Clinical And Scanning Electron Microscope Observation Of Sliver-reinforced Glass Ionomer Used In Deciduous Molars

Hi-Dense Sliver- reinforced glass ionomer is a new type of high strength glass ionomer product ,which is fromed by added 20% sliver spherical particles into glass-ionomer cement .Former studies most concentrated on the mechanical properties and clinical using of permanent tooth, my test is to campare the clinical effect of sliver- reinforced glass ionomer and silver amalgam alloy used in deciduous tooth. This test contained two parts.Part Ⅰ: One hundred and sixty six carious teeth were carried out from seventy children (3~9ages) who had more than two molars caries.96 teeth were restored with sliver- reinforced glass ionomer and 70 teeth with silver amalgam alloy,then campared clinical effection on 6months and 12months.Statistical methods is chi-square test. PartⅡ:36 teeth were choosed in vitro,divided into 2 teems randomly,one teem had 20 teeth,another has 16 teeth.Then, restored with sliver- reinforced glass ionomer (20teeth)and silver amalgam alloy(16teeth).Observed the appearance of two restorations and the distance between two kinds of restorations and the cavity wall by scanning electron microscope . Result is analysed under t-test.Results: There were not statistical difference between Hi-dense and silver amalgam alloy on the rate of secondary caries , subsidence or cracking ,and loose or drop after 6months. After one year ,sliver- reinforced glass ionomer has less secondary caries rate and loose or drop rate than silver amalgam alloy(P<0.05),but has more subsidences and crackings than it.Though Hi-dense restoration happened more subsidences and crackings, there wasn't statistical significance. Scanning electron microscope showed that Hi-dense consisted of many nonshape matter which inlaid with varying sizes spherical or multiangled particles,lots of 1~2μm cracks in it; silver amalgam alloy consisted of homogeneous matter which had some varying sizes and shape particles on it, crack was seldom,whose width was only 0.2~0.4μm.Measured under scanning electron microscope, the width between the restorations and the cavity wall ,Hi-dense was (8.014±2.436)μm,silver amalgam alloy was(12.050±4.543)μm,the difference had statistical significance.Because this study choosed the children who had at least two carious teeth at the same time that avoided bias on different oral circumstance , different oral habit ,and different dietetic habit.The conclusion showed that Hi-dense restorations had lower rate of secondary caries and of loose or drop than silver amalgam alloy restorations,but had higher rate of subsidence or cracking after 6months. There were not statistical differences between them. After one year ,sliver- reinforced glass ionomer had more subsidences and crackings than silver amalgam alloy,but no statistical significance.These results probably related to minor samples and limited time. After one year ,sliver- reinforced glass ionomer has less secondary caries, loose and drop rate than silver amalgam alloy,but has more subsidences and crackings than silver amalgam alloy. That because Hi-dense has less microleakage. My study had measured the width between the restoration and the cavity wall by scanning electron microscope , Hi-dense is(8.014±2.436)μm, silver amalgam alloy is(12.050±4.543)μm , the former's marginal leakage is significantly better than the latter's.Another reason is the bond strengths of Hi-dense is 5.36Mpa, but there isn't bond property between silver amalgam alloy and tooth.The third ,Hi-dense can release fluoride slowly,but silver amalgam alloy can't.Compaired with silver amalgam alloy ,sliver- reinforced glass ionomer has certain contraction , lower compressive strength , lower wear resistance,and loose structure observed by scanning electron microscope, so Hi-dense had more subsidence and cracking rate than silver amalgam alloy. Compaired with silver amalgam alloy ,sliver- reinforced glass ionomer has many merits ,such as stronger bonding character, fluoride release,no amalgam,non irritant to pulp tissue.But sliver- reinforced gla...