Determination of salivary flow rate and oral status in patients with primary Sjögren’s Syndrome (pSS) and diffuse cutaneous systemic sclerosis (dcSSc) and comparison with control subjects. Thirty-one pSS patients, 28 dcSSc patients, and 28 control subjects participated in this single-center, cross-sectional study. Unstimulated whole salivary flow rate (UWSFR) and stimulated whole salivary flow rate (SWSFR), salivary pH, DMFT index (D—decayed, M—missing, F—filled tooth), periodontal pocket depth (PPD), clinical attachment level (CAL), interincisal distance, and OHRQoL (oral health-related quality of life) were analyzed in all three groups of subjects. Primary SS and dcSSc patients had statistically significant lower values of UWSFR (0.20; 0.38 vs. 0.91 mL/min) and SWSFR (0.56; 0.70 vs. 1.64 mL/min) compared with control subjects (p < 0.001, Kruskal-Wallis test). Salivary pH values were statistically significantly lower in pSS and dcSSc patients compared with control subjects (6.00; 6.25 vs. 7.00, respectively) (p < 0.001, Kruskal-Wallis test). The DMFT index of dcSSc patients was higher (28.50) and statistically significant compared to control subjects (20.00) (p = 0.01). The prevalence of periodontitis was the same in pSS and dcSSc patients and control subjects (p = 0.384). Primary SS and dcSSc patients had a statistically significant decreased interincisal distance compared to control subjects (43.80; 38.00 vs. 48.00) (p = 0.003 and p < 0.001, respectively). Primary SS and dcSSc patients show decreased UWSFR and SWSFR, salivary pH values closer to an acidic medium, higher DMFT index, higher prevalence of periodontitis, decreased interincisal distance, and poorer OHRQoL, i.e., poor oral and periodontal health.