RESUMEN
OBJECTIVE: The DNA oxidation byproduct 8-hydroxy-2'-deoxyguanosine (8-OHdG) is a well-known biomarker used to evaluate oxidative stress. We previously reported that the generation of reactive oxygen species (ROS) is increased in cultured gingival fibroblasts (GF) from patients with Down syndrome (DS). Thus, the aim of this study was to evaluate 8-OHdG as a marker of oxidative stress in saliva of DS patients. MATERIALS AND METHODS: The study group consisted of DS patients (66 patients; age range 1-62 years) and systemically healthy control subjects (71 subjects; age range 4-58 years). Periodontal status was judged based on standard measurements of probing depth (PD) and gingival index (GI). The salivary levels of 8-OHdG were determined using an enzyme-linked immunosorbent assay. RESULTS: The mean of PD and GI values were not significantly different between young (1-12 years) patients with DS (DS-1) and controls (C-1) or between adult (30-62 years) patients with DS (DS-2) and controls (C-2). There were statistically significant positive correlations between the salivary 8-OHdG levels and GI in the DS-1, DS-2 and C-2 groups, but not in the C-1. There were also statistically significant positive correlations between salivary 8-OHdG levels and PD in the DS-2 and C-2 groups, but not in the DS-1 or C-1 groups. The salivary levels of 8-OHdG of DS-1 and DS-2 groups were significantly higher than in the C-l and C-2 groups, respectively. CONCLUSIONS: These results suggest that progressive oxidative stress occurred in DS patients. Oxidative stress may contribute to the clinical features of DS, particularly to the progressive periodontitis characteristic of early ageing.