不同灌注间隔时间对模型材料间结合的影响

Impact of Different Pouring Interval on Combination Between Model Materials

在口腔模型的分步灌模法中,脱模时模型与底座分离的现象时有发生,直接影响了模型的完整性和精确性。因此有必要对不同灌注间隔时间下模型材料间的结合强度进行研究,为临床操作提供参考。将超硬石膏和硬石膏灌注印模腔一侧,间隔0min、5min、10min、20min和30min后用普通石膏灌注另一侧,每组样本10个,共100个。常规自然干燥后,用电子万能实验机测量各样本的抗弯强度,用单因素方差进行统计学分析。研究结果表明超硬石膏组不同间隔时间的抗弯强度分别为:1.26、1.32、1.07、0.75、0.68MPa,硬石膏组的分别为:1.10、0.96、0.73、0.65、0.52MPa,各组之间的抗弯强度有高度统计学差别(P<0.01)。超硬石膏组的抗弯强度在5min组达到最高,随间隔时间增加快速下降,间隔30min时其抗弯强度已下降至0min组的1/2。硬石膏组的抗弯强度在0min组最大,随间隔时间的增加而持续下降。由此可见口腔临床分步灌模中,在超硬石膏或硬石膏灌注完成后应立即灌注普通石膏,或至少在10min以内灌注。以避免因间隔时间过长影响石膏间的结合强度。

In the method of pour models by steps, the phenomenon of separation between the working cast and the base often occurs. This can affect directly the completeness and the accuracy of model. Therefore it is very necessary for dental clinical to study the combination strength between model materials in different pouring interval. The methods were that super stone or dental stone was poured into one side of the die, then plaster of paris was poured into the other side after different interval time of 0, 5, 10, 20 and 30 min; the bending strength of each sample was measured by a universal test machine after drying naturally; the data were analyzed with one-way ANOVA. The results showed： the bending strength of super stone in different pouring interval was 1.26, 1.32, 1.07, 0.75 and 0.68 MPa; the bending strength of dental stone in different pouring interval was 1.10, 0.96, 0.73, 0.65 and 0.52 MPa; there was obvious difference in groups （ p 〈 0.01 ）. The highest bending strength of super stone group was group of 5 min. With the increase of interval time, the bending strength decreased quickly. The bending strength of group 30 min was 1/2 of that of group 0 min. The highest bending strength of dental stone group is 0 min group. With the increase of interval time, the bending strength decreased continuously. The results suggested that in clinical prosthodontics, plaster of paris should be poured immediately after the completion of super stone or dental stone pour, or at least within 10 min, avoiding the impact on the combination strength of model materials by the long interval.