PRG 필러를 함유한 giomer의 중합 수축 응력에 대한 평가

Abstract

Primary teeth have a limited lifespan, and caries rates are likely to be high in children so that fluoride releasing restorative materials may be helpful. But glass-ionomer cements and compomers have inferior physical properties. For improve those properties, recently "Giomer" had been developed, which contains PRG filler and has advantages releasing fluoride ions continuously. There is a close connection between secondary caries risk and polymerization shrinkage stresses. Therefore we compared the polymerization shrinkage stresses among composite resin, compomer and giomer. The strain guage method was used for evaluation of shrinkage stress. After that we measured surface microhardness of cured specimens. Obtained data were analyzed statically using repeated measures ANOVA, One way ANOVA, and Tukey test.

The results of present study can be summarized as follows: 1. All groups showed transient expansion just after irradiation of curing light. Shinkage stress was increased rapidly at the early phase of polymerization and after 200 seconds reduced slowly as time elapsed (p<0.05). 2. Generally, flowable restorative materials(group IV, V, VI) showed less shrinkage stress than packable restorative materials(group I, II, III). 3. Polymerization shrinkage stress of group I was the highest and group VI was the lowest. 4. The surface microhardness of the top surface in group II was the highest, followed by group I and V, III, VI, IV. And they were revealed statistically significant difference only between group IV and VI(p<0.05). 5. The surface microhardness rate of top to bottom surface was the highest value in group III and follwed by group V, II, VI and I, IV. But they were not revealed statistically significant difference except group IV(p>0.05).

In conclusion, giomer showed inferior polymerization shrinkage stress than composite resin in spite of its fluoride releasing abilty to prevent secondary caries. Therefore we should consider its advantages and disadvantages before clinical application of it and need to study more about giomer.

Key Words : Shrinkage stress, Giomer, PRG filler