Ultrastructural changes in epithelial cells of rats exposed to low concentration of hydrogen sulfide for 50 days.

Hydrogen sulfide (H2S) and other volatile sulfur compounds (VSCs) appear mainly in the oral air of patients with halitosis. It seems that VSCs are directly involved in the pathogenesis of gingival diseases. In previous studies, short-term (7 hours-4 days), high concentrations (5-400 ppm) of H2S applications on periodontal tissues have been evaluated in a culture medium. The aim of the present study was to investigate the potential effects of lower (equivalent to halitosis) concentrations of H2S on rat gingival tissue for longer-term inhalation. 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, the gingival sulcular tissue samples of each rat were taken and examined using transmission electron microscope. Ultrastructural changes in the sulcular epithelia of the rat gingiva showed deformation of celullar shape, vacuolization, and disintegrity of intercelullar connection by loss of desmosomes and collagen fibrils. No basal membrane damage was observed. Inhalation of low levels of H2S (equivalent of halitosis) in the oral environment causes ultrastructural celullar damages in rat sulcular mucosa. These results suggest that halitosis may be the potential reason for periodontal destruction in humans.

Effects of a single intravaneous dose of zoledronic acid on bone healing following tooth extraction in ovariectomized rabbits.

OBJECTIVE: The present study is aimed to investigate the effects of administering a single intravenous dose of zoledronic acid (ZA) on bone healing following tooth extraction in ovariectomized rabbits. MATERIALS AND METHODS: Female, New Zealand rabbits were randomly divided into three groups including Control, ovariectomy + saline (OVX) and ovariectomy + zoledronic acid group (ZOL). Bilateral ovariectomy was performed to the rabbits in OVX and ZOL groups under general anesthesia. Control group underwent sham surgery. Eight weeks later, mandibular right incisors of all animals were extracted under general anesthesia. Before the procedure, Control and OVX groups were given saline and 0.1 mg/kg ZA was administered to ZOL group intravenously. All animals were sacrificed after 12 weeks. RESULTS: The findings of histopathological and biochemical evaluations reflected insignificant differences among study groups in vascular endothelial growth factor (VEGF), increases in osteoclasts, ossification, vascularization and mononuclear cell infiltration measures (p > 0.05). In contrast, bone morphogenic protein 2 (BMP-2), tumor necrosis factor alpha (TNF-α) and organization of the extraction wound differed significantly between groups (p < 0.05). CONCLUSION: The potential beneficial effects of ZA administration on the wound healing process following tooth extraction were demonstrated via serum TNF-α, BMP-2 and VEGF levels in an osteoporotic model in ovariectomized rabbits.