Possible roles of short-chain fatty acids produced by oral bacteria in the development of alveolar osteitis.

PURPOSE: Alveolar osteitis (dry sockets) is a painful condition characterized by a limited immune response. It is typically caused by the removal of blood clots from extracted tooth sockets, which leads to the fermentation of trapped food remnants by oral bacteria in the cavities, producing high concentrations of short-chain fatty acids (SCFAs). This study examined the effects of SCFAs on immunity and bone metabolism. METHODS: Mouse macrophage Raw264.7 cells were treated with oral bacteria supernatants or SCFA mixtures, and inducible nitric oxide synthase (iNOS) levels were determined by western blot. The same cells were treated with SCFA mixtures in the presence of receptor activator of nuclear factor-kappa B ligand (RANKL), and osteoclast-like cells were counted. MC3T3-E1 cells were treated with SCFA mixtures and stained with alizarin red S. RESULTS: Raw264.7 cells treated with oral bacterial culture supernatants of Porphyromonas gingivalis and Fusobacterium nucleatum inhibited lipopolysaccharide (LPS)-induced iNOS production, likely due to SCFA content. SCFA mixtures mimicking these supernatants inhibited the number of RANKL-induced tartrate-resistant acid phosphatase (TRAP)-positive cells and MC3T3-E1 cell mineralization. CONCLUSION: These data suggest that SCFAs produced by P. gingivalis and F. nucleatum may reduce the inflammatory response and mildly induce mineralization of the alveolar walls. These results may contribute to the understanding of alveolar osteitis.

Analysis of the effect of different doses of oral tranexamic acid on melasma: a multicentre prospective study.

BACKGROUND: Melasma is pale brown to dark brown hyperpigmentation of the facial skin that commonly affects women of reproductive age. Treatment methods for melasma include oral and topical use of vitamin C, hydroquinone ointment, and laser treatment, with unsatisfactory results. Tranexamic acid (TA) has been shown to be effective against melasma, however, the optimal dose has not been investigated. OBJECTIVE: To analyse the therapeutic effect of different doses of oral TA on melasma. MATERIALS & METHODS: Patients with severe melasma were randomised to receive TA at a daily dose of 500 mg, 750 mg, 1,000 mg, or 1,500 mg. Clinical and VISIA photographs of the patients were taken at baseline, four weeks, eight weeks, six months, one year, and two years. The melasma area and severity index (MASI), as well as the melanin index, were measured. Routine blood and coagulation tests were performed at each time point. The photographs were divided into five groups according to level of improvement: apparent improvement, slight improvement, unchanged, and deterioration. RESULTS: Clinical photographs showed that all four doses of TA were effective in treating melasma, and the efficacy correlated with treatment time and dosage. However, there were no significant differences in the MASI or melanin index between the four doses. The treatment was generally safe for most patients and side effects included mild stomach upset and decreased menstruation. CONCLUSION: Oral TA was safe and effective for the treatment of melasma. Patient satisfaction was high and most patients could withstand long-term treatment.