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. 2021 Jul 29;12:699011. doi: 10.3389/fimmu.2021.699011

Table 2.

Analysis of the methodology of the included studies relying on buccal swabs in pSS patients compared to HCs and sicca patients.

Authors Year Population Confounding variables Sampling Analysis
Liquid Buccal hygiene
Almstahl et al. (23) 20 pSS
20 HC
Similar age, gender, nb of teeth
Different smoking status, medication
Sterile cotton swabs on mucosa, dorsum of the tongue, supragingival tooth surfaces, gingival crevice region Yes (UWS, SWS, nb of teeth, aspect of mucosa) Selective culture media technique:
Streptococci, S. salivarus, F. nucleatum, Prevotella intermedia/Prevotella nigrescens, Candida albicans, S. aureus, Enterics, Enterococci
Li et al. (24) 10 pSS :
- 6 taking HY
- 4 taking HY + PA
10 HC
Similar age, gender, no smoking, no antibiotics Sterile cotton swabs on bilateral buccal mucosa Yes (nb of teeth, aspect of mucosa, UWS, SWS) The 16S rRNA hypervariable region V1-V3 was sequenced, which resulted in 366 452 raw reads
van der Meulen et al. (16) 37 pSS
86 sicca
24 HC matched with pSS patients on sex
103 patients from the general population
Similar age, smoking status
Different treatment, gender
Sterile cotton swabs Yes (nb of teeth, oral dryness, UWS, SWS) The 16S rRNA hypervariable region V4 was sequenced.
van der Meulen et al. (25) 34 pSS
34 SLE
No antibiotics
Different smoking status, age, gender
Oral washing and buccal swab collected at home by patients and frozen WHO oral Health Questionnaire, Xerostomia inventory questionnaire The 16S rRNA hypervariable region V4 was sequenced.

pSS, primary Sjögren’s syndrome; HC, healthy controls; sicca, patients with dryness symptoms; SLE, systemic lupus erythaematosus; UWS, unstimulated whole saliva; SWS, stimulated whole saliva; HY, hydroxychloroquine; PA, prednisone acetas; rRNA, ribosomal ribonucleic acid.