The utility of microbiome (microbiota) and exosomes in dentistry.

The concept of the oral-systemic link is important in both basic and clinical dentistry. The microbiome (microbiota) and exosomes are two prevalent issues in the modern medical researches. The common advent of oral and general microbiological investigation originated from the initial observations of oral bacteria within the dental plaque known as oral microbiome. In addition to oral diseases related to oral microbiome, the disruption of the oral and intestinal microbiome could result in the onset of systemic diseases. In the past decade, the exosomes have emerged in the field of the medical researches as they play a role in regulating the transport of intracellular vesicles. However, with the rapid advancement of exosomes researches in recent years, oral tissues (such as dental pulp stem cells and salivary gland cells) are used as the research materials to further promote the development of regenerative medicine. This article emphasized the importance of the concept of the oral-systemic link through the examples of microbiome (microbiota) and exosomes. Through the researches related to microbiome (microbiota) and exosomes, many evidences showed that as the basic dentistry developed directly from the assistance of the basic medicine, indirectly the progress of the basic dentistry turns back to promote the development of the basic medicine, indicating the importance of the concept of the oral-systemic link. The understanding of the oral-systemic link is essential for both clinicians and medical researchers, regardless of their dental backgrounds.

Ethnicity, gender, and geographical distribution of dentists in Taiwan in 1939 (Showa 14).

Background/purpose: Taiwan's dentistry entered into a new era of modernization and flourished during the Japanese colonial period. However, we know very little about the composition of dentists at that time. This study attempted to analyze the ethnicity, gender, and geographical distribution of dentists in Taiwan in 1939 (Showa 14). Materials and methods: The methods of documentary analysis and secondary data analysis were adopted to find the composition of dentists during the late Japanese colonial period through a name list of contract dentists for the Postal Savings Insurance published in August 1939 (Showa 14) by the Taiwan Government Transportation Department Information Bureau. Results: The total number of contract dentists was 368, accounting for 86.79% of the 424 practicing dentists in Taiwan in 1939 (Showa 14). Of the 368 contract dentists (328 males and 40 females), 225 (61.14%) were Taiwanese and 143 (38.86%) were Japanese. Among the 8 prefectures in Taiwan, Tainan Prefecture had the largest number of dentists (97), followed by Taipei (84) and Taichung (78) prefectures. The number of contract dentists per 100,000 people was 6.24, equivalent to 16,021 people served by each contract dentist in 1939 (Showa 14). The chi-square test for the trend analysis of gender distribution indicated a significantly higher proportion of male than female contract dentists in either Taiwanese or Japanese ethnic group. Conclusion: In the late Japanese colonial period, the number of Taiwanese dentists exceeded that of Japanese dentists. Furthermore, there were more male than female dentists in either the Taiwanese or the Japanese population.

The mechanisms of Porphyromonas gingivalis-derived outer membrane vesicles-induced neurotoxicity and microglia activation.

Background/purpose: Periodontitis is associated with various systemic diseases, potentially facilitated by the passage of Porphyromonas gingivalis outer membrane vesicles (Pg-OMVs). Several recent studies have suggested a connection between Pg-OMVs and neuroinflammation and neurodegeneration, but the precise causal relationship remains unclear. This study aimed to investigate the mechanisms underlying these associations using in vitro models. Materials and methods: Isolated Pg-OMVs were characterized by morphology, size, and gingipain activity. We exposed SH-SY5Y neuroblastoma cells and BV-2 microglial cells to various concentrations of Pg-OMVs. Cell morphology, a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, an enzyme-linked immunosorbent assay, and Western blot analysis were used to evaluate the cellular mechanism underlying Pg-OMV-induced neurotoxicity in neuronal cells and inflammatory responses in microglial cells. Results: Exposure to Pg-OMVs induced neurotoxicity in SH-SY5Y cells, as evidenced by cellular shrinkage, reduced viability, activation of apoptotic pathways, and diminished neuronal differentiation markers. Gingipain inhibition mitigated these effects, suggesting that gingipain mediates Pg-OMVs-induced neurotoxicity in SH-SY5Y cells. Our research on neuroinflammation suggests that upon endocytosis of Pg-OMVs by BV-2 cells, lipopolysaccharide (LPS) can modulate the production of inducible nitric oxide synthase and tumor necrosis factor-alpha by activating pathways that involve phosphorylated AKT and the phosphorylated JNK pathway. Conclusion: Our study demonstrated that following the endocytosis of Pg-OMVs, gingipain can induce neurotoxicity in SH-SY5Y cells. Furthermore, the Pg-OMVs-associated LPS can trigger neuroinflammation via AKT and JNK signaling pathways in BV-2 cells.