.09) p<0.001, S	Cases: 46.77 (3.17) Controls: 33.09 (2.98) p<0.001, S
Number of teeth missing	Cases: 3.44 (3.17) Controls: 2.13 (2.01) p=0.108, NS	Cases: 1.95 (2.31) Controls: 2.44 (2.62) p=0.362, NS	NR
Number of teeth present	NR	NR	NR
Periodontitis, n (%)	Cases: 10 (56) Controls: 20 (26) p=0.015, S	Cases: 23 (47.9) Controls: 15 (31.3) p=0.095, NS	Cases: 18 (37.5) Controls: 14 (29.2) p=0.386, NS
Lopez criteria	NR	NR	NR
Average AL value >2.6 mm	NR	NR	NR

SD: standard deviation; PI: plaque index; PPD: probing pocket depth; CAL: clinical attachment loss; BOP: bleeding on probing; NR: not relevant; mNY: modified New York; AS: ankylosing spondylitis; PD: periodontal disease; AL: attachment loss; NS: not significant; S: significant.