Strengthening of dental materials by compounding short glass fibers -Development of new dental cement

本研究的目的是确定具有特定长径比（长/直径）的CaO-P_2O_3-SiO_2-Al^2O_3 （CPSA）玻璃的短纤维是否可以作为玻璃离聚体水泥的增强剂，并阐明CPSA短纤维对玻璃离聚体水泥抗弯强度的影响。在与玻璃离聚体水泥的液体混合之前，将商用玻璃离聚体水泥（非树脂改性）的粉末与不同尺寸的CPSA玻璃短纤维混合。含有60质量% CPSA玻璃短纤维（直径9.7±2.1 m，长径比5.0±0.9）的混合粉末在24h后，水泥凝块的直径抗拉强度（DTS）和抗弯强度（FS）分别达到最大值18 Mpa和35 Mpa。DTS和FS分别为1.8和4。分别比不含短纤维的玻璃离子omer水泥大5倍。此外，CPSA玻璃短纤维的增强效果明显优于Electric玻璃短纤维（一种典型的玻璃纤维）。结果表明，CPSA玻璃短纤维由于短纤维的形状和混合液与短纤维之间的反应性，可以作为玻璃离子水门铁的增强剂。此外，无论是否使用CPSA，玻璃离子水泥的强度都随着在水中储存时间的延长和热循环的增加而明显增加。热应力对含CPSA玻璃离子水泥的力学性能影响不大。具有CPSA的玻璃离聚体可以保持较好的强度，因此可能是临床应用作为填充水泥的有利材料。

The purposes of this study was to determine if short fibers of CaO-P_2O_3-SiO_2-Al^2O_3 (CPSA) glass possessing a particular aspect ratio (length/diameter) could be used as a reinforcing agent for glass-ionomer cement, and to clarify the effect of the CPSA short fibers contained in the flexural strength of the glass-ionomer cement. The powder of a commercial glass-ionomer cement (not resin modified) was mixed with variously sized CPSA glass short fibers before mixing with the liquid of the glass-ionomer cement. The mixed powders containing 60 mass% CPSA glass short fibers (diameter ; 9.7±2.1 m, aspect ratio ; 5.0±0.9) obtained maximum values of 18 Mpa and 35 Mpa for the diametral tensile strength (DTS) and flexural strength (FS) of set cements, respectively, after 24 hours. These DTS and FS values were 1.8 and 4. 5 times larger, respectively, than those of the set glass-ion omer cement not containing short fibers. Moreover, it was found that the addition of CPSA glass short fibers was remarkably more effective in the strengthening than Electric glass (a typical glass fiber) short fibers. The results suggested that the CPSA glass short fibers acted as a reinforcing agent for strengthening the glass-ionomer cement, because of the shape of short fibers and reactivity between the mixing liquid and short fibers. Moreover an appreciable increase in strength with time stored in water and with thermal cycling was seen with glass-ionomer cement, with or without CPSA. Thermal stress did not have a serious influence on the mechanical properties of the glass-ionomer cement with CPSA. The glass-ionomer with CPSA may maintain better strength, and, thus, it may be a favorable material for clinical applications as cement for filling.