| Glass ionomer cement(GIC) is formed by the setting reaction of poly(alknoic)s with a silicate glass powder. GIC is a widely used dental restorative material due to its bio-stability and fluorine release capability, but it has been used successfully only for the restorative of cavities subjected to low stresses as its low mechanical strength. The GIC must be improved in strength if it is to find a wider range of applications and many efforts have been done in recent years.This paper reports a study aimed at improving the compressive strength of GIC by modifying the chemical composition and preparation technics of the glass. The compressive strength of produced GIC attained 200MPa, which was the highest compared with commercial GICs.The main work and results are as follows:(1)Studied the effect of glass composition on the compressive strength of the GIC, the best glass composition was: SiO2 25.9%,Al2O3 18.8%,CaF2 13.3%,AlF3 4.7%,AlPO4 19.3%,Na3AlF6 18.0%(w%). And analyzed the factor that affect the compressive strength of the GIC by grainsize analyzer, powder X–ray diffraction (XRD),infrared absorption spectroscopy(IR),and field-emission scanning electron microscope(FESEM).(2)Studied the preparation technics of the poly(alknoic)s liquid of the GIC using acrylic acid and itaconic acid as starting materials, the liquid was characterized by infrared absorption spectroscopy(IR) and gel permeation chromatograph(GPC).And discussed the effect of powder:liquid ratio on the compressive strength of the GIC, the best ratio was:2.75:1.(3)Studied the preparation technics of the glass on the compressive strength of the GIC, the best preparation technics was: fusion temperature 1200℃, fusion time 2h, wet ball milling 1h, washing the glass powder by 1% acetic acid for 2h.(4)Studied the effect of additives on the compressive strength of the GIC, the best additive amount was: polyacrylic acid powder 11%, tartaric acid 7%. |
