Basic and clinical studies on the application of glass ionomer cement in the field of pediatric dental practice

(1)毒性试验研究了光活化玻璃离子水门合剂（LCIII）的体内毒性（人牙龈成纤维细胞的反应）。这些研究结果表明，LCIII在植入大鼠皮下组织或细胞培养前超过30秒的光照下没有毒性作用。(2)牙釉质表面的调节及渗漏试验：将拔牙后的前磨牙用聚丙烯酸或柠檬酸预处理后的牙凹和牙裂，在4000次热应力循环后检测牙釉质表面与LCIII之间染料的渗透情况。结果表明，柠檬酸处理组的渗漏明显小于聚丙烯酸处理组和未处理组。(3)临床评价：临床评价LCIII作为牙坑和牙裂密封材料的固位和磨损情况，为期2年。选取5 ~ 12岁儿童42例，第一恒磨牙和第二恒磨牙共65颗。临床观察显示LCIII在初次应用后至少保持良好一年。然而，在一些病例中观察到LCIII的部分丧失。在496-765天的召回访问中，超过40%的病例显示LCIII部分丧失。扫描电镜检查显示，在216 -405,406-495,496-585天的检查期内，完全保留率约为50%，586-675天为0%，676-765天为13%。在整个检查期间未观察到LCIII的完全丧失。LCIII部分脱落后继发龋5例，观察时间超过416 d。

(1) TOXICITY TESTThe toxicity of light-activated glass ionomer cement (LCIII) was investigated in vivo (responses of human gingival fibraoblast). The results of these studies indicated that there was no toxic effect when LCIII was light illuminated more than 30 seconds prior to the implantation into rat subcutaneous tissue or cell culture.(2) CONDITIONING OF ENAMEL SURFACE AND LEAKAGE TESTLCIII was applied to the pits and fissures of extracted premolars which were pretreated with polyacrylic acid or citric acid, and the dye penetration between the enamel surface and LCIII was exmined after 4000 cycles of thermal stress. The results indicated that the leakage was significantly little in the citric acid-treated groups than in the polyacrylic acid-treated groups or no treatment group.(3) CLINICAL EVALUATIONThe retention and wear of LCIII used as a pits and fissure sealant material was evaluated clinically over a period of 2 years. A total of 65 first and second permanent molars of 42 children aged 5-12 years were selected. The clinical observation revealed good retention of LCIII for at least one year after the initial application. However, partial loss of LCIII was observed in some cases thereafter. At the recall visits between 496-765 days, more than 40% of the cases showed partial loss of LCIII.The examination of replicas under scanning electron microscope showed that the complete retention rate was approximately 50% in the examination period of 316-405,406-495,496-585 days, 0% in 586-675 days and 13% in 676-765 days. Complete loss of LCIII was not observed throughout the examination period. Five cases produced secondary caries subsequent to the partial loss LCIII after the obsevation period of more than 416 days.