| Objective:To compare the marginal microleakage of Filtek Z250 composite resin, Filtek P60 composite resin and PALFIQUE ESTELITE flowable resin in filling posterior teeth, so as to provide the experiment bases for the clinical treatment.Methods:Forty intact, caries-free, subfissure-free, extracted human premolars were cleaned and were preserved in 0.9% saline at room temperature. The cavities were prepared with diamond burs in a high-speed handpiece equipped with water spray. The cavity (typeⅤ) were prepared on buccal surface of freshly extracted premolars. Every tooth has one cavity, which the cervical wall and the incisal wall were located in enamel with water spray. Typical cavities are approximately 3 mm diameter and 2 mm deep. Forty specimens were randomly divided into four experimental groups. The cavities were filled with four different materials as following. Group 1. Filtek Z250 composite resin:Group2. Filtek P60 composite resin; Group3. PALFIQUE ESTELITE flowable resin (low-flow); Group4. PALFIQUE ESTELITE flowable resin (high-flow)After all the cavities have been filled, forty specimens were putted into normal saline at ordinary temperature for 24 hours.Then, the teeth were putted into 5℃and 55℃water alternately 30 seconds in each bath. A total of 600 cycles was used for all specimens. The apical foramen of all teeth were closed with wax, then the entire tooth, except for the restoration and 1 mm of the tooth surface adjacent to the restoration, was coated with nail varnish. The teeth were then placed in a 50% ammoniacal silver nitrate aqueous solution for 24 hr in total darkness. They were rinsed in running water until no black particle can be seen, immersed in photodeveloping solution, and exposed to a fluorescent light for 8 hr so that silver ion reduction would be completed. After removal from the developing solution, the teeth were rinsed thoroughly in running water for 5 min.MCT scan parameters:voltage 70kv, current 114uA, resolution 20um, integration time400ms.The specimen was securely placed and fixed into the specimen holder of the MCT. Each specimen was entirely scanned, producing approximately 400 slices saved as DICOM files, using median filtering method for suppressing random noise and improving image quality. Surface reconstruction method was used to reconstruct the tooth. First of all the mask and editing of two-dimensional image, and then labeling and three-dimensional reconstruction of ROI, Finally selecting the volume parameter to measure the volume of silver deposits at the tooth-restoration interface between the filling and the tooth.The data were analyzed by SPSS 18.1 software package. One-way ANOVA was used to analyze the difference microleakage among four groups; LSD-t test were used for multiple-comparison. As a=0.05, if p value is<0.05, there is difference statistically.Results:The one-way analysis of variance showed a significant difference in the extent of microleakage among the four groups (F=4.474 p<0.05).LSD-t test indicated that the microleakage between group A and group C was not statistically significant(p>0.05). The same was observed for group A and group D. group C and group D (p>0.05). But the microleakage of group A was different from group B (p<0.05), group C and group D were different from group B (p<0.05).Conclusion:1. Filtek Z250 composite resin, Filtek P60 composite resin and PALFIQUE ESTELITE flowable resin have different degrees of marginal microleakage.2. The microleakage degree of Filtek z250 composite resin and PALFIQUE ESTELITE flowable resin is lower than Filtek P60 composite resin (P<0.05). |
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