A single application of hydrogen sulphide induces a transient osteoclast differentiation with RANKL expression in the rat model.

OBJECTIVE: Oral malodor is mainly attributed to volatile sulphur compounds (VSCs) such as hydrogen sulphide (H(2)S), methyl mercaptan and dimethyl sulphide. VSC accelerate periodontal soft tissue destruction. However, there is little information about the potential role of H(2)S in alveolar bone loss. The purpose of this animal study was to examine the effects of sodium hydrogen sulphide (NaHS), H(2)S donor drug, on osteoclast differentiation in rat periodontal tissue.

DESIGN: Twenty-four male Wistar rats (8 weeks old) were divided into four groups: a control group and three experimental groups, which were examined at 3h, 1 day, and 3 days after topical application of 3microl NaHS (lM in physiological saline) into the gingival sulcus of rat first molar. Expression of tumour necrosis factor (TNF)-alpha, RANKL, NF-kappaB and tartrate-resistant acid phosphatase (TRAP) was evaluated in the periodontal tissue.

RESULTS: Three hours after NaHS application, TNF-alpha expression increased in the periodontal ligament. The numbers of RANKL-positive osteoblasts and TRAP-positive osteoclasts significantly increased progressively with time and reached a maximum level after 1 day. Significant up-regulation of RANKL and NF-kappaB mRNA was observed at 3h after NaHS application.

CONCLUSIONS: H(2)S application caused a transient increase of osteoclast differentiation with up-regulation of RANKL expression in osteoblasts. H(2)S, which is primarily responsible for halitosis, may also contribute to alveolar bone resorption through RANKL expression.