Objectives:
Chronic periodontitis (CP) and oral mucocutaneous candidiasis have been considered as chronic complications of Type 2 Diabetes (T2D). The potential role of yeasts in the pathogenesis of periodontitis is especially important for diabetic patients, because antibiotics are commonly used in the treatment of periodontitis. The aim of this study was to detect Candida spp. on the tongue and in subgingival sites from systematically healthy subjects and subjects with T2D and CP. Furthermore, the present study aimed to find a potential difference in the detection of yeasts on the tongue and in subgingival samples, in order to determine subgingival areas as potential reservoirs of yeasts. Also, the study searched for confounders of positive yeast detection in mentioned samples

Methods:
A total of 146 patients were included in this study. They were divided into four groups: group A consisted of non-diabetics with healthy periodontium, group B of non-diabetics with CP, group C of patients with T2D with glycoregulation and CP and group D of patients with T2D with poor glycoregulation and CP. Cotton swab samples from tongue and subgingival samples were obtained from each patient using sterile paper points and a sterile curette. Swab cultures were made on Sabouraud dextrose agar. Two sterile paper points were placed into the pocket for 30s. Immediately after, subgingival samples were obtained from the same pocket by sterile curette. Both subgingival samples were inoculated in separate sterile plastic tubes containing 1 mL of Sabouraud dextrose broth, vortexed and 20μl of suspension was streaked on SDA. The number of CFUs was counted. Information about parameters that could potentially predict the presence of Candida spp. was collected. It included self-reported information about education, xerostomia, blood type, everyday intake of sweets and smoking habits. Fasting plasma glucose levels (FPG), HbA1c, hematological parameters (RBC, Hgb, HCT, MCV, MCH, MCHC, RDW) and sedimentation rate were measured

Results:
Candida spp. was detected on the tongue of 40/146 subjects (27.4%). Candida spp. was more prevalent in diabetics with poor glycoregulation than in other groups (χ2: A vs D, p=0.019, B vs D, p=0.002 and C vs D, p=0.025). Subjects with T2D had a significantly higher prevalence of Candida spp. detection (37.3%), than systematically healthy subjects (χ2, p=0.013). The presence of Candida spp. in subgingival areas detected by both sampling methods was 29.25% (43/146). Occurrence of Candida spp. in group D was significantly higher than in group A (χ2, p=0.018), group B (χ2, p=0.023) and group C (χ2, p=0.005). There were 22/146 (15.07%) cases where yeasts were not detected on the tongue, but were found in the subgingival area. Multivariate regression model showed that HbA1c was only the predictor of Candida spp. on the tongue and in subgingival plaque samples.

Conclusion:
Presence of Candida spp. on the tongue and subgingival sites is higher in diabetics with poor glycoregulation and is influenced only by HbA1c serum level. High frequency of Candida spp detection in subgingival areas (even when they are not found on the tongue) should be clarified as potential resevoir of these microorganisms.

Subgingival sites and oral cavity as reservoirs for Candida spp. in diabetics and non-diabetics