Sex differences of dental pathology in early modern samurai and commoners at Kokura in Japan

Mussel-Inspired Caries Management Strategy: Constructing a Tribioactive Tooth Surface with Remineralization, Antibiofilm, and Anti-inflammation Activity

Dental caries is a common chronic oral disease in humans resulting from tooth demineralization caused by acid production of bacterial plaque, which leads to the destruction of enamel and dentin and oral inflammation. However, it is still a challenge that the function of natural active ingredients in currently available oral care products is not comprehensive, especially the lack of remineralization. Here, inspired by the strong biological adhesion ability of mussels and ancient oral disease plant therapy, a multifunctional strategy is proposed to construct a bioactive tooth surface to treat dental caries. It has been demonstrated that the Turkish gall extract (TGE) can inhibit adhesion of cariogenic bacteria Streptococcus mutans and Actinomyces viscosus and destroy biofilms on the tooth surface. Meanwhile, TGE can reduce the expression of inflammatory factors. Notably, the TGE coating can induce the growth of hydroxyapatite (HAP) crystals in vivo and in vitro, recovering the enamel mechanical properties under normal oral conditions. MD simulations interpreted the adsorption mechanism by which the hydroxyl groups in TGE bind to phosphate group (PO₄^3-) on the tooth surface, attracting calcium ions (Ca²⁺) as nucleation sites for remineralization. This work underlines the importance of TGE coating in remineralization, antibiofilm, and anti-inflammation activity as a promising strategy for dental caries.

Samurai in Japan: Class System-Related Morphological Differences in Maxillofacial Regions in the Edo Period

Previous studies have reported that compared to commoners in Japan’s Edo period, samurai had long heads, more dental irregularities, and slightly worn teeth. However, these studies did not measure the mandible or only measured length. Angular analysis is essential to evaluate the maxillofacial morphology, but there are no comparative studies of samurai and commoners. This study explored the differences in maxillofacial morphology between samurai and commoners in the Edo period. Thirty male skeletons (samurai) and thirty-eight male skeletons (commoners) were used as materials from the National Museum of Nature and Science. The selected specimens were adults aged between 20 and 59 years without serious skeletal damage and with stable occlusion of the molars. We used three-dimensional scanning to measure the specimens’ skeletal, alveolar, and facial widths. The mandibular plane angle and the gonial angle were significantly larger in the samurai than in the commoners. The ratio of the intermandibular first molars, interzygomatic arch, and mandibular width was significantly shorter in the samurai than in the commoners. The samurai had a high angle tendency and smaller mandibular width than the commoners, reflecting the class system.

Comparison of Periodontal Bacteria of Edo and Modern Periods Using Novel Diagnostic Approach for Periodontitis With Micro-CT

Ancient dental calculus, formed from dental plaque, is a rich source of ancient DNA and can provide information regarding the food and oral microbiology at that time. Genomic analysis of dental calculus from Neanderthals has revealed the difference in bacterial composition of oral microbiome between Neanderthals and modern humans. There are few reports investigating whether the pathogenic bacteria of periodontitis, a polymicrobial disease induced in response to the accumulation of dental plaque, were different between ancient and modern humans. This study aimed to compare the bacterial composition of the oral microbiome in ancient and modern human samples and to investigate whether lifestyle differences depending on the era have altered the bacterial composition of the oral microbiome and the causative bacteria of periodontitis. Additionally, we introduce a novel diagnostic approach for periodontitis in ancient skeletons using micro-computed tomography. Ancient 16S rDNA sequences were obtained from 12 samples at the Unko-in site (18th-19th century) of the Edo era (1603–1867), a characteristic period in Japan when immigrants were not accepted. Furthermore, modern 16S rDNA data from 53 samples were obtained from a database to compare the modern and ancient microbiome. The microbial co-occurrence network was analyzed based on 16S rDNA read abundance. Eubacterium species, Mollicutes species, and Treponema socranskii were the core species in the Edo co-occurrence network. The co-occurrence relationship between Actinomyces oricola and Eggerthella lenta appeared to have played a key role in causing periodontitis in the Edo era. However, Porphyromonas gingivalis, Fusobacterium nucleatum subsp. vincentii, and Prevotella pleuritidis were the core and highly abundant species in the co-occurrence network of modern samples. These results suggest the possibility of differences in the pathogens causing periodontitis during different eras in history.