Meirin College

About: Meirin College is a education organization based out in Niigata, Japan. It is known for research contribution in the topics: Flexural strength & Tongue. The organization has 34 authors who have published 33 publications receiving 159 citations.

Effect of amount of grinding on flexural strength of dental ceramics.

Abstract: The aim of this study was to determine a suitable amount of grinding of a flexural test specimen for clinical evaluation of dental ceramics. Three dental ceramics (Crys-Cera, OCC and IPS Empress Cosmo) were selected. Five types of bar-shaped patterns were prepared for a three-point bending test, and four types of disk-shaped patterns for a biaxial flexural test. Ceramic specimens were fabricated using these patterns in accordance with the manufacturers' instructions. All specimens were ground with diamond polishing pads to yield either bar or disk specimens with the same final geometry. The surface roughness and X-ray diffraction (XRD) patterns of the specimens were examined. The flexural strength values of Crys-Cera and Empress decreased with increasing amounts of grinding, while that of OCC increased with increased grinding. The surfaces of all specimens were smoother when the amount of grinding was deeper. The XRD patterns of Crys-Cera and Empress changed with increased grinding; however, that of OCC did not change regardless of the extent of grinding. The flexural strengths of three dental ceramics differed with the amount of grinding probably because of changes of surface roughness and crystalline component composition. Unground specimens provided important insight into clinical failure modes.

An index for analysing the stability of lateral excursions.

Abstract: Five lateral excursions on both left and right sides of 20 healthy subjects were recorded by Gnatho-hexagraph, which was an opto-electronic system with six degrees of freedom. The incisor point, the working condylar point (WCP) and the balancing condylar point (BCP) were analysed. When the incisor point moved 1, 2, 3, 4, 5 mm on its path, the incisor point and corresponding condylar points were analysed. The linear distances from the intercuspal position (ICP) to each analysed point at each analysed position were calculated as Linear distance. The distance between five lateral excursions in x, y, z, space coordinates at each analysed position of three analysed points were calculated as Dx, y, z, s. To evaluate the stability of lateral excursions, the Index S was defined as the equation (S=D/Linear distance * 100) and calculated. From the result of Index S, the WCP showed significantly less stability than the other two analysed points (P < 0.05). The incisor point showed best stability, especially in upper-lower direction. The BCP also showed good stability. Index S revealed the characteristic movement in x, y, z, space coordinates at each analysed point and it showed clearly the stability of lateral excursions.

Extracellular enzymatically synthesized glycogen promotes osteogenesis by activating osteoblast differentiation via Akt/GSK-3β signaling pathway.

Abstract: Glycogen is the stored form of glucose and plays a major role in energy metabolism. Recently, it has become clear that enzymatically synthesized glycogen (ESG) has biological functions, such as the macrophage-stimulating activity. This study aimed to evaluate the effect of ESG on osteogenesis. MC3T3-E1 cells were cultured with ESG, and their cell proliferative activity and osteoblast differentiation were measured. An in vivo study was conducted in which ESG pellets with BMP-2 were grafted into mouse calvarial defects and histomorphometrically analyzed for the new bone formation. To confirm the effect of ESG on bone growth in vivo, ESG was orally administered to pregnant mice and the femurs of their pups were examined. We observed that ESG stimulated cell proliferation and enhanced messenger RNA expression of osteocalcin and osteopontin in MC3T3-E1 cells. ESG was taken up by the cells associated with GLUT-1 and activated the Akt/GSK-3β pathway. In vivo, the new bone formation in the calvarial defect was significantly accelerated by ESG and the maternal administration of ESG promoted fetal bone growth. In conclusion, ESG stimulates cell proliferation and differentiation of preosteoblasts via the activation of Akt/GSK-3β signaling and promotes new bone formation in vivo, suggesting that ESG could be a useful stimulant for osteogenesis.

Association between periodontitis and the Mediterranean diet in young Moroccan individuals.

Abstract: BACKGROUND & OBJECTIVES Adherence to the Mediterranean diet (MedDiet) has been reported to be associated with a lower risk of various chronic diseases. This cross-sectional study aimed to investigate the potential association between adherence to the MedDiet and periodontitis, which is highly prevalent in young Moroccan individuals. METHODS We evaluated 1075 Moroccan individuals (72% women, mean [standard deviation] age = 20.2 [1.5] years). Adherence to the MedDiet was assessed using the MedDiet score (MDS) based on the frequency of intake of eight food groups (vegetables, legumes, fruits, cereals or potatoes, fish, red meat, dairy products, and olive oil). A value of 0 (unhealthy) or 1 (healthy) was assigned to each food group, and the MDS (range, 0-8 points) was generated by adding the individual scores, with a higher score indicating better adherence to the MedDiet. The logistic regression model was used to evaluate the MDS (high [5-8 points]/low [0-4 points]) and each component score (1/0) with the presence of periodontitis, which was determined through full-mouth periodontal examinations. Age, sex, and oral health behavior were considered as potential confounders. RESULTS In total, 693 (64.5%) study participants showed high MDSs. Periodontitis was observed in 71 (6.6%) participants. No significant association between MDS and periodontitis was observed. Nonetheless, olive oil consumption, a component of the MDS, showed a significant inverse association with periodontitis (adjusted odds ratio = 0.55; 95% confidence interval, 0.32-0.96). CONCLUSIONS The MedDiet was not significantly associated with periodontitis among young Moroccans. However, frequent consumption of olive oil may have a protective effect against periodontitis, although the temporal association needs to be clarified in further studies.