Salivary immunoglobulin levels and periodontal indices in Brazilian children with and without type 1 diabetes

Abstract

This cross-sectional study evaluated the association between salivary immunoglobulins, plaque index, and gingival index in Brazilian children with and without type 1 diabetes mellitus (DM1). The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist for the reporting of observational studies was followed. The DM1 group had 38 children, and an equal number of volunteers matched by sex and age were recruited as controls. Clinical examination was performed for plaque index and gingival index determination. Non-stimulated whole saliva was collected. Concentrations of IgA, IgG, and IgM were determined by ELISA test. Data were tested by the Kolmogorov-Smirnov, Mann-Whitney, and Spearman tests and a multiple linear regression model (p<0.05) was performed. Gingival index was higher in the Control (DM1: 0.16±0.17; Control: 0.24±0.23, p=0.040). In DM1, there was a correlation between IgA and age (rho=0.371, p=0.024), IgM and IgG (rho=0.459, p=0.007), and IgM and gingival index (rho=0.394, p=0.014). In DM1, multiple linear regression showed that age (p=0.041; β=0.363), gingival index (p=0.041; β=0.398), and plaque index (p=0.008; β=-0.506) were good predictors of IgA levels in saliva. Thus, IgA was the only researched immunoglobulin that was directly associated with plaque and gingival indices in Brazilian children with DM1, but not in control subjects.

Figure 1. Comparison between immunoglobulin concentrations in the DM1 group (Mann-Whitney test; *p < 0.05).

Figure 2. Comparison between DM1 and Control groups according to immunoglobulin concentrations (Mann-Whitney test; *p < 0.05).

Figure 3. Correlation between IgA and age (A); IgG and IgM (B); and gingival index and IgM (C) in the DM1 group (Spearman’s test; *p < 0.05). (●) Control group; (▲) DM1 group.

Figure 4. ROC curve for diagnosis of diabetes based on alterations in IgA, IgM and IgG levels (A) in children aged up to 7 years (B) and over 7 years (C) of age. A cut-off point of 7 years old was established because 7 was the age median.