Molecular Fingerprint Imaging to Identify Dental Caries Using Raman Spectroscopy.

Tooth loss impairs mastication, deglutition and esthetics and affects systemic health through nutritional deficiency, weight loss, muscle weakness, delayed wound healing, and bone fragility. Approximately 90% of tooth loss is due to dental caries and periodontal disease. Accordingly, early treatment of dental caries is essential to maintaining quality of life. To date, the clinical diagnosis of dental caries has been based on each dentist's subjective assessment, but this visual method lacks objectivity. To improve diagnostic ability, highly sensitive quantitative methods have been developed for the diagnosis and prevention of dental caries and are gradually becoming a mandatory item in modern dentistry. High-resolution Raman spectroscopy is a suitable tool for recognizing the subtle structural changes that occur in dental enamel in already developed or, more importantly, incipient dental caries. Raman analysis could soon emerge as a breakthrough in dentistry because of its high diagnostic sensitivity. In this study, we build upon our previous findings in a new analysis of dental caries using Raman spectroscopy imaging and discuss the possibility of using Raman photonic imaging in support of objective diagnostics in dentistry. Our findings support the Raman method of caries detection in comparison with other conventional or new approaches.

Enhanced bioactivity of Si3N4 through trench-patterning and back-filling with Bioglass®.

Using a simple and innovative sandblasting process, disks of monolithic biomedical silicon nitride (ß-Si3N4) were texturized with a matrix of regular, discrete square trenches with a total depth in the range of hundreds of microns. The process consisted of sandblasting Si3N4 substrates through a stainless-steel wire-mesh (150 or 200 µm) using abrasive silicon carbide powders (α-SiC, ∼40 µm) under 1,034 kPa (150 psi) of gas pressure. The depth of the porosities could be controlled varying both the treatment time and the distance from the surface. Part of the samples were then filled with 45S5 Bioglass® powders to improve the osteointegration and stimulate the production of bone tissue. Due to the increased macroscopic and microscopic roughness, biological testing using human osteosarcoma cells (SaOS-2) showed improved cell proliferation and greater production of both mineral (hydroxyapatite) and organic (collagen) phases on the patterned surfaces compared to untreated ß-Si3N4 or to the biomedical titanium control samples. Both of these effects were further enhanced when the porosities were filled with Bioglass®.

Effect of Thermoresponsive Poly(L-lactic acid)-poly(ethylene glycol) Gel Injection on Left Ventricular Remodeling in a Rat Myocardial Infarction Model.

Some gel types have been reported to prevent left ventricular (LV) remodeling in myocardial infarction (MI) animal models. In this study, we tested biodegradable thermoresponsive gels. Poly(L-lactic acid)-poly(ethylene glycol) (PLLA-PEG) and poly(D-lactic acid)-poly(ethylene glycol) (PDLA-PEG) were synthesized by the polycondensation of l- and D-lactic acids in the presence of PEG and succinic acid. Each of these block copolymers was used to prepare particles dispersed in an aqueous medium and mixed together to obtain a PLLA-PEG/PDLA-PEG suspension, which was found to show a sol-to-gel transition around the body temperature by the stereocomplex formation of enantiomeric PLLA and PDLA sequences. In the present study, the G' of the PLLA-PEG/PDLA-PEG suspension in the rheological measurement remained as low as 1 Pa at 20 °C and increased 2 kPa at 37 °C. The sol-gel systems of PLLA-PEG/PDLA-PEG might be applicable to gel therapy. The effect of the PLLA-PEG/PDLA-PEG gel injection was compared with that of a calcium-crosslinked alginate gel and saline in a rat MI model. The percent fractional shortening improved in the PLLA-PEG/PDLA-PEG (20.8 ± 4.1%) and alginate gel (21.1 ± 4.8%) compared with the saline (14.2 ± 2.8%) with regard to the echocardiograph 4 weeks after the injection (p < 0.05). There were reduced infarct sizes in both PLLA-PEG/PDLA-PEG gel and alginate gel compared with the saline injection (p < 0.05). Moreover, a greater reduction in LV cavity area was observed with the PLLA-PEG/PDLA-PEG gel than with the alginate gel (p = 0.06). These results suggest that the PLLA-PEG/PDLA-PEG gel should have high therapeutic potential in gel therapy for LV remodeling after MI.

Tissue-engineered acellular small diameter long-bypass grafts with neointima-inducing activity.

Researchers have attempted to develop efficient antithrombogenic surfaces, and yet small-caliber artificial vascular grafts are still unavailable. Here, we demonstrate the excellent patency of tissue-engineered small-caliber long-bypass grafts measuring 20-30 cm in length and having a 2-mm inner diameter. The inner surface of an acellular ostrich carotid artery was modified with a novel heterobifunctional peptide composed of a collagen-binding region and the integrin α4ß1 ligand, REDV. Six grafts were transplanted in the femoral-femoral artery crossover bypass method. Animals were observed for 20 days and received no anticoagulant medication. No thrombogenesis was observed on the luminal surface and five cases were patent. In contrast, all unmodified grafts became occluded, and severe thrombosis was observed. The vascular grafts reported here are the first successful demonstrations of short-term patency at clinically applicable sizes.