Enhancement of Mechanical Properties of High-Thermal-Conductivity Composites Comprising Boron Nitride and Poly(methyl methacrylate) Resin through Material Design Utilizing Hansen Solubility Parameters.

Materials for heat sinks in automotive heat dissipation systems must demonstrate both high thermal conductivity and stress resistance during assembly. This research proposes a composite material, comprised of thermally conductive ceramic fillers and matrix resins, as a suitable option for such application. The strategy for designing this material interface is directed with Hansen solubility parameters (HSP). A composite material featuring a honeycomb-like structure made of poly(methyl methacrylate) (PMMA) and boron nitride (BN) particles was successfully fabricated through press molding. This yielded a continuous BN network exhibiting high thermal conductivity and moderate mechanical strength. The HSP evaluation led to the suggestion of introducing highly polar functional groups into the matrix resin to enhance the affinity between PMMA resin and BN fillers. In line with this recommendation, a nitrile (CN) group─a highly polar group─was introduced to PMMA (CN-PMMA), significantly enhancing the composite's maximum bending stress without noticeably degrading other properties. Surface HSP evaluation through contact angle measurements revealed an "interface enrichment effect", with the CN groups concentrating at the resin-filler interface and effectively interacting with the surface functional groups on the BN particles, which resulted in an increase in the maximum bending stress. These findings emphasize the advantage of employing HSP methodologies in designing high-performance composite materials.

Identification of OPN3 as associated with non-syndromic oligodontia in a Japanese population.

Tooth agenesis is one of the most frequent congenital abnormalities found in the maxillofacial region. Oligodontia, a severe form of tooth agenesis, occurs as an isolated anomaly or as a syndromic feature. We performed whole exome sequencing analyses to identify causative mutation in a Japanese family with three affected individuals with non-syndromic oligodontia. After variant filtering procedures and validation by Sanger sequencing, we identified one missense mutation (c.668 C > T, p.Gly223Asp) in OPN3 at 1q43, encoding a photosensitive G-protein-coupled receptor (GPCR) expressed in various tissues including brain, liver, and adipose. This mutation was predicted to be pathogenic in silico and was not found in the public databases. We further examined 48 genetically unrelated cases by targeted sequencing of the OPN3 gene region and found one additional missense variant in this gene (c.768 C > T, p.Met256Ile) that was also predicted to be pathogenic. Localization of OPN3 protein by immunohistochemical analysis using mouse embryo revealed its specific expression in the tooth gems from bud to bell stages and their surrounding tissues. These results indicated that OPN3 was involved in non-syndromic oligodontia, which has made an anchoring point for clinical application including DNA diagnostics.

A Case of Systemic Infection Caused by Streptococcus pyogenes Oral Infection in an Edentulous Patient.

BACKGROUND: Infections in the oral and maxillofacial region can sometimes extend beyond the oral cavity, with serious consequences. Most oral infections are odontogenic, occurring through the root apex of the tooth or the periodontal pocket. It thus makes sense that edentulous patients have a much lower risk of oral bacterial infection. For this reason, while there are many reports on systemic infections caused by oral infections, few of these describe such infections in edentulous patients. CASE PRESENTATION: We present a case of oral and maxillofacial cellulitis followed by sepsis due to Streptococcus pyogenes infection in an 89-year-old Japanese edentulous woman. S. pyogenes was detected in the wound of left maxilla and the blood sample. S. pyogenes has been reported to be one of the most common and influential aerobic bacteria associated with deep neck infection and subsequent systemic infection. Left maxillary sinusitis was observed, and this could be the origin of the S. pyogenes infection. S. pyogenes derived from the sinusitis and leaked to the oral cavity might have caused systemic infection through wounding of the oral mucosa. Fortunately, intensive antibiotic therapy was effective, and the patient recovered without any surgical procedures. CONCLUSIONS: We experienced a rare case of oral and maxillofacial cellulitis followed by sepsis due to a Streptococcus pyogenes infection in an old edentulous woman. This result indicated that, while edentulous patients are considered to have no risk of odontogenic infection, they still carry a risk of bacterial infection.