Structural changes in periodontium of rats exposed to a low concentration of hydrogen sulfide for 50 days

The aim of the present study was to investigate the effect of H2S inhalation at a low concentration (at human equivalent dose of pathologic halitosis) on rat periodontium over a long term (50 days). The threshold level of pathologic halitosis perceived by humans at 250 ppb of H2S was converted to rat equivalent concentration (4.15 ppm). Rats in the experimental (H2S) group (n = 8) were exposed to H2S continuously but not the control rats (n = 8). After 50 days, periodontal tissue samples were taken from the mandibular first molar region and examined histopathologically to determine inflammatory cell infiltration (ICI), osteoblastic activities, number of osteoclasts, and resorption lacunae. Sulcular epithelium layer destruction was observed in the H2S group. Frequency of ICI was significantly higher in the H2S group compared to the control group (P